EVALUATION OF THE CHEMICAL-COMPOSITION OF MANURES FROM DIFFERENT ORGANIC WASTES AND THEIR POTENTIAL FOR SUPPLY OF NUTRIENTS TO TOMATO IN A TROPICAL ULTISOL

Manures (sewage sludge, swine, rabbit and poultry manures) from four f arm or homestead wastes were analyzed for their chemical composition a nd were compared with NPK fertilizer for their ability to supply nutri ent elements to tomato plants under field conditions. The organic manu res varied considerably in their initial content of nutrient elements, their effects on soil pH and in their release of nutrients for tomato absorption. NPK fertilizer appeared more efficient than the organic m anures in supplying N, P and K, at least in the short run, while the o rganic manures had an advantage in the supply of other macro- and micr onutrient elements not contained in NPK fertilizer. There were variabi lities in the efficiency of supply or uptake of the elements contained in the various manures. Under the conditions of the experiment, the r ecommendable manure rates at which tomato gave good growth were 10 t h a(-1) for swine manure, 20 t ha(-1) for sewage, a range of 10 to 20 t ha(-1) for rabbit and poultry manures, and a combination of 100 kg N, 40 kg P and 100 kg K ha(-1) (N100P40K100 kg ha(-1) rate) for NPK ferti lizer. A high rate of 30 t ha(-1) did not produce a further advantage in tomato growth for any manure source.