British Columbia Mine Reclamation Symposia

Bioregenerating soils of problematic high elevation disturbed sites using specialty fertilizers 2009

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Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  BIOREGENERATING SOILS OF PROBLEMATIC HIGH ELEVATION DISTURBED SITES USING SPECIALTY FERTILIZERS B.P. Adams, BSF., Bioeng. Arbotec International "Adverse Site Reclamation Specialists" 11 Lennox Drive St. Albert, AB. T8N 4L8 ABSTRACT The revegetation of high elevation sites is a difficult task. Such sites are characterized by soils that are extremely variable and methods that have proven quite successful on low elevation sites, have at best, met with limited success on sites located above timberline. New and innovative approaches to revegetation are required if disturbed high elevation areas are to be successfully and permanently reclaimed. Recent research has led to a better understanding of the biological processes that are critical to the sustained health of high elevation ecosystems. This in turn has lead to the development of products designed to re-establish microbial activity in the soil thereby enhancing chances for long term, low maintenance revegetation success. The use of special organic fertilizers, in combination with site specific seed mixes, provide a viable , cost effective method of re-establishing permanent, environmentally compatible vegetation on high elevation sites that have been disturbed by either industrial activity or natural! processes. INTRODUCTION High elevation ecosystems are increasingly being threatened by industrial and recreational development activities. The potential for erosion resulting from such activities is very high due to the delicate nature of these ecosystems. The climatic conditions of high elevation sites, are for the most part, extremely harsh, being characterized by strong winds, long, cold winters and relatively short, cool growing seasons. Low year round temperatures contribute to the development of soils of low biological activity and fertility. As a result, it is difficult to utilize conventional revegetation techniques and fertilization methods to successfully mitigate the impacts that development activities have on these high elevation ecosystems. In order for reclamation to be successful, it is important that the two major processes of a functioning ecosystem, primary production and decomposition, be restored as quickly as possible. Revegetation techniques that have proven to be effective on lower elevation disturbed sites have not enjoyed equal success on sites of higher elevation. This is believed to be due in part to a lack 37 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  of biological activity in the thin, variable soils characteristic of higher elevations, combined with a climatic regime that restricts the development of humus and is generally unfavourable to the development of vegetation, particularly vegetation of a non-indigenous nature. The reclamation of high elevation disturbed sites presents special challenges that require innovative, non traditional approaches if these sites are to be successfully and permanently reclaimed. CURRENT REVEGETATION PHILOSOPHY The most common objective of high elevation revegetation in North America is the establishment of a vegetative cover that is similar to the plant community that preceeded the disturbance. Traditionally, the approach to meeting this objective has included the importation of topsoil, topographic contouring, seeding to selected low altitude native and agronomic species, and the regular application of mineral fertilizers. Unfortunately, this approach seldom leads to the re- establishment of a permanent, self-sustaining ecosystem largely because a number of the activities associated with the reclamation process further aggravate the problems being addressed. High elevation soils tend to be extremely variable in composition and are generally shallow and poorly developed, coarsely fragmented and covered by a thin layer of organic material. Site disturbances often result in the destruction of the indigenous vegetation and its supporting soil profile, with a substantial reduction in organic content. These post disturbance soils are commonly low in fertility, incapable of generating sufficient quantities of the nutritive substances needed to establish and maintain a healthy vegetative cover due to reduced biological activity. A self-sustaining ecosystem can only be achieved if microbiologial activity ensuring sustained nutrient cycling, is restored. Topographic contouring is essentially intended to serve two functions, to smooth out topographic contours, thereby reducing the potential for erosion and to promote uniform infiltration of snowmelt and retention of limited moisture supplies. Unfortunately this activity also results in further re- distribution of the limited supply of organic matter. The resultant soil profile is virtually humusless. This humusless raw soil is prone to compaction due to the general absence of biotic material in the rearranged profile, magnifying its susceptibility to erosion. The practice of spreading imported topsoil on these contoured sites is an expensive option that recent research indicates may not be 38 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  compatible with the objective of re-establishing pre-disturbance plant communities ( Timmenga, 1992 pers. comm.). Low altitude and agronomic species are not climatically adapted to higher elevations and their particular nutrient requirements can only be met through the sustained application of mineral fertilizers. While it is a strategy of most reclamation programs to make use of allochthonous species until indigenous species begin to re-invade the site, the mineral fertilizers employed to sustain the introduced vegetation during the initial establishment phase may, in fact, inhibit the re-invasion of those species. This is believed due to the aggressive behaviour that results in the introduced species that allow them to out compete native species that are adapted to the low nutrient environment. The practice of maintenance fertilizing only serves to sustain this behaviour. It can take decades and more for indigenous species to re-establish on sites occupied by introduced species and more often than not, the final vegetation cover is one that is stunted and sparse leaving the soil exposed to the forces of erosion. THE ROLE OF FERTILIZERS Mineral fertilizers have long been considered essential to the successful establishment of vegetative cover on disturbed sites and are an integral ingredient in a majority of revegetation prescriptions designed to reclaim high elevation sites. While mineral fertilizers initially provide positive benefits, primarily increased nitrogen availability, significant declines in plant production and vegetative cover are experienced once applications are discontinued. It is generally recognized that high elevation areas require years of maintenance fertilizing just to maintain the status quo. To permanently improve growing conditions, it is necessary to achieve a lasting increase in humus and with this, a biological activation of the soil. A new generation of soil amendments finding gradual acceptance in the reclamation industry are slow acting organic fertilizers, primarily those derived from dried fungal mycelium. Extensive research has shown these fertilizers to have a profound effect on on the biological activity of high elevation disturbed soils. They enhance the chemi-physical properties of the soil through the addition of organic matter and stimulate the action of soil micro-organisms leading to higher fertility and subsequently healthier vegetation. These fertilizers also impart a stabilizing effect on the physical 39 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  condition of the soil (Lynch and Poole, 1979). Haselwandter (1985) noted a potentially strong relationship between the symbiotic associations of fungi and plants, and soil stability on newly revegetated high elevation sites. The importance of mycorrhizal associations to sustained plant nutrition in relatively infertile areas has long been recognized. Until the advent of these new "bio- organic" fertilizers, reclamation specialists had few means at their disposal to increase the rate of nutrient mineralization on high elevation sites. Most of the nutrients contained in organic fertilizers can only be released through mineralization. This ensures that nutrients are released only with higher temperatures i.e. when the plants actually require them. Mineral fertilizers, on the other hand, release nutrients continually, irrespective of plant demand. Developed in Austria specifically for use in revegetating high elevation ski slopes, bio-organics, particularly those whose mode of action is through mycogenic decomposition, have been shown to be particularly effective in re-establishing vegetation on high elevation degraded or depleted soils, subsoils, heaps, tips and open pit mine castings to create a living, self-sustaining and biodiverse landscape. Sites treated with bio-organic fertilizers display consistently higher plant production, a greater degree of ground cover and more vigorous and healthy vegetation than sites treated with mineral fertilizers ( Naschberger, 1988). Furthermore, due to the slow release of the organically fixed nitrogen, bio-organics are considered superior to both soluble inorganics and manure based organics on high elevation sites with soils of low sorption capacity and high leaching potential as they effectively reduce the chance for both overdosing and losses to ground water. The effectiveness of bio-organics is currently being demonstrated in a research trial on a highly erodible site composed primarily of broken rock and sand with a humus content of less than 10% located in the Swan Hills region of Alberta. The site which has previously resisted all attempts at revegetation, is responding favourably. In Figure 1 it can readily be seen that the effect of regular applications of a bio-organic fertilizer on plant density is superior to that of mineral fertilizers. 40 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation   Fig 1: Effect of bio-organic and mineral fertilizers on vegetation density. Bio-organics can be advantageously applied to vegetation with low nutritive requirements growing on soils with low humus content due to the fact that they are slow release fertilizers, high in organic content. Regular applications have been shown to increase humus levels in high elevation soils by 0.2 to 0.3 percent per year (Naschberger, 1988). Even more significant is the improvement in the availability of phosphorous and potassium through the humate effect. The narrow C/N-ratio characteristic of bio-organics has an accelerating effect on mineralization, establishing their nutritive effect very quickly. Accelerated mineralization is considered an especially important element in rejuvenating nutrient deficient soils on high elevation sites characterized by less than favourable climatic conditions. The slow and uniform release of nitrogen, combined with low heavy metal content values, deem bio- organics to be ecologically superior to mineral fertilizers. Due to rapid nitrogen release and their solvent action, mineral fertilizers are inappropriate for use in watershed areas where the potential exists to contaminate drinking water supplies. 41 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  Figure 2 contrasts the pattern of nitrogen values in the soil solution following application of a bio- organic fertilizer, with that of a soluble mineral fertilizer. It is evident that bio-organics release nitrogen at a more or less constant rate. Mineral fertilizers, on the other hand, exhibit a pattern of rapid nitrogen release soon after application, followed by a rapid decline.  Fig. 2: Soil solution nitrogen values for bio-organic and mineral fertilizers. In order to be effective, bio-organic fertilizers must be applied initially in high volume. Depending on site conditions, initial application rates will range from 1500 to 2000 kg per hectare. Subsequent application rates can range from 450 to 1000 kg per hectare. High application rates combined with high per unit costs, when compared to mineral fertilizers, have been somewhat of a deterrent to the acceptance of bio-organics by the North American reclamation industry. However, studies of cost versus benefit show these fertilizers to be far more cost effective in the long term than mineral fertilizers and most other organics. The single greatest attribute of bio-organic fertilizers is their ability to bioregenerate soil thus re-establishing nutrient generating processes with a minimum number of treatments. The same cannot be said for mineral fertilizers. Bio-organics derived from fungal biomass have also been shown to have a stabilizing effect on soil as the fungal hyphae that develop within days of application, limit the potential for both wind and water erosion. 42 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  SUMMARY Intensive research and the results of exhaustive testing under a wide range of extreme conditions show bio-organic fertilizers to be very effective in amending soils of poor nutrient quality. Inspite of positive results however, bio-organics should not be viewed as a panacea. They are but one ingredient in a complex reclamation equation that includes, in a long list of variables, the selection of site and altitude specific seed mixes. Many problems associated with re-establishing vegetation on high elevation disturbed sites have yet to be solved. However, re-activation of biological activity in the soil is critical to long term revegetation success. For the first time, the reclamation industry has at its disposal, a tool that can truly influence and sustain site fertility to achieve a cost effective, permanent and environmentally compatible cover of vegetation on high elevation disturbed sites. 43 Proceedings of the 19th Annual British Columbia Mine Reclamation Symposium in Dawson Creek, BC, 1995. The Technical and Research Committee on Reclamation  REFERENCES Badawy, B. and K.E. Schonthaler, 1983. Tests of erosion-prevention materials for high-altitude revegetation. Journal on Bioengineering No 6. Zeitschrift fur Vegetationstechnik. Patzer Verlag GmbH u. Co. KG, Hanover. Glatzel, G. and J, Fuchs, 1986. Concerning the application of special organic fertilizers with difficult afforestations. Allgemeine Forestzeitschrift 9/10. Glatzel, G., K. Katzensteiner, H. Sterba and K. Haselwandter, 1989 Use of an organic fertilizer in revitalization of protective forests in the Austrian Alps affected by forest decline. Paper presented at the symposium "Reclamation, a Global Perspective", Calgary, AB,, Canada Hardy BBT Limited, 1990. Reclamation of disturbed alpine lands: A literature review. Alberta Land Conservation and Reclamation Council Report No. RRTAC 90-7, 37-134. Insam, H., 1989. Soil microbiological properties of reclamation sites compared to a natural succession. Paper presented at the Kananaskis Centre for Environmental Research, University of Calgary, Calgary AB., Canada Insam, H. and H. Haselwandter, 1985. The effect of different vegetation techniques on soil microbial biomass in levelled ski runs above timberline. Zeitschrift fur Vegetationstechnik 8, 23-28. Lynch, J. and N. Poole, 1979. Microbial ecology. Blackwell, London, Oxford, Edinburgh. Naschberger, S., 1988. Alpine ski slopes, the causes of the problems and possible ways of rehabilitation with the help of specialty fertilizers. Biochemie Ges.m.b.H., Kundl, Austria Naschberger, S., 1994. Ecological evaluation of organic fertilizers. Biochemie Ges.m.b.H, Kundl, Austria Naschberger, S. and L. Kock, 1983. The value of Biosol in creating green cover on ski runs. Zeitschrift for Vegetationstechnik 6, 33-36. Timmenga, H., Soil Biologist, 1992 Personal communication re: the effect of non-indigenous topsoil on the re-establishment of indigenous plant species. 44


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