Integrated management of green leaf, compost, crop-residues and inorganic fertilizers in rice (Oryza sativa)-rice system

Abstract

A field experiment was carried out in both rainy and winter seasons during 1992-98 at Maruteru, Andhra Pradesh, to find out the effect of integrated nutrient supply system in rice (Oryza sativa !-.)-rice system of coastal ecosystem. The highest (121.1 qlha) system productivity was obtained with the use of sesbania green leaf to substitute 50% NPK need. All organics in conjunction with inorganic fertilizers were superior to sole chemical fertilization in terms of agronomic efficiency. Green-leaf manuring with sesbania resulted in the maximum energy output (1 70, 079 MJIha) and with lesser energy (8,292 MJIha) involvement and resulted in the highest energy ratio (19 : 5). When half of the NPK was substituted through green leaf manure, there was maximum uptake of NPK and a low negative N balance. Phosphorus balance was positive in all treatments and its accumulation was particularly high when large amounts of compost, green- manure, and rice straw were incorporated. The pH values of all treatments declined after 6 years of continuous rice cropping. Organic carbon status declined in the control and among the normal fertilized plots, more organic carbon was present in straw-incorporated plots. Potassium values were remarkably augmented in all organic fertilized plots but more conspicuous in straw-applied treatments.