Optimum Nitrogen and Phosphors Fertilizer Rates for Upland Rice Production in North Western Ethiopia

Abstract

The national average yield of rice is about 2.8t ha-1 which is lower compared to the world average productivity of 4.6 tones ha-1 mainly constrained by soil nutrient deficiencies. An experiment on nitrogen and phosphorous fertilizer rates was conducted on upland rice on Nerica-4 variety in Fogera and Libokemkem districts in three consecutive main cropping seasons of the years 2015, 2016 and 2017 to determine the appropriate rates for production. The treatments were comprised of factorial combinations of four nitrogen rates (0, 46, 92,138 N kg ha-1) and three phosphorous rates (0, 46, 92 P2O5 kg ha-1), and laid out in randomized complete block design (RBD) with three replications. Data were collected on plant height, panicle length, and number of total tillersm-2, number of fertile panicles m-2, thousand seeds weight, grain yield, straw yield and harvest index. All collected data were subjected to analysis of variance. Economic analysis was also carried out by following CIMMYT (1988) procedures. The results of the experiment indicated that the main effect of nitrogen application significantly affected plant height, panicle length, total tillers, number of fertile panicles, grain yield, and straw yield, while that of phosphorous significantly affected total tillers, number of fertile panicles and grain yield. The interaction of nitrogen and phosphorous was significantly affecting total tillers, number of fertile panicles, grain yield and straw yield. The highest grain yield (5.5 t ha-1) was obtained from the interaction of 138 kg ha-1N with 46 kg ha-1 P2O5. The economic analysis has further revealed that the combined application of 138 kg ha-1N and 46 kg ha-1 P2O5 which gave the highest net return of Birr 68,307.5 ha-1 was the most profitable treatment to upland rice production. Thus it is concluded that application of nitrogen and phosphorous fertilizers at the rates of 138-46 N-P2O5 kg ha-1 is the best to be recommended for rainfed upland rice production in the study area and other similar agro-ecologies.