Response of Mung bean [Vigna radiata (L.) Wilczek] to Rates of Nitrogen and Phosphorus Fertilizer under Irrigation at Nura Era, Upper Awash, Central Ethiopia

Mung bean has become an important cash and food crop in dry land areas of Ethiopia. However, there are no sufficient research information on the nitrogen (N) and phosphorus (P) fertilizers rates for the crop in the study area. Thus, field experiment was conducted to assess the effect of N and P fertilizer rates on the growth, yield components and yield; and to identify economically feasible rates of N and P fertilizers. The experiment was conducted at Nura -Era, Upper Awash under irrigation during /December, 2016 – February, 2017/ cropping season using mung bean variety NVL-1. The treatments consisted of factorial combinations of three N rates (0, 23 and 46 kg N ha-1) and five P rates (0, 10, 20, 30 and 40 kg P ha-1) laid out as randomized complete block design with three replications. Result of the main effect of nitrogen rate showed significantly longest days to 90% maturity (89.11 days), highest number of primary branches per plant (4.25), highest harvest index (25.71%) at the highest rate of N (46 kg ha-1). On the other hand, 23 kg N ha-1 produced significantly highest number of pods per plant (17.70) and highest 100 seed weight (4.94 g).Similarly, the main effect of P fertilizer showed that the application of 40 kg P ha-1produced significantly highest number of primary branches per plant (4.79), highest number of pods per plant (20.85),highest pod length, highest number of seeds per pod (6.24), highest dry biomass yield (6838.83 kg ha-1), highest 100 seed weight (5.21 g) and highest harvest index (25.96%).The interaction of N and P rates was significant on days to 50% flowering, plant height and grain yield, where the combination of 23 kg N ha-1 and 40 kg P ha-1 gave the highest (1902.78 kg ha-1) grain yield. Moreover, the combination of 23 kg N and 10 kg P ha-1 also resulted the highest net-return (18,102.60 ETB ha-1) with MRR of 356.2%. Thus, from this study it can be concluded that the combined use of 23-40 kg N-P ha-1 produced significant effect on yield components and yield of mung bean. However, the results need to be evaluated with more varieties/genotypes of mung bean under different agro-climatic conditions