Nutrient management for yield maximization of rice (Oryza sativa)- wheat (Triticum aestivum) cropping system

Abstract

A field investigation was carried out during winter 1990- rainy season 1992 on loamy sand of average fertility status. The grain yield as well as the main crop pro- ductivity parameters significantly increased with maximum economic yield fertilizer level (MEYFL) of 180,30 and 30 kglha to rice (Oryza sativa L.) and 180,60 and 0 kg1 ha to wheat (Xticum aestivum L. emend. Fiori & Paol.) (grown in sequence) over the recommended fertilizer level (RFL) of 120, 30 and 30 kglha to rice and 120, 60 and 30 kglha of N, P20, and K20 respectively. The MEYFL was significantly superior to RFL with yield advantages of 16.2%in rice (average grain yield 8.6 tonneslha) and 13.5% in wheat (average grain yield 5.8 tonneslha). Green-manuring with Sesbania aculeata Pers. (20-25 tonneslha green matter) saved 60 kdha equivalent of N in rice without any residual effect on wheat. The higher levels of P and K and growth regulators cycocel (1 gllitre at 45 days), followed by cytokinin (50 mgllitre at 80 days) in 500 litres waterlha did not show any significant influence on rice and wheat. The benefit :cost ratio with additional income over additional expenditure for the rice-wheat rotation at MEYFL was 2.35 with chemical fertilizer and 1.55 with green- manured series compared with 1.47 under RFL. Both crops showed higher uptake of N, P and K with MEYFL over RFL. The total uptake (kglha of N, P and K) was respectively 107, 18.8 and 94 in rice and 106, 18.3 and 97 in wheat at MEYFL; and 99, 16.5 and 88 in rice and 92, 15.8 and 97 in wheat at RFL. The rice and wheat straw component accounted only for 12 and 17% of N and 15 and 19% of P, though fraction of K retained was quite sizeable (92.1 and 82.1% respectively).