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Effects of mulched and incorporated sawdust on some chemical and physical properties of Fraser Valley… Dargie, George 1953

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EFFECTS OF MULCHED AND INCORPORATED SAWDUST ON SOME CHEMICAL AND PHYSICAL PROPERTIES OF FRASER VALLEY UPLAND SOIL by GEORGE DARGIE A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN AGRICULTURE in the Department of Agronomy We accept this thesis as conforming to the standard required from candidates for the degree of MASTER $F SCIENTIFIC AGRICULTURE. Members of the Department of Agronomy THE UNIVERSITY OF BRITISH COLUMBIA October, 1953. ABSTRACT Effects of Mulched 'and Incorporated Sawdust on Some Chemical and Physical Properties of Fraser Valley Upland S o i l by George Dargie A Master of Scientific Agriculture Thesis The University of Br i t i s h Columbia October, 1953. The study included f i e l d , greenhouse and laboratory experiments with sawdust used as mulch and incorporated with s o i l . The f i e l d experiments were conducted with hemlock sawdust mulches on Lynden s i l t loam at Abbotsford and on Everett sandy loam at Aldergrove. In both cases the crop was strawberries. Two depths of sawdust were used, two and four inches, and these were compared with clean cultivation, with and without sprinkler irrigation. S o i l samples were taken i n t r i p l i c a t e from three depths at intervals throughout the 195>1 growing season and used for the determination of s o i l moisture. The 1951 season was one of the driest recorded and both depths of sawdust were very effective i n conserving s o i l moisture. On the Lynden s i l t loam the sawdust maintained s o i l moisture at a satisfactory level for growth throughout the growing period and was as effective as sprinkler irrigation for this purpose. However, on Everett sandy loam, sprinkler irrigation maintained s o i l moisture in a more satisfactory manner. Samples taken from the Lynden s o i l after the mulches had been down a year, indicated a reduction in Humin I nitrogen and nitrate nitrogen had occured as a result of mulching. However, the differences were not great and a more significant reduction of total nitrogen and nitrate nitrogen was noted on the irrigated plots. In the greenhouse experiment, two sizes of cedar and hemlock sawdust were incorporated at two rates with Alderwood sandy loam, f e r t i l i z e d at two rates and planted with lettuce. After one year i t was found that hemlock sawdust had increased the moisture equivalent and wilting percentage more than cedar had, but that the cedar mixtures gave a higher yield of lettuce. In a l l cases the differences were small but significant. Sawdust, when incorporated with the acidic s o i l , raised the pH slightly and increased the moisture equivalent, permanent wilting percentage and cation exchange capacity of the s o i l , the effect being greater for the higher rate of incorporation. Sawdust had the opposite effect on available moisture and lettuce yield. Apparent specific gravity of the s o i l was noticeably decreased as a result of the sawdust additions and a very large increase i n non-capillary pore space occured. This was associated with a large increase in percolation rate. Capillary porosity was affected to a very small extent by the sawdust. Nitrogen f e r t i l i z a t i o n (NH^ NO^ ) increased s o i l acidity in the control s o i l and i n the s o i l sawdust mixtures. Tests were conducted to determine the absorptic capacity of sawdust for water and ammonia. Size of sawdust affected the amount of water absorbed but not the amount of ammonia absorbed. ACKNOWLEDGEMENTS The writer wishes to acknowledge his sincere appreciation for the assistance so generously provided by Dr. C. A. Rowles and Dr. D. G. Laird of the Department of Agronomy, University of British Columbia, who served in the capacity of advisors i n this study; the Vancouver laboratory of the Forest Products Laboratory Division, Department of Resources and Development, who made this study possible; Mr. Ralph H. Gram of the British Columbia Electric Railway Co., Ltd., Agricultural Division; the American Can Company and the Pacific Growers' Co-operative, who supplied the canning equipment; E. Aho, Abbotsford and F. Seifred, Aldergrove, for use of valuable strawberry plantings for experimental purposes; Mr. F. G. Guernsey of the Vancouver laboratory of the Forest Products Laboratory Division, for his kindly interest throughout this study, and to W. E. P. Davis, of the Dominion Experimental Farm, Agassiz, for his assistance in the st a t i s t i c a l planning of the greenhouse experiments. TABLE OF CONTENTS Page „ INTRODUCTION 1 LITERATURE REVIEW 3 EXPERIMENTAL 17 METHODS AND MATERIALS 17 Field Experiments With Sawdust Mulches . . 17 Greenhouse Experiment With Soil-Sawdust Mixtures . . . . 19 Laboratory Experiments With Greenhouse Materials. . . . 19 Laboratory Experiments With Sawdust 20 RESULTS AND DISCUSSION 22 Field Experiments With Sawdust Mulches. . . 22 Greenhouse Experiments With Incorporated Sawdust 29 The Effect of Sawdust Particle Size . . . . 29 The Effect of Nitrogen F e r t i l i z e r 30 The Effect of Incorporating Sawdust . . . . 31 The Effect of Sawdust Species 32 The Effect of Incorporating Sawdust on Moisture Retention . 33 The Effect of Incorporating Sawdust on the Percolation Rate . . 3h The Effect of Incorporating Sawdust on the Apparent Specific Gravity . 3k Absorption of Water and Ammonia by Sawdust. 39 SUMMARY ^1 TABLE OF CONTENTS Page. LITERATURE CITED kk FIGURES: FIGURE I. Lynden S i l t Loam, Irrigated and Non-Irrigated 23 FIGURE II. Everett Sandy Loam, Irrigated and Non-Irrigated 2h FIGURE III. pF Curve for Soil-Sawdust Mixes (Hemlock) , 36 FIGURE IV. pF Curve for Soil-Sawdust Mixes (Cedar) 37 TABLES: TABLE I, Percent Carbon, Hydrogen, Nitrogenj Ash in Two Conifers 3 TABLE II. Evaporation From an Experiment Field S o i l With Different Coverings . . 16 TABLE III. Nitrogen Fractionation of Lynden Mulched and Unmulched, Irrigated and Non-Irrigated Plots 28 TABLE IV. Influence of the Factors Studied on pH, Cation Exchange, Moisture Equivalent, Wilting Percentage, Available Moisture and Dry Matter 35 TABLE V. The Effect of Incorporation of Different Amounts and Sizes of Sawdust on the Percolation Rate of Alderwood Sandy Loam 38 TABLE VI. The Effect of Sawdust Incorporation on The Apparent Specific Gravity of Alderwood Sandy Loam 38 TABLE OF CONTENTS Page. APPENDIX 52 APPENDIX I. Moisture Table for Irrigated and Non-Irrigated Plots . . . 52 APPENDIX II. Rainfall Distribution During Summer, 195>1, at Abbotsford . 53 APPENDIX III. Table of Mean Squares for pH . 5U APPENDIX IV. Table of Mean Squares for Cation Exchange Capacity . . . 55 APPENDIX V. Table of Mean Squares for Moisture Equivalent . . . . . 56 APPENDIX VI. Table of Mean Squares for Wilting Percentage 57 APPENDIX VII. Table of Mean Squares for Available Moisture 58 APPENDIX VIII. Table of Mean Squares for Dry Matter 59 INTRODUCTION Two of the major industries in British Columbia are Forestry and Agriculture. In Forestry there is a large amount of waste material which is essentially organic matter. In Agriculture one of the most difficult things to maintain in the soil is organic matter, especially in soils which are cultivated intensively. Some of the sawmill materials, which at one time were considered waste, are now being utilized economically by being converted into marketable products, such ass broom handle squares, shingle bands, hogged fuel, pulp chips, and domestic sawdust. Even with these new uses there is s t i l l a considerable amount of waste material, a large percentage of which is in the form of sawdust and shavings. Certain species of sawdust do not make good commercial fuel, i.e., cedar and hemlock at the Pacific coast and spruce in the interior of British Columbia. In 1951, i t is estimated there were approximately 122,000 units of hemlock and balsam sawdust produced on the Pacific coast; 1*6,000 units of spruce and balsam in the southern interior; and 117,000 units of the latter two species in the northern interior. Of this amount approximately twenty-five percent may have been utilized as fuel for power by the mills. These figures are for shavings and do not take into account the number of units of shavings which would be produced by the planer mills making finished lumber ( 30 ) . 2. This material is not only waste but i t is also costly to the mill operators in that i t is necessary to dispose of i t or store i t . This might entail cost of burning (upkeep of burners), cost of storing, or cost of haulage plus the difficulty of finding a place to dispose of i t . On a large area of the upland soils of the Fraser Valley an intensive type of agriculture is practised, which includes soft fruit growing. In the case of strawberries the plants are usually grown for four years with clean cultivation between the rows and then another crop, such as broccoli, is planted almost immediately after the strawberry crop is harvested. With this type of agriculture, which uses,mainly, inorganic fertilizers there i s a danger of large and rapid depletion of the soil organic matter. With the following thought in mind; (a) the large amount of sawmill waste material; (b) the depletion of organic matter in upland agricultural soils; i t was deemed advisable to make a study of some of the effects of applications of sawdust upon the physical and chemical properties of these upland soils. LITERATURE REVIEW COMPOSITION OF WOOD. In making additions of wood to the soil one is adding principally the elements carbon, hydrogen, oxygen and adding small amounts of nitrogen and of the mineral elements, such as potassium, calcium, magnesium and phosphorous. The actual amount of these elements will vary with species, part of the tree used, and from tree to tree, but according to Gottlieb (29) the average composition of two conifers, f i r and spruce, i s : TABLE I Percent Carbon, Hydrogen, Nitrogen, Ash in Two Conifers (from Gottlieb) Species Carbon % Hydrogen % Nitrogen % Ash % Fir 50.31 6.20 O.Oi; .37 Spruce 50.36 5.92 o.o5 .28 The chemical elements present in wood are combined into many different compounds. Wise (71) gives a scheme showing the compounds which are grouped together in wood, as follows: u. I. MAIN COMPONENTS OF THE CELL WALL: (a) Total carbohydrate fraction Cellulose Pentosans Xylans Arabans Hemicellulose Hexosans Galactans Mannans Glucosans Uronic acids (b) Lignin II. EXTRANEOUS MATERIALS: (a) Volatile oils and resin acids, volatile acids. (b) Fixed oils (fatty oils). "(c) Natural dyestuffs and precursors. (d) Tannins (e) Plysaccharides and glycosides. (f) Ash (mineral salts). (g) Organic nitrogen compounds. (h) Other compounds, like resins, phytosterols, etc. This breakdown may be grouped approximately as - $% extractives, - 30$ lignin, - 15-25$ hemicelluloses, - U0-i±5$ cellulose. Wise (71) states that the nitrogen content of wood grown in the temperate zone averages between 0.1 - 0.3$ and rarely exceeds 0 .3$, the nitrogen content being dependent on soil conditions and season of the year. 5 THE DECOMPOSITION OF ORGANIC MATERIAL IN SOIL. From the foregoing i t can readily be seen that wood is a material high in carbohydrates and low in nitrogenous material, or expressed another way, the carbon-nitrogen ratio of wood is very wide. Also, i t can be seen that wood is a complex mixture of compounds and thus that its decomposition w i l l be very complex. The organisms which decompose wood belong to a number of groups. Some organisms are carried right in the wood and contribute mainly to the i n i t i a l breakdown (21), while others, such as bacteria, fungi, actinomycetes, protozoa, worms and insect larvae are present in the soil and carry out the later stages of decomposition (66). The type of organisms taking part in the decomposition of cellulose is determined to a degree by the reaction of the soil (67). For instance, some of the maximum acidities for organisms which may take part in the breakdown of cellulose are: cellulose decomposing bacteria, pH 5.7 - 6.0, actinomyces, pH U.8, and fungi, as low as pH 1.2. Although the reaction influences the type of organism decomposing cellulose i t does not appear to affect the rate of decomposition (67). The rate of decomposition of plant materials is dependent on the chemical constituents of the material, the number and groups of organisms present in the soil, the amount of nitrogen present, the amount of surface area exposed, the degree of aeration, and temperature (66,68). In the early stages of decomposition the rate i s governed by the amount of water soluble constituents present. These are simple 6. sugars, amino acids and soluble salts, a l l of which are readily u t i l i z e d by a great number of microorganisms, both fungi and bacteria. Thus, the greater the amount of water soluble components present the more rapid the rate of breakdown (68). In the later stages of decomposition the rate i s governed by the percentage of hemicellulose, cellulose and lignin present, the higher the percentage of these compounds the slower the rate of decay (U9, 23). Bray and Andrews (13), working with pure cultures of molds and fungi, found that the rate of decomposition of wood varied with the culture used. The carbohydrate materials present i n wood provide a source of energy for microorganisms. Waksman and Tenney (68) report that the organisms u t i l i z i n g this energy source require a definite amount of nitrogen for the synthesis of their protoplasm, also, that there i s a definite ratio between the cellulose decomposed and the nitrogen required by the organisms, Waksman and Tenney (69) have shown that when plant material contains about 1.7$ nitrogen there appears to be sufficient for the growth of the microorganisms which decompose this material more or less completely. Finnish workers (3U), working with applications of straw to s o i l , arrived at results which indicated that the amount of f e r t i l i z e r necessary to prevent the immobilization of s o i l nitrogen depended on the properties of the s o i l and possibly on other environmental conditions. This fact, they concluded, might explain the reason there i s the disagreement in many f i e l d experiments with respect to the use of straw. 7. Barthel and Bengtsson (8) noted that the cellulose fermenters could readily utilize the nitrogen of bacterial cells and that the amount of cellulose fermented was dependent upon the amount of nitrogen present i f the pH was kept at a level near neutrality. Anderson (U) obtained similar results to those of Barthel and Bengtsson, but carried his work further and found that he could get increased fermentation by additions of available nitrogen until the ratio of nitrogen to cellulose was approximately 1:35. Any nitrogen in excess of this ratio seemed to have l i t t l e or no effect on the fermentation. A number of workers (5U, 66, 68, 71) agree that' during the breakdown of wood lignin tends to accumulate while the cellulose and hemicellulose fractions are broken down and disappear and although there is anaccumulation of lignin i t is s t i l l slowly undergoing decomposition. Lignin in fresh or decomposed plant material can be attacked by mixed populations, such as soil organisms, and may, i f the conditions are suitable, decompose as rapidly as the celluloses and hemicelluloses (71, 5 l ) . When plant material is well broken down i t becomes a mixture of lignins, modified lignin complexes, proteins and other complex nitrogenous compounds which are mainly microbial by-products, hemicelluloses of both plant and microbial origin, small amounts of cellulose undergoing decomposition and varying concentrations of numerous other organic complexes in the process of decomposition, resistant to decomposition or products of decomposition. This mixture has been called "humus" (68) and is not static but i s undergoing continuous change. The carbon-^nitrogen of this active organic matter always approaches a constant of approximately 12 (57, H). 8. The effect of adding wood to soil has also been studied from the standpoint of nitrification and denitrification, thus in 1922, Gibbs and Werkman (28) obtained experimental results which led them to the conclusion that when wood was added to the soil i t did not cause denitrification but did inhibit nitrification.- Four years later, Anderson (k) found that none of the soil processes, such as nitrification and ammonification, were inhibited by additions of carbohydrates to the soil. From this work i t appeared that the nitrification process is masked i f the nitrogen present is not in excess of the requirements of the bacteria. INFLUENCE OF ORGANIC MATTER ON THE CATION EXCHANGE CAPACITY OF THE SOIL. The problem of maintaining or increasing the nutrient holding capacity is very important, particularly in soils where the mineral fraction is coarse and exhibits l i t t l e exchange capacity. In some of these coarse textured, soils organic matter may be responsible for almost the entire exchange capacity (3). Albrecht (l) found that soil organic matter, like clay, is largely colloidal but that i t is five times as effective as the clay in cation exchange. Mitchell (U2) reported that the organic complexes in mineral soils contributed from forty-one to sixty-five percent of the total exchange capacity. Lignin appears to be the compound which contributes most to the cation holding capacity of the organic fraction of soil and i t has been observed that this capacity increases as the plant material in which lignin occurs is broken down (U8). Norman and Peevy (I4.9) noted in their experiments that soils which had received treatments with materials of high lignin content had exchange capacities three times as great as that 9, of the control soils and showed increases four times as great as the increase resulting from the addition of cellulosic material. Mitchell (U2) is in agreement with Norman, but found that next to lignin the hemicellulose containing fraction was an important contributor to the exchange capacity. He believed that the lignin or humus fraction is responsible for the more or less permanent exchange properties of the soil organic matter. Muller (Ult), because of the drastic methods of isolating specific compounds in soil organic matter and the changes taking place, reasoned that the exchange properties should not be assigned to specific compounds but to certain groups such as hydroxyl and carboxyl. Other workers (lit., 1|.8) also give the same assignation. EFFECT OF WOOD ON SOIL REACTION. One of the controversial factors regarding the addition of wood to soil has been the effect that such additions have on soil reaction. Mclntyre (hi) suggested that the widespread idea that incorporating raw wood into the soil will make i t acid is the most important single factor for farmer reluctance to use of wood fragments. McCool (J4.6) studied the reaction of various species of wood, leached wood and soil wood mixes. His results indicated: that the pH varied with species ranging from as low as 3 .8 for mixed commercial sawdust to 6 .6 for hemlock; that when wood was leached with distilled water the wood became more alkaline; and that when wood was mixed with soil i t either raised or lowered the acidity, depending on the species and the i n i t i a l 10. pH of the s o i l . Midgley (Hi) i s of the opinion that sawdust does not cause acidity. He reported that although softwoods do not contain the amount of basic elements that hardwoods or strawy materials contain, after the wood i s completely destroyed most of the organic acids are used up by s o i l organisms or lost to the air, thus leaving a neutral or alkaline residue. Nostitz (50) reported the use of sawdust as l i t t e r increased the acidity of soils already acid. Sawdust may have a pH as low as Iu3> to 5 . 5 , but after being used as l i t t e r i n a dairy barn'their pH may be raised as high as 7 .0 to 7 . 5 , according to Geesaman and Horris ( 2 6 ) . Dealing with the effect of organic l i t t e r from trees, such as leaves, needles, etc., and grass, Dunnewald (22) found that they are basic or acidic depending on whether the soils on which they are grown are basic or acidic. This observation may hold true in a sense with sawdust, as trees grown on basic soils may give a sawdust with a higher pH than those grown on acidic s o i l s . EFFECT OF WOOD ON PLANT NUTRIENTS. Sawdust i t s e l f i s of very l i t t l e value as a source of plant nutrients, as may be seen from Table 1, however when i t i s undergoing decomposition i t may be of value directly or indirectly i n making elements available to plants. Stephenson ( 5 9 ) , i n the study of a s o i l p rofile, found indications that active humus, microorganisms, soluble nutrients, and plant growth were closely correlated. Below the zone of active and vigorous biological processes, the horizons became less productive. In 1921, Bauer (5) related the a v a i l a b i l i t y of phosphates with decomposing 11. organic matter. He believed the solution of the phosphates was due to the organic acids produced. (61, 62) showed that a number of organic anions were effective for preventing phosphates from combining chemically with aluminum and iron. Struthers and Sieling carried their work further and showed that the effect of different anions varied with reaction and that there was an effective organic anion for the whole pH range for an agricultural soil. The most effective anions were found to be,citrate, tartrate, malate, oxalate and malonate; these anions being produced by the action of microorganisms on organic matter in the soil. Swenson et al. (62) found that humus and lignin are effective in replacing phosphates from the basic iron phosphates, probably because of the formation of stable compounds or complexes by the active iron and humus or lignin. Investigators, (18, 19) found that organic matter has about the same effect on the uptake of phosphorous as the addition of inorganic phosphate fertilizers have in a soil which was low in available phosphate. EFFECTS OF ORGANIC MATTER ON THE PHYSICAL PROPERTIES OF SOIL. In addition to affecting the biological and chemical relationships of soil, organic matter has been found to affect the physical properties as well. Thus a considerable number of workers (16, 2k} UO, 55) have found that as the organic matter content of soil is increased, aggregation also increases. Most of these workers suggest that the organic matter or the products of its decomposition act as aggregating adhesives. Kroth and Page (36) claimed that the aggregating substances are evenly distributed throughout the soil crumb, and 12. reported the substances to be of two types, polar organic compounds resulting from the decomposition of fresh organic matter, and compounds including iron and aluminum oxides, fats, waxes and resins. This latter group were thought not to be as effective soil aggregators as the former. Myers (it5) found that organic colloids are many times more effective than inorganic colloids in producing water-stable aggregates following dehydration. It has been found that microorganisms are intimately associated with the formation of soil aggregates following the addition of organic material. Thus, Hubbel and Chapman (33) report that water-stable aggregates develop only in the presence of living microbes. Martin and Waksman (39) found that the action of microorganisms resulted in marked binding and aggregation of the soil particles. The extent of the binding depended on the organisms present and the nature of the organic matter being decomposed, the more rapidly the material broke down the greater the binding effect on the finer soil particles. Some workers attribute the binding or aggregating of the soil to the products of the bacterial metabolism. Martin (38), using a number of bacterial polysaccharides, reported positive results, similarly Geoghegan and Brian (27), but they also found that the nitrogen content of these products must be relatively high, that is around .2 percent to be effective. Furthermore they do not limit the metabolic products to polysaccharides but believe that a number of products could produce an ameliorating effect on the soil. 13. Organic matter has a definite influence on the moisture relationships within the soil. Working with four soils, Baver (5) ascribed 20% to 39% of the moisture absorbed to the organic matter present. Coile (17) greatly increased the moisture equivalent of coarse textured soils by the addition of organic material, whereas additions to fine textured soils had a lesser effect. In the coarse textured soil the wilting percentage was increased, but to a lower degree than the moisture equivalent; in the fine soils the wilting percentage was relatively unchanged. Stone and Garrison (60) noted that soils which had a high organic matter content had a high available moisture content. The net result of additions of organic matter to the soil upon its plasticity, according to Baver (5), is to raise both the upper and lower plastic limits, but there may be only a very slight increase in the plastic number. Smith and associates (58), working with a soil with a relatively high infiltration capacity, were able to further increase this capacity by additions of organic matter. Similar increases were observed in both infiltration and percolation rates by Browning (15). McCool (U6) increased the rate of percolation through Grundy s i l t loam by treating i t with pine shavings but decreased the rate of percolation by adding mixed pine sawdust. 1U. EFFECT OF ORGANIC MATERIAL ON THE PHYSICAL AND CHEMICAL RELATIONSHIPS  OF SOIL, WHEN USED AS MULCH. The effects considered in the previous sections have been primarily those resulting from the incorporation of wood and other organic materials into soil. However, such materials are often used as mulches, and not immediately mixed with the s o i l below. Used in this way wood and other organic materials may have different effects than when incorporated. In respect to the effect of organic mulch on the nitrate level of soil, Albrecht (2) found that i t caused a pronounced reduction in nitrate nitrogen. However, Beaumont, Sessions and Kelly (10) found, that in the case of coarse textured well-aerated soil there was a considerable build-up of nitrate nitrogen under mulches. In comparing these apparently conflicting results i t should be noted that they were obtained with very different soil conditions and sampling methods. Harris (31) found a depression of total nitrogen after one year but no change in nitrate nitrogen level, Turk (63) compared the effect of a sawdust mulch on a soil low in nitrogen to that on a soil relatively well supplied with nitrogen. The mulch on the soil low in nitrogen proved fatal to plants unless nitrogen fertilizer was added, whereas the fertile s o i l required no added nitrogen for plant growth. Motte (U3) found that the exclusive use of large quantities of sawdust on the soil without any added fertilizer generally gave excellent plant growth showing no nitrogen deficiency. The amount of nitrogen in the percolate from mulched and unmulched soils was measured by Turk and 15. Partridge (6I4.). The nitrogen in the solution from the soil under sawdust mulch was less than that from the unmulched soil but greater than under.a straw or stover mulch. When a l l these results are considered i t appears that i f a sawdust mulch reduces the level of soil nitrogen at a l l , i t does so only at first and that eventually i t may result in an increase in available soil nitrogen. Organic mulches have been reported to affect the availability of nutrients other than nitrogen. Wander and Gourley (70) reported that there was more potassium available in a soil under mulch than in the same soil under sod which had been fertilized with a potassium fertilizer. Harris (31) reported that calcium and phosphorous were depressed and that boron availability was increased by sawdust mulches. With regard to the effect of a sawdust mulch on soil reaction, Boiler and Stephenson.(12) noted that after eighteen months the pH of the soil under sawdust had not altered, while under straw and walnut leaves i t had decreased. Harris (31) recorded a significant decrease in soil acidity after two years under sawdust. The physical effects of mulching with organic materials have been reported to be somewhat analogous to those resulting from the incorporation of organic materials. Thus, in an experiment using a straw mulch, Boiler and Stephenson (12) found that i t improved soil aggregation. This may, in part, have been due to soil organic matter under the mulch as reported to occur by some workers (31, 32), or due to the protection afforded the soil from rain and other factors which destroy aggregates in exposed soil. 16. Turk and Partridge (6U) compared the effects of sawdust, straw, stover and gravel mulches on water percolation. They found that the sawdust mulch increased percolation rate approximately f i f t y percent over the control soil. The straw, stover and gravel mulches were slightly more effective than the sawdust mulch in increasing percolation rate. Bear (9) found that organic mulches increase water intake, reduce water loss and lower soil temperature. The latter effect, that of lowering soil temperature, would be detrimental to plant growth under some conditions. It has been observed to retard maturation of some plants (72). Organic mulches have been found to retard evaporation from the soil. This effect was well demonstrated by Eser (25) in 1883 using chopped straw, beech leaves and pine and f i r needles. Some of his results are summarized below. TABLE II EVAPORATION FROM AN EXPERIMENT FIELD SOIL WITH DIFFERENT COVERINGS Water lost per 1000 sq. cm. from July 12 to August 12, 1883  Type of Bare , 0.5 cm. 5 cm, 5 cm. 5 cm. 5 cm. cover Chopped Chopped Beech Pine Fir straw straw leaves needles needles Water lost 5739 2392 571 630 878 621 - gm.  The marked reduction in moisture loss under mulches may be the result of a combination of factors such as the reduction in soil temperature and the protection from wind and sun. 17. EXPERIMENTAL The experiments were planned with the object of studying the effects of sawdust as a mulch and when incorporated on upland soils of the Fraser Valley. Field, greenhouse and laboratory tests were conducted. The field tests were organized to study the effect of two depths of sawdust mulch on soil moisture with and without irrigation. The plots were also used to study the effect of mulches on soil nitrogen. The greenhouse experiments were designed to study the effect of hemlock and cedar sawdusts of different sizes when mixed at several.ratios with alderwood sandy loam. Lettuce was used as the greenhouse indicator crop in studying plant growth on the soil-sawdust mixture, with and without fertilization. The laboratory studies were made to determine the effects of the sawdust fragments on a number of soil properties. The effects studied in the laboratory included those related to total, water soluble, humin, and basic and non-basic soil nitrogen, soil reaction, cation exchange capacity, moisture equivalent, fifteen atmospheres moisture percentage, available moisture, apparent specific gravity, pore size distribution and percolation rate. M E T H O D S A N D M A T E R I A L S . Field Experiments With Sawdust Mulches. Two mulch experiments were, set out in farmers' fields planted, to strawberries. One experiment-was on Lynden s i l t loam (35) close to Abbotsford, and the other was on Everett sandy loam (35) in the vicinity of Aldergrove, 18. The plot size on the Lynden soil was four by seventy-five feet. The strawberry rows were planted three feet apart and the plants were one and a half feet apart in rows, consequently the plot covered two rows. On the Everett soil the plots were twelve by twenty-five feet, with the same spacing of strawberry plants. The plots included four rows of plants. The plot treatments consisted of normal clean cultivation, two-inch hemlock sawdust mulch and-four-inch sawdust mulch, irrigated and non-irrigated. The plots were laid out in duplicate and randomized. The irrigation water was applied by the farmer using the sprinkler method, about one inch being applied every week on the Lynden soil and one-half inch every twelve days on the Everett. Soil samples were taken from the plots at intervals throughout the summer and used for laboratory study. For the soil moisture studies, at each sampling date three sites were sampled in each plot and samples were taken from three depths, 0 - 6 inches, 6 - 12 inches, 12 - 18 inches. In sampling, a hole was f i r s t dug with an auger and the sample removed from the desired depth by excavating in the side of the hole. The samples were placed in number 2 cans and the lids sealed on with a home canning tool. In the laboratory the moisture content of the soil was found by drying the sample at 105° C and calculating the percent moisture on the dry weight basis. In the case of the samples for the soil nitrogen studies, five samples were taken from each plot to a depth of 0 - 3 inches. The five samples from each plot were composited, and a representative sample retained. These samples were taken to the laboratory where tests were made immediately for total nitrogen, nitrate nitrogen, ammonia nitrogen, amide nitrogen, basic and non-basic nitrogen and non-hydrolyzable nitrogen, according to the method of Rendig ($2)„ 19 Greenhouse Experiment With Soil-Sawdust Mixtures. The soil used in the greenhouse test was alderwood sandy loam, sieved through a one-quarter inch screen. Two species of sawdust were used and they were sieved to two sizes. This sawdust was mixed with the soil at two rates computed to represent the approximate incorporation of two and four inch mulches. The mixtures were placed in one gallon, heavy lacquered cans with perforated bottoms. The pots were numbered and randomized with respect to size of sawdust, species, fertilizers, mixes and replicates. The design was set up to give three replicates. Phosphorous and potassium were added to a l l pots at the rate of f i f t y pounds per acre. The nitrogen levels used were zero, 300 pounds and 600 pounds per acre. These fertilizer applications were made on March 15 for nitrogen and May 9 for the phosphorous and potassium. The mixes were kept at the proper moisture content by allowing them to wet up from the bottom. New York number 12 lettuce seed was planted on December 9, 1952 and the lettuce harvested on February 7, 1953. Laboratory Experiments With Greenhouse Materials. After the lettuce was harvested the pots were taken to the laboratory. Cores for determining the apparent specific gravity and pore space distribution were taken from the center of the pots. The remaining soil was mixed and quartered, then sieved through a 2 mm. sieve. On this portion of the soil the cation exchange capacity, soil reaction, moisture equivalent, wilting percentage and available moisture were determined. 20. The yield of lettuce was determined on a dry weight basis. This was done by drying i t in an electric oven for 1|8 hours at 80° C. Soil reaction was determined by the soil paste method (20), using a model 2N Beckman pH meter. Duplicate determinations were made of the cation exchange capacity by the Schollenberger ammonium acetate procedure (56). The moisture equivalent values were found by doing quadruplicate samples of the soils by the centrifuge method (65). Wilting percentage determinations were made in triplicate in a pressure membrane apparatus using fifteen atmospheres pressure to extract the moisture (53). The available moisture as described in this paper is the moisture held in the soil between the moisture equivalent and the wilting point. Thus i t was determined as the difference between the two aforementioned moisture levels. The pore space determinations were made on the soils using the tension table procedure of Learner and Shaw (37). To find the percolation rate the soil cores were f i r s t saturated and then subjected to a constant head of water one-half inch in depth, and the flow of percolate measured until its rate became constant. In the soils examined the rate became constant within approximately two hours. The apparent specific gravity of the soils was determined by the oven dry weight of soil cores of known volume. Laboratory Experiments With Sawdust. Two experiments were conducted with sawdust alone. The first was to determine the amount of ammonia nitrogen sawdust would absorb. This was conducted with three sizes of hemlock sawdust, less than 2 mm., 21. greater than 2 mm., but less than 5> mm., and unsieved sawdust. The sawdust was placed in a saturated atmosphere of ammonia for two weeks and then left exposed to the atmosphere for one month. The total nitrogen of the wood was then determined by the Kjeldhal method. The second experiment was to determine the moisture holding capacity of hemlock sawdust of two different sizes, less than 2.,mm., and greater than 2 mm., but less than 5 mm. The procedure used was to allow the sawdust to soak in an excess of water for two periods of time, 6 hours and llj. days, and then to allow i t to drain for four different lengths of time, namely, 3 hours, 2 hours, 1 hour and 30 minutes. The percent moisture held was determined on an oven dry weight basis, after drying at 105° C for 2h hours. 2 2 . RESULTS AND DISCUSSION FIELD EXPERIMENTS WITH SAWDUST MULCHES. The mulch experimental plots were sampled five times during the 1950 season, May 22, June 9 and 27, July 17 and August 9. The samples were used to determine the moisture percentage and the results of these tests are given in Appendix I. The individual moisture percentages included in these tables are the average of six individual sample results. The average moisture percentages are shown graphically in Figure I and Figure II. When interpreting these figures i t should be noted that the 1950 season when these experiments were conducted was extremely dry. The rainfall for the period is given in Appendix II and the table shoxtfs that during the period only 2.29 inches of rain were recorded. The effect of the mulches in conserving soil moisture was very pronounced in the Lynden non-irrigated plots (Figure I). On the final date of sampling the moisture content of the 0 - 6 inch depth in the mulch plots was more than double that of the control, e.g. 2 inch mulch - 26%, h inch mulch - 28%, control - 12%. The same effect was evident in the 6 - 1 2 inch and 12 - 18 inch depths although to a lesser degree. The effect of the mulches in conserving soil moisture was not so noticeable in the non-irrigated Everett soil (Figure II). The explanation for this probably lies in the fact that the Everett soil has a much coarser texture than the Lynden and consequently fever fine pores. 23. Fig. I i Soil moisture carves for Mulcnea and Unmulched, Irrigated and Non-irrigated plots on Lynden S i l t Loam. 2ho Soil moisture curves for Mulched and Unmulched, Irrigated and Non-irrigated plots on Everett. Sandy Loam. i 2 5 . Under these circumstances as the surface of the Everett soil dried there would be less tendency for moisture to rise from depth as the mulches would be less significant in preventing breaking of moisture films. The effect of the mulches in conserving moisture was also noticeable on the Lynden soil under irrigation, the moisture in the unmulched plots being lower at a l l three depths. In the irrigated Everett plots the moisture content of the unmulched plots was usually higher than that in the mulched plots. This effect was particularly noticeable in the 6-12 and 12 - 18 inch depths. The explanation for this situation probably lies in the fact that the farmer irrigating the Everett soil was applying very light applications of water, about one-half inch per irrigation. The sawdust mulches would absorb and. hold a considerable quantity of this water and consequently less would be available for penetration to depth in the soil. It is interesting to compare the effect of mulching and irrigation on the soil moisture content. Figure I shows that in the case of the Lynden soil, mulching had a similar effect on soil moisture as irrigating the strawberry crop. At a l l depths, the moisture content of the final sampling was similar in the mulched and irrigated plots and well above the permanent wilting percentage. In the 0 - 6 inch depth the mulches appeared more effective than irrigation in maintaining uniformly high available moisture. In the Everett soil, irrigation maintained the soil moisture at a more satisfactory level than did the 26. mulches, particularly in the 6-12 and 12 - 18 inch depth (Figure II). Thus the non-irrigated plots, both mulched and non-mulched, were close to the permanent wilting percentage in both the 6-12 and 12 - 18 inch depth at the final sampling date, whereas in the irrigated plots the moisture in the control and mulched plots was considerably higher. From these results i t appears that for the strawberry crop on Lynden soil, mulches will maintain the soil moisture at as satisfactory a level as will irrigation. However, on Everett soil, irrigation is more satisfactory for this purpose. In comparing mulches and irrigation in the Fraser Valley i t should be recalled that as a result of the high winter precipitation soils always enter the growing season at field moisture capacity. In fine textured soils, such as the Lynden, this stored moisture represents considerably more available moisture for plant growth than i t does in the Everett soil. Consequently, conserving the moisture in the fine textured soils by mulching is more effective for maintaining plant growth than is the case In coarse textured soils. When the effectiveness of the two depths of sawdust are compared i t appears that on the Lynden soil the [i - inch depth was slightly more effective in conserving moisturethan the 2 - inch mulch (Figure I). However, on the Everett soil there did not seem to be any.significant difference (Figure II). But i t should be noted that there was other evidence to suggest that the use of the thicker mulch would be more satisfactory. Thus, the effective depth of the 2 - inch mulch had become 27 noticeably reduced by the end of the f i r s t season as a result of mixing with the soil. The h ~ inch mulch, however, was s t i l l fully effective after two field growing seasons. Therefore, i f a 2 - inch mulch was used on a strawberry crop regular additions would have to be made to sustain i t through the l i f e of the planting. The nitrogen studies were confined to the experiment on the Lynden soil. These plots were sampled at the end of the first year and the results of the nitrogen analysis are given in Table III. It will be noted from Table III that with the exception of humin I and nitrate nitrogen, the mulches did not significantly reduce the forms of soil nitrogen studied. The lower humin I nitrogen in the .  non-irrigated mulched plot may be due to an increase in the microbial population and thus a greater utilization of the non-hydrolyzable nitrogen compounds by them. The decrease in nitrate nitrogen under the mulch may also be the result of an increase in the soil microorganism population utilizing the nitrate nitrogen or i t may have resulted from the increased utilization of nitrogen by plants on the mulched plots as plant growth was greatly improved as a result of mulching. When comparing the nitrogen content of the soil in the irrigated plots with that in the non-irrigated i t is noted that the level in almost a l l forms is considerably lower in the irrigated soil. From this i t is evident that irrigation on the Lynden soil was responsible for a more pronounced removal of nitrogen than was mulching. TABLE III NITROGEN FRACTIONATION OF LYNDEN MULCHED AND UNMULCHED, IRRIGATED t AND NON - IRRIGATED PLOTS PLOT TOTAL N HUMIN.I N NH -N NH -N NO -N NON-BASIC N BASIC N ppm ppm ppm ppffi ppm ppm ppm NON-IRRIGATED Non-mulched 3052 1426 30 290 32 493 179 2" mulch 2971 1263 31 266 10 507 229 4" mulch 31S3 1297 17 307 4 478 242 IRRIGATED Non-mulched 2657 894 24 26*9 12 422 209 2" mulch 2464 939 23 2 S3 11 419 202 4" mulch 2770 395 25 271 7 46O -29. GREENHOUSE EXPERIMENTS WITH INCORPORATED SAWDUST. The results of the greenhouse experiments with incorporated sawdust have been statistically analyzed and the results are summarized in Table IV. The individual results have not been included as they were too numerous but the Tables of Mean Squares are given in the Appendix, Tables III, IV, V, VI, VII, VIII. The Effect of Sawdust Particle Size. Size is one of the factors which influence the rate of decomposition of organic materials; the greater the specific surface the greater the surface exposed to weathering and biological attack. From this point of view i t appeared feasible that the size of sawdust incorporated into the soil would have an effect on certain soil properties. The size of sawd\ist made no difference to the soil reaction, available moistixre or yield, but its influence was noted on the cation exchange capacity, moisture equivalent and wilting percentage of the soil (Table IV). The finer wood particles incorporated into the soil caused a significant increase in the cation exchange capacity over the coarse particles. This could be caused by the finer wood decomposing or weathering to colloidal size more rapidly than the large particles, or i t could be an increase in the exchange capacity of lignin due to decomposition of the plant material containing the lignin. The moisture equivalent and wilting percentage of the soil 30. were higher when fine sawdust was incorporated than when the coarser sawdust was added. The increase caused in the two moisture levels was proportionate, therefore, although the moisture holding capacity was increased, the available moisture was not. The rise in these moisture values may have been caused by increased decomposition of the finer particles, but i t is more probable that i t was purely a physical effect, in that the finer wood had a higher absorptive capacity for water (Table VII). The Effect of Nitrogen F e r t i l i z e r . Materials high in carbon and low in nitrogen when added to a s o i l have been found to reduce the quantity of nitrates available to the plants. This is. caused by the organisms which u t i l i z e the carbon as an energy source and thus require nitrogen for building their protoplasm. Therefore, in the experiment three rates of nitrogen were introduced, zero, 300 pounds and 600 pounds per acre, and the effects of these applications on the s o i l were noted, in order to determine a trend toward the optimum application. Nitrogen f e r t i l i z a t i o n had no influence on the cation exchange capacity, the moisture equivalent or available moisture. However, i t did affect the s o i l reaction and the yield (Table IV). The reaction of the s o i l became more acidic with each increment of f e r t i l i z e r . This phenomenon, when f i r s t observed, was believed to be caused by increase in decomposition of the wood brought about by the organisms having a more adequate supply of nitrogen, but this was not so, i t was solely a f e r t i l i z e r effect. 31. Yield resulting from 3QO pounds application of nitrogen was double that of the zero application, whereas the yield from the pots receiving 600 pounds of nitrogen was less than half that of the pots receiving no nitrogen. This latter effect is probably the result of the increase in acidity of the soil. Effect of Incorporating Sawdust. The sawdust was incorporated with alderwood sandy loam at three rates: n i l ; 1 volume soil to 1 volume sawdust; 3 volumes soil to 1 volume sawdust. These ratios correspond approximately to the effect of incorporating into the soil U-inch and 2-inch mulches respectively. The mixes caused variations in soil reaction, cation exchange capacity, moisture equivalent, wilting percentage, available moisture and yield (Table IV). The resulting effect of additions of sawdust to the soil on the reaction was the reverse of that shown by the fertilizers (Table IV). This appears to indicate that the wood has a buffering influence on the soil reaction. It is probable that i f the acidity of a soil is high then additions of sawdust will lower i t , likewise, i f the acidity is very low the sawdust will increase i t . Cation exchange capacity of the soil was increased with each increment of sawdust. Again, as has been mentioned with respect to size, this phenomenon could be caused by wood decomposition products exhibiting cation exchange properties increasing in the soil. 32. The moisture percentage at the moisture equivalent and wilting percentage increased with additions of sawdust, but the increase of the wilting percentage was greater than that of the moisture equivalent. Therefore, the net result of these increases was that the moisture available to the plant was decreased by incorporating sawdust into the soil. The high absorptive capacity of the wood itself would explain these results. The incorporation of sawdust caused a depression of yield. However, there was no difference recorded between the two applications of wood. This is understandable because both additions of sawdust were relatively high. Nitrogen deficiencies were evident in the plants in the sawdust mixes which had received no nitrogen. Thus the overall decrease of yield caused by wood may be credited to depression of nitrogen. Effects of Sawdust Species. Two species of sawdust were used, hemlock and cedar. It will be noted from Table IV that the two species did not have a significantly different effect upon soil reaction, cation exchange capacity, or available moisture. On the other hand, their effects on moisture equivalent, wilting percentage and dry matter or yield were significant. In the case of moisture equivalent and wilting percentage, the increase caused by hemlock was slightly more than that caused by cedar. In respect to yield, cedar sawdust gave slightly higher dry weight. It should be noted that even where differences between the species were found, these differences were small and indicate that one species should be as satisfactory as the other for soil incorporation. 3 3 . Effect of Incorporating Sawdust on Moisture Retention. The effect of incorporating sawdust on moisture retention i n alderwood sandy loam is shown graphically in Figures III and IV. In these Figures the moisture retained by the s o i l i s shown as a function of force or energy applied to the moisture. The curves show that the addition of sawdust caused a marked increase in the moisture at zero tension or pF 0 and that at higher tension, i.e. pF U.2, the differences were much less significant. The volume of s o i l drained, between pF 0 and pF 1.6 i s often referred to as the non-capillary porosity of the s o i l and since i t represents the quantity of larger pores in the s o i l i t may be designated as the air capacity. It w i l l be noted from the curves that the sawdust has less markedly increased the non-capillary porosity or air capacity of the s o i l . Thus the actual average air capacities for the hemlock mixtures were found to be as follows: (a) control - 30 percent; (b) 3 s o i l to 1 sawdust greater than 2 mm. - 38 percent; (c) 3 s o i l to 1 sawdust less than 2 mm. - hO percent; (d) 1 s o i l to 1 sawdust greater than 2 mm. - H9 percent; (e) 1 s o i l to 1 sawdust less than 2 mm. - 59 percent. (Figure III). Similar increases were noted with the cedar sawdust (Figure IV). The curves also show that the sawdust additions had made small effects on the t o t a l volume of smaller pores, e.g., those drained by tensions greater than pF 1 .6. The mixture showing the largest effect at the higher pF is the fine sawdust when mixed with equal portions of the s o i l . With both types of sawdust this combination showed a 3U. significant increase in moisture retention at pF U.2. It i s also noted from Figures III and IV that the larger sawdust particles when mixed i n eqtial parts with the s o i l res\ilted. i n a noticeable reduction i n moisture retention at pF's above 2.7 when compared with the smaller sawdust particles. The Effect of Incorporating Sawdust on the Percolation Rate. The effect of incorporating sawdust on the percolation rate of the s o i l i s shown i n Table V. The values included i n this Table are averages of. six individual tests and i t w i l l be noted that the sawdust markedly increased the percolation rate. In view of the large increases in non-capillary porosity noted previously, such increases i n percolation rate would be expected, as i t i s the large s o i l pores that are associated with rapid percolation. The Effect of Incorporating Sawdust on the Apparent Specific Gravity. The effect of incorporating sawdust on the apparent specific gravity of the s o i l i s presented i n Table VI. I t may be noted that with each increment of sawdust the apparent specific gravity i s reduced. An interesting observation i s that size of sawdust makes no difference to the specific gravity when cedar i s incorporated but when hemlock is incorporated, the less than 2 mm. size gives a lower specific gravity than the greater than 2 mm. size. This i s the result of more uniform packing by the two sizes of cedar than by the two sizes of hemlock. TABLE IV INFLUENCE OF THE FACTORS STUDIED ON pH, CATION EXCHANGE, MOISTURE EQUIVALENT, WILTING PERCENTAGE, AVAILABLE MOISTURE AND DRY MATTER FACTORS pH CATION EXCHANGE ^MOISTURE EQUIVALENT WILTING PERCENTAGE AVAILABLE MOISTURE DRY MATTER Size of sawdust greater than 2 mm. less than 2 mm. L.S.D. @ P s 0.05 4.75 4.82 0.127 18.31 21.38 # 2.41 22.36 24.97 # 1.40 11.53 14.14 # 0.30 10.76 10.33 1 . 3 5 15.44 13 .62 14.32 F e r t i l i z e r zero nitrogen 300 pounds nitrogen 600 pounds nitrogen 5.29 4 . 6 2 4.. 45 # d 0.03 20.03 19.33 20 . 13 23.36 23.90 23.73 12.70 12.65 13.27 10.67 11 .25 IO . 46 25.33 50.34 9.33 & L.S.D. @ P » 0.05 1 . 0 9 0.97 0 . 5 2 1.03 if 5.^ 34 Soil-sawdust mixes 1 s o i l : 1 sawdust 3 s o i l : 1 sawdust s o i l L.S.D. @ P = 0.05 4* $4 4.79 4.73 # 0.050 22.33 19.31 17.35 # 1.00 25.33 23 . 26 21.90 # 0.39 15.13 12.60 10.33 # 0.21 10.65 10.66 11.07 # . 2 6 14.39 13.31 22.90 # 4.20 Species cedar hemlock L.S.D. @ P = 0.05 4.77 4.80 0.083 20.11 19.53 0 . 6 2 23.39 23.94 # 0.46 12.44 13.29 # 0.40 10.95 10 . 64 0.63 13.76 15.31 # 2.21 36c 10 20 3 0 40 50 60 j.N70 803" go »„, 100 ,110 120 130 Per Cent. Moisture A. Control B. 3 vol. soil: 1 vol. sawdust ( 2 mm. to $ mm.) C. 3 vol. soil: 1 vol. sawdust ( 2 mm.) D. 1 vol. soil: 1 vol. sawdust ( 2 mm. to $ mm.) E. 1 vol. soil: 1 vol. sawdust ( 2 mm.) 371 Fig. IV A. Control B. 3 vol. soils 1 vol. sawdust ( 2 mm. to 5 mm.) C. 3 vol. soils 1 vol. sawdust ( 2 mm.) D. 1 vol, soils 1 vol. sawdust ( 2 mm, to 5 mm.) Eo 1 vol, soils 1 vol. sawdust ( 2 mm.) 38 TABLE V. THE EFFECT OF INCORPORATION OF DIFFERENT MOUNTS AND SIZES OF SAWDUST ON THE PERCOLATION RATE OF 'ALDERWOOD SANDY LOAM MEDIUM PERCOLATION RATE cc/min. s o i l 2 8 . 0 3 s o i l : 1 sawdust, greater than 2 mm. 37.7 3 s o i l : 1 sawdust, less than 2 mm. 57.7 1 s o i l : 1 sawdust, greater than 2 mm. 100 1 s o i l : 1 sawdust, less than 2 mm. 100 TABLE VI. THE EFFECT OF SAWDUST INCORPORATION ON THE APPARENT SPECIFIC GRAVITY OF ALDERWOOD SANDY LOAM MIXES APPARENT SPECIFIC GRAVITY No treatment 1.08 3 s o i l : 1 cedar sawdust, greater than 2 mm. .96 3 s o i l : 1 cedar sawdust, less than 2 mm. .95 1 s o i l : 1 cedar sawdust, greater than 2 mm. .79 1 s o i l : 1 cedar sawdust, less than 2 mm. .79 3 s o i l : 1 hemlock sawdust, greater than 2 mm. .95 3 s o i l : 1 hemlock sawdust, less than 2 mm. .86 1 s o i l : 1 hemlock sawdust, greater than 2 mm. .77 1 s o i l : 1 hemlock sawdust, less than 2 mm. .71 39 Absorption of Water and Ammonia by Sawdust. Experiments were performed to determine the relative absorptive capacities of different sizes of hemlock sawdust for water and ammonia nitrogen. From Table VII i t may be seen that size of sawdust particle influences the amount of moisture absorbed. The fine sawdust w i l l absorb approximately five times i t s weight, whereas the coarse sawdust absorbed only two and a half times i t s weight i n moisture. TABLE VII WATER ABSORPTION BY TWO SIZES OF HEMLOCK SAWDUST SIZE TIME OF SOAKING 'TIME OF DRAINING PERCENT MOISTURE ABSORBED 2 to 5 mm. 6 hours 3 hours 255.17 2 to 5 mm. 6 hours 2 hours 329.72 2 to 5 mm. 6 hours 1 hour 309.68 2 to 5 ram. 6 hours 30 minutes 299. Hi 2 to 5 mm. Ik days 3 hours 250.59 2 to 5 mm. lU days '2 hours 252.83 2 to 5 mm. lit days 1 hour 267.32 2 to 5 mm. Iii days 30 minutes 283.78 less than 2 mm. 6 hours 3 hours 522.16 less than 2 mm. 6 hours 2 hours 536.63 less than 2 mm. 6 hours 1 hour 574.73 less than 2 mm. 6 hours 30 minutes 524.66 less than 2 mm. 14 days 3 hours 545.60 less than 2 mm. 14 days 2 hours 556.68 less than 2 mm. Ik days 1 hour 508.87 less than 2 mm. ll; days 30 minutes $39.$1 Uo The relative absorption of ammonia by hemlock sawdust of three sizes i s shown -in Table VIII. I t w i l l be noted that the sawdust size had a relatively small effect on the amount of ammonia nitrogen absorbed and that the amount of nitrogen i n the wood was approximately two percent. This two percent exceeds the amount reported to be required i n plant material to prevent nitrogen depletion of the s o i l by microorganisms decomposing the material. TABLE VIII PERCENT NITROGEN IN SAWDUST THAT WAS EXPOSED TO A SATURATED ATMOSPHERE OF AMMONIA AND THEN AIR DRIED. SAWDUST PERCENT NITROGEN Hemlock, less than 2 mm. 2.11 Hemlock, greater than 2 mm. and less than $ mm. 2.10 Hemlock, unsieved 1.99 SUMMARY 1. Two and four inch sawdust mulches were found to be almost equally effective i n conserving moisture in upland Fraser Valley soils. 2. On Lynden s i l t loam s o i l , sawdust mulches were found to be as effective as sprinkler irrigation i n maintaining favourable s o i l moisture for the strawberry crop. In the case of Everett sandy loam, irrigation was found to be more effective i n this regard'. 3. A small reduction i n Humin I and in nitrate nitrogen was found in the s o i l under sawdust mulches. A more significant reaction in t o t a l nitrogen was found as a result of irrigation. U. When incorporated into alderwood sandy loam, hemlock sawdust increased the moisture equivalent and wilting percentage more than did cedar sawdust, but the latter produced a greater increase in y i e l d of lettuce under greenhouse conditions. However, in a l l cases the differences were not great enough to indicate that one species has preference over the other for s o i l incorporation. 5. When incorporated with alderwood sandy loam, sawdust less than 2 mm. i n size was more effective than sawdust 2 to $ mm. i n size, in increasing the cation exchange capacity, moisture equivalent and wilting percentage. 1*2. SUMMARY When incorporated into alderwood sandy loam at the rate of 1 volume sawdust to 3 volumes s o i l and 1 volume sawdust to 1 volume s o i l , sawdust significantly decreased acidity and increased cation exchange capacity, moisture equivalent . and wilting percentage, larger changes being found at the higher rates of incorporation. Incorporated sawdust also decreased the available moisture and yield, irrespective of the amount added. Sawdust when incorporated with alderwood sandy loam produced a marked increase in non-capillary porosity and percolation rate. It also had a pronounced effect i n lowering the apparent specific gravity of the s o i l , but had l i t t l e effect upon non-capillary porosity. When added to the control s o i l and to the soil-sawdust mixtures, nitrogen f e r t i l i z e r (NH^ NO-j) increased s o i l acidity, the effect being most pronounced i n the control s o i l . When added' at a rate of 300 pounds per acre the f e r t i l i z e r produced a marked increase i n yi e l d of lettuce, however, the 600 pound application reduced yield, probably as a result of the increase i n s o i l acidity. 1*3. SUMMARY The amount of water absorbed by sawdust i s affected by i t s degree of fineness, fine sawdust absorbing more water .than coarse sawdust. This was found to be the case regardless of period of soaking. Sawdust placed in an atmosphere of ammonia and then allowed to air retained two percent nitrogen. This is considered to be sufficient nitrogen to supply the organisms during decomposition without depleting s o i l nitrogen. ; •'' - ... kh. LITERATURE CITED; 1. Albrecht, W. A. Loss of Soil Organic Matter and Its Restoration. Soils and Men, Yearbook of Agriculture (1938), United States Department of Agriculture. 3U7-360. 2. Albrecht, W. A. The Nitrate Nitrogen in the Soil as Influenced by the Crop and Soil Treatments. Mo. Ag. Exp. Sta. Res. 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Journal of American Society of Agronomy, 22, no, 8, Aug., 1930. 23. Dyal, R. S., Smith, F. B. and Allison, R. V. The Decomposition of Organic Matter in Soils at Different Initial pH. Journal of American Society of Agronomy 31: 841 - 850, 1939. 24. Elson, J. A Comparison of the Effect of Certain Cropping and Fertilizer and Manuring Practises on Soil Aggregation on  Dunmore Sil t Loam. Soil Science 50: 339 - 355, 1940. 25. Eser, C. cited by Baver, L. D. Soil Physics. 2nd Ed.,' John Wiley and Sons, Inc., New York, 1948. 26. Geesaman, D. W. and Norris, T. G. Dairy Farming with Sawdust. American Forest 49: 164 - 165, 1943. 27. Geoghegan, M. J. and Brian, R. C. Influence of Bacterial Polysaccharides on Aggregate Formation in Soils. Nature 158: 837, 1946. 28. Gibbs, W. M. and Werkman, C. H. Effect of Tree Products on Bacteriological Activities in Soils. Soil Science 13, 1922. 1+7. 29. Gottlieb, E. cited by Hagglund, Chemistry of Wood. Academic Press, Inc., New York, 1951. 30. Guernsey, F. Personal Communication, Wood Utilization Laboratory, Vancouver Laboratory of the Forest Products Laboratory Division, Department of Resources and Development. 31. Harris, G. Howell, Sawdust as a Mulch for Strawberries. Scientific Agriculture 31: 52 - 60, 1951. 32. Havis, Leon and Gourley, J. H. Soil Organic Matter and Porosity of an Orchard Soil Under Different Cultural Systems. Soil Science 1*3: 1*13 - 1*20, 1937. 33. Hubbel, D. S. and Chapman, J. E. The Genesis of Two Calcareous Soils. Soil Science 62: 271 - 281,- 191*6. 3U. Kaila, A. and Kivinen, P. Observations on the Effect of Organic  Material upon Aggregation and Nitrate-Nitrogen Content of  Soil. Journal of Scientific Agriculture Society of Finland 21*: 127 - 131*, 1952. 35. Kelley, C. C. and Spilsbury, R. H. Soil Survey of the Lower Fraser Valley. Dominion of Canada Department of Agriculture, Publication 650, Technical Bulletin 20, 1939. 36. Kroth, E. M. and Page, J. B. Aggregate Formation in Soils with Special Reference to Cementing Substances. Soil Science Society of America Proceedings 11: 27 - 3l*, 191*6. 1*8. 37. Learner, R. W. and Shaw, B. T. A Simple Apparatus for Measuring Non-capillary Porosity on an Extensive Scale. Journal of American Society of Agronomy 3 3 : 1003 - 1008, 191*1 • 3 8 . Martin, J. P. Microorganisms and Soil Aggregation: II Influence of Bacterial Polysaccharides on Soil Structure. Soil Science 6 1 : 157 - 166. 39. Martin, J. P. and Waksman, S. A. Influence of Microorganisms on Soil Aggregation and Erosion I. Soil Science 50: 2 9-1* 7 . 1*0. Metzgar, W. H. and Hide, J. C. Effect of' Certain Crops and Soil  Treatment and the Distribution of Organic Carbon in Relation  to Aggregate Size. Journal of the American Society 30: 833 - 81*3, 1938. 1*1. Midgley, A. R. Use of Sawdust, Shavings and Superphosphate with  Dairy Manure, Northeastern Wood Utilization Council Bulletin 7: 27 - 31*, 191*7. 1*2. Mitchell, J. The Origin, Nature, and Importance of Soil Organic  Constituents having Base Exchange Properties, Journal of American Society of Agronomy 21*: 256 - 275, 1932. 1*3. Motte, M. H. Chemical Abstracts 25: 2059, 1927. 1*1*. Muller, J. F. Some Observations on Base Exchange in Organic  Materials, Soil Science 35: 229 - 237, 1933. 1*5. Myers, H. E. Physico-chemical Reactions Between Organic and Inorganic Soil Colloids as Related to Aggregate Formation. Soil Science Society of America Proceedings 2: 77, 1937. 46. McGool, M. M. Studies on pH Values of Sawdust and Soil Sawdust Mixtures. Boyce Thompson Institute Contribution 15, 1948. 47. Mclntyre, A. C. Wood Chips, Water and Soil. Journal of Soil and Water Conservation 6: 20 - 25, 1951. 48. Norman, A. G. and Bartlett, J. B. Changes in Lignin of Some Plant Materials as a Result of Decomposition. Proceedings of Soil Science Society of America 3: 210, 1938. 49. Norman, A. G. and Peevy, W. J. The Influence of Composition of Plant Materials on Properties of the Decomposed Residues. Soil Science 65: 209 - 225, 1948. 50. Nostitz, von A. Influence on Soil of Sawdust Used as Cattle Stall Litter. Bodenk Pflanzenernahr 3: 211 - 218, 1937 in B. A. 708 B, 1937. 51. Phillips, M., Weide, H. D. and Smith, N. R. The Decomposition of Lignified Materials by Soil Microorganisms. Soil Science 30: 383 - 390. 52. Rendig, V. V. Fractionation of Soil Nitrogen and Factors Affecting Distribution. Soil Science 71: 253 - 267, 1951. 53. Richards, L. A. and Weaver, L. R. Fifteen-Atmosphere Percentage as Related to the Permanent Wilting Percentage. Soil Science 56: 331 - 339, 1943. 54. Rose, R. E. and Lisse, M. W. The Chemistry of Wood Decay. Journal of Industrial and Engineering Chemistry 9: 284 - 287, 1917. 5o. 55. Russell, M. B., Klute, A. and Jacob, ¥. C. Further Studies on the Effect of Long-time Organic Matter Additions on the Physical  Properties of Sassafras S i l t . Soil Science Society of America Proceedings 16, no. 2, April 1952. 56. Schollenberger, E. J. and Simon, R. H. Determination of Exchange Capacity and Exchangeable Bases in Soils - Ammonium Acetate  Method. Soil Science 59: 2 5 - 2 7 , 19U5. 57. Sievers, F. J. Further Evidence Concerning the Significance of Nitrogen in Soil Organic Matter Relationships. Journal of the American Society of Agronomy 22: 10 - 13, 1930. 58. Smith, F. B., Brown, P. E. and Russell, J. A. The Effect of Organic Matter on the Infiltration Capacity of Clarion Loam. Journal of the American Society of Agronomy 29: 521 - 525, 1937. 59. Stephenson, R. E. Effect of Organic Materials and Fertilizer Treatments upon the Soluble Nutrients in Soils. Soil Science U5: U67 - U75, 1938. 60. Stone, J. T. and Garrison, C. S. Relationship Between Organic Matter Content and Moisture Constants in Soils. Soil Science 50: 253 - 256. 61. Struthers, P, H, and Sieling, D. H. Effect of Organic Anions on Phosphate Precipitation by Iron and Aluminum as Influenced  by pH. Soil Science 69: 205 - 213, 1950. 62. Swenson, R. M., Cole, C. V. and Sieling, D. H. Fixation of Phosphate by Iron and Alxwiinum and. Replacement by Organic and Inorganic Ions. Soil Science 67: 3 - 22, 19U9. 51. 63. Turk, L. M. Effect of Sawdust on Plant Growth. Michigan Agricultural Experimental Station Quarterly Bulletin 26, 1943. 64. Turk, L. M. and Partridge, N. 1. Effect of Various Mulching Materials on Orchard Soils. Soil Science 64: 111 - 125, 1947. 65. Veihmeyer, F. J., Oserkowsky, J. and Tester, K. B. Some Factors Affecting the Moisture Equivalent of Soils. Proceedings and Papers of the First International Congress of Soil Science 1: 512 - 534, 1928. 66. Waksman, S. A. Soil Microbiology. John Wiley and Sons, Inc., New York. 67. Waksman, S. A. Principles of Soil Microbiology. 2nd Ed. The Williams andWilkins Company, Baltimore, 1932. 68. Waksman, S. A. and Tenney, F. G. Composition of Natural Organic Materials and Their Decomposition in the Soil. Soil Science 28: 55 - 84, 1929. 69. Waksman, S. A. and Tenney, F. G. Nitrogen Transformation in Decomposition of Natural Organic Materials at Different  Stages of Growth. Proceedings and Papers of the First International Congress of Soil Science 3: 209 - 212, 1928. 70. Wander I. W. and Gourley, J. H. Available Potassium in Orchard Soils as Affected by a Heavy Straw Mulch. Journal of American Society of Agronomy 30: 438 - 445, 1938. 71. Wise, L. E. Wood Chemistry. Reinhold Publishing Corporation, York, 1946. 72. Woods, J. J, Mulches for Horticultural Crops. Dominion Experimental Station, Saanichton, British Columbia, Mimeo. 125, 1951. • APPENDIX I Lynden ,Soil Non-Irrigated Percent Moisture May June June July Aug 2 2 ' 9 ' 27 * 17 ' 9 May June June July Aug. s 22 9 27 17 9 _L<C — -LCJ May June June July Aug. 2 2 9 27 17 9 Unmulched 3 3 . 7 4 3 7 . 4 6 2 2 . 7 5 15.80 1 2 . 3 3 2 " mulch 3 7 . 9 8 39-32 3 4 . 0 6 2 8 . 0 3 2 6 . 1 4 4 " mulch 3 4 . 9 8 3 8 . 0 2 3 4 . 8 0 3 4 . 0 0 2 8 . 5 2 3 2 . 5 6 3 5 . 1 2 2 6 . 3 1 2 4 . 3 3 1 5 . 7 5 3 7 . 1 5 3 8 . 8 9 2 5 . 3 6 2 3 . 4 9 2 4 . 9 5 3 6 . 7 6 3 6 . 5 3 3 1 . 4 8 3 2 . 2 8 2 5 . 2 4 2 9 . 7 4 31 .08 2 2 . 1 0 2 2 . 6 0 2 4 . 6 8 3 3 . 3 1 3 4 . 1 4 2 0 . 7 5 20 .10 2 0 . 7 4 3 2 . 0 4 3 4 . 5 0 2 6 . 6 7 - 2 5 . 7 4 2 0 . 8 8 Lynden S o i l I r r i g a t e d 0 - 6 Percent Moisture 6 - 1 2 1 2 - 1 8 May June June July Aug 22 9 27 17 9 May June June July Aug. 22 9 27 17 9 May June June July Aug. 22 9 27 17 9 Unmulched37.10 38.63 2 5 . 1 8 2 0 . 1 8 2 2 . 9 1 2 " mulch 3 5 . 1 9 3 9 . 0 3 4 1 . 8 2 3 2 . 1 1 2 6 . 8 6 4 " mulch 33.27 3 6 . 8 0 3 7 . 6 3 3 3 . 6 5 3 1 . 3 2 3 4 . 5 9 3 9 . 8 8 2 7 . 9 5 2 2 . 2 7 2 5 . 3 6 3 5 . 0 3 33.19 3 3 . 9 6 2 7 . 6 7 2 4 . 6 ^ 3 2 . 5 6 3 3 . 5 9 3 6 . 0 1 29 . 2 2 2 5 . 6 i 3 2 . 3 4 3 6 . 3 4 2 5 . 8 0 1 9 . 1 5 1 9 . 1 5 3 3 . 6 1 3 2 . 3 9 2 7 . 3 5 2 4 . 2 8 2 0 . 8 8 29 .53 3 5 . 0 1 3 1 . 4 3 2 7 . 9 3 2 0 . 1 7 Everett S o i l Non- Irrigated Percent Moisture u - 0 May June June July Aug. 22 9 27 9 9 May June June July Aug, 22 9 27 9 9 A.C - - L O May June June July Aug. 22 9 27 9 9 Unmulched 1 9 . 1 5 20.05 1 4 .60 10.07 1 0 . 9 3 2 " mulch 17.39 22.87 22.07 14.01 18.13 4" mulch 16.41 20.66 19.71 10.93 17.96 19.71 21.74 16.54 12 . 3 7 12.49 16.51 21.05 17.56 15.21 10 .19 .15,83 20 . 0 5 19.63 1 4 . 9 3 13.80 17.74 19.14 12.51 14.63 11.88 14.86 17.71 11.83 21.46 6 . 7 4 16.38 16.40 11,54 ,20.53 11.2,6 Everett S o i l I rrigated Percent Moisture May June June July Aug. 22 9 27 9 9 May June June July Aug. 22 .9 27 9 9 May June June July Aug. 22 9 2 7 9 9 Unmulched 2" mulch 4 " mulch 20.50 16.39 16.08 19.59 16.31 17 . 2 6 21.39 21.69 14.26 20.95 16.95 23.19 22.14 10.68 20.96 23.56 22 . 2 6 19.68 19.79 14.2G 17.51 19.13 18.67 17.02 17.5^ 17.25 20.52 15.61 15.68 14.9'/ 24.72 20.70 17.73 16 . 2 7 1 9 . 3 5 16.73 14.54 13.27 20.73 14 . 9 1 15.50 10.76 10.37 22.46 12.32 53. APPENDIX II RAINFALL DISTRIBUTION DURING SUMMER, 1951 at ABBOTSFORD, BRITISH COLUMBIA DATE: ' INCHES OF RAINFALL: June July 23 .ou 2h .1+8 25 .09 28 .05 29 .02 3 . 0 1 u .03 5 .05 6 .51 7 trace 11 .05 12 .01 13 .21 3 .07 ii .01 5 .03 12 .ou 1U .oU 21 trace 27 . U U 28 trace 29 .11 Total 2.29 inches APPENDIX III TABLE OF MEAN SQUARES FOR pH SOURCE d.f. SUM OF SQUARES Reps 2 .0537 Size of p a r t i c l e 1 .1295 Reps X Size (Error A) 2 .0476 F e r t i l i z e r s 2 14.3195 F e r t i l i z e r s X Size 2 .0072 F e r t i l i z e r s X Size X Reps (Error B) 8 .1314 Mixe s ,2 .2553 Mixes X Size 2 .0034 Mixes X F e r t i l i z e r s 4 .1369 Mixes X Size X F e r t i l i z e r s 4 .0345 Mixes X Size X F e r t i l i z e r s X Reps (Error C) 24 .2567 Species 1 .0261 Species. X Size 1 .0011 Species X F e r t i l i z e r 2 .0661 Species X Mixes 2 .0516 Species"X Size X F e r t i l i z e r 2 .0932 Species X Size X F e r t i l i z e r X Mixes X Reps (Error D) 46 .7117 MEAN TABLED F SQUARE F .05 .01 0.0293 1.23 19.00 0.1295 5.44 13.51 0.0233 7.1593 0.0036 0.0227 315.41 4.46 3.65 0.1276 0.0042 0.0342 0.0036 11.93 .39 3.20 .30 3.40 2.73 5.61 4.22 0.0107 0.0261 1.63 0.0011 .07 0 .0330 2.13 0.0253 1.66 0.0466 3.01 0.0155 4.05 7.21 3.20 5.10 3.20 5.10 APPENDIX IV TABLE OF MEAN SQUARE S FOR CATION; EXCHANGE CAPACITY SOURCE , d . f . SUM OF MEAM F TABLED F SQUARES SQUARE . 0 5 . 0 1 Reps 2 1 9 . 4 8 4 3 9 . 7 4 2 1 1 . 1 7 Size o f P a r t i c l e 1 2 5 3 . 6 1 3 5 2 5 3 . 6 1 3 5 3 0 . 4 8 I9 .OO 9 9 . 0 0 Reps X Size (Error A) 2 1 6 . 3 2 1 3 6*.3213 F e r t i l i z e r 2 1 1 . 9 4 6 5 5 . 9 7 3 2 1.-50'-' 4 . 4 6 F e r t i l i z e r X Size 2 1 4 . 5 8 8 2 7 . 2 9 4 1 I . 8 3 F e r t i l i z e r X Size X Reps (Errer B) 8 3 1 . 8 5 5 9 3 . 9 8 2 O Mixes 2 4 5 6 . 2 3 0 7 2 2 8 . 1 1 5 4 5 3 . 7 2 3 . 4 0 5 . 6 1 Mixes X Size 2 1 0 0 . 7 4 2 4 5 0 . 3 7 1 2 1 1 . 86 3 . 4 0 5 . 6 1 Mixes X F e r t i l i z e r 4 i l . 0 9 2 1 2 . 7 7 3 0 Mixes X Size X F e r t i l i z e r 4 7 . 2 9 9 8 1 . 8 2 5 0 Mixes X Size X F e r t i l i z e r X Reps (Err®r C) 2 4 1 0 1 . 9 1 3 8 '. 4 . 2 4 6 4 w M N H Species 1 7 . 4 6 8 2 7 . 4 6 8 2 2 . 9 0 4 . 0 5 Species X Size 1 9 . 3 7 5 0 9 . 3 7 5 0 3 . 6 3 Species X Mix 2 0 . 3 9 7 3 0 . 1 9 8 6 0 . 0 8 3 . 2 0 Species X F e r t i l i z e r 2 1 5 . 6 0 2 8 7 . 8 0 1 4 3 . 0 2 3 . 2 0 Species X Size X F e r t i l i z e r 2 1 5 . 7 4 2 7 7 . 8 7 1 3 3 . 0 5 3 . 2 0 Species X Size X F e r t i l i z e r X Mix X Reps (Errcr D) 46 I I 8 . 6 3 8 5 2 . 5 7 9 1 TABLE OF MEAN SQUARES FOR MOISTURE EQUIVALENT• SOURCE d.f. SUM OF MEAN F TABLED F SQUARES SQUARE .05 .01 Reps 2 19 . 103 9.551 3.33 1 9 . 0 0 Size 1 183.763 133.763 64.07 13.51 93.49 Reps X Size (Error A) 2 5.737 2.363 F e r t i l i z e r 2 5.423 2.711 F e r t i l i z e r X Size 2 10.377 5.133 1 . 6 2 F e r t i l i z e r X Size X Reps (Error B) 8 25.514 3.139 Mixes 2 236.963 143.431 216.41 3.40 5.61 Mixes X Size 2 1 9 4 . 9 2 7 97.463 147.00 3 . 4 0 5.61 Mixes X F e r t i l i z e r 4 3.947 .937 Mixes X Size X F e r t i l i z e r 4 3 . 1 9 3 2.043 3.09 2.73 4.22 Mixes X Size X F e r t i l i z e r X Reps (Error C) 24 15.926 .663 Species 1 3.013 3.013 5.59 4.05 7.21 Species X Size 1 .017 .017 Species X F e r t i l i z e r 2 4.407 2.203 Species X Mixes 2 1.597 .793 Species X Size X F e r t i l i z e r 2 13.736 6.393 4 .31 3.20 5.10 Species X Size X F e r t i l i z e r X Mixes X Reps (Error D) 46 65.344 1.431 TABLE OF MEAN SQUARES FOR WILTING POINT SOURCE D.F. SUM OF MEAN F TABLED F SQUARES SQUARE . 0 5 . 0 1 Reps 2 8 . 7 9 9 4 . 3 9 9 4 . 6 6 1 9 . 0 0 Size 1 1 7 3 . 5 5 9 1 7 3 . 5 5 9 1 8 4 . 0 4 1 8 . 5 1 Reps X Size (Err©r A) 2 1 . 8 8 7 . 9 4 3 F e r t i l i z e r 2 8 . 4 9 2 4 . 2 4 6 4 . 6 1 4 . 4 6 8 . 6 5 F e r t i l i z e r X Size 2 2 . 9 7 1 1 . 4 8 5 F e r t i l i z e r X Size X Reps (Error B) 8 7 . 3 7 2 . 9 2 1 Mixes 2 3 4 3 . 8 4 3 1 7 1 . 9 2 1 8 8 6 . 1 9 3 . 4 0 5 . 6 1 Mixes X Size 2 2 1 1 . 2 0 6 1 0 5 . 6 0 3 5 4 4 . 3 4 3 . 4 0 5 . 6 1 Mixes X Size X F e r t i l i z e r 4 1 . 2 4 2 . 3 1 0 Mixes X Size X F e r t i l i z e r X Reps (Error C) 24 4 . 6 6 8 . 1 9 4 Species 1 1 9 . 4 9 9 1 9 . 4 9 9 1 8 . 0 0 4 . 0 5 7 . 2 1 Species X Size 1 29.422 2 9 . 4 2 2 2 7 . 1 6 4 . 0 5 7 . 2 1 Species X F e r t i l i z e r 2 1 . 1 2 3 . 5 6 1 Species X Mixes 2 9 . 4 7 8 4 . 7 3 9 4 . 3 7 3 . 2 0 5 . 1 0 Species X Size X. F e r t i l i z e r 2 3 . 0 0 6 1 . 5 0 3 Species X Size X F e r t i l i z e r X Mixes X Reps (Error Dj- 46 4 9 . 8 1 2 I . O 8 3 TABLE OF MEAN SQUARES FOR AVAILABLE MOISTURE SOURCE d.f, SUM OF SQUARES MEAN SQUARE TABLED F ,05 .01 Reps Size Reps X Size (Error A) 1 2 15 .840 .156 5.284 7 . 9 2 . 1 5 6 2 . 6 4 2 2.997 19.00 18.51 F e r t i l i z e r 2 F e r t i l i z e r X Size 2 F e r t i l i z e r X Size X Reps (Error B) 8 1 2 . 2 0 4 18.032 31.695 6.102 9.016 3.962 1 . 5 4 2.27 4 . 4 6 8.65 Mixes Mixes X Size Mixes X F e r t i l i z e r Mixes X Size X F e r t i l i z e r Mixes X Size X F e r t i l i z e r X Reps (Error C) 2 2 4 4 24 4.241 2.185 1.523 8.639 6.732 2.120 1.092 .381 2.16 .281 7.54 3 . 8 8 3.40 3.40 5.61 5.61 7.68 2.78 4.22 Species Species X Size Species X F e r t i l i z e r Species X Mixes Species X Size X F e r t i l i z e r Species X Size X F e r t i l i z e r X Mixes X Reps (Error D) 1 1 2 2 2 4 6 2 . 5 8 8 3 0 . 5 9 3 1 . 9 9 4 4 - 3 7 3 1 . 3 4 3 1 2 0 . 1 9 4 2.588 30.593 .997 2.186 .671 2.613 1 1 . 7 1 4.05 7 . 2 1 TABLE OF MEAN SQUARES FOR DRY SOURCE d-.f. SUM OF SQUARES Reps Size of P a r t i c l e Reps X Size (Error A) 2 1 2 2 0 3 . 0 6 9 1 2 7 2 . 9 0 7 9 6 0 1 . 7 5 0 0 F e r t i l i z e r s 2 4 4 0 5 . 9 0 6 9 F e r t i l i z e r s X Size 2 1 4 2 . 9 7 6 9 F e r t i l i z e r s X Size X Reps (Error B) g 7 6 9 . 6 8 7 5 Mixes Mixes X Size Mixes X F e r t i l i z e r s Mixes X Size X F e r t i l i z e r s Mixes X Size X F e r t i l i z e r s X Reps (Error C) 2 1 8 6 4 . 5 5 6 3 2 1 1 7 . 6 3 0 5 4 1 3 2 0 5 . 6 0 0 6 4 4 1 9 . 9 0 3 3 24 1 7 9 5 . 0 4 5 7 Species Species X Size Species X F e r t i l i z e r Species X Mixes Species X Size X F e r t i l i z e r Species X Size X F e r t i l i z e r X Mixes X Reps (Error D) 1 1 2 2 2 3 2 2 . 1 2 7 2 3 5 . 1 5 7 4 1 6 . 0 4 9 5 1 6 0 . 6 6 8 3 8 4 5 . 4 5 1 0 4 6 1 4 9 8 . 8 7 2 3 s MEAN SQUARE F ^TABLED F . 0 5 . 0 1 1 0 1 . 5 3 4 5 0 . 3 3 7 1 9 . 0 0 2 7 2 . 9 0 7 9 0 . 9 0 7 1 8 . 5 1 3 0 0 . 8 7 5 0 2 2 0 2 . 8 5 3 4 2 2 . 8 9 4 . 4 6 8 . 6 5 7 1 . 4 8 8 4 0 . 7 4 9 6 . 2 1 0 9 9 3 2 . 2 7 8 1 1 2 . 4 6 3 . 4 0 5 . 6 1 5 8 . 8 1 5 2 0 . 7 9 3 3 0 1 . 1 5 0 1 4 4 . 1 4 2 . 7 8 4 . 2 2 1 0 4 . 9 7 5 8 1 . 4 0 7 4 . 7 9 3 5 3 2 2 . 1 2 7 2 3 5 . 1 5 7 4 8 . 0 2 4 7 8 0 . 3 3 4 1 4 2 2 . 7 2 5 5 9 . 8 9 1 . 0 9 0 . 2 5 2 . 4 7 1 2 . 9 7 4 . 0 5 7 . 2 1 3 . 2 0 5 . 1 0 3 4 . 5 8 4 1 

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