Four organic manures and NPK fertilizer, each at four rates, were assessed under field conditions for their comparative effects on tomato growth and yield. Tomato fruit yields (49 and 47 t ha−1) were best with swine or poultry manure applied at the rate of 10 t ha−1. Yields of 42–47 t ha−1 were obtained with sewage sludge or rabbit manure applied at the rate of 20 t ha−1, while with NPK the best yield (35 t ha−1) was obtained with the formulation of N100P40K100 kg ha−1. Very high manure application of 30 t ha−1 depressed growth and yield, irrespective of the manure source. The potential fertilizer values of the organic manures were not fully reflected by early growth parameters as they were with NPK treatment, apparently due to slow release of the elements that were still bound in organic forms in the manures. The ultimate yield advantages associated with the organic manures compared with NPK fertilizer were, in part, ascribed to their probable effects on the soil physical characteristics, and their supply of macro- and micronutrient elements not contained in NPK fertilizer.
Bioresource Technology 12/1993; 45(1-45):21-25. DOI:10.1016/0960-8524(93)90138-2