The study was initiated to investigate the effects of slow nitrogenreleasing fertilizer (UREA Stabil ) on yield, yield components and nitrogen use efficiency indices of bread wheat at Emba Alaje and Hawzien Districts in Tigray, Ethiopia in 2015 at six farmers' field and arranged in a randomized complete block design with three replications. Treatments were four levels of nitrogen (0, 32, 64 and 96) kg ha −1 . The nitrogen source was UREA Stabil , which is slow N-releasing fertilizer. Conventional urea at the recommended rate (64 kg N ha −1 ) was included as a positive control at both sites. A full dose of UREA Stabil were applied at planting while prilled urea (conventional urea) was applied in two splits 1/3 at planting and 2/3 at tillering. Application of UREA Stabil significantly influenced yield and yield components at both soil types. The highest grain yield was obtained on plots treated with 64 kg N ha −1 in the form of UREA Stabil and prilled urea (conventional urea) in Hawzien and Emba Alaje districts, respectively. The highest nitrogen uptake was recorded on plots treated with 64 kg N ha −1 in the form of UREA Stabil and prilled urea (conventional urea) in Hawzien and Emba Alaje, respectively. Nitrogen uptake, agronomic, physiological and apparent recovery efficiency were significantly influenced by the application of slow-releasing and conventional nitrogen fertilizers at both sites. In Hawzien, the application of slow-releasing N fertilizer in the form of UREA Stabil reduces the amount of N used and application time. Hence, it could be concluded application of slow-releasing fertilizer could be used as an alternative source of nitrogen for wheat production in the study site.

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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.

The N recovery by crops from the soluble N fertilizers such as urea is often as low as 30-40%, with a potentially high environmental cost associated with N losses via NH 3 volatilization, NO 3 -leaching and N 2 O emission to the atmosphere. This study was initiated to evaluate the effects of slow releasing nitrogen fertilizer in nitrogen uptake, nitrogen use efficiency and grain protein content of wheat. A field experiment was carried out in 2015 main cropping season at Hawzien district in Tigray Regional State, Ethiopia. The experiment were arranged in a randomized complete block design with three replications at three farmer's field. Treatments were four levels of nitrogen (0, 32, 64 and 96) kg ha -1 . The nitrogen source was UREA Stabil , which is slow N releasing fertilizer. Conventional urea at recommended rate (64 kg N ha -1 ) was included as positive control at both sites. The highest grain and straw N uptake, and total uptake (41.81 kg ha

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