Optimization of organic and inorganic nitrogen for rainfed maize (Zea mays) in dry sub-humid inceptisols

Abstract

A field experiment on maize (Zea mays L.) was conducted in rainy season (kharif) during 1998 to 2005 with a set of nine fertilizer treatments in separate blocks of maize, blackgram and maize + blackgram under dry sub-humid inceptisols of Jammu. An attempt was made to select an efficient treatment that has maximum sustainability over years, apart from optimizing organic and inorganic fertilizer N for different crop-seasonal rainfall situations to attain maximum maize yield. The analysis of variance indicated that treatments differed significantly from each other every year and also pooled over years. Treatment-wise regression models of yield were calibrated as a function of crop-seasonal rainfall and crop-growing period to assess the sustainability of treatments. Application of N @ 60 kg/ha proved superior in maize and maize + blackgram blocks, whereas 15 kg N (Leucaena) + 20 kg N (urea) was superior in blackgram block. A pooled regression model of yield as a function of rainfall, crop-growing period and fertilizer N was used to derive optimum fertilizer N at different rainfall situations. The inorganic and organic N ranged from 44 to 57 kg/ha and 23 to 27 kg/ha respectively at 700 mm rainfall, and from 56 to 73 kg/ha and 27 to 31 kg/ha respectively at 1,100 mm rainfall for attaining maximum maize yield in different blocks. The corresponding doses of inorganic and organic N ranged from 39 to 49 kg/ha and 18 to 22 kg/ha at 700 mm compared with 51 to 65 kg/ha and 22 to 26 kg/ha at 1,100 mm for attaining economic yield of maize.