EFFECT OF COMBINED USE OF GREEN-MANURE AND NITROGEN ON THE PRODUCTIVITY OF MAIZE (ZEA-MAYS) - WHEAT (TRITICUM-AESTIVUM) SYSTEM

A field experiment was conducted during 1987 - 88 and 1990 -- 91 to st udy the impact of green-manuring in relation to nitrogen use on the pr oductivity of maize (Zea mays L.)-wheat (Triticum aestivum L. emend. F iori & Paol.) system. Six combinations of green-manure crops, viz. pri ckly sesban [Sesbania cannabina (Retz.) Pers.], Cowpea [Vigna unguicul ata (L.) Walp.] and their 3 burial periods (1, 8 and 15 days before so wing of maize) apart from clean fallow in 7 main plots and 3 N rates i n 3 subplots. These were laid out in split-plot design. Nitrogen' accu mulated by tops of prickly sesban and cowpea at 45 days were 105 and 1 13 kg/ha respectively. Maize-yield response to green-manuring was 16 q /ha, whereas response of succeeding wheat to the residual effect of gr een-manuring was 5q/ha. Green-manuring increased the productivity of m aize-wheat system by 21 q/ha. Combined use of green-manuring and 60 kg N/ha gave maize-grain yield 37.5 q/ha, whereas the productivity was o nly 29.6 q/ha at 120 kg N/ha the absence of green-manuring. Incorporat ion of green-manure crop at 1, 8 and 15 days before maize sowing equal ly efficient in increasing the productivity of maize-wheat system. Gre en-manuring also improved the organic carbon content of the soil.