Nitrogen balance studies in rice using ¹⁵N-labelled urea and urea supergranules

Abstract

Recovery of applied nitrogen by the rice crop is invariably low, often 30–50% (Prasad & De Datta 1979). The poor recovery has been attributed to different types of losses occurring in the rice field. Recovery improved with split application, delayed application or deep placement (Pillai & Vamadevan 1978; Craswell & Vlek 1979), indicating that the management factor plays an important role in increasing fertilizer nitrogen efficiency. To investigate such factors, and seasonal effects, field experimentswere carried out using 15 N-labelled urea (PU) and urea supergranules (USG). The recovery of fertilizer 15 N by the plant and retention in the soil were studied in both dry and wet seasons.