Forging a Link Between Composting and Sustainable Agriculture
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. c Forging A Link Between Composting And Sustainable Agriculture The concept of composting has always Agriculture, and the Food and Drug Ad- been rooted in a soil conservation philosophy ministration could lead the way for the that recognizes the role of organic matter in availability of more research to better un- agriculture. The paradox has been that the re- derstand the role of composted organic cent rise in composting interest has come residuals in sustainable agriculture from the need for waste management solu- (Goldstein, 1993). tions which emphasize economical and envi- ronmental alternatives, not the need for soil An example of such research is a pro- improvement and nutrient recycling. This re- ject on a Boynton Beach, Florida farm view traces some early researches on the link that grows 200 acres of sweet peppers in between compost application and crop pro- double rows on beds which are covered ductivity and urges greater support for re- with plastic mulch and treated with search that shows how compost can reduce methyl bromide to kill weed seed nema- pesticide use, improve farm economics and, todes. Researchers from the University of in general, support the goals of sustainable Florida are testing the use of composts agriculture. from municipal solid waste and sewage sludge/yard trimmings (Roe, et. a?., sustainable agricultural system 1993). Amust be economically sound, social- In 1986, Hoitink and Fahy reviewed ly acceptable, and environmentally com- the research literature citing examples of patible, writes William B. Lacy of the Col- how diseases caused by soilborned plant lege of Agricultural Science at Penn State pathogens were controlled by composts. University (Lacy, 1993). The challenge of “Activity of antagonists involved in bio- sustainable agricultural research and ed- logical control is affected by nutrients ucation programs is to develop systems present in compost. For example, highly that meet these three interconnected stabilized organic matter, such as sphag- goals, he notes. “A sustainable approach num peat, does not support an actively requires producers to substitute manage- suppressive biomass. On the other hand, ment, scientific information, and on-farm ‘properly’ stabilized composts do sup- resources for the purchased inputs on port such activity. This review therefore which their farming enterprises current- emphasizes the role of organic matter in ly depend.” , activity of antagonists involved in bio- \;. \;. Some of those purchased inputs are logical control of plant pathogens” ................... .............................................. pesticides and fertilizers. Over the years, (Hoitink and Fahy, 1986). .........., .._ .- . ., a number of research projects have fo- Fahy and Hoitink provide some ad- cused on the ability of compost to reduce ditional examples for using compost to the need for those inputs. The impor- control disease. Composted larch bark is tance of these past studies as well as the used by vegetable growers in Japan to limited research currently underway protect the Chinese yam from brown rot. was emphasized in June with the an- Composts from tree leaves and rice hulls nouncement by three federal agencies of were effective for control of clubroot on a major policy shift aimed at reducing the Chinese cabbage. Decomposed ammoni- use of chemicals for production of the ated Douglas fir bark was useful for con- food supply in the United States. The trolling Phytophthora disease on straw- joint announcement by the Environmen- berries. Composted municipal sludge tal Protection Agency, the Department of (CMS) was effective for reducing lettuce 48 Compost Science 8 Utilization Summer, 1993 r drop caused by Sclerotiniu minor. A range workers involved actual observations on of studies also have been conducted to the survival of selected pathogens under measure the effects of CMS on root rot, a variety of conditions in composting. In crown rot and wilting of different vege- general, their results confirmed the pre- tation with varying results (Hoitink and dictions of the U.S. researchers, although Fahy, 1986). the required durations of exposure proved to be somewhat longer. ~~~ ~ Composting Perspectives Research on composting received a Clarence Golueke in 1972 reviewed considerable impetus in the mid-1960s the progress of composting beginning both as a result of funds made available with Sir Albert Howard who in the early through the passage of the 1965 Solid 1900s began to systematize the tradition- Wastes Act, and of a beginning of con- al compost procedures as ”one of the cern by the public for its environment. most ancient of the agricultural The research was characterized in large arts.”(Golueke, 1972) His collaborators part by the rediscovery of the findings were Jackson and Ward, and the compost made by the early researchers. Perhaps system became known as the Indore sys- the most unfortunate part of this period tem - i.e., named for the region of India of ”rediscovery” was that in many in- in which it was developed. According to stances, the new ”discovers” were un- Golueke, the 1940s and the early 1950s aware of the findings of their predeces- marked the beginning of a surge of inter- sors. The major difference between the est in the use of composting as a means of two groups was that the reports of the reclaiming plant nutrients in municipal latter were couched in a more sophisti- refuse. cated terminology than were the earlier ”It was at that time that a need began works. to be felt for undertaking studies to de- Continues Golueke in his 1972 re- velop the scientific principles of com- view: The late 1960s not only brought a posting and to bring some order and deepening public concern with preserv- shed some light upon the welter of folk- ing the quality of the environment, but lore and superstition that characterized also a willingness persists despite politi- the practice until that time. Thus, re- cal and industry generated attempts to search conducted by the New Zealand discourage both trends. One of the spin- Government’s Inter-Departmental Com- offs of this renewed concern with conser- mittee for the Disposal of Organic Wastes vation and the environment is a renewed led to the publication of two reports in interest in composting. For one thing, the which were explored the scientific as- fallacy of the ”double-standard” has pects of the mechanics of the soil im- been abandoned, and now the idea of provement accomplished by incorporat- composting as a paying proposition in a ing compost in the soil. It was also at this purely monetary sense has been practi- time that the University of California be- cally universally abandoned. Instead, the gan its research on composting, an out- process is being evaluated in terms of its come of which was technical bulletin no. complete social benefits. For example, 9, ”Reclamation of Municipal Refuse by the transition has been made from the Composting.” point at which the worth of the compost The efforts of European researchers product was judged primarily upon the during this period were largely oriented dollar-and-cents value of its nitrogen, towards the hygienic aspects of compost- phosphorus, and potassium (NPK) con- -~~ ing. While the U.S. researchers were con- tent. Now, the NPK monetary value of cerned about the survival of pathogenic compost has been recognized for what it _I_ organisms, they did little actual experi- is -quite minor in terms of environment mentation on the subject. On the other betterment and improvement of soil hand, research by several European quality. Maximum productivity of the Compost Science 8 Utilization Summer, 1993 49 soil is the proper criterion - not a bal- into the soil, and undesirable gases, such ance between cash value of increased as carbon dioxide, move out. The loose, crop production per dollar spent on the friable soil does not restrict root move- NPK needed to bring about the increase. ment as compared with a compacted soil. Thus, the effect of the compost product Thus, composted sewage sludge im- on the lasting improvement of the soil is proves soil conditions, providing a desir- receiving its due attention. Another ap- able environment for plant growth. ." plication beginning to receive attention is "Cooperative studies are being con- that of incorporating compost into the ducted at Beltsville to determine the use- soil to prevent nitrogen contamination of fulness of composted sewage sludge as a ground waters by converting it (nitro- low grade fertilizer for lawns, potting gen) into a relatively insoluble form, mixtures for plants, for revegetating namely, microbial protoplasm. The ni- mine spoil land with grasses and trogen is released in a gradual manner legumes, and for other field and veg- through the death and decay of the mi- etable crops. crobes. Attention was focused on this de- "Preliminary data show that com- sirable trend as a result of the growing posted sewage sludge has a fertilizer rat- alarm over the increasing contamination ing of about 0.9 percent nitrogen, 2.3 per- of our water supply attending the exces- cent phosphoric acid and 0.2 percent sive use of inorganic nitrogen fertilizers potash. This means that it will take five to in large-scale agriculture, concluded 10 times as much composted sludge to Golueke. supply the same plant nutrients as an or- dinary 5-10-5 chemical fertilizer (five Compost As A Soil Conditioner percent nitrogen, 10 percent phosphoric And Fertilizer Source acid, and five percent potash). Therefore, In September, 1973, the United States farmers probably could not afford to use Department of Agriculture's Research compost unless it were very inexpensive Station at Beltsville, Maryland held a or given away. "Sludge Composting Field Day" to demonstrate that composting was eco- Heavy Metals In Compost nomical and that the method produced "Adding composted sludge to soil si- "a valuable soil conditioner and fertiliz- multaneously adds appreciable amounts ing material.