Yield of maize hybrids could be low when grown below optimum management practices. Use of improved varieties and optimum nitrogen fertilizer application practices are unlocking the high yielding potential of hybrids maize. With these in view, a field experiment was executed on farmers' field to determine the effect of varieties and nitrogen fertilizer rate on yield and yield components of maize in two cropping seasons. It is laid out with randomized complete block design in factorial arrangement with three replications. Five maize varieties (BH-540, BH-543, BH-661, BH-660, and BH-140) as main factor and two levels of nitrogen (55 and 110 Kg N ha −1 ) as subfactor were used with one maize variety (BH-543) without fertilizer as control. Leaf area and leaf area index of maize varieties were significantly affected by application of nitrogen fertilizer rates. Interaction of maize varieties with nitrogen fertilizer rates significantly affected all yield and yield components of maize. Application of half and full recommended nitrogen fertilizer produced mean grain yield advantages of 31 and 41% over control. Therefore, application of half and full recommended nitrogen fertilizer for improved maize varieties has significantly improved grain yield and recommended for maize production in midaltitude area of western Ethiopia.

Barley is an important food and beverage crop in the highlands of Ethiopia, although intensive cultivation and suboptimal fertilizer application have caused nutrient depletion and yield decline. With this in view, integrated inorganic and organic fertilizer sources on yield and yield components of barley were studied. Ten treatments involving the sole NP, vermicompost, conventional compost, and farmyard manure based on N equivalency were laid out in a randomized complete block design with three replications in 2015 and 2016 cropping seasons. Significantly higher grain yield and biomass yield of barley were obtained with the application of sole recommended NP and the integrated use of 50 : 50% vermicompost and conventional compost with recommended NP. Mean grain yield of 2567 and 2549 kg·ha−1 barley was obtained from application of 50 :50% conventional compost and vermicompost based on N equivalence with recommended NP fertilizer rate, which markedly reduce the cost of chemical NP fertilizer required for the production of barley. The economic analysis confirmed the profitability of the integrated use of 50 : 50% conventional compost and vermicompost with recommended NP fertilizer for barley production. Therefore, the integrated use of 50 : 50% conventional compost and vermicompost based on N equivalency with recommended NP fertilizer was recommended for sustainable barley production in Chelia district and similar agroecology.

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Faba bean production is a common practice in Lemu Bilbilo areas. However, faba bean productivity is affected and limited by poor soil fertility and lack of alternative technologies such as application of optimum phosphorus fertilizer for different faba bean varieties. In view of this, a field experiment was conducted on farmer's field during the 2017 main cropping season at Lemu Bilbilo with the objectives to determine the response of faba bean varieties to different rates of P fertilizer and its influence on yield and yield components of faba bean varieties. The treatments include three faba bean varieties (Tumsa, Gebelcho and Dosha) and five phosphorus levels (0, 10, 20, 30 and 40 kg Original Research Article

A trial was conducted to determine the effects of crop rotation with N-P rates on grain yield of maize and soil fertility in Bako over a period of five years. The experiment was laid out in a randomized complete block design in factorial arrangement with rotation crops (Niger seed, haricot bean and tef) as main factor and two levels of NP fertilizers (half recommended (55/23 kg N-P2O5 ha-1 and recommended (110/46 kg N-P2O5 ha-1) rate as sub factor and continuous maize with three replications. Higher mean grain yield of maize was recorded from maize following rotation crops with recommended rate of fertilizer compared to continuous maize. Maize following rotation crops gave mean grain yield advantage of 640 to 830 and 1921 to 1968 kg ha-1 compared to continuous maize at half and full recommended N-P fertilizer rate. Maize following Niger seed produced mean grain yield advantage of 971 and 1527 kg ha-1 compared to haricot bean and tef. Primary nutrient (N, P and K) composition of the tissue and grain of maize were significantly higher with maize following rotation crop compared to continuous maize, indicting the enhancement of the nutrient use efficiency of maize following rotation crops. Crop rotation with fertilizer amendment improved the pH of the soil. Crop rotation and N-P amendment enabled maize yields and soil fertility to be maintained at a higher level. Multiple advantages accrue from the use of crop rotation. Higher grain yield and high net return of maize were realized following Niger seed, haricot bean and tef compared to continuous maize. Maize following Niger seed followed by haricot bean with the recommended rate of fertilizer is a better management option for sustainable maize production in Western Oromia.