Effect of Nitrogen Application Timing on Growth, Grain Yield and Nitrogen Use efficiency of Rice (Oryza Sativa L) in Fogera Plain, North Western Ethiopia

Abstract: Nutritional management in rice (Oryza sativa L.) crops is mainly associated with N fertilization, which is difficult to adjust in field conditions due to variations in soil type and climatic conditions. A field experiment was carried out to determine the effect of time of nitrogen fertilizer application for increasing nitrogen use efficiency in lowland rice (Oryza sativa L.) Fertilizer rate of 69/23 kg N/P2O5 ha-1 and seven nitrogen application times was conducted on Vertisols of Fogera plain during 2016/2017and 2017/2018 cropping season. The treatments were 1/2 at sowing + 1/2 at tillering (control), 1/3 at sowing + 2/3 at tillering , 1/3 at 15 days after sowing + 2/3 at panicle initiation, 1/3 at 25 days after sowing + 2/3 at panicle initiation, 1/3 at sowing + 1/3 at mid tillering + 1/3 at panicle initiation, 1/3 at 15 days after sowing +1/3 at panicle initiation +1/3 at heading and 1/3 at 25 days after sowing + 1/3 at panicle initiation +1/3 at heading. RCB Design with three replications was used. The objective of the experiment was to select appropriate time of N fertilizer application for maximum rice yield in the study area. Results showed significant difference in Panicle length, Number of total tillers, Number of Fertile Panicles and Number of filled spicklets per Panicles but not in grain yield and straw yield in response to time of N application. The highest agronomic Nitrogen Use Efficiency (42.9) was recorded from 1/3 of N applied at 15 days after sowing + 2/3 of N at panicle initiation stage of the rice crop. The economic analysis showed that the highest net benefit of Birr 84776. ha-1 was obtained from 1/3 of N at 15 days after sowing + 2/3 of the recommended Nitrogen fertilizer at panicle initiation stage of the crop, which is 17760.00 Birr more than the net Benefit obtained from the control treatment. Based on the economic analysis, the highest NB Birr 84776 ha-1 and highest grain yield (5.6 t/ha) was observed from the time of Nitrogen application one third of N 15 days after sowing and the remaining two third of the recommended nitrogen at Panicle initiation stage of rice crop was found to be the best and appropriate time of nitrogen fertilizer application for rainfed lowland rice production system of Fogera plain and other similar agro ecologies.