NITROGEN-USE EFFICIENCY AS INFLUENCED BY NITROGEN AND WEED MANAGEMENT IN RICE (ORYZA-SATIVA) - WHEAT (TRITICUM-AESTIVUM) SEQUENCE

A field experiment was conducted during 1983-84 and 1984-85 to find out the effect of nitrogen and weed management on nitrogen-use efficiency in rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend. Fiori. & Paol.) sequence. The N uptake in rice at harvest was significantly higher under chemical weeding. Among sources of N, urea supergranules proved significantly superior to neemcake-coated urea and prilled urea. The grain yield (35.8 q/ha) of rice was higher at 100 kg N/ha and urea supergranules proved significantly superior to prilled urea or neemcake-coated urea. Chemical and hand-weeding were at par. In succeeding wheat also, significantly higher grain yields were recorded under hand-weeding and chemical weeding than under weedy check. The N uptake in wheat was the highest under hand-weeding. The carry-over effect of neemcake-coated urea @ 100 kg N/ha applied to the rice crop produced the highest grain yield (20.6 q/ha) of wheat. But apparent N recovery in wheat decreased significantly with an increase in N level applied to preceding rice crop. The N sources neemcake-coated urea and urea supergranules proved superior to prilled urea in rice-wheat sequence.