RECYCLING OF MUNICIPAL AND INDUSTRIAL ORGANIC WASTES IN AGRICULTURE -BENEFITS, LIMITATIONS, AND MEANS OF IMPROVEMENT (REPRINTED FROM PLANTNUTRITION FOR SUSTAINABLE FOOD-PRODUCTION AND ENVIRONMENT, 1997)

There are various reasons for improving the recycling of municipal and industrial organic waste on agricultural land. These include: Benefit s to crop production due to the recycling of organic matter and minera l nutrients, and possible suppression of soil-borne pathogens. Conserv ation of naturally available but limited supplies of nutrient resource s. Avoidance of alternative disposal methods which are environmentally damaging, expensive, or limited by space. A prerequisite for agricult ural utilization of organic waste as fertilizers is an effectiveness o f the containing mineral nutrients and/or the soil improvement. Over-a pplication increases the potential for nitrogen mineralisation with ti me and the risk of nutrient losses. In order to avoid this, applicatio n rate of organic waste has to get limited. Other problems involved wi th the application of organic wastes are. greater management difficult ies regarding optimized nitrogen supply to plants compared with minera l fertilizers; the possible contamination with environmental pollutant s such as heavy metals and organic toxics; hygienic aspects; high cont ents of extraneous materials. Consequently a comprehensive legal frame work for the use of municipal and industrial organic wastes in agricul ture must take into account the use of fertilizer depending on nutrien t demand, the necessity to avoid the input of contaminants into the so il and the food-chain and the maintenance of quality control. An incre asing problem in densely populated industrial countries is that lack o f land area often does not allow for the proper application of organic waste fertilizers.