Refining Fertilizer Rate Recommendation for Maize Production Systems in Assosa, North Western Ethiopia

Maize growers need balanced crop nutrition to maximize its yield potential and get the most out of their fertilizer investment. In practice, this requires making all of the required nutrients available to the maize crop by the right amount or rate. The objectives of this study was to determine optimum N, P, K and S response curve under balanced fertilization and to establish economic mixes blended fertilizers and determine soil, crop specific optimum N, P, K and S fertilizers rates for maize crop grown in Assosa areas. The experiment was conducted using randomized complete block design (RCBD) with three replications consisting of a total of 8 treatments for N, P, K and 10 treatments for S. Therefore; the result revised that the N level was highly significant (P<0.05) on grain yield. The highest grain yield (7292.5 kg ha-1) was obtained at the lowest nitrogen rate with balanced fertilizer of 46 kg N ha-1+PKSZnB while significantly the lowest grain yield (3298.6 kg ha-1) was records from control. The application of 69 kg ha-1 P resulted in grain yield increases, aboveground biomass yield was also affected in the same amount of P with balanced fertilizers having increased biomass yield with P application. Even if the ANOVA results shows significant difference on that of treated with K fertilizer, there was slight variation within treatments except the highest rates of K fertilizer. Across the S rate studies, all S rates with balanced fertilizers had a statistically significant yield increment from the control and Recommended NP. From the across-treatment yield increase, treatment 10 Kg S ha-1+NPKZnB gives maximum yield (6717.7 kg ha-1). Analyzed across S rate, the economic optimum S rate was also 10 Kg S ha-1 for the clay textured soils of Assosa.