A field experiment was carried out during the rainy season (June-October) of 1998 at the Research Farm of the Indian Agricultural Research Institute, New Delhi, India to study the effect of coating prilled urea with eco-friendly neem (Azadirachta indica A. Juss.) formulations in improving the efficiency of nitrogen use in hybrid rice. The experiment was laid out in a split-plot design with three replications. Two rice cultivars, hybrid rice (NDHR-3) and Pusa Basmati-1, formed the main plots, with the levels of nitrogen (0, 60, 120 and 180 kg N ha-1) and various forms of urea at 120 kg N ha-1 in the sub-plots. The results obtained in this study showed that the rice hybrid NDHR-3 performed significantly better than the scented variety Pusa Basmati-1 for almost all the agronomic traits tested (growth, yield attributes, grain and straw yields, nitrogen uptake and apparent N recovery) The advantage of grain yield in hybrid NDHR-3 was nearly 16 q/ha over Pusa Basmati-1. Increasing levels of nitrogen significantly increased the number of effective tillers hill-1, panicle length, panicle weight, grain and straw yields and nitrogen uptake, thereby revealing a significant decline in agronomic nitrogen use efficiency (NUE). Among the sources of N, Pusa Neem Golden Urea proved to be significantly superior to other sources with regards to panicle length, grain yield, N uptake, agronomic nitrogen use efficiency and apparent N recovery (%), indicating that coating urea with neem formulations not only increased the grain yield, NUE and apparent N recovery, but also helped to reduce the environmental hazards associated with the use of large amounts of urea.
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