Optimum NP Fertilizers Rate For Wheat Production on Alfisols of Arjo and Shambu Highlands, Western Ethiopia

Abstract

The study was conducted on Alfisols of Arjo and Shambu highlands of western Ethiopia under the farmers’ condition to determine optimum NP fertilizers rate for wheat production. The treatments used were four levels of N (0, 23, 46, and 60 kg ha 1 ) and three levels of P (0, 15, and 23 kg ha 1 ) in factorial arrangement. The treatments were laid out in randomized complete block design with three replications using the local wheat variety. The main effects of N were significant (P 0.05) on grain yield at all locations and seasons except for 2008 at Shambu and 2010 at Arjo. The soil analytical data showed that most of the farmers allocated the fertile parts of their land for wheat production. The economic analysis revealed that the highest net benefit were 2937.50 Eth. Birr/ha with the sole application of 23 kg N ha 1 . However, the highest marginal rate of return (MRR) was achieved with the sole application of 46 kg N ha 1 which provided 16785.70% MRR, followed by 2470.37% with the use of 23/23 kg N/P ha 1 . As P is also the limiting plant nutrients in Alfisols of Arjo and Shambu highlands, the use of 23/23 kg N/P ha 1 is found to be economical and practical for wheat production in the study area. Sensitivity analysis was carried out as well with 10% increases in inputs (labor and NP fertilizers) that maintained the recommendation. However, the recommendation (23/23 kg N/P ha 1 ) should be used, taking into account the farmers’ soil fertility classification systems. The full dose of the recommended rate should be used on the farmers’ field classified as low fertile. This implies that no need to use NP fertilizers on soils classified as fertile by farmers since the resultant lodging and disease incidence significantly reduce the grain yield.