Maize Fertilizer Requirement Estimates Through Nutrient Use Efficiency and Economic Analysis from Assosa, Western Ethiopia

Scientific information with regards to the response of maize (Zea mays L.) to different blended fertilizer rates for its optimum production in Nitisols of Assosa area is limited. Therefore, a field experiment was conducted on Nitisols of Assosa Agricultural Research Centre during 2016/17 cropping season to investigate the response of growth, yield and nutrient use efficiency of maize (Zea mays L.) to different blended fertilizer rates and types. The treatments consists of: control, three rates of N and P combined (92/46, 115/57 and 138/69 N/P<sub>2</sub>O<sub>5</sub> kg ha<sup>-1</sup> and two formula of blended fertilizers with different rates, formula 2 consists of 100 kg NPSB+ 73.9 N, 150 kg NPSB +110.8 N and 200 kg NPSB + 147.8 N kg ha<sup>-1</sup> and formula 4 consists of 100 kg NPSZnB + 75.1 N, 150 kg NPSZnB + 112.6 N <sup>1</sup> and 200 kg NPSZnB +150.2 N kg ha<sup>-1</sup>. The treatments were laid out as a Randomized Complete Block Design with three replications. Application of blended fertilizers (NPSB, NPSZnB) hastened days to tasseling silking and maturity by 10, 7 and 15 days, respectively as compared to combined N and P rates. Application of blended fertilizer increases significantly (p < 0.01) the plant height, cob weight, ear length, 100 kernels weight, number of kernels per row and ear height as compared to combined N and P and the control. The analysis of variance revealed that fertilizer types and rates significantly (P < 0.01) affected on grain yield, straw yield and harvest index. However there was no significant difference between the two blended fertilizer types. Maximum grain yield (7056.2 kg ha<sup>-1</sup>) was recorded with 200 Kg NPSZnB + 150.2 N kg ha<sup>-1</sup> application, while minimum grain yield 2996.0 kg ha<sup>-1</sup> was recorded from control treatment. The application of 150 kg NPSB + 110.8 N kg ha<sup>-1</sup> had highest Marginal rate of return (MRR%) and net benefit. Therefore, we recommended the treatment (150 Kg NPSB + 110.8N kg ha<sup>-1</sup>) since it produced high marginal rate of return, high net benefit and relatively small total cost of production, for maize production in Asossa area. Furthermore, based on yield, net benefit and relatively low total cost of production the farmer of Asossa area also can use 150 kg NPSZnB + 112.6 N in case of absence of NPSB in market.