Studies on the Bio-Efficacy of Neem Coated Urea on Rice

In rice ecosystem about 60-70% of the applied nitrogen got lost due to different losses viz., leaching, volatilization etc. The increase in nitrogen use efficiency by 1% will lead to a substantial increase in rice productivity. Therefore a field experiment was conducted to study the effect of different product of neem based nitrification inhibitors to increase the nitrogen use efficiency along with the recommended practice of inorganic N application in rice during Pishanam 2003-04. The study on the effect of nitrogen source on the yield parameters, yield, nutrient uptake and B-C ratio of rice in Tamirabarani tract revealed that the application of 120 kg N/ha as neem coated urea in 3 splits recorded the highest plant height, number of tillers/plant, productive tillers/plant (13.9) and the grain (7.59 t/ha) and straw (11.5 g/ha) yields, total uptake of N (93.4 kg/ha), P (26.0 kg/ha) and K (132 kg/ha) and B-C ratio of 1.21 rupees per rupee invested in rice (var. ADT 39). Although the nitrogen use efficiency was found marginally lower (13.9) in neem coated urea at 120 kg/ha than the application of 96 kg N/ha (80% of the recommended N) as nimin coated urea in 3 splits (15.1), the highest B-C ratio of 1.61 rupees per rupee invested was recorded over the normal recommended practice of applying urea at the rate of 120 kg N/ha in 3 splits (1.00) and found economically viable.