INTEGRATED MANAGEMENT OF GREEN MANURE, FARMYARD MANURE, AND NITROGEN-FERTILIZER IN A RICE-WHEAT ROTATION IN NORTHWESTERN INDIA

Sesbania (Sesbania aculeata) is an important green manure crop for wet land rice, and it can fix large amounts of N2. Farmyard manure (FYM) i s traditionally a valuable source of nutrients, but it can meet only a part of the N requirement of the rice crop. Limited information is av ailable on the nitrogen fertilizer value of green manure and complimen tary and synergistic effects of green manure, FYM, and nitrogen fertil izer. A field experiment was conducted during 1989-1993 to evaluate th e effectiveness of sesbania green manure and FYM (77-105 kg N ha-1) ap plied either alone or in combination with green manure for wetland ric e. Sesbania accumulated 90 to 135 kg N ha-1 in 52 days. During each ye ar, the total N addition to green manure and FYM amended plots was adj usted to 150 kg N ha-1 by applying additional N th rough urea. The gra in yield of rice increased significantly up to 150 kg N ha-1. Green ma nure-N proved as efficient as urea-N in increasing rice yield. The ava ilability of N from FYM was much lower than from urea or green manure. The combined application of FYM and green manure could meet all the N requirements (150 kg fertilizer N ha-1) of the high-yielding rice and improved the yield potential observed with urea alone. Physiological efficiency (kg grain kg-1 N uptake) was higher with green manure plus FYM treatment than urea or green manure alone. Incorporation of FYM al one or in combination with green manure increased organic carbon and a vailable P and K contents in soil and significantly improved the yield of the succeeding crop of wheat.