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Agricultural land evaluation in the Kailali District in Nepal : using resource inventory data as a basis… Shah, Pravakar Bickram 1984

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AGRICULTURAL LAND EVALUATION IN THE KAILALI DISTRICT IN NEPAL USING RESOURCE INVENTORY DATA AS A BASIS FOR NATIONAL LAND USE PLANNING By PRAVAKAR BICKRAM SHAH M.Sc, Friendship University Moscow, 1968 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department of S o i l Science We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA July 1984 © Pravakar Bickram Shah, 1984 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6 (3/81) i i . ABSTRACT The objective of t h i s research project was to demonstrate how bio-physical information of the land resource survey i n Nepal can be interpreted for land use planning and improvement of a g r i c u l t u r a l production. This was accomplished by devising a s u i t a b i l i t y r a t i n g scheme for six major crops presently grown i n the study area. A modified F.A.O. s u i t a b i l i t y scheme was developed based on optimum, marginal and unsuitable conditions derived most-l y from l i t e r a t u r e and l o c a l knowledge. P o t e n t i a l land use was determined for double and t r i p l e crop r o t a t i o n schemes with and without i r r i g a t i o n . A s u i t a b i l i t y r a t i n g for each mapping unit was assigned, and based on the inherent physical and chemical s o i l l i m i t a t i o n s , the most appropriate crop r o t a t i o n sequences were formulated. A comparison between current and proposed land use with and without i r r i g a t i o n was made i n order to determine where expansion of c e r t a i n crops and rotations are f e a s i b l e and to j u s t i f y the proposed land use over the e x i s t i n g one. This quantitative analysis showed that a g r i c u l t u r a l land can be increased by nearly 84% at the expense of forest land, which i s at present degraded and not commercially v i a b l e . Increase i n crop production i s not only achievable by increasing the area for c u l t i v a t i o n , but also by improving crop r o t a t i o n and introducing i r r i g a t i o n . Based on currently obtained average y i e l d , crop production can be increased by nearly 96% for improved land use without i r r i g a t i o n and 230% for improved land use with i r r i g a t i o n . These improvements are based on introducing double and t r i p l e crop r o t a t i o n systems. Under more c a p i t a l intensive management, such as i r r i g a t i o n , a r t i f i c i a l f e r t i l i z e r s can be introduced and modest target y i e l d s can be obtained which i l l . are s i g n i f i c a n t l y higher than present y i e l d s . With such conditions, future o v e r a l l production can be increased by nearly twelve times over current production. Long term f e r t i l i z e r problems can be anticipated by knowing the inherent l i m i t a t i o n s of each mapping unit and using a F e r t i l i z e r C a p a b i l i t y C l a s s i f i c a t i o n Assessment scheme (FCC) . It i s hoped that by using the best crop r o t a t i o n sequences, maximizing organic matter management and introduc-ing a r t i f i c i a l f e r t i l i z e r s , long term f e r t i l i t y and p r o d u c t i v i t y can be maintained in the more i n t e n s i v e l y c u l t i v a t e d areas. The model developed i s simple, easy to use and can be applied a l l to other Terai D i s t r i c t s i n Nepal, where s i m i l a r b iophysical data are now a v a i l a b l e . This w i l l f a c i l i t a t e national land use planning, help i n the i d e n t i f i c a t i o n of new p o t e n t i a l a g r i c u l t u r a l areas and provide a basis for increasing the national a g r i c u l t u r a l production. Iv. TABLE OF CONTENTS Page I. INTRODUCTION 1 A. AIMS 1 B. OVERVIEW 2 C. GENERAL DESCRIPTION OF THE STUDY AREA 6 1. Physiography 6 2. S o i l s 9 3. Climate 14 4. Vegetation 19 5. Land Use 19 a. Active A l l u v i a l or Flood Threatened Farming Systems 20 b. Recent A l l u v i a l or the Main Terai Farming Systems • 20 c. Older A l l u v i a l or the Upper Terai Farming Systems • 21 II. BACKGROUND AND LITERATURE REVIEW 22 A. BACKGROUND 22 B. LAND SYSTEMS APPROACH IN NEPAL 25 1. Physiographic Regions 27 2. Land Systems 27 3. Land Units 28 4. Land Types 28 C. LAND EVALUATION 29 1. Land Ca p a b i l i t y Evaluation Scheme for Agriculture .... 31 a. Categoric Systems 31 b. Parametric Systems 35 V. Page i . Additive Systems 35 i i . M u l t i p l i c a t i v e Systems 37 i i i . Complex Parametric Systems 39 c. S o i l F e r t i l i z e r C a p a b i l i t y C l a s s i f i c a t i o n 41 d. Land S u i t a b i l i t y Evaluation Scheme for Agriculture 43 i . Analogue Approach 44 i i . S i t e Factor Approach 47 i i i . System Analysis and Simulation Approach .... 50 D. SUMMARY 52 III. METHODOLOGY 53 A. DEVELOP METHOD TO IDENTIFY ESSENTIAL BIOPHYSICAL PARAMETERS FOR A SUITABILITY CLASSIFICATION FOR SIX MAJOR CROPS IN THE KAILALI DISTRICT 54 B. DEVELOP METHOD TO EVALUATE CROP SUITABILITY OF ALL MAPPING UNITS FOR DOUBLE CROPPING WITHOUT IRRIGATION AND TRIPLE CROPPING WITH IRRIGATION 57 C. QUANTITATIVE ASSESSMENT AND COMPARISON OF CURRENT LAND USE AND IMPROVED LAND USE FOR THE KAILALI DISTRICT BASED ON SUITABILITY EVALUATION 60 D. EXAMINATION OF LONG TERM FERTILITY IMPLICATIONS UNDER CURRENT AND IMPROVED LAND USE 62 E. SUMMARY 63 IV. RESULTS OF LAND SUITABILITY ASSESSMENTS FOR THE KAILALI DISTRICT 65 A. SOIL, SITE AND CLIMATIC REQUIREMENTS TO ESTABLISH SUITABILITY CLASSES FOR SIX MAJOR CROPS IN THE TERAI REGION OF NEPAL 65 v i . Page 1. E s t a b l i s h i n g Optimum, Marginal and Undesirable Environmental Conditions for Six Major Crops on the Basis of L i t e r a t u r e Data 65 2. Defining Parameters and Class Limits for E s t a b l i s h -ing a Modified F.A.O. S u i t a b i l i t y Assessment 69 B. SUITABILITY ASSESSMENT FOR TWO AND THREE ANNUAL CROP ROTATIONS IN THE KAILALI DISTRICT 77 1. Crop Rotations and S u i t a b i l i t y Assessment for Rainfed (Without I r r i g a t i o n ) Conditions 77 2. Crop Rotations and S u i t a b i l i t y Assessment for Ir r i g a t e d Conditions 83 C. COMPARISON BETWEEN CURRENT LAND USE AND IMPROVED LAND USE . 84 1. Quantitative Assessment of Current Land Use 84 2. Comparison Between Current and Improved Land Use Under Non-Irrigated and Ir r i g a t e d Conditions 89 3. Summary of A g r i c u l t u r a l Improvements Emphasizing Size and^Type of C u l t i v a t i o n System 95 D. LONG TERM FERTILIZER IMPLICATION RESULTING FROM DOUBLE AND TRIPLE CROP ROTATIONS 96 1. S o i l F e r t i l i t y C a p a b i l i t y 96 2. F e r t i l i t y Needs and Management 100 E. SUMMARY 104 V. SUMMARY AND CONCLUSIONS 106 ¥1. REFERENCES 110 APPENDIX I Detailed Results of S o i l and Climate Requirements For S p e c i f i c Crops 120 APPENDIX II Assessment of Mean Crop Rotation S u i t a b i l i t y Ratings for Non-Irrigated and Ir r i g a t e d Conditions 133 v i i . Page APPENDIX I I I Method of F e r t i l i z e r C a p a b i l i t y C l a s s i f i c a t i o n (FCC) . 139 APPENDIX IV _> Maps f-^T v i i i . LIST OF TABLES Page TABLE 1 Mean Monthly P r e c i p i t a t i o n and Temperature For Dhangadi, K a i l a l i D i s t r i c t 17 TABLE 2 Structure of Land Ca p a b i l i t y C l a s s i f i c a t i o n 32 TABLE 3 F.A.O. Land S u i t a b i l i t y Evaluation Scheme Structure of Land S u i t a b i l i t y C l a s s i f i c a t i o n 46 TABLE 4 Comparison Between D i f f e r e n t Methods of S u i t a b i l i t y Assessments 51 TABLE 5 Conversion from L i t e r a t u r e Assessment to F.A.O. S u i t a b i l i t y 55 TABLE 6 Rating C r i t e r i a for Rice S u i t a b i l i t y 56 TABLE 7 S o i l Requirements for Major Crops Based on L i t e r a t u r e ... 67 TABLE 8 Climatic Requirements for Major Crops Based on L i t e r a t u r e 68 TABLE 9 Rating C r i t e r i a for Rice S u i t a b i l i t y 71 TABLE 10 Rating C r i t e r i a for Corn S u i t a b i l i t y 72 TABLE 11 Rating C r i t e r i a for Wheat S u i t a b i l i t y 73 TABLE 12 Rating C r i t e r i a for L e n t i l S u i t a b i l i t y 74 TABLE 13 Rating C r i t e r i a for Mustard S u i t a b i l i t y 75 TABLE 14 Rating C r i t e r i a for M i l l e t S u i t a b i l i t y 76 TABLE 15 Optimum Crop Rotation for Dominant Mapping Units Without I r r i g a t i o n 79 TABLE 16 Converting Subunit S u i t a b i l i t y for Non-Irrigated Conditions 80 TABLE 17 To t a l Arable Area and Production Under Improved Land Use Without I r r i g a t i o n 82 TABLE 18 Optimum Crop Rotation for Dominant Mapping Units With I r r i g a t i o n 85 TABLE 19 Converting Subunit S u i t a b i l i t y for I r r i g a t e d Conditions . 86 i x . Page TABLE 20 Total Arable Area and Production Under Improved Land Use With I r r i g a t i o n 88 TABLE 21 Current Land Use A e r i a l S t a t i s t i c s for D i s t r i c t 90 TABLE 22 T o t a l Arable Area and Production Under Current Land Use . 92 TABLE 23 Crop Production Under D i f f e r e n t Land Use 93 TABLE 24 Differences i n Land Use Area 94 TABLE 25 F e r t i l i z e r C a p a b i l i t y C l a s s i f i c a t i o n 98 TABLE 26 Summary of F e r t i l i z e r C a p a b i l i t y for the K a i l a l i D i s t r i c t 99 TABLE 27 Currently Obtained Average Yields Under Current Land Use (kg/ha) 102 TABLE 28 F e r t i l i z e r Requirements for Current and Targeted Yie l d s (kg/ha) 102 TABLE 29 Y i e l d s and F e r t i l i z e r Requirements Under Current And Improved Land Use With I r r i g a t i o n for the K a i l a l i D i s t r i c t 103 X. LIST OF FIGURES Page FIGURE 1 Overview of Land Evaluation Procedure Used to Assess the K a i l a i D i s t r i c t i n Nepal 5 FIGURE 2 Location of Study Area 7 FIGURE 3 Schematic Cross Section of Terai From Indian Border to the Siwalik Mountains 8 FIGURE 4 Cross Section of Land Systems and Land Units i n the Terai 10 FIGURE 5 Description of Land System 1 11 FIGURE 6 Description of Land System 2 12 FIGURE 7 Description of Land System 3 13 FIGURE 8 Terai Moisture Regimes, Seasonal Fluctuations i n Water Table on Selected S o i l s 15 FIGURE 9 T e r a i Moisture Regimes. Approximate Depth of Water Table i n Monsoon and Dry Season for a Medium Textured S o i l 16 FIGURE 10 Seasonal V a r i a t i o n i n Moisture Regime, P r e c i p i t a t i o n , and Temperature, Dhangadi, K a i l a l i D i s t r i c t 18 FIGURE 11 Example of Method Used to Devise Multiple Cropping System 59 FIGURE 12 Improved Land Use Without I r r i g a t i o n 81 FIGURE 13 Improved Land Use With I r r i g a t i o n 87 FIGURE 14 Current Land Use 91 x i . ACKNOWLEDGEMENTS I am greatly indebted to my Supervisor, Dr. Hans Schreier, for his help, encouragement and guidance which have contributed greatly towards t h i s t hesis and i t s presentation. His friendship throughout the entire duration of my stay i n Canada i s greatly appreciated. I also wish to express my sincere appreciation to Dr. A.A. Bomke, Dr. C. Rowles, Dr. L.M. Lavkulich and Dr. D. Moon for th e i r constructive c r i t i c i s m s of t h i s t h e s i s . I would also l i k e to acknowledge Mr. B. Carson for his help, advice and assistance i n conducting t h i s research. I am grateful to the Government of Nepal for granting me educational leave. The f i n a n c i a l aid provided by the Canadian International Development Agency (CIDA) i s greatly appreciated. I also thank Ms. Deb Shunamon si n c e r e l y for typing t h i s t h e s i s . L a s t l y to my family, whom I missed dearly, I would l i k e to extend my appreciation for the i r patience and sincere encouragement. 1. I. INTRODUCTION A. AIMS The problems facing Nepal's a g r i c u l t u r a l sector are enormous. By almost any d e f i n i t i o n Nepal has one of the poorest r u r a l sectors i n the world. Most of the population are farmers, the vast majority employed i n a subsistence type of agr i c u l t u r e to provide the barest of nece s s i t i e s for the farm family. Because of population pressure i n the h i l l y regions, even marginal lands are being c u l t i v a t e d and most forest lands are degraded to a point where they can hardly be considered forests i n the normal sense. S o i l f e r t i l i t y i s d e c l i n i n g due to the low productivity of the forest areas which have t r a d i t i o n a l l y been used to concentrate nutrients on a g r i c u l t u r a l land through grazing, fodder and fuelwood c o l l e c t i o n . As f e r t i l i t y declines, the terrace farming systems which have been b u i l t up over an extended period of time have to be abandoned for pasture. Abandoned terraces are not properly maintained by the farmers and hence become prone to erosion, and reduce the r a t i o of arable land to population. The continuous population pressure i n the h i l l y regions, combined with degraded fo r e s t , low f e r t i l i t y , and erosion problems, has caused large seg-ments of the population to immigrate into the Terai-lowlands, i n both spontaneous and government planned resettlement schemes. Most of the Lower Piedmont areas have been r e s e t t l e d i n this manner and people are now being s e t t l e d on the Upper Piedmont areas presently under f o r e s t . In order to come up with a comprehensive plan for the whole country, facing so many c o n f l i c t i n g land use problems, a resource inventory was undertaken. The land resources mapping project came into being i n a jo i n t undertaking between the Governments of Nepal and Canada through the Canadian 2. International Development Agency (CIDA). The land resources mapping project was designed to produce a m u l t i -d i s c i p l i n a r y inventory and analysis of, land resources, land use c a p a b i l i t y and present land use. The data generated can serve as a basis for develop-ment planning on a national, regional or d i s t r i c t l e v e l . Inventory data i t s e l f i s i n s u f f i c i e n t when dealing with land use problems. What i s needed are i n t e r p r e t a t i o n s . Careful i n t e r p r e t a t i o n of the resource information i s needed for a number of land uses and i t i s the aim of t h i s research to accomplish the following: 1. Develop a framework for evaluation of resource inventory data to improve a g r i c u l t u r e land use i n Nepal using the K a i l a l i D i s t r i c t as a case study. 2. Using the resource inventory data as the basis , develop a s u i t a b i l i t y r a t i n g scheme for crops under rainfed and i r r i g a t e d conditions. 3. Compare crop r o t a t i o n s u i t a b i l i t y with current land use to demonstrate where crop production and land use can be improved. 4. Provide a basis for land use planning to be applied to the resource inventory data which i s currently being c o l l e c t e d on a national b a s i s . B. OVERVIEW The Land Resource Inventory surveys currently being c a r r i e d out i n Nepal provide valuable baseline information for land use planning and r e -settlement. The Land Systems (CSIRO) approach was used to map s o i l s and assess the a g r i c u l t u r a l p o t e n t i a l of the country. Land Systems maps, plus other biophysical Information of the integrated survey were published at a scale of 1:50,000. The Land Systems maps, within the l i m i t a t i o n s imposed 3. by scale, show the d i f f e r e n t land systems and land units i n r e l a t i o n to other features i n the landscape. By combining these information with other resource inventory data one can demonstrate i t s usefulness and i n t e r p r e t i v e value i n a s s i s t i n g land use planners, managers and p o l i c y makers i n decision-making. The Interpretations made are predictions of performance and are not supposed to be recommendations for use of the land. In order to demonstrate the usefulness of the Resource Inventory data, the K a i l a l i D i s t r i c t i n the T e r r a i Region was chosen. It has great poten-t i a l for evaluating land use and improving a g r i c u l t u r a l production systems as i t i s mostly under natural vegetation. It also possesses a f a i r amount of good q u a l i t y land for resettlement and the d i s t r i c t has a great p o t e n t i a l for hydro power development i n the Karnali High Dam. It i s hoped that the methodology developed i n t h i s study can be applied to other areas along with the national scheme of the country. The methodology developed for assessing a g r i c u l t u r a l s u i t a b i l i t y of s p e c i f i c crops i s based on quantitative s o i l , s i t e and c l i m a t i c conditions. S u i t a b i l i t y ratings were derived for the following crops: r i c e , corn, wheat, l e n t i l s , mustard and m i l l e t . The procedure used i n t h i s research i s given i n Figure 1 and included the following steps: 1. I d e n t i f y i n g c r i t i c a l s o i l and c l i m a t i c parameters. 2. Determining quantitative and c r i t i c a l values for each crop. 3. Developing models on climate and s o i l based on the above parameters for s u i t a b i l i t y r a t i n g s . This approach was based on the l i t e r a t u r e and i s a useful f i r s t step for i d e n t i f y i n g c r i t i c a l s o i l and c l i m a t i c parameters for s p e c i f i c crops. 4. 4. Applying a s u i t a b i l i t y r a t i n g scheme for s p e c i f i c crops to resource inventory data of the D i s t r i c t , and matching the derived model and s u i t a b i l i t y ratings to the Land System Inventory. Some important information w i l l not be s u f f i c i e n t and available from the Resource Inventory for detailed assessments, but c a r e f u l i n t e r p r e t a t i o n of the available data allow us to make reasonable recommendations regarding crop s u i t a b i l i t y . 5. For the land s u i t a b i l i t y evaluation "The Framework for Land Evaluation" (FAO, 1976) was modified to assess the s u i t a b i l i t y of i n d i v i d u a l crops and rotations under rainfed and i r r i g a t e d conditions. 6. Resource Inventory Data was rela t e d to current land use information by superimposing current land use on Land Systems. F i e l d data and c a p a b i l i t y r a t i n g s , which are curr e n t l y c o l l e c t e d as part of the Resource Inventory Survey can be compared with resource data and s p e c i f i c land use i n order to determine whether the land i s u t i l i z e d to i t s f u l l p o t e n t i a l . This w i l l consist of an assessment of optimum versus not optimum use for major crops. 7. Compare s u i t a b i l i t y ratings with current land use, to indicate where expansion of c e r t a i n crops are f e a s i b l e and also to compare the e x i s t -ing land use with the one proposed. 8. F i n a l l y , an o v e r a l l q u a l i t a t i v e land assessment was made for pred i c t i n g optimum use, y i e l d s and s u i t a b i l i t y of the d i s t r i c t as a whole for land use planning. F e r t i l i z e r recommendations and requirements were only assessed i n general terms for pr e d i c t i n g y i e l d s and l i m i t a t i o n s from the point of view of f e r t i l i t y management. 5. Figure 1 OVERVIEW OF LAND EVALUATION PROCEDURE USED TO ASSESS THE KAILALI DISTRICT IN NEPAL. Resource Inventory DATA Climate, S o i l , Vegetation and Geology Resource Inventory DATA Land U t i l i z a t i o n Mapping Current Land Use Evaluation of Climate and S o i l Parameters Important for A g r i c u l -ture Production of: Rice, Corn, Wheat, L e n t i l s , Mustard and M i l l e t . 1-4 S u i t a b i l i t y Assess-ments for Individual Crops: SI, S3, Nl, N2 Ratings 5 S u i t a b i l i t y Assess-ments for Crop Rotations for Rainfed Conditions Without I r r i g a t i o n 5 S u i t a b i l i t y Assess-ments for Crop Rotation Under I r r i g a t e d Conditions 5 z Superimpose Current Land Use on Land System and Land Unit Mapping Scheme 6 Comparison Between Current Land Use and S u i t a b i l i t y Ratings Without IRRIGATION 7 Comparison Between Current Land Use and S u i t a b i l i t y Ratings with IRRIGATION 7 Overall Quantitative Land Assessment for Pr e d i c t i n g OPTIMUM Use and Yields 8 6. C. GENERAL DESCRIPTION OF THE STUDY AREA The K a i l a l i D i s t r i c t i s located i n the Terai Physiographic Region of the Far Western Development Region of Nepal ( F i g . 2). The d i s t r i c t i s located i n the Indo-Gangatic P l a i n with Dhangadi as the d i s t r i c t headquar-t e r . R e l i e f i s very gentle i n t h i s area with slopes less than 1° over 80 percent of the land surface. The remainder of the alluvium has been u p l i f t -ed t e c t o n i c a l l y and has a r o l l i n g to undulating appearance. The d i s t r i c t was chosen as the study s i t e because the area at present i s r e l a t i v e l y undeveloped and 57 percent of the mapped d i s t r i c t i s forested. The climate and s o i l s are favourable for growing most a g r i c u l t u r a l crops grown i n the Terai and the available i n f r a s t r u c t u r e , such as roads (East-West Highway) gives the d i s t r i c t a high p o t e n t i a l for a g r i c u l t u r a l development. Large scale resettlement programmes are being c a r r i e d out, making the area i d e a l for developing a framework for land evaluation using the available inventory data. The d i s t r i c t also possesses tremendous p o t e n t i a l for i r r i g a t i o n from the K a r n a l i r i v e r and t h i s could be exploited to improve a g r i c u l t u r a l pro-duction and pro d u c t i v i t y of the area. 1. Physiography The d i s t r i c t under study consists of recent and post pleistocene a l l u v i a l deposits forming a piedmont adjacent to the Himalayan Mountain Range ( F i g . 3). I t i s bordered by India on the south and by the Siwalik Physiographic Region to the north, with elevations ranging from 60 to 330 meters. The land i s generally f l a t to very gently sloping. Using the Land System approach (CSIRO) developed by C h r i s t i a n and Stewart (1968), the d i s t r i c t was divided into three land systems - active, Figure 2 LOCATION OF STUDY AREA NEPAL Figure 3 SCHEMATIC CROSS SECTION OF TERAI FROM THE INDIAN BORDER TO THE SIWALIK MOUNTAINS (based on LRMP, Land Systems Report, 1982) India border - — 1 2a ower piedmont ——» 2b — upper piedmor 3a it — » 3b 8 / S iwal ik. front typic haplaquepts frequent ponding i n monsoon water table (perched or regional) (0-2m) aerie haplaquepts occasional ponding i n monsoon water table (perched) (0-6m) typic h a p l u s t o l l s typic ustochrepts no ponding i n monsoon water table (1-10 m) ty p i c haplustc f l a s h floods i n some areas water table a l l s 9. recent and older a l l u v i a l deposits. To a very large extent t h i s method was based on the i n t e r p r e t a t i o n of 1:50,000 a i r photographs and the three systems were separated on the basis of p o s i t i o n i n the landscape and geo-morphic nature as they a f f e c t landuse, s o i l s and vegetation . The resultant maps showing the d i s t r i b u t i o n of land system was produced on a scale of 1:50,000, which i s e s s e n t i a l l y a reconnaissance assessment of natural resources of the d i s t r i c t . The three land systems were further subdivided into twelve land units, each of which has s i g n i f i c a n t l y d i f f e r e n t s o i l c h a r a c t e r i s t i c s and topography that a f f e c t land use. A schematic cross-sec-t i o n of the Terai Land Systems and i t s r e l a t i v e p o s i t i o n i n the landscape of the d i f f e r e n t land units are shown i n F i g . 4. 2. S o i l s The s o i l s of the study area are divided into three land systems, based on land form as i t a f f e c t s pedogenic development of the s o i l p r o f i l e (LRMP, Land Systems Report, 1982). Each land system was further subdivided into four land units having d i f f e r e n t s o i l properties and p o s i t i o n i n the land-scape that a f f e c t land use management. In general, the s o i l s tend to be stone free and are either s l i g h t l y acid or neutral to somewhat a l k a l i n e i n r e a c t i o n . S o i l s i n Land System 1 are subject to severe r i v e r flooding that a f f e c t land use, while in Land System 2, ponding i s common and because of t h e i r use i n wetland r i c e c u l t i v a t i o n , have poor structure. In Land System 3 the s o i l s are more mature and weathered and have good structure, but are coarser i n texture. A short d e s c r i p t i o n of each land system with t h e i r associated land units and d i f f e r e n t i a t i n g c r i t e r i a are given i n the following section. Figure 4 CROSS SECTION OF LAND SYSTEMS AND LAND UNITS IN THE TERAI (based on LRMP, Land Systems Report, 1982) (Vertical scale greatly exaggerated) Land System 1 includes those areas on lower ground adjacent to major r i v e r s . These s o i l s are subject to severe flooding and r i v e r bank erosion, and pose a continual threat to a g r i c u l t u r a l production. S o i l s In the system show l i t t l e pedogenetic development. Land System 1 i s subdivided Into four land u n i t s . The c h a r a c t e r i s t i c s of each are provided i n Figure 5 below. Figure 5 DESCRIPTION OF LAND SYSTEM 1 (based on LRMP, Land Systems Report, 1982) •Land System 1 I I I I Maximum Flood Level l a — > l — lb I Water lc Coarse I I I I No | Grasses, | I Vegeta- | Shrubs I t ion Khair, Sisso Forest Land System 2 Land System Land Form Active A l l u v i a l Pic i n (depositional) l a present r i v e r channel l b sand and gravel bars Dominant S o i l s Ustorthents Fsamments Dominant Slopes Dominant Texture Sandy/ Cobbly Seasonal Range of Depth to Water Table 0 - 2m Drainage subject to riv e r flood-ing l c low terrace Ustifluvents Fluvoquents <1° Sandy 0 - 2m variable; subject to severe r i v e r flooding Id higher terrace Ustochrepts Haplaquepts Loamy 0 - 4m variable; subject to occasional r i v e r flood-ing Land System 2, which is on slightly higher ground, occupies areas in the lower piedmont plain that support a large portion of the dist r i c t ' s population. Greater stability of the area results in somewhat more mature s o i l development, and the system is subdivided into four land units as shown in Figure 6 below. Figure 6 DESCRIPTION OF LAND SYSTEM 2 (based on LRMP, Land Systems Report, 1982) 1 Rice, Wheat I ——~~ Water 'Tic7, " a l l o w " T a b l e * Flooding and ponding common i n low areas but sediment deposition i s not excessive. Land System Land Form Recent A l l u v i a l P la in "Lower Piedmont" (depos i t iona l and eros ional ) Land Unit Dominant So i l s Dominant Slopes 2a depressional Haplaquepts < l / 2 ° 2b Intermediate Haplaquepts (aer ie ) < l / 2 " <1° 2c intermediate p o s i t i o n , Haploquepts Ustochrepts Dominant Texture Fine Loamy Loamy v a r i a b l e Seasonal Range of Depth to Water Table 0 - 2m 0 - 6m dependent on p o s i t i o n Drainage 2d high p o s i t i o n Hap lus to l l s Ustochrepts <1° Loamy 10 m 13. Land System 3 includes the upper piedmont plain. Due to the local tectonic u p l i f t the area is somewhat dissected and prone to erosion. The soils found here are the most matured in the d i s t r i c t and exhibit consider-able weathering. The present lack of Irrigation water and the existing forest zoning results in Land System 3 not being extensively cultivated at present. The system Is subdivided into four land units as shown in Figure 7. Figure 7 DESCRIPTION OF LAND SYSTEM 3 (based on LRMP, Land Systems Report, 1982) Land System 3 3b , , Tropical Land System Land Form A l l u v i a l Fan Apron Complex "Upper Pied-mont" (eros lona l ) Land Uni t 3a very gent le slopes 3b gent le slopes 3c undula t ing 3d h igh ly Dominant So i l s Hap lus to l l s Dystochrepts Ustochrepts Hap lus to l l s Hap lus to l l s Ustochrepts Dominant Slopes <1° 1-5° 1-3° 0-20° Dominant Texture Loamy Loamy/ Loamy Loamy Seasonal Range of Depth to Water Table 1 - 10m 2 - 10m 2 - 10m >2m Drainage moderately we l l rap id w e l l rap id 14. 3. Climate The climate of the d i s t r i c t i s su b - t r o p i c a l , with most of the r a i n f a l l concentrated i n the monsoon months which l a s t from May to September. About 80% of the p r e c i p i t a t i o n f a l l s during this period and the remaining months of October to May are mainly dry, although occasional p r e c i p i t a t i o n occurs i n the form of winter r a i n s . Winter temperatures are mild and minimum recorded a i r temperatures are above freezing, although farmers i n some areas complain of ground f r o s t which can damage young crops. It i s also of in t e r e s t to note that r a i n f a l l increases as one nears the Siwalik Range to the north of the Indian border. This e f f e c t i s primarily seen i n the t o t a l r a i n f a l l rather than In the length of the rainy season. R a i n f a l l during the monsoon season greatly exceeds p o t e n t i a l evapotranspira-t i o n , and i n many cases the i n t e r n a l and external drainage i s such that saturated and flooded s o i l conditions occur, which are i d e a l for r i c e pro-duction but pose serious constraints for the production of other crops i f drainage i s not adequate. The fl u c t u a t i o n s of water table depth correspond to the seasons and are of primary concern to farmers and agronomists. In Figures 8 the major s o i l s of the d i s t r i c t and the i r seasonal f l u c t u a t i o n of water tables are presented and i n Figure 9 an approximate depth of the water tables i n the monsoon and dry seasons for some important s o i l s are shown. The seasonal v a r i a t i o n s of mean monthly r a i n f a l l (mm) and d a i l y mean temperature (°C) are shown in Table 1 and Figure 10. The d i s t r i c t has a mean annual p r e c i p i t a t i o n of 1667 mm and a mean annual temperature of 24°C. Figure 8 TERAI MOISTURE REGIMES (based on LRMP, Land Systems Report, 1982) SEASONAL FLUCTUATIONS IN WATER TABLE* ON SELECTED SOILS Depth to *water table may be perched Figure 9 TERAI MOISTURE REGIMES (based on LRMP, Land Systems Report, 1982) APPROXIMATE DEPTH OF WATER TABLE* IN MONSOON AND DRY SEASON FOR A MEDIUM TEXTURED SOIL S o i l Depth water table depth in monsoon — — — water table depth i n dry season —• • — - — *water table may be perched t—* Table 1 MEAN MONTHLY PRECIPITATION AND TEMPERATURE FOR DHANGADI, KAILALI DISTRICT. Station Dhangadl 167 meters elevation Mean Monthly R a i n f a l l (mm) and Daily Mean Temperatures (°C) January February March A p r i l May June July MEAN MONTHLY RAINFALL (mm) 25 21 20 14 40 258 535 DAILY MEAN TEMPERATURE (°C) 13.9 15.9 21.6 26.0 29.7 30.6 29.2 August September October November December Total Year 411 280 78 3 8 1667 28.8 28.0 25.3 19.9 15 24.0 DHANGADHI 167 METERS ELEVATION Ppt mm 1667 - 600 • 100 50 Figure 10 SEASONAL VARIATIONS IN MOISTURE REGIME, PRECIPITATION, AND TEMPERATURE, DHANGADHI, KAILALI DISTRICT (Based on Thornthwaite, 1948). 19. 4. Vegetation The d i s t r i c t i s covered by large tr a c t s of f o r e s t . At present about 57% i s s t i l l under natural vegetation. Sal (Shorea rubusta) i s the major fo r e s t type i n the area. Because of the q u a l i t y of timber and i t s a c c e s s i -b i l i t y , i t i s the primary e x p l o i t a b l e , renewable resource of the d i s t r i c t . Where s o i l moisture i s more r e a d i l y a v a i l a b l e , t r o p i c a l deciduous mixed hardwood forest represents a more advanced stage. A r i v e r i n e forest type containing Khair (Acacia catechu) and sissoo (Dalbergia sissoo) occurs along r i v e r s , stream banks and on gravel i s l a n d s . Forests are very important i n the Nepali household, with families r e l y -ing on them for f u e l wood for basic heating and cooking, timber, poles, fodder, l i t t e r and compost. Other benefits of the forests are found i n the form of s o i l conservation, slope s t a b i l i t y and water storage due to a decreased surface water run-off and evaporation. Commercially, the forest i s not only u t i l i z e d for i t s valuable timber, but also as a source of f u e l wood for cooking, heating and f i r i n g the many bri c k f a c t o r i e s i n the d i s t r i c t . The government revenues generated from the forest industries i n the d i s t r i c t greatly exceed those a v a i l a b l e from other sectors. However these forests have been over-exploited i n d i s c r i m i n a t e l y without proper management i n the past making i t commercially not viable at the present time. 5. Land Use Because of the present forest zoning the d i s t r i c t i s not i n t e n s i v e l y used at present, but the area possesses a tremendous pot e n t i a l for a g r i c u l t u r a l production and resettlement. Most of the area i n the d i s t r i c t i s suitable for a g r i c u l t u r a l production and the d i s t r i c t can be divided into 20. three d i s t i n c t farming systems corresponding to the three Land Systems -a c t i v e , recent and older a l l u v i a l deposits. a. Active A l l u v i a l or Flood Threatened Farming Systems These farming systems occur i n the meandering, highly mobile, active flood plains of the r i v e r s on the d i s t r i c t (Land System 1). The a g r i c u l -t u r a l system i s dominated by monsoon r i c e production followed by fallow, but where i r r i g a t i o n water i s available i n winter, high value vegetable crops, wheat or mustard are grown. The cropping patterns tend to be s i m i l a r to the main Terai (Land System 2) areas but are threatened at least every few years with deep water and/or erosive flooding. Most of the grazing land (grass-land) in the d i s t r i c t i s located in t h i s area to compensate for the high r i s k of crop loss due to flooding. b. Recent A l l u v i a l or the Main Terai Farming Systems The farming systems i n these areas are rice-based and are associated with Land System 2. They coincide with the monsoon rice-based cropping patterns and include cash crops such as sugarcane. The least intensive system i s the monsoon r i c e followed by dry season fallow, but under inten-sive c u l t i v a t i o n l e n t i l s are relayed into the r i c e crop as a second crop and mustard i s also grown. Where some i r r i g a t i o n water i s available i n winter, r i c e i s usually followed by wheat. On moderately well drained s i t e s usually monsoon corn i s followed by mustard or m i l l e t . The r i c e system of c u l t i v a -t i o n i s r e l a t i v e l y stable from a f e r t i l i t y point of view, although i n many areas winter crops of wheat or other crops are grown. Under these circum-stances chemical f e r t i l i z e r s w i l l be required to maintain current l e v e l s of f e r t i l i t y . 21. c. Older A l l u v i a l or the Upper Terai Farming Systems These farming systems occupy the l i g h t e r textured, well drained s o i l s i d e n t i f i e d i n Land System 3. These areas are not e s p e c i a l l y suitable for r i c e production although r i c e i s the common crop where supplementary monsoon i r r i g a t i o n i s possible, followed by fallow. Being at the base of the Siwalik Mountains the r a i n f a l l i s much higher and i n addition, being nearest to the h i l l y regions, i t has great p o t e n t i a l for providing i r r i g a t i o n water i n some areas for double cropping of r i c e . Rice production i s concentrated i n map unit (3a) (when i r r i g a t i o n i s ava i l a b l e ) and depressional areas of map unit (3d). The remainder of map unit (3d) and unit (3b) are very d i f f i c u l t to use for a g r i c u l t u r e because of steep slopes and coarse textures s o i l s , so the land would l i k e l y be more productive as managed forest, while unit (3c) would require s p e c i a l i z e d r o t a t i o n s . Most of the crops grown i n t h i s system require well drained s o i l s . Monsoon corn i s the most important crop, and i s usually followed by mustard, m i l l e t or l e n t i l s . Wheat i s grown following the corn crop only when some i r r i g a t i o n water i s a v a i l a b l e , as these s o i l s are dryer, coarser i n texture, and have a low water holding capacity. F e r t i l i t y i n some of the r e s e t t l e d areas i s d e c l i n i n g r a p i d l y and the system cannot be considered sustainable in i t s present form in the long run. A more balanced type of farming system and r o t a t i o n w i l l have to be designed for these areas i f sustained production Is to be obtained. Given the inputs, these farming systems have great p o t e n t i a l for improving the a g r i c u l t u r a l production of the d i s t r i c t . At present most of these units are under f o r e s t . 22. II. BACKGROUND AND LITERATURE REVIEW A. BACKGROUND Like most developing countries, Nepal's need for Resource Inventory Data was very acute p r i o r to th i s project (LRMP). Many projects did not come into being because basic information was inadequate or not a v a i l a b l e . There are many approaches that could be taken - genetic, parametric or land-scape - i n order to f i l l i n the missing information so desperately needed by the country. The genetic approach i s a broad c l a s s i f i c a t i o n of the landscape where large units are developed from deductive c l a s s i f i c a t i o n s by l o g i c a l sub-d i v i s i o n of the landscape on the basis of causal environmental f a c t o r s . Mabbut (1968) points out some p r a c t i c a l advantages of th i s approach. F i r s t , they provide a coordinating framework which i s useful for c o r r e l a t i n g analogous areas. Secondly, they aid in the reconnaissance of large areas by providing an o v e r a l l view of genetic r e l a t i o n s which helps economize e f f o r t of sampling. T h i r d l y , they have educational value i n explaining world patterns, and are e s p e c i a l l y valuable to s p e c i a l i s t s such as h i s t o r i a n s and planners. The genetic approach of land c l a s s i f i c a t i o n has been used extensively in Canada to map large areas for E c o l o g i c a l Land C l a s s i f i c a t i o n . As Canada i s a huge country with large t r a c t s of forest lands i n the north, such an approach was appropriate for reconnaissance l e v e l study to provide an over-a l l assessment of the area. The genetic approach on the other hand, has a number of disadvantages which r e s t r i c t t h e i r p r a c t i c a l usefulness. The units are large, usually extending to thousands of square kilometers and they have both great 23. i n t e r n a l complexity and vague boundaries. Genetic subdivision cannot r e a d i l y be accomplished i n order to a r r i v e at units small enough to be homo-geneous for most types of land. P r e c i s i o n i s s a c r i f i c e d i n exchange for an o v e r a l l c o r r e l a t i v e framework. This vagueness of d e f i n i t i o n i n large units was the reason why t h i s approach was not used i n Nepal. The parametric approach can be defined as the c l a s s i f i c a t i o n and sub-d i v i s i o n of land on the basis of selected a t t r i b u t e values. It i s more quantitative and less dependent upon subjective in t e r p r e t a t i o n s of the land-forms. It i s a more s t a t i s t i c a l l y r e l i a b l e means of measuring variance, formulating r a t i o n a l sampling p o l i c y and expressing the p r o b a b i l i t y l i m i t s of the fi n d i n g s . It i s better adapted to the use of new remote sensors which are able to scan d i r e c t l y those t e r r a i n a t t r i b u t e s which have to be i n f e r r e d to from associated features. The approach i s also better suited to the increasing use of e l e c t r o n i c data handling which favours information i n quantitative form. F i n a l l y , i t leads to a system which i s more f l e x i b l e , giving land units which are more e a s i l y modified in the l i g h t of expanding knowledge. This method has been most f u l l y developed for m i l i t a r y purposes by the U.S. and Canadian agencies, mainly by the Quartermaster Research and Engineering Centre at Natick, Massachusetts (QREC), the U.S. Army Engineer Waterways Experiment Station at Vicksburg, M i s s i s s i p p i (USAEWES), and the Canadian Defence Research Board. These three organizations have somewhat d i f f e r e n t objectives, the f i r s t being concerned mainly with aspects of the environment from which an army requires protection, and the other two with the environment i n terms of off-road m o b i l i t y . 24. There are also some disadvantages to t h i s system. It i s d i f f i c u l t to decide on the righ t parameters and the class l i m i t s to measure for any given land use. Measurements of the earth's surface cannot be extrapolated beyond t h e i r place of measurement other than by reasoning from physiographic analogy between landforms recognized on a e r i a l photographs. Since the pre-d i c t i v e capacity i s severely l i m i t e d i n t h i s way, more d e t a i l , slow and c o s t l y ground samplings are needed for the mapping of each parameter. More-over, i t tends to be r e s t r i c t e d to small areas where detai l e d information i s needed. F i n a l l y , because information i s based on point samples only, accuracy tends to f a l l o f f r a p i d l y between the sampling points unless remote scanning of a t t r i b u t e s has been possible to f i l l i n the intermediate areas. On the whole, the parametric approach s a c r i f i c e s comprehensiveness and ease of recognition for the r e l i a b i l i t y and quantitative output of a d e f i n i -tion based on measured properties. It has the advantage that the picture i t gives becomes incr e a s i n g l y complete and r e a d i l y obtainable with the use of scanning and computing techniques. The parametric approach i s useful for de t a i l e d survey, where greater p r e c i s i o n and r e l i a b i l i t y i s required which i s expensive and slow. For these reasons the parametric approach was not used i n Nepal as the landscape approach o f f e r s the p o s s i b i l i t y of more rapid survey at lower cost. Its r e l i a b i l i t y i s adequate for reconnaissance surveys and, with moderately intensive sampling, for semi-detailed surveys, i t has the advantage of combining a l l survey work into a single operation. The landscape approach helps to explain the fundamental causes of land-scape d i f f e r e n t i a t i o n , a s s i s t reconnaissance and f a c i l i t a t e the appreciation of regions as a whole. I t i s generally aimed at data a c q u i s i t i o n for a g r i -c u l t u r e , engineering, m i l i t a r y or planning purposes. It i s based on the assessment of recurring morphological features discerned from a e r i a l photographs and the approach was pioneered by MEXE i n the United Kingdom and CSIRO i n A u s t r a l i a . The method also known as systems approach was tested i n representative areas i n the following c l i m a t i c zones: a r i d , savanna, humid, temperate and t r o p i c a l r a i n f o r e s t . Short studies i n the Near and Middle East, East A f r i c a , U.K. and Malaysia (MEXE, 1965) gave encouraging r e s u l t s for t e s t i n g the idea i n d e t a i l i n the U.K.. It was demonstrated that units recurred and could be recognized and delimited on a e r i a l photographs with the aid of geological maps and a r e l a t i v e l y small amount of f i e l d work, and that each was adequately homo-geneous and d i f f e r e n t from the others to be used for p r a c t i c a l predictions within the study area (Beckett and Webster, 1969; Webster and Beckett, 1970). The disadvantages of the landscape approaches, however, are the high degree of generalization, the variable and somewhat i l l defined basis of the mapping units, the s t a t i c nature of the information presented and weakness of the evaluation stage. Some of these weaknesses are not inherent in the approach but l i e i n the way i n which i t has been applied. So, although open to the jibe of being an "academic exercise", complete coverage of a country at reconnaissance scale does serve some s c i e n t i f i c and planning purposes. B. LAND SYSTEMS APPROACH IN NEPAL Nepal i s a land of extremes - climate ranges from subtropical to a r c t i c ; physiography encompasses vast a l l u v i a l plains to very rugged, permanently snow-covered peaks; vegetation ranges from subtropical s a l forests to barren tundra; and at the same time, bananas and apples might be ripening only a few miles apart. In the mountainous t e r r a i n , v a r i a b i l i t y of s o i l type i s so great that meaningful reconnaissance information based on s o i l series or even associations of s o i l series did not seem f e a s i b l e . The Land Systems Approach was taken as i t provides a methodology f l e x i b l e enough to employ both genetic and e x i s t i n g pragmatic c r i t e r i a i n delineating map u n i t s . The Land Systems Approach, also c a l l e d integrated survey, i s f u l l y described by C h r i s t i a n and Stewart (1968); outlines of the technique are given by many authors such as Cooke and Doornkamp (1974), M i t c h e l l (1973), Vink (1975) and Young (1976). King (1970) described how a pragmatic approach can be applied to land system c l a s s i f i c a t i o n . To a very large extent t h i s method i s based on the i n t e r p r e t a t i o n of a e r i a l photographs and areas with a recurring pattern of topography, s o i l and vegetation are mapped as i n d i v i d u a l land systems. The c e n t r a l concept i s that i n s p e c i f i c areas a l l the environmental c h a r a c t e r i s t i c s (topography, s o i l s , vegetation, geology and geomorphology and climate) w i l l i n t e r r e l a t e , r e s u l t i n g i n d i s t i n c t i v e patterns on a e r i a l photographs. In Nepal the Land System Approach, u t i l i z i n g the physiographic land region through to s i t e s p e c i f i c land type, provides such a framework and permits l e v e l s of generalization appropriate to any l e v e l of survey i n t e n s i t y . The approach i s described as integrated because the method depends on i d e n t i f y i n g d i s t i n c t i v e areas r e s u l t i n g from the int e g r a t i o n of environment-a l variables; the survey i s also executed by a team of s c i e n t i s t s , a geo-morphologist, geologist, pedologist, ecologist and an a g r i c u l t u r a l i s t . For the planning of a g r i c u l t u r a l development, such surveys are able to i d e n t i f y 27. areas of l i t t l e or no p o t e n t i a l , but more detailed investigations are required i n areas which seem to o f f e r scope for development. One can also describe the approach as e c o l o g i c a l since areas are mapped on the basis of patterns resultant upon the i n t e r a c t i o n of physical c h a r a c t e r i s t i c s ; Vink (1975) v i s u a l i z e s an integrated survey as being e c o l o g i c a l l y based. The h i e r a r c h i a l system used i n Nepal consisted of the following four subdivi-sions : 1. Physiographic Regions The Landsat Mapping Project by Nelson (F.A.O.) 1981, was chosen for d elineating physiographic regions. These physiographic regions (Terai, Siwaliks, Middle Mountains, High Mountains and High Himal) are well recognized by a l l Nepalese geographers, geologists, f o r e s t e r s , s o i l s c i e n t i s t s and agronomists a l i k e . They represent well defined geographic areas with d i s t i n c t physiography, bedrock geology, geo-morphology, climate and vegetation. The actual boundaries are a l t e r e d somewhat from these delineated by Nelson i n 1981, f a c i l i t a t e d by use of 1:50,000 a e r i a l photographs, and more detai l e d f i e l d i nvestigations of geology and s o i l during the course of f i e l d survey. 2. Land Systems Within these physiographic regions, mutually exclusive land systems are defined according to current patterns of landforms, geo-l o g i c materials, slopes and arable a g r i c u l t u r a l l i m i t s which are r e a d i l y observable on 1:50,000 a e r i a l photographs. These c r i t e r i a are both genetic and pragmatic i n nature and break out very important 28. land s u i t a b i l i t y d i f f e r e n c e s . Each physiographic region has i t s own exclusive land systems, regardless of s i m i l a r i t i e s i n geomorphology with other regions. 3. Land Units Mappable land surface areas within land systems which are s i g n i -f i c a n t from some user-oriented point of view are delineated and were c a l l e d land u n i t s . These land units are d i f f e r e n t i a t e d by landscape c h a r a c t e r i s t i c s such as p o s i t i o n , slope, surface d i s s e c t i o n , flooding frequency and s o i l c h a r a c t e r i s t i c s such as drainage, depth, texture, p r o f i l e development and pH. 4. Land Types Land types occur within land systems or land units and they form a complex of land types that are either too small or too complex to be mapped on 1:50,000 a e r i a l photographs. They are, however, e a s i l y recognized i n the f i e l d and have very important physical c h a r c t e r i s t i c s for determining s u i t a b i l i t i e s . These land types are noted where they occur and are described within a schematic cross-section of land systems. It i s these land types that could become the major s o i l map-ping units for future major i r r i g a t i o n works on the Terai and for watershed management i n the h i l l s . The f l e x i b i l i t y of Land System Mapping to describe and map t e r r a i n c h a r a c t e r i s t i c s , considered important for s u i t a b i l i t y c l a s s i f i c a t i o n at d i f f e r e n t l e v e l s of generalization, i s a very desirable aspect of t h i s mapping system. 29. This approach was considered the most appropriate as i t i s a rapid method for describing, c l a s s i f y i n g and mapping large areas, i d e a l for developing countries where resource inventory data i s lacking. The survey i s reconnaissance i n nature, which intends to provide a broad view of the land resources of the area, to serve as a guide for plan-ning and development, and a framework for a more detai l e d survey. The survey i s by no means confined to s o i l but covers the whole of the physical environment to the extent that i t a f f e c t s land use p o t e n t i a l . C. LAND EVALUATION Land evaluation i s "the process of c o l l a t i n g and i n t e r p r e t i n g basic inventories of s o i l , vegetation, climate and other aspects of land i n order to i d e n t i f y and make a f i r s t comparison of promising land use a l t e r n a t i v e s i n simple socio-economic terms" (Brinkman and Smyth, 1973). Land evaluation therefore bridges the gap between the p h y s i c a l , b i o l o g i c a l and technological means of land use and i t s s o c i a l and economic purposes. Land evaluation i s not economics, but neither i s i t purely a physical d i s c i p l i n e ; i t i s the u t i l i z a t i o n of s o c i a l and economic parameters i n evaluating physical data. Therefore, the objective of land evaluation or assessment i s to judge the value of an area for defined purposes. B a s i c a l l y , land evaluation i s a process of i n t e r p r e t i n g resource inven-tory data for a g r i c u l t u r a l c a p a b i l i t y and s u i t a b i l i t y assessments. For evaluation at a reconnaissance scale, resource inventory data (biophysical) are interpreted i n the best way for i n d i c a t i n g development p o s s i b i l i t i e s of large areas r e l a t i v e l y quickly and cheaply. Land evaluation at t h i s scale might enable developers to see, for example, where the best areas for 30. large-scale food-crop production are to be found. Such evaluations are based on current s u i t a b i l i t y , and provide q u a l i t a t i v e c l a s s i f i c a t i o n of s u i t a b i l i t i e s for major kinds of land use. They require a wider range of data than can be obtained from s o i l survey alone, and can conveniently be based on land systems surveys. Many developing countries have commissioned land evaluation studies of t h i s nature as an i n i t i a l guide to development p o s s i b i l i t i e s . Among developed countries, Canada and A u s t r a l i a have both surveyed large areas. Evaluation forms a major component of the survey i n Canada but has been subsidiary to land systems d e s c r i p t i o n i n A u s t r a l i a . Land evaluation for a g r i c u l t u r e includes the assessment of land cap-a b i l i t y for general a g r i c u l t u r e and land s u i t a b i l i t y for s p e c i f i c crops (McRae and Burnham 1981). Cap a b i l i t y i s the p o t e n t i a l of the land for use i n s p e c i f i e d ways or with s p e c i f i e d management practices (Dent and Young 1981). The range of uses may be, for general a g r i c u l t u r e , f o r e s t r y or r e c r e a t i o n a l development. However, land c a p a b i l i t y i s more d i f f i c u l t to assess than s u i t a b i l i t y since p r i o r i t i e s must be established between uses, e.g., i s mediocre arable land better than h i g h - y i e l d i n g grassland unsuitable for c u l t i v a t i o n , or i s land capable of growing only one sort of crop better or worse than v e r s a t i l e land which w i l l grow a number of crops but none quite successfully? This d i s -t i n c t i o n between s u i t a b i l i t y and c a p a b i l i t y i s commonly made when evaluating land. Land s u i t a b i l i t y evaluation i s the process of assessing the s u i t a b i l i t y of land for s p e c i f i c kinds of uses (Dent and Young 1981). These may be major kinds of land use, such as rainfed a g r i c u l t u r e , l i v e s t o c k production, f o r e s t r y , etc., or land u t i l i z a t i o n types described i n more d e t a i l , for 31. example rainfed arable farming based on maize and m i l l e t production, i r r i -gated r i c e production, or tea plantations. S u i t a b i l i t y i s assessed, c l a s s i -f i e d and presented separately for each kind of crop. There i s nothing new about the p r i n c i p l e of s u i t a b i l i t y evaluation. From the e a r l i e s t times, farmers have been deciding which crops are best for the land they possess or, as s e t t l e r s , where there i s to be found land suited to the crops they wish to grow. 1. Land Capability Evaluation Scheme for Agriculture Land c a p a b i l i t y evaluation for ag r i c u l t u r e i s based either on the categoric or parametric systems. Both systems have been extensively used for c a p a b i l i t y assessment i n terms of land use schemes. a. Categoric Systems Categoric systems group land into numbers of d i s c r e e t l y ranked cate-gories, usually from 1 to 8 according to the l i m i t i n g values of a number of s o i l , s i t e and c l i m a t i c properties. Category one usually r e l a t e d to the best land where a l l crops or land uses can occur uninhibited. As soon as a l i m i t i n g factor i s present, the land automatically f a l l s into a higher category as i l l u s t r a t e d i n Table 2. The most widely used categoric system for evaluating a g r i c u l t u r a l land c a p a b i l i t y i s the USDA system. It i s a two l e v e l system where the land i s f i r s t c l a s s i f i e d into one of eight classes on the basis of numbers and extent of l i m i t i n g factors to crop growth. Then subclasses are made by i d e n t i f y i n g the causes of the l i m i t a t i o n s (e.g. Hedge and K l i n g e b i e l , 1957; K l i n g e b i e l , 1958). A s u f f i x notation was introduced for the four major kinds of l i m i t a t i o n recognized at subclass l e v e l : 32. w c e s erosion hazard excess water s o i l l i m i t a t i o n s within the rooting zone c l i m a t i c l i m i t a t i o n s Subclasses were denoted by appropriate s u f f i x (with a maximum of two) placed a f t e r the class number, e.g. l i e , IIIws. Class I has no subclasses. The classes f a l l into two groups. Classes I-IV can be used for arable c u l t i v a t i o n , while classes V-VIII cannot. The r i s k of erosion increases through classes I to IV, progressively reducing the choice of crops and re q u i r i n g more expensive conservation practices and more c a r e f u l management. Classes I-IV can conveniently be thought of as "very good", "good", "moderate" and "marginal" arable land, r e s p e c t i v e l y . Class V i s a l l o t t e d to land rendered unsuitable for c u l t i v a t i o n by reasons other than erosion hazard, i . e . wetness, excessive stoniness. Classes VI-VIII are precluded from arable use by severe permanent l i m i t a t i o n s ; for the most part i t consists of steeply sloping land. Class VI can be managed under improved pasture, Class VII only under rough grazing or woodland, while Class VIII cannot be used for commercial plant production of any kind. Table 2. STRUCTURE OF USDA LAND CAPABILITY CLASSIFICATION Ca p a b i l i t y Class C a p a b i l i t y Subclass C a p a b i l i t y Unit S o i l Mapping Unit arable I II III IV l i e , erosion IIw, wetness l i s , s o i l IIe-1 IIe-2 IIe-3 P s e r i e s Q seri e s R series non-arable V VI VII VIII l i e , climate l i e s etc. 33. Modifications have been made to adapt the USDA Land C a p a b i l i t y C l a s s i -f i c a t i o n for use outside the United States. The system has been extensively used i n many developed, as well as underdeveloped, countries with some major refinements to su i t t h e i r own needs and requirements. Canadian Method - Land C a p a b i l i t y C l a s s i f i c a t i o n i n Canada, for example, was i n i t i a t e d by the Canada Land Inventory which was established i n 1963 as a r e s u l t of the A g r i c u l t u r a l R e h a b i l i t a t i o n and Development Act (ARDA) of 1961. This Inventory i s a comprehensive survey of land c a p a b i l i t y and i s designed to provide a basis for resource and land use planning (Canada Land Inventory, 1970). The system i s used i n land use planning on a national scale rather than for management at the municipal and p r o v i n c i a l l e v e l s . The Canadian land c a p a b i l i t y scheme i s modelled on the USDA method, though some important differences must be stressed. Besides being a method of s o i l c a p a b i l i t y c l a s s i f i c a t i o n for a g r i c u l t u r e , there are separate land c a p a b i l i t y assessment schemes for f o r e s t r y , recreation and w i l d l i f e -further separated into ungulates and waterfowl. The Canadian c a p a b i l i t y schemes have seven classes i n contrast to the eight of the USDA method. As with the USDA scheme subclasses are indicated by . l e t t e r s , but the Canadian method has a wider range of such l i m i t a t i o n s than the USDA. In B r i t a i n the S o i l Survey has developed a land use c a p a b i l i t y c l a s s i -f i c a t i o n (Bibby and Mackney, 1969) modelled on the USDA approach. Major modifications were that the system has only 7 classes. Class 5 of the USDA method i s excluded since i t re f e r s s p e c i f i c a l l y to f l a t wet areas and thus breaks the theme of progressively greater l i m i t a t i o n s (Mackney, 1974). 34. The American subclasses are used but with addition of a subclass for topography and climate. The S o i l Survey of Scotland has further refined the assessment of cl i m a t i c conditions by producing one map based on accumulated temperature and p o t e n t i a l water d e f i c i t (Birse and Dry, 1970) and another on exposure and accumulated f r o s t (Birse and Robertson, 1970). For general land use planning purposes, maps showing c a p a b i l i t y classes and subclasses seem thoroughly adequate, but l e v e l s of c l a s s i f i c a t i o n are s a t i s f a c t o r y at more d e t a i l planning l e v e l s . In Nepal the Land Resources Mapping Project has developed a land use c a p a b i l i t y c l a s s i f i c a t i o n (LRMP, Land C a p a b i l i t y Report, 1982) modelled on the USDA scheme. Like the Canadian and B r i t i s h Schemes, the Nepalese scheme has only 7 classes, but 5 subclasses and 4 sub-divisions according to the i r opportunities, l i m i t a t i o n s and hazards for d i f f e r e n t sustainable uses. Emphasis i s placed on arable a g r i c u l t u r e , however the lands are also evaluated for other uses including perennial cropping, f u e l and fodder production, timber extraction, grazing, and watershed protection. The arrangement of classes r e f l e c t s decreasing opportunities for use as well as decreasing i n t e n s i t y of use. Erosion hazards generally increase from Class I to VII but can be kept within t o l e r a b l e l i m i t s by the prescribed land management. Classes are c l e a r l y defined and based on observable physical character-i s t i c s , subclasses are subj e c t i v e l y defined but can be c l o s e l y correlated with elevation, and sub-divisions represent estimates of yearly s o i l moisture averages based on l i m i t e d information. 35. The Land C a p a b i l i t y C l a s s i f i c a t i o n System developed for Nepal i s a q u a l i t a t i v e c l a s s i f i c a t i o n , based mainly on the physical productive poten-t i a l of the land, with economics only present as a background. Guidelines for placing lands i n d i f f e r e n t categories are based on slope l i m i t s , s o i l depths, a l t i t u d i n a l range, r a i n f a l l , erosion control requirements and opportunities for d i f f e r e n t kinds of land use. b. Parametric Systems Land evaluation using parametric methods involves assigning numerical scores to various s o i l and s i t e properties (parameters) that are believed to influence y i e l d , and then are combined into a mathematical formula (Beek, 1978). The resultant values can be used for assessment purposes, or a l t e r n a t i v e l y they may be used to rank s o i l s into c a p a b i l i t y c l a s s e s . Three main kinds of systems can be recognized: Additive M u l t i p l i c a t i v e and Complex. i . Additive Systems Numerous addi t i v e systems have been developed i n many countries but the general concepts are very s i m i l a r , e.g. P = A + B + C where P i s the parametric r a t i n g , score or index, and A, B and C are s o i l and s i t e properties. These can either be d i r e c t values, such as depth (cm) or the values can be rated on a scale of 0-100 points. In Germany such additive systems are used to assess land taxes, to a s s i s t In the planning of food production, and to provide a basis for land use planning (Weieres and Reid, 1974). Appropriate evaluation applied to arable and pasture lands to produce a s o i l or pasture base figure using a national standard of 100 points for the best q u a l i t y lands and others, were expressed as a percentage of the nation-a l standard. Y i e l d index for each f i e l d were then calculated and i t i s claimed that i t cor r e l a t e s well with actual y i e l d s (Nieschlag, 1974). Similar s o i l ratings were developed i n Russia (e.g. Blagovidov, 1960; Gavrilyuk, 1967, 1977; Taichinov, 1971; Hooper, 1974b). There the q u a l i t y of a given piece of land i s rel a t e d to a standard taken as 100 points by adding points for s o i l features such as genetic s o i l type, humus content, t o p s o i l thickness, texture and f e r t i l i t y and s i t e factors such as topography and drainage. The product prices credited to State and C o l l e c t i v e Farms are inversely r e l a t e d to the mean point r a t i n g of the land belonging to each farm. In Romania an elaborate additive system has been developed (Teaci, 1970; Teaci and Burt, 1964, 1974; and others). Detailed maps of s o i l , topo-graphy and climate were compiled to produce maps of "Homogeneous E c o l o g i c a l T e r r i t o r i e s " (TED's) at 1:50,000. Each TED comprises a single s o i l type and l i e s within a defined range of topographic and c l i m a t i c properties, which i s comparable to a land c a p a b i l i t y u n i t . A maximum of 50 points i s awarded for the q u a l i t y of the s o i l , by reference to tables r e l a t i n g crop performance to s o i l type. Empirical curves derived r e l a t e crop y i e l d to s i g n i f i c a n t and measurable s o i l and s i t e properties, e.g. temperature, p r e c i p i t a t i o n , slope, surface waterlogging, and ground water influences. Correction tables which are then produced from these Indicate points to be added or subtracted from the s o i l points for each crop. 37. The most commonly used m u l t i p l i c a t i v e systems are based on the Storie Index and an example of th i s has been used i n Saskatchewan for many years ( M i t c h e l l , 1940, 1950; Bowser, 1940; Freeman, 1940). Unfortunately, the r a t i n g did not r e l a t e well to long-term y i e l d s of wheat and Moss (1972) proposed an additive system for non-irrigated land i n Saskatchewan. The system i s : F i n a l r a t i n g = S o i l Rating - Landscape Factor = (C + T + P) - L where the maximum points are 40 for C ( c l i m a t i c f a c t o r ) , 40 for T ( s o i l texture and organic matter), and 20 for P (the genetic s o i l p r o f i l e and rel a t e d features). The landscape features (topography, drainage and s a l i n i t y , stoniness, erosion and wood cover) where favourable, no deductions are made from the s o i l r a t i n g . Where there are unfavourable features, tentative guidelines are given which w i l l reduce the f i n a l r a t i n g to 30 or less i f the conditions are very unfavourable, and make corresponding smaller reductions i f the problems are not so severe or i f the s o i l r a t i n g i s already below 30. If the landscape features make the land completely unsuitable for a g r i c u l t u r e , the landscape r a t i n g i s made equal to the basic r a t i n g to give a f i n a l r a t i n g of zero. This i s a p a r t i c u l a r l y clear example of the way most parametric systems are adjusted to lend apparently objective support to the subjective judge-ment of the evaluator. i i . Multiplicative Systems The best-known m u l t i p l i c a t i v e system for r a t i n g the q u a l i t y of land i s the Storie Index Rating which originated i n C a l i f o r n i a . It f i r s t appeared 38. i n 1933, but has been revised and reprinted on several occasions ( S t o r i e , 1933, 1937, 1944, 1948, 1953, 1955, 1964a, 1976, 1978). Adaptations of the system have been used i n many other parts of the world, often after some modifications for l o c a l conditions. O r i g i n a l l y ( S t o r i e , 1933) the Storie Index Rating (SIR) i s given by: SIR A x B x C Character of Texture of Miscellaneous factors S o i l P r o f i l e Surface S o i l (such as drainage, a l k a l i n i t y , steep slope) L a t e r , Storie (1944) introduced a new factor C to evaluate slope and the o r i g i n a l factor C became factor X (miscellaneous factors that can be modi-f i e d by management), as that the SIR became: SIR = A x B x C x X Character of Texture of Slope Miscellaneous S o i l P r o f i l e Surface S o i l Factors A percentage r a t i n g i s calculated for each of these factors - the optimum and maximum figure being 100. Each factor i s scored as a percentage but m u l t i p l i e d as a decimal. The f i n a l index i s expressed as a percentage. The Storie index was developed primarily to a s s i s t with land assessment for taxation purposes i n C a l i f o r n i a (Storie and Weir, 1942; Storie and Harradine, 1950; S t o r i e , 1954). It had to be modified i n other areas to include factors which are not important i n C a l i f o r n i a . Inclusion of a factor for climate i s common, for example, i n Hawaii (Nelson, 1963; Olson, 1974), and India (Shome and Raychaudhuri, 1960). In New Zealand, Leamy (1962, 1974) has included a factor for management l e v e l , and for the humid tr o p i c s Sys and Frankart (1972) and Frankart and Sys (1974) include factors for s o i l colour and for the development of an organic r i c h s o i l . In some cases there i s an apparent increase i n the number of factors which are considered. This i s usually because s o i l and s i t e properties included i n with the miscellaneous (X) factors In the basic Storie Index Rating are drawn out as separate fa c t o r s , e.g. s a l i n i t y (Bowser, 1940; Omar and E l K a l e i , 1969; Borden and Warkentin, 1974; Sys and Verheye, 1974; Sys, 1979). For development projects the FAO (Bramao and Riquier, 1967; Riquier et a l . , 1970) has proposed a new Index of S o i l P r o d u c t i v i t y . Index of S o i l P r o d u c t i v i t y where P T N S 0 A M = D = H = P x T x ( N o r S ) x O x A x M x D x H e f f e c t i v e s o i l depth texture and structure of A horizon base status soluble s a l t s content organic matter of A1 horizon mineral exchange capacity and nature of clay i n B horizon reserves of a l t e r a b l e minerals i n B horizon drainage s o i l moisture content i l l . Complex Parametric Systems Some complex parametric systems combine both the additive and multi-p l i c a t i v e approaches. A system proposed by Le Vee and Dregne (1951) for New Mexico includes the following f a c t o r s : 40. P r o f i l e Land = Rating x Slope x Erosion x Special Factor Rating (adjusted for Rating Rating Rating associated s o i l factors) Each r a t i n g i s expressed as a percentage. The P r o f i l e Rating i s , however, obtained by summing values for t o p s o i l , s u bsoil and, i n some cases, substratum, and i s then m u l t i p l i e d by values for a number of associated s o i l f a c t o r s . Harris (1949) has proposed a si m i l a r combined additive and m u l t i p l i c a t i v e system for Arizona. Some systems have been developed into extremely complex mathematical model invo l v i n g M i t s c h e r l i c h y i e l d functions (Riquier, 1972). Others by comparison, the "square root" system of Strzemski (1972) i s extremely simple: Index = A/ (ps.pc.pr.pa) where A = an empirical c o e f f i c i e n t ps = s o i l pc = climate pr = r e l i e f pa = water conditions. Parametric systems are simple, appear to be objective, are e a s i l y applied by non-specialists and have proved popular for taxation or related purposes. The main v i r t u e of a m u l t i p l i c a t i v e system i s that the least favourable factor dominates the f i n a l r e s u l t whereas i n additive systems quite severe l i m i t a t i o n s may not be given due weight ( S t o r i e , 1933; Bowser, 1940; Marin-Lafleche, 1972). Promising future developments appear to be either the introduction of more complex factors into the formula (e.g. Riquier, 1972) or better c a l i b r a t i o n of each factor against crop performance as i n the Romanian system (Teaci and co-workers). This system has the a d d i t i o n a l benefit of allowing separate assessments for each crop, but also has the considerable disadvantage that i t requires large amounts of experimental data to e s t a b l i s h the system. For the moment, however, m u l t i p l i c a t i v e systems appear to give more r e a l i s t i c r e s u l t s and they have proved more popular than additive systems. c. Soil F e r t i l i z e r Capability Classification A s p e c i a l case of the c a p a b i l i t y assessment for a g r i c u l t u r e i s the F e r t i l i z e r C a p a b i l i t y C l a s s i f i c a t i o n system (FCC). It was developed i n an attempt to bridge the gap between the su b d i s c i p l i n e s of s o i l c l a s s i f i c a t i o n and s o i l f e r t i l i t y (Buol, 1972; Buol et a l . , 1975). The system uses s o i l survey and c h a r a c t e r i z a t i o n information for detecting the most important l i m i t i n g factors for most common crops i n large areas where s o i l s have not been s u b s t a n t i a l l y changed by man. The a b i l i t y of the system to group s o i l s that are a l i k e from the point of view of s o i l f e r t i l i t y l i m i t a t i o n s or management requirements has been checked using experimental and s o i l property information c o l l e c t e d i n several t h i r d world countries. It i s a te c h n i c a l c l a s s i f i c a t i o n system designed to group s o i l s on the basis of s o i l factors that have a d i r e c t Influence on s o i l - f e r t i l i z e r - p l a n t r e l a t i o n -ships. The main objective of the system i s to focus attention on s i g n i f i -cant properties of the s o i l that may be used for i n t e r p r e t i n g and extra-polating the r e s u l t s of s o i l - f e r t i l i t y management experiments. S o i l - f e r t i l i t y management i s mainly concerned with manipulation of the c h a r a c t e r i s t i c s of the plough-layer, simply because present techniques have a l i m i t e d a b i l i t y to change subsoil c h a r a c t e r i s t i c s . In south-eastern United States as much as 70% of crop y i e l d v a r i a b i l i t y can be a t t r i b u t e d to t o p s o i l properties (Soper and McCracken, 1973). Texture of the surface s o i l 42. i s one of the most important single factors a f f e c t i n g s o i l management. In addition to texture, the chemical and mineralogical nature of the s o i l m aterial determines the a b i l i t y of the s o i l to r e t a i n nutrients i n a form ava i l a b l e for plant growth. Thus, soil-fertility-management i s most d i r e c t -l y r e l a t e d to only a few of the s o i l parameters normally included i n most s o i l survey reports. Thus, the FCC was designed to group s o i l s that have the same kind of l i m i t a t i o n s from the point of view of s o i l f e r t i l i t y management (Buol, 1972). As such i t i s the f i r s t t e c h n i cal s o i l c l a s s i f i c a t i o n system that groups s o i l s according to t h e i r f e r t i l i t y constraints i n a quantitative manner and emphasizes only one s o i l use ( C l i n e , 1949). Some information contained i n s o i l survey reports i s used i n the FCC, and s o i l s are grouped only by the c h a r a c t e r i s t i c s that make them s i m i l a r for f e r t i l i t y management purposes. S o i l i n d i v i d u a l s i n one FCC class may belong to d i f f e r e n t classes for taxonomic purposes. FCC classes indicate the main f e r t i l i t y r elated s o i l c o n s t raints, which can be interpreted i n r e l a t i o n to s p e c i f i c farming systems or land u t i l i z a t i o n types. S o i l maps can be interpreted and redrawn as FCC units when necessary data become a v a i l a b l e . The system also allows s o i l - f e r t i l i t y s p e c i a l i s t s to group experimental s i t e s that are expected to respond s i m i l a r l y to soil-management pr a c t i c e s , and to extrapolate t h e i r findings to s o i l s that can be expected to behave i n a s i m i l a r manner. The FCC system does not indicate the amount of f e r t i l i z e r needed. Individual crop needs and f e r t i l i t y carry-over from previous crops both vary, but the FCC system does provide a guide for the extrapolation of f e r t i l i z e r - r e s p o n s e experience. The system i t s e l f focuses on the upper 20 cm of s o i l . Texture i s examined and the c a p i t a l l e t t e r s S, L, C or 0 are assigned according to tex t u r a l classes or organic matter content. If a marked change in texture i s observed within a 50 cm depth, a second c a p i t a l l e t t e r (S, L, C, or R) i s assigned to i d e n t i f y that substrata texture. S o i l properties other than texture are c a l l e d "condition modifiers". They are i d e n t i f i e d by lower case l e t t e r s . The r e s u l t i n g combination of c a p i t a l l e t t e r s (type and substrata type) and lower case l e t t e r s (condition modifiers) constitute the name of the FCC c l a s s . C o l l e c t i v e l y i t indicates the kind of f e r t i l i t y and management l i m i t a t i o n s that are common to the s o i l units i n that c l a s s . In conclusion one can view the FCC system as a c h e c k - l i s t of s o i l properties that should be considered when comparing and extrapolating r e s u l t s of f i e l d crop t r i a l s . The FCC system i s not as d e f i n i t i v e of a l l s o i l properties as the natural taxonomic systems. Rather, i t focuses attention on those s o i l properties most d i r e c t l y r e l a t e d to management of crops i n the f i e l d and i s best used as an i n t e r p r e t i v e c l a s s i f i c a t i o n i n conjunction with a more i n c l u s i v e natural s o i l c l a s s i f i c a t i o n system. d. Land S u i t a b i l i t y Evaluation Scheme for A g r i c u l t u r e Land s u i t a b i l i t y i s "the f i t n e s s of a given t r a c t of land for a defined use" (Brinkman and Smyth, 1973). In i t s most quantitative form, i t i s the expression of the physical and e c o l o g i c a l p o t e n t i a l of a land ( s i t e ) based upon c e r t a i n s o c i a l and economic assumptions. In evaluating land s u i t -a b i l i t y for p r o d u c t i v i t y or performance of a given t r a c t of land, b a s i c a l l y there are three d i f f e r e n t approaches: 44. A B C Analogue Site Factor System Analysis. 1. Analogue Approach The t r a d i t i o n a l analogue approach i s based upon general m u l t i a t t r i b u t e s o i l and land c l a s s i f i c a t i o n systems. This method does not require any a p r i o r i knowledge of functional r e l a t i o n s h i p s between s i t e parameters and the s p e c i f i e d form of b i o l o g i c a l production, although such c r i t e r i a may be incorporated. The base land resources, either t o t a l complex (e.g. land systems - land unit) or separate major components (e.g. land forms, s o i l , vegetation, climate) are c l a s s i f i e d on the basis of a number of observed and measurable c h a r a c t e r i s t i c s . It i s f i r m l y based upon concepts of transfer by analogy and the physical input/output data necessary for evaluation are extrapolated from experimental s i t e s or from experience to analogous areas defined by land or s o i l c l a s s i f i c a t i o n . Subsequently land evaluation i s based on the hypothesis that a l l occurrences of a p h y s i c a l l y defined and characterized land or s o i l class w i l l respond i n a s i m i l a r fashion to management for any s p e c i f i e d form of use. The use of such a general, m u l t i - a t t r i b u t e c l a s s i f i c a t i o n system w i l l depend l a r g e l y upon the relevance of the observed and measured a t t r i b u t e s used. R e s t r i c t i o n of time and space not only l i m i t the range of a t t r i b u t e s selected but commonly lead to subjective methods of s e l e c t i o n . If the a t t r i b u t e s measured are s i g n i f i c a n t for a l l possible uses and a l l such a t t r i b u t e s are measured, then m u l t i - a t t r i b u t e systems of c l a s s i f i c a t i o n may, s a t i s f y the conditions necessary for predictions of s i t e p r o d u c t i v i t y . Land evaluation by analogue methods can be e f f e c t i v e , p a r t i c u l a r l y where a t t r i b u t e s are known to be relevant, however, the predictions made are 45. generally l o c a t i o n s p e c i f i c and can have no general v a l i d i t y . The FAO developed a system of land evaluation which has been used for a long time i n a g r i c u l t u r a l studies In many developed and developing countries. The system i s known as The Framework for Land Evaluation (FAO, 1976) and describes a s u i t a b i l i t y scheme for land s u i t a b i l i t y assessment. The term s u i t a b i l i t y i s used rather than c a p a b i l i t y to avoid p o t e n t i a l confusion with the American and other c a p a b i l i t y schemes. According to the framework (FAO, 1976) "land s u i t a b i l i t y i s the f i t n e s s of a given type of land for a defined use". Four l e v e l s of decreasing generalization are defined: 1. Land s u i t a b i l i t y orders: r e f l e c t i n g kinds of s u i t a b i l i t y . 2. Land s u i t a b i l i t y classes: r e f l e c t i n g degree of s u i t a b i l i t y within orders. 3. Land s u i t a b i l i t y subclasses: r e f l e c t i n g kinds of l i m i t a t i o n s , or main kinds of improvement meas-ures required, within c l a s s e s . 4. Land s u i t a b i l i t y u n i t s : r e f l e c t i n g minor differences i n required management within sub-classes . At the order l e v e l , an assessment i s made as to whether the land i s s u i t a b l e or not for sustained use of the kind under consideration and y i e l d i n g benefits which must j u s t i f y the inputs. Classes indicate the degree of s u i t a b i l i t y - up to a maximum of f i v e , although three i s common. Examples of classes are highly suitable (SI), moderately suitable (S2) and marginally s u i t a b l e (S3). Subclasses i n d i c a t e the type of l i m i t a t i o n , e.g. moisture deficiency, erosion hazards, drainage, flooding, s o i l nutrient deficiency, 46. etc., and are represented by lower-case l e t t e r s , for example, S2m for s u i t -able land of Class 2 with s p e c i f i c l i m i t a t i o n s of moisture a v a i l a b i l i t y . The most deta i l e d l e v e l i n the c l a s s i f i c a t i o n structure i s the un i t . Units are of the same class and subclass, but they vary i n t h e i r production c h a r a c t e r i s t i c s or i n minor aspects of t h e i r management requirements. This l e v e l i n the structure i s designed to be applicable to i n d i v i d u a l farms. Units are Indicated by arable numbers, e.g. S2m-1, S2m-2, etc. A phase c o n d i t i o n a l l y s u i t a b l e (Sc) may be added i n instances to condense and si m p l i f y presentation. Within a survey area, some areas of land may be unsuitable or poorly suitable for a p a r t i c u l a r use under management s p e c i f i -ed for that use, but suitable given that c e r t a i n conditions are f u l f i l l e d , e.g. l o c a l i z e d phenomena of poor s o i l drainage. Table 3 FAO LAND SUITABILITY EVALUATION SCHEME STRUCTURE OF LAND SUITABILITY CLASSIFICATION. Order S.suitable -> highly moderately marginally phase: Sc, c o n d i t i o n a l l y s u i t a b l e N, not suitable c u r r e n t l y permanently Category Class SI S2 -S3 etc . Sc2 Nl -N2 Subclass S2m S2e -S2me etc. Sc2m Nlm Nle etc. Unit S2e-1 S2e-2 etc. i i . S i t e Factor Approach The s i t e factor approach seeks to i d e n t i f y key a t t r i b u t e s which may then be used to generate s p e c i a l c l a s s i f i c a t i o n s for a s p e c i f i c purpose. I t seeks to re l a t e key parameters to b i o l o g i c a l p r o d u c t i v i t y within a given environment. The method i s based upon paired measurements of b i o l o g i c a l p r o d u c t i v i t y and selected s i t e factor over a wide range of s i t e s . These data are analysed and parameters rel a t e d to y i e l d are i d e n t i f i e d . The y i e l d at a s i t e within a region studied i s described by multiple regression equation from: Y g = a + biX], + b 2 x 2 + b n x n where Yg i s equal to the predicted y i e l d of a s p e c i f i e d genotype, b 1b 2... b n are the p a r t i a l regression c o e f f i c i e n t s , and x^ , x 2...x n are the observed values of independent s i t e parameters. The s i t e factor method commonly i d e n t i f i e d as s o i l - s i t e study has been extensively used i n forest management. Forest s o i l - s i t e studies are used when a d i r e c t measurement of s i t e Index, or the height of the larger trees i n the stand at a s p e c i f i e d age, i s not possible ( s i t e index has been found to be the most useful i n d i c a t o r of the land's p o t e n t i a l productivity for many tree species) Nix (1968). These studies usually incorporate a wide range of s i t e factors such as l i t h o l o g y , landform, slope c l a s s , slope aspect, depth to least permeable horizon, s o i l physical and chemical c h a r a c t e r i s t i c s , climate, and management. Steinbrenner (1979), i n an i n v e s t i g a t i o n of s o i l - s i t e c o r r e l a t i o n s i n the Douglas-fir region of north-western U.S.A., measured various s i t e f a c t o rs and evaluated their influence on tree growth. For the glaciated s o i l s of western Washington a regression equation was developed which 48. explained 81% of the v a r i a t i o n i n y i e l d for Douglas-fir. Site factors used to predict the s i t e index for t h i s region included: the e f f e c t i v e s o i l depth, the depth of the A horizon, the clay content of the B horizon, the slope p o s i t i o n , and mathematical transformations of these f a c t o r s . Steinbrenner's study of forest s o i l p r o d u c t i v i t y r e l a t i o n s h i p s repre-sents a successful example of the c o r r e l a t i o n of s i t e factors with s i t e index. More than one hundred and seventy s o i l - s i t e studies have previously been reviewed by Carmean (1975). These studies have been used i n associa-t i o n with mapping schemes to assess the s p a t i a l extent of each land unit of a given l e v e l of p r o d u c t i v i t y . In i t s completed form t h i s land evaluation provides the forester with an inventory of the quantity and q u a l i t y of land in a p a r t i c u l a r area. The use of the s i t e factor method i n a g r i c u l t u r e as a means of estab-l i s h i n g the land's po t e n t i a l p r o d u c t i v i t y has been l i m i t e d (Nix, 1968). The •attempts have been centered around observation and measurement of . s o i l , c l i m a t i c and management f a c t o r s . Odell (1958) obtained c o r r e l a t i o n s between grain corn y i e l d and the depth of the A s o i l horizon. Rust and Odell (1957) studied corn y i e l d s i n I l l i n o i s and found high c o r r e l a t i o n s with y i e l d and nitrogen added. Fink and Ochtman (1961) worked on i r r i g a t e d s o i l s i n the Sudan and found a c o r r e l a t i o n between y i e l d of cotton and the clay content of the surface s o i l . Krogman and Milne (1968) studied chemical and physical a t t r i b u t e s of saline and a l k a l i s o i l s l i k e l y to influence the growth of crops under i r r i -gation in f i e l d and greenhouse t r i a l s . Stepwise multiple l i n e a r regression analysis indicated that the available phosphorus, sodium'adsorption r a t i o , hydraulic conductivity and hydrogen ion a c t i v i t y explained most of the v a r i a t i o n i n f i e l d y i e l d s , while hydraulic conductivity and available phos-phorus explained most of the v a r i a t i o n i n greenhouse t r i a l y i e l d s . Hoffman (1971) investigated the assessment of s o i l p roductivity i n order to provide quantitative value for Canada Land Inventory (CLI) capabil-i t y classes and to determine which factors influence crop y i e l d s . Independ-ent variables studied included CLI c a p a b i l i t y c l a s s , management fact o r s , c l i m a t i c factors and some s o i l f a c t o r s . P r e d i c t i v e equations were derived for y i e l d s of corn, barley and oats. As expected, s o i l class accounted for most of the y i e l d v a r i a b i l i t y i n the equation. By d e f i n i t i o n , s o i l capa-b i l i t y class represents the sum of a l l factors a f f e c t i n g p r o d u c t i v i t y . Hoffman (1971) and v a n V I i e t et a l . (1979) were reasonably successful i n t h e i r attempts to evaluate land p r o d u c t i v i t y . Their studies, when r e s t r i c t e d to the area under i n v e s t i g a t i o n , s u c c e s s f u l l y evaluated land p r o d u c t i v i t y . One d i f f i c u l t y i n the a p p l i c a t i o n of the i r model to other areas i s the difference i n pro d u c t i v i t y for a given c a p a b i l i t y class throughout the country. The techniques adopted i n s i t e factor studies are e s s e n t i a l l y l o c a t i o n and use s p e c i f i c . The s t a t i s t i c a l equations developed are s t a t i c repre-sentations of dynamic systems and are v a l i d only within the range of s i t e properties and for the form of b i o l o g i c a l product studied. Nevertheless, with the stated region such equations can have pre d i c t i v e values and serve as a basis for delineating areas of land with appropriate combinations of s i t e f a c t o r s . 50. i i i . System Analysis and Simulation Approach System analysis and simulation methods are based on pred i c t i n g bio-l o g i c a l p r o d u c t i v i t y of a stated genotype at any l o c a t i o n . This approach i s concerned with r e s o l u t i o n of a complex system into a large number of simple component processes and subsequent synthesis into a symbolic representation or mathematical model of the whole system. When a model i s developed, i t should accurately describe the behaviour of a complex system that can be generated through time In simulation studies and used to show how the system can be manipulated for optimum r e s u l t s . In applying these techniques to land evaluation for b i o l o g i c a l produc-t i o n , the primary objective should be to develop r e a l i s t i c working models of crop ecosystems. The i d e n t i f i c a t i o n of key b i o l o g i c a l and physical para-meters i s a c o r o l l a r y to such model development. Following t h i s , the inven-tory of land resources should be directed towards the development of methods for management or estimation of the s p a t i a l and temporal v a r i a t i o n of these key parameters. Then the inventory, coupled with an appropriate model, can be used to predict output or y i e l d of any crop under a defined system of management at any l o c a t i o n . The a p p l i c a t i o n of t h i s method to complex b i o l o g i c a l systems i s s t i l l i n i t s infancy, but a few studies have been conducted such as the study of forest insect pest management (Watt, 1964) and the management analysis for a salmon f i s h e r y (Paulik and Greenough, 1966). A comparison between the d i f f e r e n t methods of s u i t a b i l i t y assessments i s presented i n Table 4. Table 4 COMPARISON BETWEEN DIFFERENT METHODS OF SUITABILITY ASSESSMENTS ANALOGUE APPROACH SITE FACTOR APPROACH SYSTEM ANALYSIS APPROACH BASIC CONCEPT: Relate s i t e experience to other s i t e s w i th s imi la r or analogue cond i t i ons . Relate key parameters to pro-d u c t i v i t y w i t h i n a given environment. I d e n t i f y b i o l o g i c a l and phys i -c a l pathways, processes and I n t e r a c t i o n s , and attempt to develop a q u a n t i t a t i v e model to simulate a b i o l o g i c a l eco-system. PARAMETERS EMPHASIZED: Mostly physical parameters that are r e a d i l y observable and measurable. Select ive physical and c l ima-t o l o g i c a l parameters that have a d i r e c t Inf luence on produc-t i v i t y and y i e l d . Processes r e l a t i n g to energy, water , n u t r i e n t s and b i o t a . NATURE OF APPROACH: S ta t i c S ta t i c Dynamic ADVANTAGES: 1) In In tens ive ly used areas p r o d u c t i v i t y data can be obtained from farm records and experimental p l o t s . 2) No previous knowledge on func t i ona l re la t ionsh ips i s needed. 1) I d e n t i f i e s those fac tors tha t d i r e c t l y in f luence pro-d u c t i v i t y and y i e l d . 2) Under constant management y i e l d / s i t e fac to r i n t e r r e -la t i onsh ips are i d e n t i f i e d . 1) I d e n t i f i e s func t iona l path-ways . 2) Helps to understand, quan-t i f y , and pred ic t behaviour and response of the eco-system. DISADVANTAGES: 1) Often there i s a poor r e l a -t i onsh ip between parameters and p r o d u c t i v i t y . 2) Many years of repeated management and product ion are necessary to a r r i ve at r e l i a b l e est imates. 3) Present land use inf luences p r o d u c t i v i t y assessments since data for other crops and uses Is not r e a d i l y a v a i l a b l e . 1) Only v a l i d w i t h i n the range of s i t e proper t ies examined and only v a l i d fo r the form of b i o l o g i c a l p r o d u c t i v i t y under cons idera t ion . 1) Complexity of b i o l o g i c a l system makes model l ing and h o l i s t i c approach d i f f i c u l t to develop. Based on Nix, H.A. 1968. The assessment of b i o l o g i c a l p r o d u c t i v i t y . I n : Land Eva lua t ion , (Ed. G.H. S tewar t ) , Macml l l ian, A u s t r a l i a , pp. 77-78. 52. D. SUMMARY This chapter reviewed many of the most commonly used land evaluation methods. The fundamental concept of genetic and parametric land c l a s s i f i c a -t i o n was discussed and the evaluation of inventory data for a g r i c u l t u r a l c a p a b i l i t y and s u i t a b i l i t y assessments were reviewed. Examples of the major a g r i c u l t u r a l land c a p a b i l i t y schemes included such categoric schemes as the USDA, CLI and LUGC systems and the parametric schemes proposed by Moss and S t o r i e . S u i t a b i l i t y methods were reviewed and summarized using examples of the analogue, s i t e f a c t o r s , and the system analysis method. F i n a l l y , a sp e c i a l c a p a b i l i t y method to acess f e r t i l i t y l i m i t a t i o n FCC was also review-ed. 53. III. METHODOLOGY The data base were compiled from the Land Resources Mapping Project (LRMP), which included inventory on landforms, geology, s o i l s , native vegetation, land use and climate ( p r e c i p i t a t i o n , temperature and moisture regime) at various scales: - C l i m a t o l o g i c a l Maps at 1:250,000 - Geological Maps at 1:125,000 - Land Systems Maps ( s o i l s ) at 1:50,000 - Land U t i l i z a t i o n Maps (current land use) at 1:50,000 - Land Ca p a b i l i t y Maps at 1:50,000 For the K a i l a l i D i s t r i c t a l l a v a i l a b l e data set was used as mentioned above. The Land System data base was c o l l e c t e d over a period of 2 weeks by a group of surveyors using the transect method. The i n t e n s i t y of inspection s i t e s are approximately 1 s i t e per 700 hectares with about 10 man days work per 1:50,000 map sheet. The project area was divided into 3 Land Systems co n s i s t i n g of 12 land u n i t s , which were further subdivided into 22 land types for management purposes. At the time the survey was c a r r i e d out no attempt was made to evaluate the data for s p e c i f i c land uses and the present research project was i n i t i a t e d to f i l l t h i s gap. The project w i l l provide a framework to evaluate the available survey data for a g r i c u l t u r a l production for six major crops grown i n r o t a t i o n s . The method developed was applied to a case study - the K a i l a l i d i s t r i c t , and since the same type of survey data i s a v a i l a b l e for the ent i r e country i t i s anticipated that the evaluation method can r e a d i l y be applied to other parts of the country. The method was developed i n f i v e steps and included the following tasks: 54. A. . Develop method to i d e n t i f y e s s e n t i a l biophysical parameters for a s u i t a b i l i t y c l a s s i f i c a t i o n for growing six major crops i n the K a i l a l i d i s t r i c t . B. Develop method to evaluate crop s u i t a b i l i t y of a l l mapping units for double cropping without i r r i g a t i o n and t r i p l e cropping with i r r i g a t i o n . C. Quantitative assessment and comparison of current land use and improved land use for the K a i l a l i d i s t r i c t based on s u i t a b i l i t y evaluation. D. Examination of long term f e r t i l i t y implications under current and improved land use. A. Develop Method to I d e n t i f y E s s e n t i a l Biophysical Parameters for a S u i t a b i l i t y C l a s s i f i c a t i o n f or Six Major Crops i n the K a i l a l i D i s t r i c t Six major crops were selected for t h i s study. They included r i c e , corn, wheat, l e n t i l s , mustard and m i l l e t . These crops are currently grown i n the region, are well adapted to the p r e v a i l i n g environmental conditions, are the main staples and are of national economic importance. An extensive l i t e r a t u r e review was c a r r i e d out i n order to determine optimum and marginal s o i l , s i t e and c l i m a t i c conditions for each crop. Emphasis was given to crop assessments i n subtropical monsoon c l i m a t i c conditions and twelve s o i l and s i t e conditions and eight c l i m a t i c conditions were judged to be of s i g n i f i c a n c e . Given the lack of p r e c i s i o n i n the l i t e r a t u r e data and the reconnaissance nature of the b i o p h y s i c a l data a v a i l -able for the Nepalese Survey, i t was decided to divide the s o i l and s i t e conditions into three basic categories: optimum, marginal and unsuited conditions, and quantitative c l a s s l i m i t s were established for each para-meter. 55. These findings were then related to the FAO s u i t a b i l i t y assessment scheme and since t h i s sytem has f i v e categories some modifications had to be made. The way the l i t e r a t u r e based system i s converted into the FAO s u i t -a b i l i t y scheme i s given i n Table 5. Based on the av a i l a b l e l i t e r a t u r e the quantitative s i t e and s o i l condi-tions necessary to determine the S2 s o i l s u i t a b i l i t y class could not be determined for any one of the crops. As a consequence a s i m p l i s t i c assess-ment of optimum, marginal, unsuited condition was determined for every crop under i n v e s t i g a t i o n . The Nl category was used only i n those cases where the Table 5 CONVERSION FROM LITERATURE ASSESSMENT TO FAO SUITABILITY FAO S u i t a b i l i t y Rating L i t e r a t u r e Based S o i l and Sit e Conditions  51 highly suitable optimum conditions 52 moderately su i t a b l e — 53 marginally suitable marginal conditions Nl currently not sui t a b l e marginal or unsuited conditions because of lack of water N2 permanently not sui t a b l e unsuited conditions other than lack of water l i m i t i n g conditions could be overcome by the introduction of i r r i g a t i o n water. An example of the quantitative evaluation scheme used to determine s u i t a b i l i t y of each mapping unit i s given i n Table 6 and applies to r i c e only. Based on the l i m i t e d c l i m a t i c data a v a i l a b l e i t appears that there are r e l a t i v e l y small c l i m a t i c v a r i a t i o n within the Terai Physiographic Region. If based on r o t a t i o n a l crop sequences the sub-humid subtropical climate i s such that i t i s not l i m i t i n g to any one of the six crops used i n t h i s study. There are no temperature l i m i t a t i o n s and moisture d e f i c i e n c i e s Table 6 RATING CRITERIA FOR RICE SUITABILITY S u i t a b i l i t y SI S3 N2 Parameters Optimum Marginal Not Suitable Natural drainage poor well drained rapid S o i l depth (cm) >100 50-20 <20 S o i l texture f i n e clayey f i n e s i l t y f i n e loamy loamy coarse sand coarse sandy loam coarse sand Available water holding capacity (cm/cm) 0.200 - 0.226 0.114 0.088 S a l i n i t y (mm hos/cm at 25°C) <4 8-16 >16 pH 5.5 - 6.5 3.5 - 5.0 or 8.5 - 9.0 <3.5 or >9.0 Depth to ground water table during growing season (cm) 25 - 50 100 - 150 >150 Slope (degree) 0 - 1 3 - 5 >5 Flooding none some severe Water require-ment during growing season (mm) >700 450 <400 Permeability (cm/hr) <0.15 15.0 - 5.0 >50.0 Gravels, cobbles on the surface (%) <3 15 - 35 >50 \ 57. during the dry summer season can be overcome by i r r i g a t i o n . As a conse-quence only moisture d e f i c i e n c i e s r e l a t i n g to s o i l type was used i n the s u i t a b i l i t y assessment. B. Develop Method to Evaluate Crop S u i t a b i l i t y of A l l Mapping Units for Double Cropping Without I r r i g a t i o n and T r i p l e Cropping with I r r i g a t i o n In order to assess land s u i t a b i l i t y for crop r o t a t i o n the inherent c h a r a c t e r i s t i c s of each mapping unit had to be evaluated i n r e l a t i o n to the seasons. The main growing season i s during the rainy or monsoon season (June to September) when the temperatures are warm with p l e n t i f u l p r e c i p i t a -t i o n . This i s followed by the winter season (October to January) which i s cool and somewhat dry with only occasional r a i n s . The summers (February to May) are usually hot and dry with hardly any p r e c i p i t a t i o n . Depending on the s o i l and s i t e conditions i t i s therefore possible to i n i t i a t e s e l e c t i v e double cropping without i r r i g a t i o n since the monsoon season i s the main growing season the crops that can be grown depend on the a v a i l a b i l t y of water and for d i f f e r e n t crops i t i s often possible to require very contradictory conditions. A good s u i t a b i l i t y r a t i n g for r i c e may be a poor s u i t a b i l i t y for corn. It i s thus necessary to adopt a s u i t a b i l i t y scheme which i s s p e c i f i c to a given crop r o t a t i o n on a s p e c i f i c mapping u n i t . For double cropping systems the ratings were f i r s t given to i n d i v i d u a l crops for the main growing season (monsoon season) and a second r a t i n g was then done for the dryer winter season. The best choice i n crop r o t a t i o n was selected from the seasonal crop r o t a t i o n table provided i n Figure 11. For each land mapping unit the s u i t a b i l i t y for the monsoon and winter season was 58. tabulated for a l l crops and rotations and the mean value for the two ratings was used as an index of s u i t a b i l i t y , the lowest mean value being the best s u i t a b i l i t y r a t i n g . The crop r o t a t i o n sequence which had the best average s u i t a b i l i t y r a t i n g was i d e n t i f i e d as the most appropriate land use and i n cases where several rotations had the same ratings the r o t a t i o n with low f e r t i l i z e r demands and high s t r a t e g i c demand for national production was selected. The same procedure was followed i n assessing t r i p l e crop r o t a t i o n under a regional i r r i g a t i o n scheme. The K a i l a l i D i s t r i c t possesses a tremendous" po t e n t i a l for regional development under i r r i g a t i o n since there are no serious c l i m a t i c l i m i t a t i o n s r e s t r i c t i n g the growth and performance of the crops selected. T r i p l e cropping r o t a t i o n scheme ratings under i r r i g a t i o n were f i r s t given to i n d i v i d u a l crops for the monsoon season; a second r a t i n g was then given for the winter season and a t h i r d r a t i n g was done for the dry, hot summer season. For each mapping unit the s u i t a b i l i t y for the three seasons were tabulated for a l l crops and rotations and the mean value of the three ratings was used as an index of s u i t a b i l i t y , the lowest being the best. In t h i s r o t a t i o n scheme the seasonal dependence of crops i s less c r i t i c a l as i r r i g a t i o n water i s available throughout the growing period (see Figure 11). Three of the twelve mapping units used i n t h i s project are pure units while the others are complex units made up of two to three d i f f e r e n t compon-ents. Because of the scale of mapping and the i n t r i c a c y of the pattern i t was not possible to subdivide these complex units into the i n d i v i d u a l components. In the evaluation part t h i s problem was addressed i n two ways. On the map the crop s u i t a b i l i t y i s provided only for the dominant component 59. Figure 11 EXAMPLE OF METHOD USED TO DEVISE MULTIPLE CROPPING SYSTEM Corn Ear ly / Corn Ear ly / Rice Ear ly Wheat / IRRIGATED Corn (Monsoon) 7~ s /. Mustard or M i l l e t L e n t i l s Wheat or Winter Corn Rice Late L e n t i l s Mustard 21 Wheat Rice Late L e n t i l s Mustard or M i l l e t Wheat or Winter Corn NON-IRRIGATED Corn (Monsoon) M i l l e t L e n t i l s Wheat Mustard 7" Wheat Rice Late Mustard L e n t i l s Upland C u l t i v a t i o n Lowland C u l t i v a t i o n Upland C u l t i v a t i o n Lowland C u l t i v a t i o n i i i i i i • i i i i 0 4 8 12 16 20 24 28 32 36 40 44 48 WEEKS Ju MONTHS SUMMER MONSOON OR RAINY WINTER SEASONS 60. and an i n d i c a t i o n of the percentage dominance per unit i s provided. In the table and text each component of the mapping unit was assessed separately. The dominant component was considered unique, while the co-dominant compon-ents were rel a t e d to the most appropriate remaining mapping u n i t s . It i s thus possible to have two and i n some cases three, s u i t a b i l i t y ratings per complex u n i t . In these cases the proportional areal subdivision of the complex i s provided. C. Quantitative Assessment and Comparison of Current Land Use and Improved  Land Use for the K a i l a l i D i s t r i c t Based on S u i t a b i l i t y Evaluation As part of the resource inventory a land use survey was c a r r i e d out but t h i s task was separate from the survey and the land use mapping units were not r e l a t e d to the physiographic framework used for the rest of the inven-tory. Fortunately both the land use and biophysical resource survey were c a r r i e d out at 1:50,000 scale, and i n order to use the physiographically based land units for evaluation and p r e d i c t i v e purposes i t was necessary to q u a n t i t a t i v e l y determine the type and amount of current land use for each of the twelve types of land units which cover the K a i l a l i d i s t r i c t . This was accomplished by f i r s t t r a n s f e r r i n g the land use boundaries from the land use maps to the resource inventory or land systems maps. This was then followed by quantitative measurements of each type of land use i n each unit using a Lasico 1250D d i g i t a l planimeter. The data was then summarized to allow a compilation of the amount and type of land use for each land unit on the map. The current land use for the most dominant cropping patterns include: 61. Major Rotations Monsoon Winter/Dry Season 1 2 3 4 5 Rice or Corn Corn-Millet (intercropped) Rice Rice Rice Fallow Cereal or Oilseed Pulses Wintercrop Fallow 6 7 Corn Corn Mustard Cereal Since the current land use and the s u i t a b i l i t y ratings were based on the physiographically based mapping un i t s , i t was e s s e n t i a l to f i r s t c a l c u -l a t e a l l biophysical Information on the basis of the twelve types of land mapping u n i t s . The areal d i s t r i b u t i o n of each type of land unit i n the K a i l a l i D i s t r i c t was f i r s t determined and the current and most suitable land use was then calculated for the same u n i t s . This allowed a three way comparison which included current land use, improved land use without regional i r r i g a t i o n , and improved land use with a regional i r r i g a t i o n scheme. For each unit the crop r o t a t i o n with the best o v e r a l l s u i t a b i l i t y r a t i n g was chosen as the optimum use and since most mapping units were complex units an assessment was made for each member of the complex u n i t . In addition, a l l areas were reduced by a weight factor of 20% since a s i g n i f i c a n t portion of each mapping unit i s taken up by road networks, seasonal canals, f i e l d bunds, i n f r a s t r u c t u r e and uncultivatable land. The r e s u l t s of t h i s analysis were provided i n a) comparative tables where the ratings for each mapping unit and each crop r o t a t i o n was indicated and b) a crop s u i t a b i l i t y map i n d i c a t i n g where the crop rotations with the best s u i t a b i l i t y r a t i n g for the dominant mapping unit occur i n the K a i l a l i 62. d i s t r i c t . In addition, a quantitative comparison between current land use and improved land use with and without i r r i g a t i o n was made for the d i s -t r i c t . The t o t a l area for each land use was calculated and m u l t i p l i e d by the current average y i e l d s for each crop. This was done to demonstrate i n a conservative manner what the maximum changes i n production w i l l be as a r e s u l t of d i f f e r e n t improvement i n land use i n t h i s d i s t r i c t . D. EXAMINATION OF LONG TERM FERTILITY IMPLICATIONS UNDER CURRENT AND  IMPROVED LAND USE A s u i t a b i l i t y assessment without f e r t i l i z e r consideration i s not sustainable i n the long run. Under current land use, using t r a d i t i o n a l methods of farming p r a c t i c e s , the system i s only sustainable i n the lower piedmont p l a i n (lower Terai) as i t i s r i c e dominated, but i n the upper pied-mont p l a i n (upper t e r a i ) the system cannot be c a l l e d sustainable i n the long run. The s o i l s i n the upper t e r a i are coarser i n texture, droughty and vulnerable to leaching losses of nutrients as soon as the land i s brought under c u l t i v a t i o n . The type of crop rotations such as maize and wheat which require an open aerated s o i l lead to rapid depletion of organic matter unless legumes are incorporated i n sui t a b l e long term r o t a t i o n s . Improved land use systems using double and t r i p l e cropping systems are considered high demanding i n terms of f e r t i l i z e r requirements and are vulnerable to nutrient depletions i n the long run. Current land use or t r a d i t i o n a l land use i s labour intensive and uses only organic f e r t i l i z e r s with very l i t t l e inputs, while improved land uses without i r r i g a t i o n are considered low c a p i t a l intensive systems with only a l i m i t e d amount of inputs i n chemical f e r t i l i z e r s and management, and 63. improved land use with i r r i g a t i o n i s c a p i t a l intensive r e q u i r i n g high inputs. For f e r t i l i z e r consideration, the F e r t i l i t y C a p a b i l i t y C l a s s i f i c a t i o n System was used to group s o i l s that have the same kind of l i m i t a t i o n s from the point of view of f e r t i l i t y management. The inherent l i m i t a t i o n of each mapping unit was i d e n t i f i e d , so i n t e r p r e t a t i o n i n r e l a t i o n to s p e c i f i c farm-ing systems of rotations could be modified to su i t that use. A s p e c i a l consideration was given to cropping sequences and s e l e c t i o n of crop r o t a t i o n s . The f e r t i l i t y of these s o i l s can be maintained for a considerable time period i f rotations i n v o l v i n g legumes are developed i n a mixed-farming environment. A good r o t a t i o n sequence with a multiple choice of crops i s better than mono-culture r o t a t i o n . The nitrogen f i x i n g capacity of legumes are considered highly b e n e f i c i a l to the following crop i n the ro t a t i o n . A t h i r d consideration to f e r t i l i z e r a p p l i c a t i o n i s the use of chemical f e r t i l i z e r s i n the improved land use systems to sustain high y i e l d s i n the long run. This i s the c a p i t a l intensive system re q u i r i n g high inputs from a l l sectors. In the forseeable future chemical f e r t i l i z e r s w i l l play an even more important r o l e i f high y i e l d s are to be sustained under intensive management of t r i p l e cropping r o t a t i o n systems under i r r i g a t i o n . E. SUMMARY The method outlined was designed to integrate a l l resource inventory data and land use information into a common data base for quantitative assessment for a single d i s t r i c t . This was followed by evaluating the bio-physical information for crop s u i t a b i l i t y assessment of sin g l e , double and t r i p l e yearly cropping systems for six economically important crops. The land system's mapping units were then used as a base for predicting s u i t -a b i l i t y ratings for crops and r o t a t i o n systems. Next, the areal extent of current land use was calculated and compared with improved i r r i g a t e d and non-irrigated use and the o v e r a l l production improvements were determined using the currently available y i e l d data. A quantitative examination of the land use a l t e r n a t i v e s and production improvements for the K a i l a l i d i s t r i c t was then determined. F i n a l l y , t h i s case study w i l l be used as a demonstra-t i o n project for land use planning and the methodology developed i n t h i s project w i l l be applied to other parts of Nepal where s i m i l a r b i o p h y s i c a l information i s a v a i l a b l e . 65. IV. RESULTS OF LAND SUITABILITY ASSESSMENTS FOR THE KAILALI DISTRICT The r e s u l t s obtained i n t h i s study w i l l be discussed i n the following sequences: i n section A the r e s u l t s of the l i t e r a t u r e review are presented i n which optimum s o i l , s i t e and c l i m a t i c conditions are summarized for each of the six crops used i n t h i s study. This i s followed by presenting the s o i l and s i t e c l a s s l i m i t s considered e s s e n t i a l to convert the environmental conditions into the FAO s u i t a b i l i t y c lasses. Section B w i l l present the r e s u l t s of the s u i t a b i l i t y evaluation scheme for double and t r i p l e annual crop r o t a t i o n s . In section C the current land use and improved land use, which includes crop r o t a t i o n s , w i l l be compared with the s u i t a b i l i t y assess-ment, and f i n a l l y section D w i l l deal with short and long term f e r t i l i z e r implications r e s u l t i n g from double and t r i p l e crop r o t a t i o n s . A. SOIL, SITE AND CLIMATIC REQUIREMENTS TO ESTABLISH SUITABILITY CLASSES  FOR SIX MAJOR CROPS IN THE TERAI REGION OF NEPAL. The approach taken for conducting t h i s study included: i n the f i r s t phase f i n d i n g optimum s o i l and c l i m a t i c conditions for the six crops chosen through a l i t e r a t u r e search, and i n the second phase defining parameters and class l i m i t s for s u i t a b i l i t y assessments. 1. Establishing Optimum, Marginal and Undesirable Environmental Conditions  for Six Major Crops on the Basis of Literature Data An extensive l i t e r a t u r e review was conducted to determine s o i l , s i t e and c l i m a t i c conditions for r i c e , corn, wheat, l e n t i l , mustard and m i l l e t , using l i t e r a t u r e mainly for subtropical monsoon c l i m a t i c conditions. In each case e s s e n t i a l s o i l / s i t e conditions were tabulated separately from c l i m a t i c conditions. The following e s s e n t i a l s o i l / s i t e parameters that influence crop per-formance were selected for th i s study: slope, s o i l depth, organic matter, texture, drainage, pH and s e n s i t i v i t y to s a l i n i t y . The selected c l i m a t i c parameters c r i t i c a l for optimum crop production were: t o t a l growing period, day length requirement for flowering, tempera-ture requirement for growth, water requirements for the growing season, s e n s i t i v i t y to water supply, water u t i l i z a t i o n e f f i c i e n c y for harvested y i e l d s , and p r e c i p i t a t i o n . Detailed r e s u l t s for each crop are provided i n Appendix I which includes a climate and s o i l / s i t e table for each of the six crops. The summary of the l i t e r a t u r e review for s o i l and s i t e conditions i s given i n Table 7 while the summary of the c l i m a t i c requirements i s provided i n Table 8. There are a number of problems with the data i n these two summary tables: a) they are not very accurate as they are not s i t e s p e c i f i c , b) they give a very poor estimate and understanding of crop requirement and performance, and c) the biophysical data are i n s u f f i c i e n t for accurate predictions or assumptions for the crops chosen. Nevertheless, the general information c o l l e c t e d can be u t i l i z e d to produce maps and tables concerning the crops chosen for planning purposes, synthesizing biophysical data relevant to crop production. Information about s o i l and s i t e properties e s s e n t i a l for crop requirements are the raw material for i n d i r e c t land evaluation. These land c h a r a c t e r i s t i c s can be d i r e c t l y assessed from Resource Inventory data. The information c o l l e c t e d can be interpreted to give a s u i t a b i l i t y appraisal for the crops chosen, and then the general f e a s i b i l i t y of land improvements can be assessed. Table 7 SOIL REQUIREMENTS FOR MAJOR CROPS BASED ON LITERATURE REVIEW CROPS SLOPE OPTIMUM SOIL (< DEPTH :m) ORGANIC MATTER TEXTURAL CLASS DRAINAGE pH SENSITIVITY TO SALINITY Optimum Range Optimum Range Optimum Range Optimum Range Rice 0-2 >100 20-100 high f i ne clayey coarse s l l t y to f i ne clayey poor to somewhat poor we l l to very poor 5.5-6.5 3.5-8.4 to le ran t to s a l i n i t y Corn 0-8 50-100 10-100 moderate to high s l l t y to c lay loams sandy loam to heavy clays moderately we l l to we l l Imperfect to some-what excessive 5.5-8.2 5.0-8.5 moderately sens i t i ve Wheat 0-8 50-100 10-100 moderate to high loam to c lay loams sandy loam to heavy clays moderately we l l to we l l imperfect to some-what excessive 5.5-8.2 5.2-8.5 moderately t o l e r a n t L e n t i l 0-2 50 15-50 medium loams loamy sands to heavy clays moderately we l l to we l l w e l l to imperfect 6 .8-7.5 4 .5 -9 .0 moderately sens i t i ve Mustard 0-5 moderately deep (50) vide range medium sandy loam to loams loamy sands to c lay we l l moderately w e l l to excessive 6.5-7.0 5.5-8.0 moderately sens i t i ve Finger M i l l e t 0-8 >75 25-75 medium to low sandy loam to c lay loams loamy sands to clays moderately we l l to we l l imperfect to excessive 5.5-7.5 5.0-8.2 moderately sens i t i ve * Based on 40 l i t e r a t u r e sources reviewed and i l l u s t r a t e d In Appendix I . Table 8 CLIMATIC REQUIREMENTS FOR MAJOR CROPS BASED ON LITERATURE REVIEW CROPS TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH "C Optimum (Range) WATER REQUIREMENTS mm/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (% moisture) PRECIPITATION onn Rice 90-150 short day/ day neut ra l 20-38 (12-45) 350 - 1000 high (>1.15) 0-70 - 1.2 Rice (15-20) 1200 - 4000 Corn 100-180 short day/ day neut ra l 21-32 (12-35) 400 - 800 high (1 .15) 0.80 - 1.60 gra in (10-13Z) 500 - 2300 Wheat spr ing 100-130 win ter 180-250 day n e u t r a l / long day 15-31 (0-37) 450 - 650 medium to high ( w i n t e r : 1.0 s p r i n g : 1.15) 0.80 - 1.00 gra in (12-15%) 650 - 1500 L e n t i l ea r l y 80-110 l a t e 125-150 short day/ day neut ra l 15-25 (0-45) 150 - 790 medium to h igh (1 .0 - 1.15) 0.30 - 0.80 (8 - 10Z) 650 - 700 Mustard 80-160 not c r i t i c a l 15-20 (5-35) <500 low (<0.85) 0.40 - 0.80 400 - 700 Finger M i l l e t 70-180 short day/ day neut ra l 20-35 (8-45) 330 - 760 medium-low (0.85 - 1.0) 0.15 - 0.30 400 - 1156 * Based on 39 l i t e r a t u r e sources reviewed and i l l u s t r a t e d i n Appendix I . 69. On the basis of t h i s , the most suitable land for any s p e c i f i c crop can be evaluated and related to the mapping u n i t s . Crop s u i t a b i l i t y for each map unit can be estimated from the s p e c i f i c agronomic requirements and general crop s u i t a b i l i t y can be interpreted. Information c o l l e c t e d from a l i t e r a t u r e search and management practices appropriate to d i f f e r e n t combina-tions of s o i l s and crops can be generalized. Further more, the approach i s a quick and rough estimate of the area s u i t a b i l i t y for future regional land use strategy and land a p p r a i s a l , and hopefully f a c i l i t a t e s the decision-mak-ing process. 2. Defining Parameters and Class Limits for Establishing a Modified FAQ  Suit a b i l i t y Assessment. In de f i n i n g parameters and class l i m i t s for e s t a b l i s h i n g a modified FAO s u i t a b i l i t y assessment only c r i t i c a l s o i l and s i t e parameters e s s e n t i a l for crop growth and performance were used. The c l i m a t i c parameters e s s e n t i a l for growth were not stressed as the study area f a l l s within the sub-humid subtropical c l i m a t i c zone, which, based on l i t e r a t u r e review, shows that i t i s well suited for the crops and crop rotations proposed. Based on the a v a i l a b l e c l i m a t i c record for the area i n the T e r a i , there are no c l i m a t i c l i m i t a t i o n s for growing these crops and the c l i m a t i c v a r i a b i l i t y based on very l i m i t e d data appears to be i n s i g n i f i c a n t . As a consequence no c l i m a t i c considerations were made to determine s u i t a b i l i t y assessments i n the K a i l a l i D i s t r i c t . As i d e n t i f i e d from the l i t e r a t u r e review, twelve s o i l and s i t e parameters were used to define optimum, marginal and unsuitable conditions for each crop. The r e s u l t s are presented i n tables and from the a v a i l a b l e data i t was not possible to come up with more than 3 categories, as the 70. knowledge on crop requirements and management were i n s u f f i c i e n t and the e x i s t i n g s o i l information from the inventory data base was inadequate for greater subdivision. By using only three of the stated categories the scheme was converted in t o the FAO s u i t a b i l i t y categories, and provisions were made for unsuited areas with adequate topographic conditions to be placed i n Nl category, cur r e n t l y not s u i t a b l e . In order to meet the optimum SI category, requirements for a l l i d e n t i -f i e d s o i l and s i t e conditions had to be s a t i s f i e d , otherwise i t was auto-m a t i c a l l y placed into the lower S3 category - marginally s u i t a b l e . If one or more s o i l and s i t e conditions are not met i n class S3, then i t i s c l a s s i -f i e d as permanently unsuitable N2, except where adequate topographic condi-tions p r e v a i l , then i t i s classed as Nl - currently not s u i t a b l e . In cases where i r r i g a t i o n water i s a v a i l a b l e , class Nl i s c l a s s i f i e d as S3 to ind i c a t e that i t i s marginally s u i t a b l e for a g r i c u l t u r a l development under such conditions. The r e s u l t s of the modified FAO s u i t a b i l i t y r a t i n g scheme are presented for each crop i n Tables 9, 10, 11, 12, 13 and 14. A general comparison between the tables show that three d i s t i n c t types of s o i l and s i t e condi-tions are optimum for the i d e n t i f i e d crops. F i r s t , the s o i l and s i t e requirements for r i c e are unique from a l l the other crops as i t i s best suited for poorly drained areas having heavy textured s o i l s with low perme-a b i l i t y . Secondly, conditions for corn and wheat seem to be s i m i l a r as they both require deep, well-drained s o i l s with adequate moisture holding capa-c i t y . T h i r d l y l e n t i l , mustard and m i l l e t seem to be i n a class by them-selves, having requirements for s o i l s that are moderately deep with somewhat 71. Table 9 RATING CRITERIA FOR RICE SUITABILITY Sui t a b i l i t y - SI S3 N2 Par ameters Optimum Marginal Not Suitable Natural drainage poor well drained rapid S o i l depth (cm) 100 20 - 50 <20 S o i l texture f i n e clayey f i n e s i l t y f ine loamy loamy coarse sand or coarse sandy loam coarse sand Available water holding capacity (cm/cm) 0.206 - 0.200 0.114 0.088 S a l i n i t y (mm hos/cm at 25°C) <4 8 - 1 6 >16 pH 5.5 - 6.5 3.5 - 5.0 or 8.5 - 9.0 <3.5 or >9.0 Depth to ground water table during growing season (cm) 25 - 50 100 - 150 >150 Slope (degree) 0 - 1 3 - 5 >7 Flooding none some severe Water require-ment during growing season (mm) >700 450 400 Permeability (cm/hr) <0.15 15.0 - 5.0 >50.0 Gravels, cobbles on the surface (%) <3 15 - 35 >50 Table 10 RATING CRITERIA FOR CORN SUITABILITY S u i t a b i l i t y SI S3 N2 Parameters Optimum Marginal Not Suitable Natural drainage well drained imperfect or rapid poor or excessive S o i l depth (cm) >100 10 - 25 <10 S o i l texture loamy s i l t y clay or coarse sandy loam f i n e clayey/ s i l t y or coarse sand Available water holding capacity (cm/cm) 0.159 >0.191 or <0.114 0.226 or 0.088 S a l i n i t y (mm hos/cm at 25°C) <4 6 - 8 >10 pH 6.0 - 7.0 3.5 - 5.0 or 8.5 - 9.0 <3.5 or >9.0 Depth to ground water table during growing season (cm) 100 25 10 Slope (degree) 0 - 4 10 - 15 >15 Flooding none occasional severe Water require-ment during growing season (mm) 800 500 300 Permeability (cm/hr) 1.5 - 5.0 0.15 - 0.50 or 15.0 - 50.0 <0.15 >50.0 Gravels, cobbles on the surface (%) <3 15 - 35 >50 Table 11 RATING CRITERIA FOR WHEAT SUITABILITY S u i t a b i l i t y SI S3 N2 Parameters Optimum Marginal Not Suitable Natural drainage well drained imperfect or rapid poor or excessive S o i l depth (cm) >100 10 - 15 <10 S o i l texture loamy s i l t y clay or coarse sandy loam f i n e clayey/ s i l t y or coarse sand Available water holding capacity (cm/cm) 0.159 >0.191 or <0.114 0.226 or 0.088 S a l i n i t y (mm hos/cm at 25°C) <5 10 - 15 >16 pH 6.0 - 6.5 3.5 - 5.0 or 8.5 - 9.0 <3.5 or >9.0 Depth to ground water table during growing season (cm) 80 - 100 25 15 Slope (degree) 0 - 4 10 - 15 >15 Flooding none occasional severe Water require-ment during growing season (mm) 650 350 <300 Permeability (cm/hr) 1.5 - 5.0 0.15 - 0.50 or 15.0 - 50.0 <0.15 >50.0 Gravels, cobbles on the surface (%) <5 15 - 35 >50 Table 12 RATING CRITERIA FOR LENTIL SUITABILITY S u i t a b i l i t y SI S3 N2 Parameters Optimum Marginal Not Suitable Natural drainage well drained Imperfect or rapid poor or excessive S o i l depth (cm) >50 >20 <10 S o i l texture loamy s i l t y clay or loamy coarse sand f i n e clayey/ s i l t y or coarse sand Available water holding capacity (cm/cm) 0.154 >0.191 or <0.114 0.226 or 0.088 S a l i n i t y (mm hos/cm at 25°C) 1.3 5.3 >16 pH 7.0 - 7.5 3.5 - 4.5 or 9.0 <3.5 or >9.5 Depth to ground water table during growing season (cm) >50 20 - 30 15 Slope (degree) 0 - 2 12 - 15 >15 Flooding none occasional severe Water require-ment during growing season (mm) 500 200 - 300 <150 Permeability (cm/hr) 1.5 - 5.0 0.15 - 0.50 or 15.0 - 50.0 <0.15 >50.0 Gravels, cobbles on the surface (%) 5 15 - 35 >50 Table 13 RATING CRITERIA FOR MUSTARD SUITABILITY 75. S u i t a b i l i t y SI S3 N2 Parameters Optimum Marginal Not Suitable Natural drainage well drained imperfect or rapid poor or excessive S o i l depth (cm) >50 10 - 20 <10 S o i l texture sandy loam to loam s i l t y clay/ clays or loamy coarse sand f i n e clayey/ s i l t y or coarse sand Available water holding capacity (cm/cm) 0.154 - 0.159 >0.191 or <0.114 0.226 or 0.088 S a l i n i t y (mm hos/cm at 25°C) <4 18 - 15 >15 pH 6.5-7.0 3.5 - 5.0 or 8.5 - 9.0 <3.5 or >9.0 Depth to ground water table during growing season (cm) >50 20 10 Slope (degree) 0 - 4 10 - 15 >15 Flooding none occasional severe Water require-ment during growing season (mm) 450 300 <200 Permeability (cm/hr) 1.5 - 5.0 0.15 - 0.50 or 15.0 - 50.0 <0.15 >50.0 Gravels, cobbles on the surface (%) 5 15 - 35 >50 Table 14 RATING CRITERIA FOR MILLET SUITABILITY S u i t a b i l i t y SI S3 N2 Parameters Optimum Marginal Not Suitable Natural drainage well drained imperfect or rapid poor or excessive S o i l depth (cm) >75 10 - 25 <10 S o i l texture sandy loam to loam s i l t y clay/ clayey or coarse sandy loam f i n e clayey/ s i l t y or coarse sand Available water holding capacity (cm/cm) 0.154 - 0.159 >0.191 or <0.114 0.226 or 0.088 S a l i n i t y (mm hos/cm at 25°C) <4 8 - 1 5 >15 pH 6.5-7.0 3.5 - 4.5 or 8.5 - 9.0 <3.5 or >9.0 Depth to ground water table during growing season (cm) 50 25 <15 Slope (degree) 0 - 5 10 - 15 >15 Flooding none occasional severe Water require-ment during growing season (mm) 650 350 <300 Permeability (cm/hr) 1.5 - 5.0 0.15 - 0.50 or 15.0 - 50.0 <0.15 >50.0 Gravels, cobbles on the surface (%) 5 15 - 35 >50 coarser texture, and less water requirement during the growing season. A l l mapping units and t h e i r subunits were assessed for s u i t a b i l i t y r a t ings using the c r i t e r i a stated i n the above mentioned tables. B. SUITABILITY ASSESSMENT FOR TWO AND THREE ANNUAL CROP ROTATIONS IN THE  KALILALI DISTRICT The s u i t a b i l i t y assessment for two crop rotations without i r r i g a t i o n and three crop rotations with i r r i g a t i o n were obtained in the following manner. 1. Crop Rotations and Suitability Assessments for Rainfed (Without  Irrigation) Conditions Crop rotations under rainfed conditions are determined by the amount of water available and the requirements of the selected crop. The a v a i l a b i l i t y of water and the water holding capacity of the s o i l d i c t a t e s the crops that can be selected. The main crop i s grown In the monsoon or the rainy season. These crops ( r i c e or corn) are the most preferred t r a d i t i o n a l crops - they consume large amounts of water and have an economically stable market. The second crop i s grown during the dry season when the growing season i s shorter, and consequently c u l t i v a t i o n i s r e s t r i c t e d to those map-ping units that have s u f f i c i e n t moisture storage capacity. These crops, such as l e n t i l , mustard and m i l l e t , consume less water and have shorter growing periods. During this period corn and wheat are grown only i n those areas where some I r r i g a t i o n water i s a v a i l a b l e . The s u i t a b i l i t y ratings under rainfed conditions for double cropping rotations were determined by taking into account the inherent physical and 78. chemical c h a r a c t e r i s t i c s of the mapping unit, the season and the require-ments of the crops selected. Two crop ratings were given to each mapping unit (one for the monsoon and one for the dry season (winter) and mean s u i t -a b i l i t y for the units was then c a l c u l a t e d . The crop r o t a t i o n that best f i t -ted the c l i m a t i c cycle and which obtained the best mean s u i t a b i l i t y ratings was then selected for each mapping u n i t . The r e s u l t s of the i n d i v i d u a l crops and the mean crop r o t a t i o n s u i t a b i l i t y ratings i s provided in Appendix II and the best crop rotations for the dominant twelve major mapping units are provided in Table 15. The a e r i a l d i s t r i b u t i o n of optimum land use i s given i n Map 2 " A g r i c u l t u r a l S u i t a b i l i t y Without I r r i g a t i o n " i n Appendix IV. The land units which were mapped a l l have unique conditions, but these mapping units are not pure and since the complex subunits make up a s i g n i -f i c a n t p ortion of the area, they had to be considered separately. This was done i n the following manner. F i r s t , a l l dominant components of the mapping units were assessed for th e i r s u i t a b i l i t y . Since we are dealing with recurring patterns i t was possible to find equivalent ratings for each of the subcomponents. For example, a l c mapping unit i s made up to 70% l c ^ and 30% l c 2 . The l c j i s a unique unit, while the l c 2 i s equivalent to l d ^ , which i s the dominant (70%) component of the Id mapping u n i t . In order to indicate what subunit corresponds to what land unit a summary table was constructed in Table 16. From t h i s equivalent s u i t a b i l i t y ratings can be converted and t h i s allows a more precise q u a n t i f i c a t i o n of areal measurement for the D i s t r i c t . Based on the assumptions made above, the area calculated was corrected f o r the percentage of subcomponents having similar equivalent s u i t a b i l i t y r a t i n g s . A seasonal diagram with a summary of the percentage of area under Table 15 OPTIMUM CROP ROTATION FOR DOMINANT MAPPING UNITS WITHOUT IRRIGATION LAND UNITS SUB-UNITS % RICE-ALL CORN-ALL MOST OPTIMUM USE FOR DOMINANT SUBUNITS % OPTIMUM SUITABILITY OPTIMUM USE OPTIMUM SUITABILITY OPTIMUM USE RICE-ALL CORN-ALL l a -100 - - - -3.4% l b l b ! l b 2 70 30 4 -4 - - -l c l C l l c 2 70 30 4 3 I - I V I - I V 4 4 I - I V I - I V I - I V I - I V 0.70% I d I d ! l d 2 l d 3 70 20 10 3 5 5 I - I V I - I V I - I V 4 5 5 I - I V I - I V I - I V I - I V I - I V 1.42% 2a -100 2 I I I 4 I I I I I I I I I 0.88% 2b -100 2 I I - IV 3 I I - IV I I - IV I I - IV 16.45% 2c 2c i 2c 2 2c 3 50 35 15 3 2 5 I I - IV I I I I - I V 2 4 5 I I - IV I I I I - I V I I - IV I I - IV 23.15% 2d 2d! 2 d 2 80 20 3 4 IV I - I V 2 4 IV I - I V IV IV 0.71% 3a 3a i 3 a 2 75 25 3 4 I I - IV I - I V 2 4 I I - IV I - I V I I - IV I I - IV 16.29% 3b 3b i 3b 2 3b 3 60 25 15 4 3 5 I - I V IV I - I V 4 2 5 I - I V IV I - I V I - I V I - I V 9.30% 3c 3c! 3c 2 55 45 4 3 I - I V I I - IV 3 2 I - I V I I - IV I - I V I - I V 13.91% 3d 3d! 3 d 2 3d 3 60 30 10 5 3 2 I - I V IV I I I 5 2 4 I - I V IV I I I I - I V I - I V 13.76% TOTAL 100% 4 « Current ly not s u i t a b l e = Nj 5 « Permanently not su i t ab le - N2 Table 16 CONVERTING SUBUNIT SUITABILITY FOR NON-IRRIGATED CONDITIONS RICE - ALL ROTATION: RICE - ALL CORN - ALL X = Equivalent units or subunits Figure 12 IMPROVED LAND USE WITHOUT IRRIGATION 81 100 90 80 — 70 60 — 50 — 40 30 20 — 10 Wheat M i l l e t J River Courses, Sand and Gravel Bars Commercial Forest P ro tec t ion Forest Grassland I I I I I Corn (Monsoon) Corn (Monsoon) M i l l e t Mustard L e n t i l s Wheat Rice Late T" Maturing / / Rice Late Matur ing Wheat L e n t i l s / / • M I l I I M i l l e t Mustard Unproductive Forest Grassland Dryland or Upland A g r i c u l t u r e Wetland A g r i c u l t u r e 1 • I | 1 1 1 1 1 0 k 8 12 16 20 24 28 32 36 40 44 48 Weeks J F M A M J J u A S O N D Months 82. Table 17 TOTAL ARABLE AREA AND PRODUCTION UNDER IMPROVED LAND USE WITHOUT IRRIGATION LAND USE AREA (ha) ARABLE AREA (ha) - 20% OF TOTAL YIELDS (tonnes) ROTATIONS I CROP II CROP I CROP II CROP 1 2 3 4 r i c e r i c e r i c e r i c e wheat l e n t i l s m i l l e t mustard 11312 26395 11312 18854 9050 21116 9050 15082 13575 31674 13575 22623 7285 9017 8616 7149 TOTAL WETLAND 67873 54298 81447 32067 1 2 3 4 corn corn corn corn wheat l e n t i l s mustard m i l l e t 11312 11312 22625 18854 9050 9050 18100 15082 7846 7846 15693 13076 7285 3864 8579 14358 TOTAL DRYLAND 64103 51282 44461 34086 TOTAL CULTIVATION AND PRODUCTION 131976 105580 125908 66153 GRASSLAND 3771 - - -PROTECTION FOREST 30166 - - -COMMERCIAL FOREST 16968 - - -UNPRODUCTIVE 5656 - - -GRAND TOTAL 188537 105580 125908 66153 each r o t a t i o n using the best ratings i s given In Figure 12. F i n a l l y , the percentage under each r o t a t i o n was calculated and by using the average crop y i e l d for the region from the LRMP A g r i c u l t u r a l Report, 1982 t o t a l arable area and production was calculated for the D i s t r i c t as depicted i n Table 17, which gives a concise picture of the area under improved land use without i r r i g a t i o n . 2. Crop Rotations and S u i t a b i l i t y Assessments for I r r i g a t e d Conditions With crop rotations under i r r i g a t e d conditions, a gradual change from single or double cropping to t r i p l e cropping i s possible on either low land or upland c u l t i v a t i o n s as there are no c l i m a t i c r e s t r i c t i o n s hampering the growth of the crops selected. With i r r i g a t i o n ' s u p p l y i n g water throughout the year, the growing season can be extended to the en t i r e year, making i t possible to grow two ad d i t i o n a l crops a f t e r the harvest of the main crop. In other words the same piece of land can be u t i l i z e d three times i n one year, and many types of multiple cropping rotations can be practiced. The crops and crop rotations are very s i m i l a r to those mentioned under rainfed conditions, except that they are now under t r i p l e cropping rotations as a r e s u l t of the a v a i l a b i l i t y of i r r i g a t i o n water. The procedures followed for s u i t a b i l i t y r a t i n g under i r r i g a t e d condi-tions are the same as i n rainfed conditions except that three crop ratings are given to each mapping unit (one for the monsoon, winter (dry) and summer (dry) seasons) and then a mean s u i t a b i l i t y for the units were c a l c u l a t e d . The crop rotations that suited the c l i m a t i c regime of the region and that had the best mean s u i t a b i l i t y ratings were selected for each mapping u n i t . The ratings for each i n d i v i d u a l crop and the mean crop r o t a t i o n s u i t a b i l i t y 84. ratings are i l l u s t r a t e d i n Appendix II and the best crop rotations for the dominant mapping units are given i n Table 18. The areal d i s t r i b u t i o n of optimum land use with i r r i g a t i o n i s shown i n Map 3 i n Appendix IV. The same method was followed when assessing the s u i t a b i l i t y of the dominant and co-dominant subunits as i n rainfed conditions. For a more precise q u a n t i f i c a t i o n of areal measurement of the study area, a summary table i n d i c a t i n g what subunits correspond to which land units i s provided i n Table 19. Seasonal diagram summaries depicting the percentage of area under each r o t a t i o n using the best crop r o t a t i o n s u i t a b i l i t y ratings are shown in Figure 13. The area under each r o t a t i o n , with the arable area and produc-t i o n using the average y i e l d for the region, was calculated as indicated in Table 20 to give a concise review of the D i s t r i c t under i r r i g a t i o n . C. COMPARISON BETWEEN CURRENT LAND USE AND IMPROVED LAND USE The objectives of t h i s analysis i s to present the land use planners and decision makers with options and a l t e r n a t i v e s for land use changes and how to improve a g r i c u l t u r a l production. This was done by comparing the current land use with improved land use without and with i r r i g a t i o n . 1. Quantitative Assessment of Current Land Use A quantitative assessment of land use was made using the presently available Land U t i l i z a t i o n Map of the D i s t r i c t which shows the percentage of area under d i f f e r e n t land use and crop r o t a t i o n s . In order to use the Land Systems mapping units for crop s u i t a b i l i t y assessments, current land use had to be determined for each mapping u n i t . This was done by superimposing the Land U t i l i z a t i o n Maps onto the Land Systems Maps and by c a l c u l a t i n g the area Table 18 OPTIMUM CROP ROTATION FOR DOMINANT MAPPING UNITS WITH IRRIGATION ROTATIONS RICE-RICE-ALL CORN-RICE-ALL CORN-CORN-ALL MOST OPTIMUM USE FOR DOMINANT SUBUNITS x LAND SUB- Z OPTIMUM OPTIMUM OPTIMUM OPTIMUM OPTIMUM OPTIMUM RICE-RICE CORN-RICE CORN-CORN UNITS UNITS SUITABILITY USE SUITABILITY USE SUITABILITY USE ALL ALL ALL l a -100 _ 3.4Z l b l b ! 70 - - - - - - - - _ l b 2 30 4 I - IV 4 I - IV 4 I - IV - - -l c l C l 70 4 I - IV 4 I - IV 4 I - IV I - IV I - IV I - IV 0.70% l c 2 30 3 I - IV 3 I - IV 4 I - IV - - -I d ! 70 3 I - IV 3 I - IV 4 I - IV I - IV I - IV I - IV Id l d 2 20 5 I - IV 5 I - IV 5 I - IV - - - 1.42Z " 3 10 5 I - IV 5 I - IV 5 I - IV — - — 2a -100 1 I or I I I 2 I or I I I 3 I or I I I I or I I I I or I I I I or I I I 0.88% 2b -100 1 I - IV 1 I - IV 2 I - IV I - IV I - IV I - IV 16.45Z 2c x 50 2 I I - IV 1 I I - IV 1 I I - IV I I - IV I I - IV I I - IV 2c 2c 2 35 1 I or I I I 2 I or I I I 3 I I or I I I 23.15Z 2=3 15 5 - 5 - 5 -2d 2di 80 2 I I - IV 1 I I - IV 1 I I - IV I I - IV I I - IV I I - IV 0.71Z 2d 2 20 3 I - IV 3 I - IV 3 I - IV 3a 3*1 75 1 I - IV 1 I - IV 1 I - IV I - IV I - IV I - IV 16.29Z 3a 2 25 3 I - IV 3 I - IV 3 I - IV 3b! 60 4 I - IV 4 I - IV 4 I - IV I - IV I - IV I - IV 3b 3b 2 25 2 I I - IV 1 I I - IV 1 I I - I I I - - - 9.30Z 3b 3 15 5 - 5 - 5 - - - • — 3c 3cj 55 3 I - IV 3 I - IV 2 I - IV I - IV I - IV I - IV 13.91Z 3c 2 A5 1 I - IV 1 I - IV 1 I - IV 3di 60 5 I - IV 5 I - IV 5 I - IV I - IV . I - IV I - IV 3d 3d 2 30 2 I I - IV 1 I I - IV 1 I I - IV - - - 13.76Z 3d 3 10 1 I or I I I 2 I or I I I 3 I or I I I — — — TOTAL 100% 4 = Current ly not su i tab le = 5 » Permanently not su i tab le = N, 86. Table 19 CONVERTING SUBUNIT SUITABILITY FOR IRRIGATED CONDITIONS RICE - RICE - ALL ROTATION: RICE - RICE - ALL CORN - CORN - ALL X = Equivalent units or subunits Figure 13 IMPROVED LAND USE WITH IRRIGATION River Courses, Sand and Gravel Bars Commercial Forest P ro tec t ion Forest Grassland J Mustard J" M i l l e t L e n t i l s Wheat or Winter Corn Unproductive Forest Grassland Upland A g r i c u l t u r e Lowland A g r i c u l t u r e Rice Ear ly i r — 1 — r 0 4 8 12 16 20 24 28 32 36 40 44 48 Weeks J F M A M J J u A S O N D Months 88. Table 20 TOTAL ARABLE AREA AND PRODUCTION UNDER IMPROVED LAND USE WITH IRRIGATION LAND USE AREA (ha) ARABLE AREA (ha) - 20* OF TOTAL YIELDS (tonnes) ROTATIONS I CROP I I CROP I I I CROP I CROP I I CROP I I I CROP 1 r i c e r i c e r i c e u n i 7541 j O I W 6033 9050 9050 9050 2 r i c e r i c e wheat 11312 9050 13575 13575 7285 3 r i c e r i c e mustard 11312 9050 13575 13575 4290 4 r i c e r i c e l e n t i l s 15085 12066 18099 18099 5152 5 corn r i c e wheat 7541 6033 5231 9050 4857 6 corn r i c e mustard 7541 6033 5231 9050 2860 7 corn r i c e l e n t i l s 7541 6033 5231 9050 2576 TOTAL WETLAND 67873 54298 69992 81449 36070 1 corn r i c e wheat 7541 6033 5231 9050 4857 2 corn r i c e mustard 11313 9050 7846 13575 4290 3 corn r i c e l e n t i l s 11313 9050 7846 13575 3864 4 corn corn wheat 7541 6033 5231 5231 4857 5 corn corn l e n t i l s 7541 6033 5231 5231 2576 6 corn corn m i l l e t 11313 9050 7846 7846 8616 7 corn corn mustard 7541 6033 5231 5231 2860 TOTAL UPLAND 64103 51282 44462 59739 31920 TOTAL CULTIVATION AND PRODUCTION 131976 105580 114454 141188 67990 GRASSLAND 3771 - - - -PROTECTION FOREST 30166 - - - -COMMERCIAL FOREST 16968 - - - -UNPRODUCTIVE LAND 5656 - - - -GRAND TOTAL 188537 105580 114454 141188 67990 89. of each land use category with a d i g i t a l planiraeter. A summary of the d i s t r i c t showing areas under current land use i s displayed i n Table 21. The major land use categories include protection and commercial f o r e s t , forest lands convertible to upland or lowland a g r i c u l t u r a l systems and the p r e v a i l -ing crop r o t a t i o n schemes as shown i n Map 1 under Appendix IV. The current land use of the d i s t r i c t i l l u s t r a t i n g the d i f f e r e n t forms of uses i s provided In Figure 14, which shows that 57% i s under natural forest cover. Arable areas and production y i e l d s for the d i s t r i c t using average y i e l d s for the region were calculated and the r e s u l t s presented i n Table 22 show that 8% i s under wetland fallow, 14% under wetland r o t a t i o n , 12% under dryland or upland, and 4% under mixed land cropping systems. The remaining part i s under forest (57%) and grassland ( 2 %). 2. Comparison Between Current and Improved Land Use Under Non- Irrigated and Irrigated Conditions A comparison between current land use and improved land use with and without i r r i g a t i o n was made so that quantitative assessment could be made for land use improvements over present land use. A comparison between crop production under d i f f e r e n t land uses i s provided i n Table 23. It shows that the o v e r a l l y i e l d can be expanded by nearly 230% over current land use. Differences between land use areas are given i n Table 24 and indicate that improved land use i s greatly increased at the cost of forest land. The increases i n y i e l d s are associated with an increase i n area under c u l t i v a -t i o n , improvement of crop rotations and more intensive land management. The conversion of forest lands to improved a g r i c u l t u r a l development can be j u s t i f i e d , as the present forests are degraded and not very productive under Table 21 CURRENT LAND USE AREAL STATISTICS FOR DISTRICT (HECTARES) RIVER LAND USE FOREST WETLAND WETLAND MIXED COURSE CONVERTABLE GRASSLAND COMMERCIAL FALLOW ROTATION DRYLAND PROTECTION LAND SAND 4 TOTAL % MAPPING TO FOREST FARMING FARMING FARMING FOREST FARMING GRAVEL AREA UNITS AGRICULTURE BARS l a 293.8 293.8 0.16 lab 2951.8 2951.8 1.56 lb 15.0 3.0 41.3 3174.9 3234.2 1.71 lc 594.0 39.3 34.7 28.7 612.6 6.4 1315.7 0.70 Id 953.6 174.6 142.0 119.0 45.6 174.7 1041.1 21.3 2671.9 1.42 2a 575.0 610.8 301.4 102.0 78.0 1667.2 0.88 2b 5575.4 528.4 7723.0 11085.9 6098.8 2.3 31013.8 16.45 2c 9183.3 1104.5 6038.3 7870.8 9461.6 2594.2 . 7390.3 43643.0 23.15 2d 4.3 29.0 64.1 355.0 891.6 1344.0 0.71 3a 19000.8 467.4 1222.0 6007.9 4008.8 30706.9 16.29 3b 16795.1 210.7 521.0 17526.8 9.30 3c 24183.3 314.0 215.1 421.4 1097.3 26231.1 13.91 3d 101.7 82.7 24.9 41.6 25686.4 25937.3 13.76 TOTAL 59577.4 3837.7 16937.1 15804.9 25948.2 22094.8 30496.6 7420.3 6420.5 188537.5 100X AREA X 31.60 2.0 9.0 8.4 13.8 11.7 16.2 3.9 3.4 100Z 91. Figure 14 CURRENT LAND USE 100 90 80 — 70 — 60 — 50 40 30 Intermixed R i c e - L e n t i l s or Wheat Corn-Mustard or Wheat 20 — 10 River Courses _ Sand and Gravel Forest Grassland Mixed Land Cropping Dryland or Upland Cropping Wetland Rotat ion Cropping Wetland Fallow Cropping T 1 r-12 16 20 24 28 32 36 40 44 48 ' WEEKS M A M J J u A S O N D MONTHS Table 22 TOTAL ARABLE AREA AND PRODUCTION UNDER CURRENT LAND USE LAND USE AREA (ha) ESTIMATED FROM LAND USE SURVEY ARABLE AREA (ha) - 20% OF TOTAL CURRENT YIELDS (tonnes) ROTATIONS I CROP I I CROP I CROP I I CROP 1 2 3 4 r i c e r i c e r i c e r i c e f a l l o w wheat l e n t i l s mustard 15083 11312 7541 7541 9 12066 9050 6033 6033 18099 13574 9050 9050 7285 2576 2860 TOTAL WETLAND 41477 33182 49773 12721 1 2 3 corn corn corn l e n t i l s wheat mustard 1/A.lljfUll 3771 3771 15083 » 3017 3017 12066 2616 2616 10461 1288 2429 5719 TOTAL DRYLAND 22625 18100 15693 9436 1 2 3 r i c e r i c e corn wheat l e n t i l s mustard 1885 1885 3772 1508 1508 3018 2262 2262 2617 1214 644 1413 TOTAL MIXED LAND 7542 6034 7141 3289 TOTAL CULTIVATION AND PRODUCTION 71644 57316 72607 25446 FOREST 107446 - - -GRASSLAND 3771 - - -UNPRODUCTIVE 5656 - - -GRAND TOTAL 188537 57316 72607 25446 Table 23 CROP PRODUCTION UNDER DIFFERENT LAND USE LAND USE CURRENT IMPROVED WITHOUT IRRIGATION IMPROVED WITH IRRIGATION % PRODUCTION I t CURRENT U ICREASE OVER IND USE CROPS CURRENT YIELDS (T) ARABLE AREA (ha) PRODUC-TION (T) ARABLE AREA (ha) PRODUC-TION (T) ARABLE AREA (ha) PRODUC-TION (T) WITHOUT IRRIGATION WITH IRRIGATION r i c e 1.5 36198 54297 54298 81447 120663 180998 50 233 corn 0.867 21118 18310 51282 44461 96530 83694 143 357 wheat 0.805 13575 10928 18100 14570 27149 21855 33 100 l e n t i l 0.427 10558 4508 30166 12881 33182 14169 186 214 mustard 0.474 21117 10010 33182 15728 30166 14299 57 43 m i l l e t 0.952 — — 24132 22974 9050 8616 100 38 TOTAL 102566 98053 211160 192061 316740 323632 96 230 Table 24 DIFFERENCES IN LAND USE AREA LAND USES CURRENT LAND USE IMPROVED LAND USE WITHOUT IRRIGATION IMPROVED LAND USE WITH IRRIGATION Z AREA INCREASE OVER CURRENT LAND USE IMPROVED LAND USE WITHOUT IRRIGATION IMPROVED LAND USE WITH IRRIGATION TOTAL AREA (ha) TOTAL AREA (ha) TOTAL AREA (ha) Arable Agr i cu l tu re 57316 105580 105580 84 84 I n f r a -s t ruc tu re 14328 26396 26396 84 84 Prot« Force t i c t l o n — •vat lon — 107466 30166 30166 -56 -56 Conse: 16968 16968 Grassland 3771 3771 3771 — — Unproductive Land 5656 5656 5656 — — TOTAL 188537 188537 188537 — — 9 5 . the e x i s t i n g forest management schemes. Only areas suitable for a g r i c u l -t u r a l development were considered, consequently areas with topographic l i m i t a t i o n s prone to erosion were kept under protection or commercial f o r e s t . Change i n a g r i c u l t u r a l land use patterns are not only the r e s u l t s of improvements i n crop r o t a t i o n , but also due to the introduction of i r r i g a t i o n water into the cropping system. 3. Summary of Agricultural Improvements Emphasizing Size and Type of  Cultivation System A summary of a g r i c u l t u r a l improvements shown i n Table 23 indicates that under improved land use without and with i r r i g a t i o n a g r i c u l t u r a l production can be increased by 96-230% re s p e c t i v e l y , over current production. At the same time Table 24 i l l u s t r a t e s that arable area suitable for a g r i c u l t u r a l production can be expanded by nearly 84% at the expense of forest land. Marginal lands were kept under protection or commercial forests to safeguard against s o i l erosion and protect land use management below. Under e x i s t i n g forest management schemes, large tr a c t s of forests are degrading r a p i d l y , which under a g r i c u l t u r e can be very productive. These forest lands occur i n r e l a t i v e l y gentle topography, and the removal of forest does not cause s i g n i f i c a n t s o i l degradation, but w i l l greatly improve a g r i c u l t u r a l produc-ti o n and y i e l d s . Removal of such forest lands can be j u s t i f i e d as neither s o i l erosion nor forest production i s s i g n i f i c a n t l y affected by such conver-sions. Nearly 50% of the e x i s t i n g forest land can be safely converted to a g r i c u l t u r a l land without any serious side e f f e c t s . The proposed changes i n land use r e s u l t i n increased areas under pro-duction and increases i n i n t e n s i t y (double and t r i p l e cropping) with the 96. a v a i l a b i l i t y of i r r i g a t i o n water and improved crop r o t a t i o n s . Associated with these changes, consideration for f e r t i l i z e r management i s to be accomplished with the incorporation of leguminus crops i n crop rotations and the use of a r t i f i c i a l f e r t i l i z e r s . These pot e n t i a l increases in t o t a l area for crop production indicate that the d i s t r i c t has an improved production p o t e n t i a l because the arable area can be increased by nearly 2 times over current land use with the introduction of multiple annual crop r o t a t i o n , i r r i g a t i o n , and appropriate changes in the land use. D. LONG TERM FERTILIZER IMPLICATION RESULTING FROM DOUBLE AND TRIPLE CROP  ROTATIONS Long term f e r t i l i z e r problems are bound to increase i f double and t r i p l e cropping systems are introduced into the study area. Careful s o i l f e r t i l i t y management i s e s s e n t i a l i f long term a g r i c u l t u r a l production i s to be maintained. Due to lack of basic survey information for the test area a d e t a i l e d s o i l f e r t i l i t y management assessment could not be made. Instead, two approaches were pursued. F i r s t , the resource inventory data was interpreted for f e r t i l i z e r c a p a b i l i t y and secondly, f e r t i l i z e r needs for current and improved land use were calculated and compared for the K a i l a l i D i s t r i c t . 1. Soil Fertility Capability Using the resource inventory mapping units a l l s o i l s were .grouped into categories with s i m i l a r f e r t i l i z e r l i m i t a t i o n s according to the F.C.C. method described by Buol, 1972. S o i l f e r t i l i z e r management i s re l a t e d to only a few parameters normally included i n most s o i l surveys. Texture of 97. the surface s o i l i s the most important factor followed by the chemical and mineralogical nature of the s o i l m a t e r i a l . The l a t t e r determines the a b i l i t y of the s o i l to r e t a i n nutrients i n an a v a i l a b l e form for plant growth. The parameters normally included are cation exchange capacity, cl a y mineralogy, s a l i n i t y , a c i d i c or basic i n reaction, etc., as indicated by Buol and Couto, 1981. The obtained f e r t i l i z e r c a p a b i l i t y classes provide a useful framework for management of f e r t i l i t y at the l o c a l l e v e l since the main l i m i t i n g f a c t o rs are i d e n t i f i e d . An example of the type of interpreted c a p a b i l i t y classes obtained with t h i s method i s provided below: S'Rdebf" means: gravelly, sand over boulders, root r e s t r i c t i n g layer; high i n f i l t r a t i o n rate, low water-holding capacity; dry, s o i l moisture l i m i t a t i o n s ; * low c.e.c; calcareous i n reaction; severe flooding hazards Lde(l-3) means: loamy s o i l s , good water-holding and medium i n f i l t r a t i o n capacity; somewhat droughty, low c . e . c ; with 1-3 degree slope Explained i n Appendix I I I Using t h i s method a l l mapping units for the K a i l a l i D i s t r i c t were examined and the r e s u l t s are presented i n Table 25. 98. Table 25 FERTILIZER CAPABILITY CLASSIFICATION LAND UNITS SUBUNITS AREA (ha) % F.C.C. CLASSES l a — 294 0.2 River courses lab — 2952 1.6 River courses & gravel bars l b l b ! 2264 1.2 Gravel and sand bars l b 2 970 0.5 S'Rdebf l c l C l 921 0.5 S'Rdebf l c 2 395 0.2 L'debf Id 1*1 1870 1.0 L'debf l d 2 534 0.3 Sdebf l d 3 267 0.1 Sdebf 2a — 1667 0.9 Cglb 2b — 31014 16.5 Lgb 2c 21821 11.5 Lde 2c 2 15275 8.1 Lgb 2c 3 6564 3.5 Sde (1-2) 2d 1075 0.6 Lde 2d 2 269 0.1 Lsde 3a '3 3 l 23030 12.2 Lde 3a 2 7677 4.1 Sde 3b 3b : 10516 5.6 SRde (1-3) 3b 2 4382 2.3 Lde (1-3) 3b 3 2629 1.4 S'Rde (1-5) 3c 3ci 14427 7.6 LSdeb (1-3) 3c 2 11804 6.3 Lde (1-3) 3d 3di 15562 8.2 Ldeb (10-20) 3d 2 7781 4.1 Lde (1-5) 3d 3 2594 1.4 Lgb See Appendix III for abbreviations 99. Table 26 SUMMARY OF FERTILIZER CAPABILITY FOR THE KAILALI DISTRICT GROUPS FCC CLASSES FERTILITY CONDITIONS AND PROBLEMS SUBUNIT6 AREA (ha) X OF TOTAL AREA FOR DISTRICT A Sdebf (S 'L 'R) sandy or g r a v e l l y , droughty, h igh I n f i l t r a t i o n r a t e s , low water ho ld -ing capac i ty , low c . e . c , basic In r e a c t i o n , occasional to extreme r i s k of f l ood ing hazards l b 2 , l c l t l c 2 , l d j , l d 2 , l d 3 4958 2.6 B Cgib c layey, low i n f i l t r a t i o n r a t e s , g l e y i n g , anaerobic subsoi ls i n mon-soon, P f i x a t i o n capac i t y , basic i n reac t ion 2a 1667 0.9 C Lgb loamy, good water -ho ld ing capac i ty , g l e y i n g , anaerobic subsoi l i n mon-soon, sometimes basic i n reac t ion 2b, 2 c 2 , 3d 3 48883 26.0 D Lde (1 -3 -5 ) loamy, good water -ho ld ing and medium i n f i l t r a t i o n capac i ty , somewhat droughty s o i l s , low c . e . c , w i t h 1 to 3 or 5 degree slopes 2 c x , 2 d l t 3a, 3 b 2 , 3 c 2 , 3d 2 69894 37.0 E L or Sde ( b , 1-2-3) loamy or loamy sands, h igh i n f i l -t r a t i o n r a t e , low water ho ld ing capac i t y , droughty s o i l , low c . e . c , sometimes basic i n r e a c t i o n , w i t h 1 to 3 degree slope 2 c 3 , 3 a 2 , 2 d 2 , 3 C l 28937 15.3 F SRde ( S ' , 1-3-5) sandy or sometimes g rave l l y sand, stoney, root r e s t r i c t i n g l a y e r , high i n f i l t r a t i o n r a t e , low water ho ld ing capac i ty , droughty s o i l s , moisture l i m i t a t i o n dur ing growing pe r iod , low c . e . c , w i th 1-5 degree slopes 3 b l f 3b 3 13145 7.0 G Ldeb (10-20) loamy s o i l s , good water ho ld ing and i n f i l t r a t i o n capac i t y , s o i l mois-ture l i m i t a t i o n dur ing growing season, low c . e . c , basic i n reac-t i o n , s lop ing lands, w i t h 10 to 20 degree slopes 3dj 15562 8.2 100. The 25 subunits can be grouped into seven general f e r t i l i t y c a p a b i l i t y categories as i l l u s t r a t e d i n Table 26. From t h i s i t i s evident that the majority of the s o i l s i n the D i s t r i c t 70% are low i n CEC and consequently have low a b i l i t y to r e t a i n nutrients for plants. About 27% of the s o i l s have anaerobic subsoil conditions during the monsoon season making i t i d e a l for r i c e only. Of the 70% of the s o i l s that have low CEC, 25% are coarse textured and droughty, 8% have topographic l i m i t a t i o n s with severe erosional problems, and 37% seem to have loamy, well drained s o i l s with good water holding c a p a c i t i e s . They are well suited for upland crops and are also suited for r i c e production i f a d d i t i o n a l i r r i g a t i o n water i s made a v a i l a b l e , but these s o i l s become somewhat droughty i n the l a t t e r part of the dry season. Mapping units having the same FCC class e s , f e r t i l i t y l i m i t a t i o n s or problems, should be managed and improved i n the same way. Most of the problems could be overcome i f a combination of practices were c a r r i e d out, i e : f e r t i l i z e r a p p lications i n s p l i t doses, intensive management, and maintenance of organic matter and appropriate crop rotations with leguminous crops. 2. F e r t i l i t y Needs and Management S u i t a b i l i t y assessments without f e r t i l i z e r management i s considered inappropriate, since long term production cannot be maintained with the introduction of double and t r i p l e crop r o t a t i o n s . At present, under current land use crop rotations are l i m i t e d with the u t i l i z a t i o n of only organic f e r t i l i z e r s (compost and farm yard manures). In future under Improved land use with and without i r r i g a t i o n , more extensive 101. crop rotations w i l l be introduced with double and t r i p l e cropping systems, which require the u t i l i z a t i o n of a l l e x i s t i n g organic f e r t i l i z e r s , i n addi-t i o n to a r t i f i c i a l f e r t i l i z e r s , to maintain targeted y i e l d s . The f e r t i l i z e r needs for the d i s t r i c t were assessed i n three ways: 1. current land use - no input, 2. improved land use without i r r i g a t i o n with minimal inputs, 3. improved land use with i r r i g a t i o n , which i s c a p i t a l intensive with the use of a r t i f i c i a l f e r t i l i z e r s . Under a balanced use of crop rotations with organic f e r t i l i z e r and addition-a l a r t i f i c i a l f e r t i l i z e r , current minimum y i e l d s can be improved to target l e v e l s , as shown i n Table 27. Current average y i e l d s for the d i s t r i c t were available from the A g r i -c u l t u r a l report (L.R.M.P. 1982) and the i r f e r t i l i z e r requirements were calculated based on the use of av a i l a b l e organic f e r t i l i z e r s . This was then compared with targeted y i e l d s and f e r t i l i z e r requirements that could be r e a d i l y achieved under modest c a p i t a l inputs once the regional i r r i g a t i o n system i s i n place. F e r t i l i z e r requirements for current and targeted y i e l d s are given i n Table 28. Based on these assumptions, t o t a l a d d i t i o n a l f e r t i l i z e r requirements for the d i s t r i c t were calculated to improve current to targeted y i e l d s based on s u i t a b i l i t y assessments. F e r t i l i z e r requirements under current and targeted production for the K a i l a l i D i s t r i c t i s provided i n Table 29, which shows that f e r t i l i z e r requirements under improved i r r i g a t e d land use i s nearly eight times higher for a l l n u t r i e n t s . The requirements for nutrients under the improved i r r i g a t e d system show that 27,000 tonnes of N w i l l be required for targeted y i e l d s , of which 5% 102. Table 27 CURRENTLY OBTAINED AVERAGE YIELDS UNDER CURRENT LAND USE (KG/HA) CROPS SUITABILITY RATING RICE CORN WHEAT LENTIL MUSTARD MILLET SI >1500 >867 >805 >427 >474 >952 S2 1500 867 805 427 474 952 TARGETED YIELDS UNDER IMPROVED IRI t l GATED LAND USE (KG/HA) SI >4000 >4000 >4000 >2000 >2000 >4000 S2 4000 4000 4000 2000 2000 4000 Table 28 FERTILIZER REQUIREMENTS FOR CURRENT AND TARGETED YIELDS (KG/HA) CROPS SUITABILITY RATING RICE CORN WHEAT LENTIL MUSTARD MILLET N P K N P K N P K N P K N P K N P K Current S2 42 8 28 35 8 29 20 4 22 21 6 17 21 14 7 15 4 51 Targeted S2 70 18 45 100 18 68 95 22 64 100 28 78 90 60 30 62 18 215 For convers ion: 1 kg P • 2.4 kg P2O5 1 kg K - 1.2 kg K 2 0 Source: Sanchez, 1976 Table 29 YIELDS AND FERTILIZER REQUIREMENT UNDER CURRENT AND IMPROVED LAND USE WITH IRRIGATION FOR THE KAILALI DISTRICT CROPS AVERAGE CURRENT YIELDS (tonnes) CUi IRE NT LAND USE IMPI 10VED LAND USE WITH IRRIGATION AREA UNDER PRODUCTION (ha) TOTAL CROP PRODUCTION (tonnes) FERTILIZE! t REQUIREME1 fTS (TONS) TARGETED YIELDS (tonnes) AREA UNDER PRODUCTION (ha) TOTAL CROP PRODUCTION (tonnes) FERTILIZER REQUIREMENTS (TONNES) N P K N P K Rice 1.5 36198 54297 1520.3 289.6 1013.5 4 120663 482652 8446.4 2171.9 5429.8 Corn 0.867 21118 18310 739.1 168.9 612.4 4 96530 386120 9653.0 1737.5 6564.0 Wheat 0.805 13575 10928 271.5 54.3 298.6 4 27149 108596 2579.2 597.3 1737.5 L e n t i l 0.427 10558 4508 211.7 63.3 179.5 2 33182 66364 3318.2 929.1 2588.2 Mustard 0.474 21117 10010 443.5 295.6 147.8 2 30166 60332 2714.9 1810.0 905.0 M i l l e t 0.925 — — — — — 4 9050 36200 561.1 162.9 1945.7 TOTAL 102566 98053 3186.1 871.1 2251.8 316740 1140264 27272.8 7408.7 19170.2 o 104. could be substituted by the inherent f e r t i l i t y of the s o i l and 15% by leguminous crops i n r o t a t i o n s . This means that only 80% of the required N and 100% of the other e s s e n t i a l P and K f e r t i l i z e r s w i l l have to be imported into the d i s t r i c t . E. SUMMARY F e r t i l i z e r requirements and s o i l f e r t i l i t y maintenance were examined i n two ways: FCC c a p a b i l i t y scheme and f e r t i l i z e r requirement to improve production to modest target y i e l d s . Findings from the FCC c a p a b i l i t y scheme indicate that the major s o i l f e r t i l i t y problems r e l a t e to low CEC (70%), of which 25% are coarse textured and droughty, 8% have topographic problems, and 37% have generally good conditions. The remaining 27% have anaerobic subsoil conditions during the monsoon season. O v e r a l l , 37% of a l l s o i l s are considered well suited for upland crops with minor f e r t i l i z e r l i m i t a t i o n s , 27% exhibit good f e r t i l i t y conditions (under anaerobic behaviour) for low-land crops such as r i c e , and 15% of the coarse textured and droughty s o i l s could be u t i l i z e d under improved management, while 18% of the d i s t r i c t are considered as unsuitable for a g r i c u l t u r e . The f e r t i l i z e r needs for the d i s t r i c t were assessed i n three d i f f e r e n t ways. The current land use r e f l e c t s the t r a d i t i o n a l farming system which only uses currently a v a i l a b l e organic f e r t i l i z e r inputs. Improved land use without i r r i g a t i o n uses minimal inputs, and r e l i e s mainly on crop r o t a t i o n with leguminous crops and organic matter management. Improved land use with i r r i g a t i o n i s c a p i t a l intensive and w i l l be based on improved crop r o t a t i o n with the introduction of a r t i f i c i a l f e r t i l i z e r s In order to guarantee long term f e r t i l i z e r maintenance. 105. F e r t i l i z e r requirements under improved land use with i r r i g a t i o n are estimated to be eight times higher than current land use, with the p o t e n t i a l of a twelve f o l d increase i n production. The production under improved land use without I r r i g a t i o n could be two times greater than current land use, and t h i s would be accomplished with the use of appropriate crop rotations and available organic f e r t i l i z e r management. These increases i n production are not only due to the expansion of a g r i c u l t u r a l area under c u l t i v a t i o n , but also due to more Intensive, improved and i r r i g a t e d crop rotations and the use of a r t i f i c i a l f e r t i l i z e r s . The optimum choice of crop rotations balanc-ed with the use of organic and a r t i f i c i a l f e r t i l i z e r s are required to give the best r e s u l t s for long term f e r t i l i z e r management. 106. VI. SUMMARY AND CONCLUSIONS Acute population pressure i n the h i l l y regions of Nepal has led to the immigration of large segments of the population into the Terai Region i n both spontaneous and government planned resettlement schemes. These Terai lands are at present under natural vegetation and are only considered sustainable farm lands i f proper measures i n crop r o t a t i o n s , improved management and adequate f e r t i l i z e r a pplications are considered. The purpose of t h i s study was to analyse the Land Resource Inventory data c o l l e c t e d for the K a i l a l i D i s t r i c t and to develop a methodology for evaluating the b i o -physical data for a g r i c u l t u r a l improvements and future land use planning. The method examined a g r i c u l t u r a l s u i t a b i l i t y for six major crops under non-i r r i g a t e d and i r r i g a t e d conditions and the r e s u l t s were then compared to the current land use. The project was c a r r i e d out i n a quantitative manner to demonstrate what improvement options e x i s t and what type of development i s most cost e f f e c t i v e . The p o t e n t i a l increase i n a g r i c u l t u r a l production i s the r e s u l t of expanding a g r i c u l t u r a l land use into new areas not cu r r e n t l y used, introducing double and t r i p l e annual crop rotati o n s , examining the regional i r r i g a t i o n p o t e n t i a l , and assessing f e r t i l i z e r management require-ments. As a r e s u l t of t h i s research the following conclusions were reached. 1. Interpreting Crop Suitability from Land Resource Inventory Data Based on the land resource survey information land s u i t a b i l i t y i n t e r -pretations were made for six a g r i c u l t u r a l crops i n the K a i l a l i D i s t r i c t . Under the given c l i m a t i c conditions non-irrigated double annual crop rota-tions and i r r i g a t e d t r i p l e annual crop r o t a t i o n systems were judged to be f e a s i b l e . Using a modified version of the F.A.O. S u i t a b i l i t y scheme crop 107. r o t a t i o n sequences and s u i t a b i l i t y ratings were determined for a l l mapping units i n the d i s t r i c t . This r e l a t i v e l y simple method provides basic land use information for planning and can r e a d i l y be extended to other d i s t r i c t s for which s i m i l a r biophysical information i s a v a i l a b l e . 2. Quantitative Comparison Between Current and Improved Land Use I t was thought f e a s i b l e to convert nearly 50% of the e x i s t i n g unproduc-tiv e and somewhat degraded forest land into a g r i c u l t u r a l c u l t i v a t i o n , and i n addition, production could be increased further by the introduction of more intensive crop r o t a t i o n s , f e r t i l i z e r management and i r r i g a t i o n . Using the land systems mapping unit as a basis for predictions, quantitative areal measurement showed that the current area under crop production could be expanded by nearly 60332 ha. With the introduction of double cropping systems and improved organic matter management the o v e r a l l crop production could be increased by 96% and t h i s with minimum Inputs and based on current-l y obtained y i e l d s . If a regional i r r i g a t i o n scheme i s introduced there w i l l be no further increase in the area under c u l t i v a t i o n , but production can be s i g n i f i c a n t l y improved with the introduction of t r i p l e crop r o t a t i o n schemes. In t h i s case current production w i l l be improved by nearly 230%, based on c u r r e n t l y obtained average y i e l d s . As c a p i t a l input with i r r i g a t i o n i s anticipated current y i e l d s can be further increased by more intensive management and the use of a r t i f i c i a l f e r t i l i z e r s . Using modest target y i e l d s for the six crops obtained from other developing projects i n s i m i l a r c l i m a t i c zones, an over-a l l production increase of 1042211 tonnes or twelve times over current pro-duction i s considered f e a s i b l e for the d i s t r i c t . 108. 3. F e r t i l i t y Limitations The F e r t i l i t y C a p a b i l i t y C l a s s i f i c a t i o n System (F.C.C.) was designed to group s o i l s that have the same kinds of l i m i t a t i o n s from the point of view of f e r t i l i t y management. By the F.C.C. scheme a l l land systems mapping units were interpreted for t h e i r main l i m i t a t i o n s and management considera-t i o n s . The d i s t r i c t could be grouped into seven general f e r t i l i t y c a p a b i l -i t y categories, with each category having s i m i l a r l i m i t a t i o n s for f e r t i l i z e r management. It was estimated that 64% of the land that i s sui t a b l e for a g r i c u l t u r a l development have only minor f e r t i l i t y problems such as low CEC or anaerobic subsoil conditions during the monsoon. F i f t e e n percent have droughtiness problems due to low water holding c a p a c i t i e s and could be managed under improved management, and 18% are considered unsuitable for ag r i c u l t u r e . The main f e r t i l i t y problems r e l a t e to generally low CEC values for nearly 70% of the d i s t r i c t . This suggests that organic matter management and maintenance i s c r i t i c a l when considering the introduction of a r t i f i c i a l f e r t i l i z e r . About 18% of the s o i l s are coarse textured and/or steeply sloping, and are thus considered prone to erosion and unsuited for a g r i c u l -t u r a l development. 4. Long Term F e r t i l i z e r Management The current land use u t i l i z e s organic matter as the main source of f e r t i l i z e r s . Under modified rainfed conditions s o i l f e r t i l i t y can be main-tained by using appropriate crop r o t a t i o n schemes with leguminous crops and organic f e r t i l i z e r s . In the case of i r r i g a t e d land use with t r i p l e cropping r o t a t i o n s , a combination of organic matter, selected crop r o t a t i o n s , and 109. introduction of a r t i f i c i a l f e r t i l i z e r s i s needed i n order to maintain long term p r o d u c t i v i t y . In order to obtain and maintain target y i e l d s i t has been calculated that 21,600 tonnes of N, 7400 tonnes of P and 19,200 tonnes of K i n the form of a r t i f i c i a l f e r t i l i z e r s w i l l have to be introduced into the area on an annual basis. 5. Framework for Land Use Planning The method developed i n t h i s study i s r e l a t i v e l y simple and i s aimed at general land use planning. 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APPENDIX I DETAILED RESULTS OF SOIL AND CLIMATE REQUIREMENTS FOR SPECIFIC CROPS CLIMATIC REQUIREMENTS FOR RICE SOURCES TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH, "C OPTIMUM (RANGE) WATER REQUIREMENTS MM/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (X MOISTURE) PRECIPITATION (mm) 1 90-150 short day/ day neut ra l 22-30 (18-35) 350-700 high P 1 . 1 5 ) 0.70-1.10 r i c e (15-20) 2 90-150 short day/ day neut ra l 22-30 (15-32) 450-700 — — 3 120-150 short day/ day neut ra l 21-35 (17-42) — high (>1.15) — 4 130-150 short day/ day neut ra l 20-31 (14-38) — high (>1.15) — 5 130-150 short day/ day neut ra l — 1000 — — 1200-1500 6 130-150 short day/ day neut ra l 20-38 — — — 2000 7 130-150 short day/ day neut ra l 23-31 (12-45) 600-800 — 1.1-1.2 2000-4000 90-150 short day/ day neut ra l 20-38 (12-45) 350-1000 high (>1.15) 0.70-1.2 r i c e (15-20) 1200-4000 va r i ab le Sources: 1. Doorenbos, J . and A.H. Kassam, 1979; 2. Matsushlma, S., 1980; 3. Nuttonson, M.Y., 1965; 4. Luh, Bar. S., 1980; 5. Hopkins, J . , 1964; 6. G r i s t , D.H., 1975; 7. De Dat ta, S.K., 1981. Ky - y i e l d response fac tor to water d e f i c i t , the y i e l d decreases per un i t of r e l a t i v e evapotrans-p i r a t i o n d e f i c i t . For ca l cu la t i on see Doorenbos and P r u l t t (1977) . CLIMATIC REQUIREMENTS FOR CORN SOURCES TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH, °C OPTIMUM (RANGE) WATER REQUIREMENTS MM/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (X MOISTURE) PRECIPITATION (mm) 1 100-140+ short day/ day neu t ra l 24-30 (15-35) 500-800 high (1.25) 0.80-1.60 gra in (10-13%) 2 — — 29-32 (12-35) — — — 3 — — 23-29 — — — 4 — — — (14-25) 460-600 — 1 1000 5 100-150 short day/ day neut ra l — (10-30) 400-600 — — 2300 6 100-130 short day/ day neut ra l 21-32 ( — ) 450-600 high (1.25) — 750 7 170-180 140-150 130-140 short day/ day neut ra l 24-28 (14-30) 500 high — >500 100-180 short day/ day neut ra l 21-32 (12-35) 400-800 high (1.25) 0.80-1.60 g ra in (10-13%) 500-2300 Sources: 1 . Doorenbos, J . and A.H. Rassam, 1979; 2. A l d r i c h , S.R., 1970; 3. A l d r i c h , S.R. and E.R. Leng, 1965; 4 . M i rac le , M.P. 1966; 5. Berger, J . , 1962; 6. Shaw, R.H., 1976; 7. Dube, P.A., 1981. Ky - Y ie ld response fac tor to water d e f i c i t , the y i e l d decreases per u n i t of r e l a t i v e evapotrans-p i r a t l o n d e f i c i t . For c a l c u l a t i o n see Doorenbos and P r u i t t (1977) . CLIMATIC REQUIREMENTS FOR WHEAT SOURCES j TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH, °C OPTIMUM (RANGE) WATER REQUIREMENTS MM/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (X MOISTURE) PRECIPITATION (mm) 1 spr ing 100-130 w in te r 180-250 long day/ day neut ra l 15-20 (10-25) 450-650 medium high ( s p r i n g : 1.15 w in te r : 1.0) 0.80-1.00 gra in (12-15%) 2 spr ing 100-120 w in te r 180-250 long day/ day neut ra l 25-30 (14-35) — medium — 700-850 3 105-113 long day/ day neut ra l 16-19 — — — 4 — — — low to medium medium — 5 — — 25-31 (5-37) — — — 1250 6 100+ — 20 — — — 1000 7 — — 25 — — — 625-750 8 — — 25-30 (0-30) 513 — — 1500 9 — — 18-24 (4-32) — — — 650-1000 spr ing 100-130 win ter 180-250 long day/ day neut ra l 15-31 (0-37) 450-650 medium to-high ( s p r i n g : 1.15 w in te r : 1.0) 0.80-1.00 gra in (12-15%) 650-1500 Sources: 1. Doorenbos, J . and A.H. Kassam, 1979; 2. Dube, P.A., 1981; 3. Young, Chi Tsu i , 1957; 4. Vink, A.P.A. , 1975; 5. Chang, Jen-hu, 1968; 6. Klages, K.H.W., 1942; 7. Mar t in and Leonard, 1949; 8. Wolfe and Kipps, 1959; 9. T r e i d l , R.A., 1978. Ky » Y ie ld response fac to r to water d e f i c i t , the y i e l d decreases per un i t of r e l a t i v e evapotrans-p i r a t i o n d e f i c i t . For ca l cu la t i on see Doorenbos and P r u l t t (1977). CLIMATIC REQUIREMENTS FOR LENTILS CO u CJ 06 => o CO TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH, °C OPTIMUM (RANGE) WATER REQUIREMENTS MM/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (X MOISTURE) PRECIPITATION (mm) 1 120-150 short day/ day neut ra l 15-20 (0-25) 300-500 medium - high (1 .0 -1 .15) 0.30-0.60 (8-10%) 700 2 — day neut ra l 15-25 (5-45) — — — 3 ear ly 80-110 l a te 125-130 day neut ra l 24 (6 .3-27.3) 790 — — 4 ear ly 80-110 la te 125-130 day neut ra l 24 (0-30) — medium — 700 5 — q u a n t i t a t i v e long day 15-25 (5-45) 200-500 — — 650 6 90-120 short day/ day neut ra l 15-20 (5-30) — — 0.40-0.80 7 — — — 150-480 — — 8 90-120 — — — — — S u — r y ear ly 80-110 l a te 125-150 short day/ day neut ra l 15-25 (0-45) 150-790 medium - high (1 .0 -1 .15) 0.30-0.80 (8-10^) 650-700 Sources: 1 . L e n t i l s , 1981; 2. Hawtin, G.C. et a l . , 1978; 3. Duke, J .A . , 1981; 4 . Kay, D.E., 1979; 5. Saxena, M.C., 1978; 6. F.A.O., 1978; 7. Rung, P., 1971; 8. Smartt , J . , 1976. Ky » Yie ld response fac to r to water d e f i c i t , the y i e l d decreases per u n i t of r e l a t i v e evapotrans-p i r a t i o n d e f i c i t . For ca l cu la t i on see Doorenbon and P r u i t t (1977). CLIMATIC REQUIREMENTS FOR MUSTARD SOURCES TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH, °C OPTIMUM (RANGE) WATER REQUIREMENTS MM/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (Z MOISTURE) PRECIPITATION (mm) 1 90-120 no l i m i t a -t i o n by photoperlod 15-25 (5-30) — low « 0 . 8 5 ) — 400-600 2 88-96 no l i m i t a -t i on by photoperlod — — — — 3 85-100 — — — — — 4 85-100 — — — — — 400-500 5 85-160 not c r i t i c a l — <500 — — 6 80-90 not c r i t i c a l 15-20 (5-35) — — 0.40-0.80 500-700 S u - a r ? 80-160 not c r i t i c a l 15-20 (5-35) <500 low (<0.85) 0.40-0.80 400-700 Sources: 1 . Weiss, E.A., 1983; 2. Dube, P.A., 1981; 3. Rapeseed Associat ion Canada, 1970; 4 . Singh, D., 1958; 5. Godin, V . J . £ t a l . , 1971; 6. F.A.O., 1978. Ky - Y ie ld response fac tor to water d e f i c i t , the y ie ld decreases per un i t o f r e l a t i v e evapotrans-p i r a t l o n d e f i c i t . For c a l c u l a t i o n see Doorenbos and P r u l t t (1977) . CLIMATIC REQUIREMENTS FOR FINGER MILLET SOURCES TOTAL GROWING PERIOD (DAYS) DAY LENGTH REQUIREMENT FOR FLOWERING TEMPERATURE REQUIREMENTS FOR GROWTH, °C OPTIMUM (RANGE) WATER REQUIREMENTS MM/GROWING PERIOD SENSITIVITY TO WATER SUPPLY (ky) WATER UTILIZATION EFFICIENCY FOR HARVESTED YIELDS Ey, kg/m 3 (Z MOISTURE) PRECIPITATION (mm) 1 90-120 short day/ day neut ra l 20 (15-35) 400-450 medium - low (0 .85-1 .0 ) — 500-1000 2 85-150 short day/ day neut ra l 24 (8-40) 350-400 — — 500-1000 3 70-90 day neut ra l 30-35 (15-45) — low 0.15-0.30 — 4 — — — 560 low (<0.85) — 400-800 5 — — — 548 — — 548-1156 6 — — — 330-760 — — — 7 105-180 short day 27 — — — — S u - a r y 70-180 short day/ day neut ra l 20-35 (8-45) 330-760 medium - low (0 .85-1 .0) 0 .15-0.30 400-1156 Sources: 1 . Thomas, D.G., 1970; 2. Rachie, K.O. et^al_. , 1977; 3. F.A.O., 1978; 4 . F.A.O., 1980; 5. Hulse, J .H. et a l , 1980; 6. Kung, P., 1971; 7. Purseglove, J.W., 1972 Ky - Y ie ld response fac tor to water d e f i c i t , the y i e l d decreases per u n i t of r e l a t i v e evapotrans-p i r a t i o n d e f i c i t . For c a l c u l a t i o n see Doorenbos and P r u i t t (1977) . SOIL REQUIREMENTS FOR RICE LCES SLOPE I SOIL DEPTH (cm) ORGANIC MATTER TEXTURAL CLASS DRAINAGE Pi 1 SENSITIVITY TO SALINITY SPECIFIC PROPERTIES SOUB OPTIMUM OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE 1 — — — — heavy c lay — poor — 5.5-6.0 " — moderately sens i t i ve h igh ly t o l e r a n t to 0 2 d e f i c i t 2 deep — — loam to c lay loam sandy loam to c lay poor — 6.3 5 .8-6 .8 moderately sens i t i ve — 3 l e v e l — — — medium to heavy wide range poor s l i g h t l y ac id wide range t o l e r a n t to s a l i n i t y — 4 l e v e l — — — heavy wide range poor — 5.5-6.5 wide range t o l e r a n t to s a l i n i t y — 5 l e v e l — — — clayey s o i l s wide range poor — t o l e r a n t to s a l i n i t y — 6 l e v e l — — — heavy wide range poor — 5.5-6.5 wide range t o l e r a n t to s a l i n i t y — 7 — deep high f i ne heavy texture wide range poor poor ly to we l l 5.5-6.5 4 .7 -8 .2 — best crop fo r t o l e r a t i n g s a l t s 8 1 moderatel; deep — — clayey — poor — mid-pH 4 .5 -8 .0 t o l e r a n t to s a l i n i t y best crop fo r t o l e r a t i n g s a l t s 9 2 >100 20-100 — f i ne clayey coarse s i l t y to f i ne clayey somewhat poor we l l to very poor — — t o l e r a n t to s a l i n i t y 0-2 >100 20-100 high f i ne clayey coarse s i l t y to f ine clayey poor to somewhat poor w e l l to very poor 5.5-6.5 3 .5-8 .4 t o l e r a n t to s a l i n i t y h igh l y t o l e r a n t to 0 2 d e f i c i t and best crop fo r t o l e r a t i n g s a l t s . Sources: 1. Doorenbos, J . and A.H. Kassam, 1979; 2. Matsushima, S., 1980; 3. Nuttonson, M.Y., 1965; 4. Luh, B.S., 1980; 5. Hopkins, J., 1964; 6. G r i s t , D.H., 1975; 7. De Datta, S.K., 1981; 8. Tinsley, R.L., 1981; 9. Chun, Soo Shin, 1971. SOIL REQUIREMENTS FOR CORN ICES SLOPE x SOIL DEPTH (cm) ORGANIC MATTER TEXTURAL CLASS DRAINAGE PH SENSITIVITY TO SALINITY SPECIFIC PROPERTIES SOUI 1 OPTIMUM OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE 1 — deep — — — — wel l — 5.0-7.0 moderately sens i t i ve needs aerated s o i l s w i t h deep water tab le wi thout water logging 2 — deep — high medium — we l l — 6.0-7.0 —- moderately sens i t i ve 3 — deep — — medium — wel l — 6.0-7.0 5 .6-7 .5 4 — — — — — — wel l — 7.0 5 .0-8 .0 5 — deep — high loam to s i l t loam sandy to clayey we l l — 6.0-7.0 — moderately sens i t i ve gives good response to f e r t i l i z e r s 6 2 deep — high loam to s i l t loam sandy loam to s i l t y c lay loam we l l — 6.5 — — 7 — deep — high loam to c lay loam wide range we l l 6.5 5 .5-7 .0 — Inherent f e r t i l i t y l e v e l should be high 8 0-8 50 10-50 moderate s i l t to c lay loam sandy loam to heavy c lay moder-a te l y wel l to we l l imper-fec t to lomewhat exces-sive 5.5-8.5 5 .2-8 .5 moderately s e n s i t i v e inherent f e r t i l i t y l e v e l should be moderate 0-8 MOO 10-100 moder-a t e l y to high s i l t to c lay loam sandy loam to heavy c lay moder-a te l y we l l to we l l imper-f e c t to somewhat exces-sive 5.5-8.2 5 .0-8 .5 moderately sens i t i ve needs aerated s o i l s w i t h deep water tab le wi thout water logg ing ; gives good response to f e r t i l -i ze rs a inherent s o i l f e r t i l i t y l eve l should be moderate to high Sources: 1. Doorenbos, J . and A.H. Kassam, 1979; 2. A l d r i c h , S.R., 1970; 3. A l d r i c h , S.R. and E.R. Leng, 1965; 00 4. Mi rac le , M.P., 1966; 5. Berger, J . , 1962; 6. Shaw, R.H., 1976; 7. Dube, P.A., 1981; 8. Dumanski, J. and R.B. Stewart, 1981. SOIL REQUIREMENTS FOR WHEAT ISOURCES SLOPE % OPTIMUM SOIL DEPTH (cm) ORGANIC MATTER TEXTURAL CLASS DRAINAGE pH SENSITIVITY TO SALINITY SPECIFIC PROPERTIES ISOURCES OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE 1 — — — — medium textured — —. — 6.0-8.0 moderately t o l e r a n t r e l a t i v e l y t o l e r a n t to high water tab le 2 0-8 50 10-50 — s i l t loam, c lay loam sandy loam to heavy clays moder-a t e l y we l l to we l l imper-fec t to some what exces-sive 5.5-8.2 5.2-8.5 moderately t o l e r a n t — 3 — deep — high loam to clay wide range we l l — 6.5 6 .0-7 .0 — prefers f e r t i l e s o i l s 4 — — — — loamy c lay loam to s i l t y c lay loam w e l l — — • — — — 5 — — — — medium loamy to clayey — — — — moderately t o l e r a n t — 6 — — — moder-a te l y high medium — moder-a t e l y we l l — neu t ra l to s l i g h t l y a l k a -l i n e s l l g h t l ac id to s l l g h t l ; a l k a -l i n e moderately ' t o l e r a n t — 7 — deep — — loam to c lay loam sandy loam to clay we l l — — — — — 8 — — — high clay loam loam to clayey w e l l — mid pH — — 0-8 50-100 10-100 moderate to high loam to c lay loam sandy loam to heavy c lay moder-a t e l y we l l to we l l imper-fec t to lomewhat exces-sive 5.5-8.2 5.2-K.5 moderately t o l e r a n t pre fers f e r t i l e s o i l s ; r e l a t i v e l y tol 'S'- int to high water tab le VO Sources: 1 . Doorenbos, J . and A.K. Kassam, 1979; 2. Dumanskl, J . and R.D. Stewart, 1981; 3. Dube, A.A. , 1981; 4. Young, Chi -Tsu i , 1957; 5. Vlnk, A.P.A. , 1975; 6. Klages, K.H.W., 1942; 7. Mar t in and Leonard, 1949; 8. Wolfe and Kipps, 1959. SOIL REQUIREMENTS FOR LENTILS SOURCES SLOPE X OPTIMUM SOIL DEPTH (cm) ORGANIC MATTER TEXTURAL CLASS DRAINAGE pH SENSITIVITY TO SALINITY SPECIFIC PROPERTIES SOURCES OPTIMUM RANGE OPTIMUM RANCE OPTIMUM RANGE OPTIMUM RANGE 1 0-2 50 15-50 medium loams loamy sand to clay we l l w e l l to imper-fect 7.0-7.5 5 .5-9 .0 moderately s e n s i t i v e performs we l l on land of moderate to low f e r t i l i t y 2 — — — — — — — — 6.8 4 .5 -8 .2 moderately s e n s i t i v e — 3 — — — — loams l i g h t loam to clay — — — — moderately sens i t i ve 4 — 50 — — loams sandy to heavy c lay we l l we l l to imper-fec t — — moderately sens i t i ve gives good response to P 2 0 5 5 — — — — medium wide range clayey — —• — wide range moderately s e n s i t i v e h igh l y suscept ib le to zinc def ic iency i f grown i n r i c e s o i l s 6 — — — — wide range moder-a t e l y we l l — — 7.0-8.5 moderately s e n s i t i v e moderately r e s i s t -ant to water logging 7 — — — — — wide range we l l — — — — — 8 — — — l i g h t to medium wide range — — — — — 0-2 50 15-50 medium loams loamy sand to heavy c lay moder-a te l y we l l to we l l we l l to imper-fec t 6.8-7.5 4 .5 -9 .0 moderately sens i t i ve performs w e l l on land of moderate to low f e r t i l i t y ; gives good response to P 2 0 5 ; suscep t i -b le to zinc **<*fictpncy; pw>^er— a t e l y res i s tan t to water logging Sources: 1 . Saxena, M.C., 1981; 2. Duke, J .A . , 1981; 3. Purseglove, J.W., 1968; 4. Kay, D.E., 1979; 5. Saxena, M.C., 1978; 6. F.A.O., 1959; 7. Smartt, J . , 1976; 8. Arnon, J . , 1972. O SOIL REQUIREMENTS FOR MUSTARD ,CES SLOPE x SOIL DEPTH (cm) ORGANIC MATTER TEXTURAL CLASS DRAINAGE pH SENSITIVITY TO SALINITY SPECIFIC PROPERTIES SOUR OPTIMUM OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE 1 — moder-a t e l y deep wide range medium medium loam loam to c lay loam we l l moder-a te l y w e l l to exces-sive 6.5 5 .5-8 .0 moderately sens i t i ve 2 — moder-a te l y deep — — medium loam sandy loam to clay loam we l l — — — moderately sens i t i ve t o l e r a n t to a l k a -l i n e and s l i g h t l y sa l ine s o l i 3 0-5 — — — — wide range w e l l — — — —— — A — — — — — wide range we l l — — — —— —— 5 — — — — sandy loam to loam loamy sand to clay we l l — 7.0 — moderately sens i t i ve s e n s i t i v e to water logg ing and t o l e r -ant to s a l i n i t y 6 — — — — — — — — — wide range — high s a l t to lerance S u - a r y 0-5 moder-a te l y deep wide range medium sandy loam to loam loamy sand to clay we l l moder-a te l y we l l to exces-sive 6.5-7.0 5 .5-8 .0 moderately sens i t i ve h igh s a l t t o l e r -ance; t o l e r a n t to a l k a l i n e and s l i g h t l y sa l ine s o i l ; sens i t i ve to water logging Sources: 1 . Weiss, E.A., 1983; 2. Dube, P.A., 1981; 3. Rapeseed Associat ion of Canada, 1970; 4 . Singh, D., 1958; 5. Godin, V . J . et a l . , 1971; 7. Ra i , M., 1977. SOIL REQUIREMENTS FOR FINGER MILLET Ul (J SLOPE x SOIL DEPTH (cm) ORGANIC MATTER TEXTURAL CLASS DRAINAGE pH SENSITIVITY TO SALINITY SPECIFIC PROPERTIES SOUR OPTIMUM OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE OPTIMUM RANGE 1 1-5 moder-a t e l y deep — medium to low loam sandy loam clay loam we l l we l l to moder-a te l y we l l 7.0 6 .0-8 .0 moderately s e n s i t i v e low f e r t i l i z e r requirement 2 —' — — — sandy loam loamy sand to c lay loams we l l — — — t o l e r a n t t o l e r a n t to s a l t and a l k a l i n i t y 3 0-8 >75 25-75 low s i l t loam to c lay loam loamy sand to s i l t y clays moder-a te l y we l l imper-fec t to exces-sive 5.5-7.5 5.2-8.2 moderately sens i t i ve low f e r t i l i t y requirements 4 — — — low l i g h t textured — wel l — — — — adapted to low s o i l f e r t i l i t y 5 moder-a te l y deep — — sand loam to loam loamy sand to c lay loam we l l — 7.0 5.0-7.8 moderately s e n s i t i v e h igh requirement f o r sulphur 6 — — — low sandy loam to loam sandy to clay loam we l l - — — — — cannot wi thstand water logging and adapted to i n f e r -t i l e s o i l 7 — — — low wide range we l l — — — — adapted to low s o i l f e r t i l i t y 0-8 >75 25-75 medium to low sandy loam to c lay loam loamy sand to clays moder-a t e l y we l l to we l l lmner-fec t to exces-sive 5.5-7.5 5.0-8.2 moderately s e n s i t i v e adaoted to low s o i l f e r t i l i t y , h igh requirement fo r su lphur , cannot wi thstand water logging Sources: 1 . Thomas, D.G., 1970; 2. Rachie, K.0. e t _ a l . , 1977; 3. F.A.O., 1978; 4. F.A.O., 1980; 5. Hulse, J .H. et a l . , 1980; 6. Purseglove, J.W., 1972; 7. Leonard, W.H., et a l . , 1963. APPENDIX II ASSESSMENT OF MEAN CROP ROTATION SUITABILITY RATINGS FOR NON IRRIGATED AND IRRIGATED CONDITIONS SUITABILITY RATING FOR DOUBLE ROTATION RICE-ALL WITHOUT IRRIGATION ROTATIONS NO. • I I I I I I IV SUM (I) OF MEAN SIITTABTT.TTY STITTARTT.TTY SEASONS M W M W M W M W I IATING Rr iTING OPTIMUM OPTIMUM ROTATION SEQUENCES + SUITABILITY USE fjm? A T MTTQTARfl LAND fVtlEiAl OR nuo 1AIVU OR UNITS SUBUNITS Z CORN RICE CORN CORN CORN LENTILS CORN MILLET I I I I I I IV I I I I I I IV l a -100 — — — — — — — — l b l b t 70 _ l b 2 30 5 4 5 4 5 4 5 4 9 9 9 9 4.5 4.5 4.5 4.5 4 I - IV l c l C l 70 5 4 5 4 5 4 5 4 9 9 9 9 4.5 4.5 4.5 4.5 4 I - IV l c 2 30 5 4 5 4 5 4 5 4 9 9 9 9 4.5 4.5 4.5 4.5 4 I - IV l d i 70 5 4 5 4 5 4 5 4 9 9 9 9 4.5 4.5 4.5 4.5 4 I - IV I d l d 2 20 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I - IV l d 3 10 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I - IV 2a — -100 5 4 5 4 5 3 5 4 9 9 8 9 4.5 4.5 4 4.5 4 I I I 2b — -100 3 4 3 3 3 3 3 3 7 6 6 6 3.5 3 3 3 3 I I - I V 2ci 50 1 4 1 3 1 3 1 3 5 4 4 4 2.5 2 2 2 2 I I - I V 2c 2c 2 35 5 4 5 4 5 3 5 4 9 9 8 9 4.5 4.5 4 4.5 4 I I I 2c 3 15 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I - IV 2d 2di 80 1 4 1 4 1 4 1 3 5 5 5 4 2.5 2.5 2.5 2 2 IV 2d 2 20 4 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I - IV 3a 3a i 75 1 4 1 3 1 3 1 3 5 4 4 4 2.5 2 2 2 2 I I - I V 3a 2 25 4 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I - IV 3b i 60 4 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I - IV 3b 3b 2 25 1 4 1 4 1 4 1 3 5 5 5 4 2.5 2.5 2.5 2 2 IV 3b 3 15 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I - IV 3c 3ci 55 3 4 3 4 3 4 3 4 7 7 7 7 3.5 3.5 3.5 3.5 3 I - IV 3c 2 45 1 4 1 3 1 3 1 3 5 4 4 4 2.5 2 2 2 2 I I - I V 3d 3d! 60 5 5 5 5 5 5 5 5 10 TO 10 10 5 5 5 5. 5 I - IV 3d 2 30 1 4 1 4 1 4 1 3 5 5 5 4 2.5 2.5 2.5 2 2 IV 3d 3 10 5 4 5 4 5 3 5 4 9 9 8 9 4.5 4.5 4 4.5 4 I I I SUITABILITY RATING FOR DOUBLE ROTATION CORN-ALL WITHOUT IRRIGATION ROTATIONS NO. • I II III IV SUM (I) OF MEAN C1TTTAP.TT TTV eilTTAOTT TTV SEASONS H W M W M W M W RATING RATING OPTIMUM OPTIMUM ROTATK )N SEQUENCE! WHEAT MUSTARD SUITABILITY USE LAND OR OR UNITS SUBUNITS z RICE RICE RICE CORN RICE LENTILS RICE MILLET I II III IV I II III IV la -100 lb lb! 70 l b 2 30 5 4 5 4 5 4 5 4 9 9 9 9 4.5 4.5 4.5 4.5 4 I-IV lc l c . 70 5 4 5 4 5 4 5 4 9 9 9 9 4.5 4.5 4.5 4.5 4 I-IV l c 2 30 3 4 3 4 3 3 3 4 7 7 7 7 3.5 3.5 3.5 3.5 3 I-IV Id, 70 3 4 3 4 3 4 3 4 7 7 7 7 3.5 3.5 3.5 3.5 3 I-IV Id l d 2 20 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I-IV "3 10 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I-IV 2a 2a -100 4 1 4 1 3 1 4 5 5 4 5 2.5 2.5 2 2.5 2 III 2b 2b -100 1 4 1 3 1 3 1 3 5 4 4 4 2.5 2 2 2 2 II-IV 2c! 50 4 3 3 3 3 3 3 7 6 6 6 3.5 3 3 3 3 II-IV 2c 2c 2 35 1 4 1 4 1 3 1 4 5 5 4 5 2.5 2.5 2 2.5 2 III 2c3 15 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I-IV 2d 2d, 80 3 4 3 4 3 4 3 3 7 7 7 6 3.5 3.5 3.5 3 3 IV 2d2 20 * 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I-IV 3a 3a! 75 3 4 3 3 3 3 3 3 7 6 6 6 3.5 3 3 3 3 II-IV 3a2 25 4 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I-IV 3bi 60 4 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I-IV 3b 3b2 25 3 4 3 4 3 4 3 3 7 7 7 6 3.5 3.5 3.5 3 3 IV 3b3 15 5 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I-IV 3c 3c i 55 4 4 4 4 4 4 4 4 8 8 8 8 4 4 4 4 4 I-IV 3c 2 45 3 4 3 3 3 3 3 3 7 6 6 6 3.5 3 3 3 3 II-IV 3di 60 5 5 5 5 5 5 5 10 10 10 10 5 5 5 5 5 I-IV 3d 3d2 30 3 4 3 4 3 4 3 3 7 7 7 6 3.5 3.5 3.5 3 3 IV 3d3 10 1 4 1 4 I 3 1 4 5 5 4 5 2.5 2.5 2 2.5 2 III SUITABILITY RATING FOR TRIPLE ROTATION RICE-RICE-ALL WITH IRRIGATION ROTATIONS NO. • I II III IV SUM (I) OF SUITABILITY RATING MEAN SUITABILITY RATING OPTIMUM SUITABILITY OPTIMUM USE SEASONS • S M W S M W S M U s M W ROTATIC )N SEQUENCE! i • RICE RICE RICE RICE RICE WHEAT OR CORN RICE RICE LENTILS RICE RICE MUSTARD OR MILLET I II III IV I II III IV LAND UNITS SUBUNITS Z la -100 lb l b ! l b 2 70 30 3 5 3 3 5 3 3 r 3 3 5 3 11 11 11 11 3.7 3.7 3.7 3.7 4 I-IV l c l c , l c 2 70 30 I 3 3 I 3 3 3 3 3 3 3 3 3 3 3 3 11 9 11 9 11 9 11 9 3.7 3 3.7 3 3.7 3.7 3 3 I-IV Id Id! l d 2 l d 3 70 20 10 5 I 5 5 \ 3 5 5 3 5 5 5 5 3 5 5 \ 5 9 15 15 9 15 15 9 15 15 9 15 15 3 5 5 3 5 5 5 3 5 5 5 I-IV I-IV I-IV 2a — -100 1 1 1 1 1 3 1 1 1 1 1 3 3 5 3 5 1 1.7 1 1.7 1 I or III 2b — -100 1 1 1 1 1 1 1 1 1 1 1 1 3 3 3 3 1 1 1 1 1 I-IV 2c 2c, 2c 2 2c 3 50 35 15 5 5 \ j \ 1 1 5 3 1 5 \ \ 3 1 5 5 I 7 3 15 5 5 15 5 3 15 5 5 15 2.3 1 5 1.7 1.7 5 1.7 1.7 1.7 5 5 II-IV I or III I-IV 2d 2d, 2d 2 80 20 I 3 I I 3 1 3 3 3 3 3 3 3 3 3 7 9 5 9 5 9 5 9 2.3 3 1.7 3 1.7 1.7 3 I II-IV I-IV 3a 3a, 3a 2 75 25 3 \ 3 3 \ 1 3 1 3 3 3 1 3 \ \ 3 9 3 9 3 9 3 9 1 3 1 3 \ 1 3 3 I-IV I-IV 3b 3b, 3b 2 3b 3 60 25 15 3 I 3 \ I 3 1 5 3 3 5 3 3 5 I I 9 7 15 9 5 15 9 5 15 9 5 15 3 2.3 5 3 1.7 5 1.7 3 1.7 5 I I-IV II-IV I-IV 3c 3c, 3c 2 55 45 I \ I \ 3 1 3 1 I ; 3 1 I I 9 3 9 3 9 3 9 3 3 1 3 1 I 3 1 I I-IV I-IV 3d 3d, 3d 2 3d 3 iSO 30 10 I J i \ \ 5 1 3 5 3 1 J : 5 3 1 1 3 11 7 3 15 5 5 15 5 3 15 5 5 5 2.3 1 5 1.7 1.7 1.7 5 1.7 1.7 I II-IV I or III SUITABILITY RATING FOR TRIPLE ROTATION CORN-RICE-ALL WITH IRRIGATION ROTATIONS NO. • I II III IV SUM (E) OF RITTTAATI.TTY MEAN SUITABILITY SEASONS + S M U S M V S M w S M W RATING RAT [NG OPTIMUM OPTIMUM ROTATIC iN SEQUENCE! WHEAT OR CORN MIICTADrt SUITABILITY USE LAND UNITS SUBUNITS Z CORN RICE RICE CORN RICE CORN RICE LENTILS CORN RICE nub L AKU OR MILLET I II III IV I II III IV la -100 — — — — — — — — — — — — lb lb, l b 2 70 30 3 5 3 3 5 3 3 5 7 3 5 3 11 11 11 11 3.7 3.7 3.7 3.7 4 I-IV lc l c , l c 2 70 30 3 \ I 3 3 5 3 I 3 3 5 3 I 3 3 5 3 3 3 11 9 11 9 11 9 11 9 3.7 3 3.7 3.7 3.7 4 3 I-IV I-IV Id Id, l d 2 l d 3 70 20 10 \ 5 5 3 5 5 3 5 5 5 3 5 5 3 5 5 5 3 5 5 3 5 5 3 5 5 9 15 15 9 15 15 9 15 15 9 15 15 3 5 5 5 5 5 3 5 5 I-IV I-IV I-IV 2a — -100 3 1 1 3 1 3 3 1 3 1 3 5 7 5 7 1.7 2.3 1.7 2.3 2 I or III 2b — -100 1 1 1 1 1 1 1 1 1 1 1 3 3 3 3 1 1 1 1 1 I-IV 2c 2c, 2c 2 2c 3 50 35 15 \ \ 1 3 5 1 1 5 1 1 3 5 1 1 5 5 1 3 5 1 1 5 1 3 5 5 5 15 3 7 15 3 5 15 3 7 15 1.7 1.7 5 2.3 1.7 2.3 1 2 5 II-IV I or III I-IV 2d 2d, 2d 2 80 20 \ 3 I 1 3 1 3 I 1 3 1 3 \ 1 3 1 3 1 3 5 9 3 9 3 9 3 9 1.7 3 3 \ 3 1 3 II-IV I-IV 3a 3a, 3a 2 75 25 3 3 3 1 3 1 3 3 1 3 1 3 3 1 3 1 3 1 3 3 9 3 9 3 9 3 9 1 3 3 3 3 1 3 I-IV I-IV 3b 3b, 3b 2 3b 3 60 25 15 \ I I 3 1 5 3 1 5 I 3 1 5 3 1 5 3 1 5 3 1 5 3 1 5 9 5 15 9 3 15 9 3 15 9 3 15 3 1.7 5 I 1 5 3 1 5 I-IV II-IV I-IV 3c 3c, 3c 2 55 45 I I I 3 1 3 1 I 3 1 3 1 1 3 1 3 1 3 1 9 3 9 3 9 3 9 3 3 1 I I I 3 1 I-IV I-IV 3d 3d, 3d 2 3^ 3 60 30 10 3 1 I 5 I 3 5 1 1 5 1 3 5 1 1 5 1 3 5 1 1 5 1 3 15 5 5 15 3 7 15 3 5 15 3 7 5 1.7 1.7 7.1 1,7 2.3 5 1 ? II-IV I or III SUITABILITY RATING FOR TRIPLE ROTATION CORN-CORN-ALL WITH IRRIGATION ROTATIONS NO. • I II III IV SUM (E) OF Q I I T T A R T I T T V MEAN SUITABILITY SEASONS • S M U S M W S M W S M W RATING RATI NG OPTIMUM OPTIMUM ROTATIC iN SEQUENCE! WHEAT OR CORN SUITABILITY USE LAND UNITS SUBUNITS X CORN CORN RICE CORN CORN CORN CORN LENTILS CORN CORN m i d I A K U OR MILLET I II III IV I II III IV l a -100 lb lb, l b 2 70 30 3 5 3 3 5 3 3 5 3 3 5 3 11 11 11 11 3.7 3.7 3.7 3.7 4 I-IV lc l c , l c 2 70 30 3 3 I I 5 5 3 3 I 5 5 3 3 I 5 5 3 3 11 11 11 11 11 11 11 11 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 4 4 I-IV I-IV Id Id, l d 2 70 20 10 3 5 5 i 5 5 5 5 5 3 5 5 5 5 3 5 5 5 5 5 5 3 5 5 11 15 15 11 15 15 11 15 15 11 15 15 3.7 5 5 3.7 3.7 5 5 3.7 4 5 5 I-IV I-IV 1-IV 2a — -100 3 5 1 3 5 3 3 5 1 3 5 3 9 11 9 11 3 3.7 3 3.7 3 I or III 2b — -100 1 3 1 1 3 1 1 3 1 1 3 1 5 5 5 5 1.7 1.7 1.7 1.7 2 I-IV 2c 2c, 2c 2 2c 3 50 35 15 1 3 5 5 5 1 5 5 \ | 1 5 5 1 1 5 \ 1 5 5 1 3 5 5 9 15 3 11 15 3 9 15 3 11 15 1.7 3 5 3.7 1 3 5 3.7 1 3 5 II-IV I or III I-IV 2d 2d, 2d 2 80 20 1 3 \ I 3 1 3 3 3 1 3 1 3 3 1 3 1 3 5 9 3 9 3 9 3 9 1.7 3 3 1 3 3 1 3 II-IV I-IV 3a 3a, 3a 2 75 25 1 3 3 3 3 1 3 \ \ 1 3 1 3 3 1 3 1 3 3 9 3 9 3 9 3 9 1 3 3 1 3 3 1 3 I-IV I-IV 3b 3b, 3b 2 3b 3 60 25 15 3 1 5 I 3 1 3 1 5 5 I 3 1 5 3 1 5 3 1 5 3 1 5 9 5 15 9 3 15 9 3 15 9 3 15 3 1.7 5 I 3 1 5 I 3 1 5 I-IV II-IV I-IV 3c 3 c l 3=2 55 45 : 3 1 1 \ \ 1 1 I I 1 1 3 1 I 1 1 3 1 7 3 7 3 7 3 7 3 2.3 1 2.3 2.3 1 2.3 2 1 I-IV I-IV 3d 3d, 3d, 3d 3 60 30 10 5 1 3 1 3 1 5 1 5 I I 5 1 S 5 1 1 1 5 1 5 5 1 3 15 5 9 15 3 11 15 3 9 15 3 11 5 1.7 3 3.7 5 1 3 3.7 5 1 3 I-IV II-IV I or III APPENDIX III METHOD OF FERTILIZER CAPABILITY CLASSIFICATION (FCC) 140. DESCRIPTION OF TYPE, SUB-TYPE AND MODIFIER CLASSES USED IN THE FERTILITY CAPABILITY CLASSIFICATION SYSTEM Type Texture of plough-layer or surface 20 cm (8 i n ) , whichever i s shallower. S = sandy t o p s o i l s ; loamy sands and sand (by USDA d e f i n i t i o n ) L = loamy t o p s o i l s ; <35% clay but not loamy sand or sand C = clayey t o p s o i l s ; >35% clay 0 = organic s o i l s ; >30% O.M. to a depth of 50 cm (20 in) or more Substrata Type (Texture of Subsoil) Used only i f there i s a textural change from the surface or i f a hard r o o t - r e s t r i c t i n g layer i s encountered within 50 cm (20 i n ) . S = sandy su b s o i l ; texture as i n type L = loamy su b s o i l ; texture as i n type C = clayey subsoil; texture as i n type R = rock or other hard root r e s t r i c t i n g layer Condition Modifiers Where more than one c r i t e r i o n i s l i s t e d for each modifier, only one needs to be met to place the s o i l . g = (g l e y ) : s o i l or mottles <2 chroma within 60 cm (24 in) of surface and below a l l A horizons or saturated with H 20 for >60 days i n most years. d = (dry): u s t i c or xe r i c environment (dry >90 cumulative days per year within 20-60 cm depth). e = (low c . e . c ) : (applies only to plough-layer or surface 20 cm (8 i n ) , whichever i s shallower). <4 meq./lOO g s o i l by T bases + KCl-extractable A l <7 meq./lOO g s o i l by I cations at pH 7 <10 meq./lOO g s o i l by £ cations + Al + H at pH 8.2 a = ( A l t o x i c ) : >60% EA saturation of c.e.c. by £ bases + KCl-extractable Al within 50 cm (20 in) >67% A l saturation of c.e.c. by £ cations pH 7 within 50 cm (20 in) 141. >86% EA saturation of c.e.c. by £ cations at pH 8.2 within 50 cm (20 in) or pH < 5.0 i n 1:1 H 20 except i n organic s o i l s . EA = exchange a c i d i t y . h = (Acid): 10-60% Al saturation of c.e.c. by £ bases + KCl-extractable A l within 50 cm (20 in) or pH i n 1:1 H 20 between 5.0 and 6.0 i = (Fe-P f i x a t i o n ) : (used only i n clay (C) types) % Free Fe 20 3/% clay > 0.15 or, hues of 7.5 YR or redder and granular structure x = (X-ray amorphous): (applies only to plough-layer or surface 20 cm (8 i n ) , whichever i s shallower) pH > 10 i n IN NaF, or p o s i t i v e to f i e l d NaF test or other i n d i r e c t evidence of allophane dominance i n clay f r a c t i o n v = ( V e r t i s o l ) : Very s t i c k y p l a s t i c clay: >35% clay and >50% of 2:1 expanding clays; COLE > 0.09. Severe t o p s o i l shrinking and swelling. k = (K d e f i c i e n t ) : <10% weatherable minerals i n s i l t and sand f r a c t i o n within 50 cm of s o i l surface or exchange. K < 0.20 meq./lOO g or K < 2% of £ bases, i f £ of bases < 10 meq./lOO g. b = (Basic r e a c t i o n ) : Free CaC03 within 50 cm of s o i l surface ( f i z z i n g with HC1) or pH > 7.3 s = ( S a l i n i t y ) : >4 mmhos/cm of saturated extract at 25°C within 1 m depth n = ( N a t r i c ) : >15% Na saturation of c.e.c. within 50 cm (20 in) of surface c = (Cat c l a y ) : pH i n 1:1 H 20 i s <3.5 a f t e r drying and J a r o s i t e mottles, with hues of 2.5 Y or yellower and chromas 6 or more are present within 60 cm. = (gravel): a prime (') denotes 15-35% gravel or coarser (>2 mm) p a r t i c l e s by volume to any type or substrata type texture (example: S'L = gravelly, sand over loamy; SL' = sandy over gravelly loam); two prime marks ('') denote more than 35% gravel or coarser p a r t i c l e s (>2 mm) by volume i n any type or substrate type (example: L C ' = loamy over clayey s k e l e t a l ; L ' C ' = gravel l y loam over clayey s k e l e t a l ) . 142. % = (slope): where i t i s desirable to show slope with the FCC, the slope range percentage can be placed In parentheses af t e r the l a s t condition modifier (example: sb(l-6%) = uniformly sandy s o i l , calcareous i n reaction, 1-6% slope). f = flooding hazard by r i v e r Source: Buol, S.W. and W. Couto, 1981. 143. SAMPLE MANAGEMENT INTERPRETATIONS OF FCC NOMENCLATURE A. I n t e r p r e t a t i o n of FCC Types and Substrata Types L: Good water-holding capacity, medium i n f i l t r a t i o n capacity S: High rate of i n f i l t r a t i o n , low water-holding capacity C: Low i n f i l t r a t i o n rates, p o t e n t i a l high run-off i f sloping, d i f f i c u l t to t i l l except when i modifier i s present 0: A r t i f i c i a l drainage i s needed and subsidence w i l l take place. Possible micronutrient deficiency, high herbicide rates usually required. SC, LC, LR, SR: Susceptible to severe s o i l d e t e r i o r a t i o n from erosion exposing undesirable s u b s o i l . High p r i o r i t y should be given to erosion c o n t r o l . B. I n t e r p r e t a t i o n of FCC Condition Modifiers When only one condition modifier i s included i n the FCC class nomen-cl a t u r e the following l i m i t a t i o n s or management requirements apply to the s o i l . Interpretations may be s l i g h t l y modified when two or more modifiers are present simultaneously or when text u r a l classes are d i f f e r e n t . Modifiers Main Lim i t a t i o n s and Management Requirements g D e n i t r i f i c a t i o n frequently occurs i n anaerobic subsoil and t i l l a g e operations and c e r t a i n crops may be adversely a f f e c t -ed by excess r a i n unless drainage i s improved by t i l e s or other drainage procedures. d S o i l moisture i s l i m i t e d during the growing season unless i r r i g a t e d . Planting date should take into account the flush of N at onset of r a i n . e Low a b i l i t y to r e t a i n nutrients for plants, mainly Ca, K, Mg. Heavy applications of these nutrients should be s p l i t . P o t e n t i a l danger of overliming. a Plants se n s i t i v e to aluminum t o x i c i t y w i l l be affected unless lime i s deeply incorporated. Extraction of s o i l water below depth of lime incorporation w i l l be r e s t r i c t e d . Lime requirements are high unless an e modifier i s also indicated. h Strong to medium s o i l a c i d i t y . Requires liming for most crops. i High P f i x a t i o n capacity. Requires high l e v e l s of P f e r t i l i z e r . Sources and method of P f e r t i l i z e r a p p l i c a t i o n should be considered c a r e f u l l y . 144. x High P f i x a t i o n capacity. Amount of most convenient source " of P to be determined. v Clayey textured t o p s o i l . T i l l a g e i s d i f f i c u l t when too dry or too moist but s o i l s can be highly productive. k Low a b i l i t y to supply K. A v a i l a b i l i t y of K should be moni-tored and K f e r t i l i z e r s may be required frequently for plants r e q u i r i n g high l e v e l s of K. b Basic react i o n . Rock phosphate and other non-water-soluble phosphates should be avoided. P o t e n t i a l deficiency of c e r t a i n micronutrients, p r i n c i p a l l y i r o n and z i n c . s Presence of soluble s a l t s . Requires s p e c i a l s o i l management practices for saline s o i l s . n High l e v e l s of sodium. Requires sp e c i a l s o i l management practices for a l k a l i n e s o i l s . c P o t e n t i a l acid sulphate s o i l . Drainage i s not recommended without s p e c i a l p r a c t i c e s . Should be managed with plants tolerant to flood and high l e v e l of water table. f Flooding hazards and deposition of s i l t and sand. Source: Buol, S.W. and W. Coute, 1981. APPENDIX IV MAPS 1, 2 AND 3 

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