Efficacy of slow release nitrogen-fertilizers to rice (Oryza sativa) and their residual effect on wheat (Triticum aestivum)

Abstract

A field experiment was conducted during 1989-91 on sandy clay loam soil at Ranchi to study the efficiency of forms of urea, viz. prilled (PU), lac-coated (LCU), rock phosphate-coated (RCU), karanj cake-coated (KCU) and neem cake-coated (NCU) at varying N rates (0, 40, 80, 120 kglha) on the productivity of rice (Oryza sativa L.) and their residual effect on succeeding wheat (Triticum aestivum L. emend. Fiori 8 Paol.). The LCU, NCU, and KCU gave 24, 14.2 and 12.7% more grain yield of rice respectively than PU. Each incremental N levels recorded higher grain yield over its preceeding levels. However, nitrogen-use efficiency decreased with increasing N level. Application of LCU, NCU and KCU favourably affected soil-available N after rice which consequently exhibited more residual effect on the productivity of suc- ceeding wheat. Rice fertilized with 120 kg Nlha also recorded maximum grain yield of succeeding wheat (23.1 qlha).