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.
Variability in crop response and nutrient use efficiencies to fertilizer application is quite common under varying soil and climatic conditions. Understanding such variability is vital to develop farm- and area- specific soil nutrient management and fertilizer recommendations. Hence the objectives of this study were to assess maize grain yield response to nutrient applications for identifying yield-limiting nutrients and to understand the magnitude of nutrient use efficiencies under varying soil and rainfall conditions. A total of 150 on-farm nutrient omission trials (NOTs) were conducted on farmers’ field in high rainfall and moisture stress areas. The treatments were control, PK, NK, NP, NPK and NPK+ secondary and micronutrients. Maize grain yield, nutrient uptake, agronomic and recovery efficiencies of N and P differed between fertilizer treatments and between the contrasting agro-ecologies. The AEN ranged from 24.8 to 32.5 kg grain kg-1 N in Jimma area and from 1.0 kg grain kg-1 N (NK treatment) to 10.2 kg grain kg-1 N (NPK treatment) at Adami Tullu and from 0.1 kg grain kg-1 N (NK treatment) to 8.3 kg grain kg-1 N (NPK treatment) at Bulbula. The differing parameters between the agro-ecologies were related to difference in rainfall amount and not to soil factors. Grain yield response to N application and agronomic efficiencies of N and P were higher in the high rainfall area than in the moisture stress areas. Grain yield responded the most to nitrogen (N) application than to any other nutrients at most of the experimental sites. Owing to the magnificent yield response to N fertilizer in the current study, proper management of nitrogen is very essential for intensification of maize productivity in most maize growing areas of Ethiopia.
Hulless barley (Hordeum vulgare L. var. nudum Hook. f.) and wheat (Triticum aestivum L.) are important crops for the highlands of western Shewa in Ethiopia. Information is scarce regarding the determination of fertilizer recommendations for barley and wheat with location specificity. On-farm trials were conducted to determine yield response to N and P and to diagnose K-Mg-S-Zn-B deficiencies in western Shewa. Grain yields were higher and responses to N and P were greater for these trials compared with results from earlier trials. Grain yield increases occurred with N application for all trials, ranging from 0.42 to 2.8 Mg ha −1 for barley and from 1.4 to 3.8 Mg ha −1 for wheat, fitting curvilinear to plateau or quadratic functions. Barley yield was maximized with 60 kg ha −1 N, and 98% of maximum yield was achieved with 50 kg ha −1 N, but wheat yield was projected to maximize with >100 kg ha −1 N. About 50% of the trials had yield increases with P application. Many farmers in this area are financially constrained regarding fertilizer use and can achieve a mean of 48% greater net return on their investment with the application at 50% rather than 100% of the rate to maximize profit per hectare. The yields and response to applied nutrients were generally less with earlier results compared with the current results, whereas the economically optimal rate of nutrient application or the rate expected to maximize net return per hectare to nutrient application was similar or slightly less for the earlier results. The profit opportunity with fertilizer use in western Shewa is great for N, less for P, and negligible for K-Mg-S-Zn-B.Abbreviations: CP, kilograms of barley or wheat required to equal the cost of 1 kg of nutrient applied; EOR, economically optimal nutrient rate; PCR, profit to cost ratio.
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