Maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) are important intermediate and low elevation crops in Ethiopia but yields are low. The information for determination of nutrient rate recommendations with site specificity is scarce. On-farm and on-station trials were conducted to determine the yield responses to N and P and to diagnose K–Mg–S–Zn–B deficiencies in central, northern and western Ethiopia. Mathematical functions for grain yield response to applied nutrients were fitted, the economical optimum rates (EOR) were determined, and profit potential for fertilizer use was assessed. Maize and sorghum grain yields were inconsistently affected by N and P application across trials with no response in some cases. The overall mean EOR for N were 47 and 60 kg ha⁻¹ for maize and 23 and 37 kg ha⁻¹ for sorghum with high and low cost fertilizer-N, respectively. The overall maize response to P was linear with EOR of P > 30 kg ha⁻¹ for all fertilizer-P costs. The overall sorghum response to P was too inconsistent to fit a response function and the results indicated an EOR of 0 kg ha⁻¹ for all fertilizer costs considered. The overall maize and sorghum responses to N were curvilinear to plateau implying that the profit to cost ratio can be improved by applying fertilizer-N at less than EOR giving an opportunity to farmers who are financially-constrained in fertilizer use.

中文翻译：

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埃塞俄比亚玉米和高粱的养分响应功能

玉米（Zea mays L.）和高粱（Sorghum bicolor L. Moench）是埃塞俄比亚重要的中低海拔作物，但单产较低。确定具有特定部位营养指标的建议的信息很少。进行了农场和现场试验以确定埃塞俄比亚中部，北部和西部对氮和磷的产量响应并诊断钾-镁-硫-锌-硼缺乏症。拟合了谷物产量对施用养分响应的数学函数，确定了经济上的最佳施用率（EOR），并评估了肥料使用的潜在利润。在整个试验中，氮和磷的施用对玉米和高粱谷物的产量产生了不一致的影响，在某些情况下没有反应。N的总平均EOR为47和60 kg ha ^-1高氮和低成本肥料-N分别对玉米和高粱分别为23和37 kg ha ^-1。对于所有肥料P成本，玉米对P的总体响应与EOR为P  > 30 kg ha ^-1呈线性关系。高粱对磷的总体响应过于不一致，无法满足响应功能，结果表明，考虑到所有肥料成本，EOR为0 kg ha ^-1。玉米和高粱对氮的总体响应曲线对高原呈曲线，这意味着通过以少于EOR的量施用氮肥可以提高利润/成本比，从而为受肥料限制的农民提供了机会。