Pot experiments were carried out in a completely randomized design in the screenhouse of Faculty of Agriculture, South Valley University, Egypt, to evaluate the application effects of different organic wastes (sewage sludge, filter mud cake, compost, filter mud cake-compost mixture and sewage sludge-compost mixture) at different levels (5, 15 and 30 ton/fed. on the release and availability of N, P and K in three different soils (clay, calcareous sandy, and sandy soils). Corn plants followed by wheat plants were grown during two successive seasons of summer 2011 and winter of 2011/2012.
Total Nitrogen (N), available phosphorus (P) and available potassium (K) in soils as well as plant dry matter and the uptake of these nutrients by plants were determined to evaluate the N, P and K released in the soil and their uptake by these plants.
The application of these organic wastes at different levels showed significant increases in N, P and K that were released in the studied soils as well as plant dry matter yield and the uptake of these nutrients by corn and wheat plants. In general, use of these investigated organic wastes at the level of 30 ton/fed. in these studied soils gave the best results