QUALITY OF COMPOST PRODUCED FROM ANIMAL WASTES

The characteristics of animal waste composts produced in Japan were su mmarized. Animal waste composts are useful for supplying nutrients to plants and for.improving the soil properties. The contents of nutrient s in the composts were in the order of poultry > swine > cattle. Thus, the effectiveness as fertilizer followed the same order. The contents of heavy metals in the animal waste composts were studied. The conten t of copper was very high in the swine waste composts, and the content of zinc was also high in those from swine and poultry. Such high cont ents of heavy metals are caused by the addition of these elements to f eeds. The objectives of composting were summarized. One of the objecti ves is to convert the raw animal wastes into products which are easy t o handle and safe to health. Another objective is to convert the anima l wastes into organic fertilizers which are safe for plant and soil. T he maturing process of composting was characterized. Poultry wastes we re more easily decomposed than cattle and swine wastes, and the decomp osition rate of cattle wastes was almost similar to that of swine wast es. Maturity is an important factor related to the quality of the comp ost. The detection of nitrate by diphenylamine, the determination of c ation-exchange capacity (CEC), and the germination test are recommende d as methods of estimating the degree of maturity.