Project Directorate for Cropping Systems Research, Modipuram, Meerut, Uttar Pradesh, 250 100
A field experiment was conducted during 1992–93 to 1998–99 on sandy-loam soil (Typic Ustochrept) in semi-arid conditions, to evaluate the production potential of rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend. Fiori & Paol.) system in sole and alley cropping with subabul (Leucaena leucocephala) under integrated nitrogen supply system. In alley cropped rice-wheat system, loppings of L. leucocephala incorporated @ 6 tonnes/ ha/year in the soil as green manure before rice and wheat planting added approximately 80 kg organic nitrogen/ ha/year to system which replaced 25% mineral fertilizer N. Increasing levels of nitrogen enhanced grain yield of rice and wheat significantly up to 90 kg N/ha, beyond which increase was marginal and non-significant. Further. association of L. leucocephala reduced grain yield of rice and wheat by 9.9 and 5.5% compared to sole cropping of rice and wheat respectively. In addition to this, L. leucocephala also provided 6–7 tonnes/ha/year green fodder and 5–6 tonnes/ha/year fuel wood and resulted in net saving of Rs 6,539/ha/year at 90 kg N/ha. Green manuring of L. leucocephala decreased the pH of soil from 8.74 to 8.43 and bulk density from 1.70 to 1.50 g/cc and soil organic carbon by 39.10, nitrogen content by 24.10, available P2O5 by 13.40, available K2O by 18.40 and infiltration rate by 38.20% under alley cropping, but a slight change in these soil characteristics was also observed under sole cropping of rice-wheat system.
Alley cropping, Leuceana leucocephala, Crop productivity, Soil fertility, Rice-wheat system
