Processed residential refuse from four municipal composting plants was evaluated as a source of plant nutrients and as a soil amendment. Indicator plants were turnip, pearl millet, cranberry beans, tomato, and sorghum. Three of the composts used were high in carbon and low in nitrogen, which resulted in delayed nitrification accompanied by poor plant growth. Total soluble salts in those composts were relatively high and could affect seed germination. Extracts of compost (160 g/500ml H2O) greatly reduced germination in radish and turnip seed, and extracts from 320 g compost/500ml H2O reduced germination to 0 in turnip and radish seed and to about 40 percent in oat and millet seed. After a period of time in the soil, compost applications above 32 metric tons/ha increased plant yields and improved soil cation exchange capacity and water-holding capacity. In laboratory studies with compost incorporated at various levels in Arredondo sand, almost no nitrification occurred. When mixed with cow manure in equal parts, compost effectively curtailed nitrification in the cow-manure almost 100 percent. (Modified author abstract)