The response of wheat to the application of different rates of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) under balanced fertilization on different soil types and agroecologies has not been well studied in Ethiopia. Therefore, the objectives of this study were to (1) determine soil-specific responses of wheat to N, P, K, and S under balanced fertilization; (2) quantify agroecology-specific N, P, K, and S response of wheat under balanced fertilization; and (3) determine nutrient use efficiency of wheat on different soil types under balanced fertilization. Trials were conducted on farmers’ fields across 24 locations covering 4 soil types and 5 agroecological zones (AEZs) from 2013 to 2017. The mean grain yields of wheat significantly varied with applied N and P fertilizer rates with soil types and AEZs. With balanced application of other nutrients, the optimum N rates for wheat were 138 kg N ha−1 on Cambisols and Luvisols, 92 kg N ha−1 on Vertisols, and 176 kg N ha−1 on Nitisols, while the optimum P rate was 20 kg P ha−1 on Cambisols and Vertisols. The nutrient dose–response curve did not reveal consistent pattern for K and S applications on all soil types. The agronomic efficiency of wheat decreased with increasing rates N and P on all soil types. The highest agronomic efficiency of N (15.8 kg grain kg−1 applied N) was recorded with application of 92 kg N ha−1 on Vertisols, while the highest agronomic efficiency of P (49 kg grain kg−1 applied P) was achieved with application of 10 kg P ha−1 on Cambisols. We conclude that applications of 92–138 kg N ha−1, 20 kg P ha−1, 18 kg K ha−1, and 10 kg S ha−1 under balanced application of zinc and boron could be recommended depending on soil type for wheat production in the study areas.

This study was initiated to investigate the effect of nitrogen fertilizer on agronomic efficiency, yield and yield components of barley after faba bean precursor crop. A field experiment was carried out in 2015 main cropping season at district at Ayba and Tek'a kebeles in Tigray Regional State, Ethiopia. The experiments were arranged in a randomized complete block design with three replications. Treatments were six levels of nitrogen (0, 11.5, 23, 34.5, 46 and 69 kg N ha-1). Soil samples were collected before planting and analyzed for selected physicochemical properties. Pre-planting soil analysis results revealed that total N was low at Tek'a kebelle (0.09%) and medium at Ayba (0.186%). The organic carbon content of experimental fields was medium at Ayba and low at Tek'a. Application of nitrogen had significantly influenced yield and yield components of barley at Tek'a site but not at Ayba after fababean precursor crop. This is consistent with the initial soil nitrogen and contribution of the precursor crop for nitrogen fixation. The highest agronomic efficiency was recorded from the addition of 23 kg N ha-1 (31.52 kg kg-1) and 34.5 kg N ha-1 (31.44 kg kg-1) at Ayba kebelle and Tek'a, respectively. Both biological and partial budget analysis depicted that application of 34.5 kg N ha-1 was found to be economical. Therefore, application of nitrogen after legume crop should consider initial soil result..

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Article InformationCrop rotation is a common practice in the study area, but there is no enough information on the specific rate of nitrogen to be applied after legumes for wheat production. Hence, on farm field experiments were conducted to determine the amount of nitrogen fertilizer rates needed for bread wheat after chick pea, grass pea, fababean and field pea precursor crops. The field experiments were conducted during 2014 main cropping season at Hawzien after chick pea and grass pea and at Emba Alaje after fababean and field pea precursor crops. The experiment consists of six nitrogen rates (0, 11.5, 23, 34.5, 46 and 69 kg Nha -1 ) laid in a RCBD with three replications. Phosphorus, sulfur and potassium fertilizers were also applied as basal for all plots at sowing. Surface soil samples were collected before planting and analyzed for selected soil properties. Soil analysis result of the experimental sites revealed that total nitrogen content (%) of the soil after chickpea-wheat (0.0695), grass pea-wheat (0.067), fababean-wheat (0.074) crop rotation were categorized under low range and after field pea-wheat (0.102) under medium range. Application of nitrogen had significantly increased grain and straw yield at Hawzien district after chick pea and grass pea precursor crops. At Emba-Alaje the highest grain yield was recorded on plots treated with 69 kg N ha -1 (6242 kg ha -1 ). Grain and straw yields of wheat increased up to a rate of 46 kg N ha -1 after fababean at Emba-Alaje district. There is no significant difference in grain and straw yields of wheat due to application of nitrogen after field pea crop rotation. In Hawzien the highest agronomic efficiency after chick pea and grass pea was recorded from plots treated with 46 kg N ha -1 and 34.5 kg N ha -1 , respectively. In Emba Alaje the highest agronomic efficiency after faba bean and field pea was recorded from plots treated with 11.5 kg N ha -1 and 23 kg N ha -1 , respectively. At Hawzien, the partial budget analysis revealed that application of 46 kg N ha -1 for bread wheat after chick pea and grass pea was economical with 1545% and 796 % marginal rate of return, respectively. At Emba Alaje, the partial budget analysis revealed that application of 34.5 kg N ha -1 for bread wheat after fababean was economical with 895% marginal rate of return. It could be concluded that application rate of N for wheat after leguminous crops should consider initial soil N and precursor crop.