To study variability in the nutritional quality of organic composts and its effects on produce quality is very important to organic agriculture and for the development and utilization of marginal desert lands.For this experiment eight combinations of two compost types mixed in different proportions sandy soil were used to grow musk melon (Cucumis melon L.).The two types of composts were cattle manure with straw (CS) and sheep manure with straw (SS).The total content and loss of N,P,and K increased with the ratio of compost added to the substrate,and was higher in SS substrates than in CS substrates of equivalent compost:soil ratios.