Abstract Millet yields are highly variable even within the same farm in the Sahel. A conceptual model of the phenomenon was designed and quantitative analysis of key relationships was conducted based on the available published studies. We found that the high spatial variability of millet yield is due to two main edaphic factors: soil fertility properties and water availability. It is still unknown whether the spatial variability of the two main factors is inherent to Sahelian soils. However, some biotic and abiotic factors induce and even maintain the variability of the main factors. The biotic factors include the presence of trees, termite’s activity, fertility management practices, pests, and diseases. Abiotic factors include rainfall (amount, intensity, and distribution) and wind erosion. The major soil chemical properties which strongly influence spatial yield variability include organic carbon, pH, aluminum saturation, and available phosphorus. Millet yield was positively and strongly correlated with P (r2=0.80, p < 0.001), moderately with pH (r2=0.30, p < 0.001), but strongly and negatively with the logarithm of aluminum saturation (r2=0.54, p < 0.001). Water availability is affected mainly by the soil physical properties, which strongly impact millet yield variability through infiltration rate and water retention capacity. The underlying properties are soil structure, texture, and soil surface conditions. The inadequate consideration of soil heterogeneity could also explain the low level of farmer adoption of the recommendations regarding soil fertility improvement based on experimental research or decision support. This situation calls for improved precision agriculture technologies that are compatible with Sahelian farmers’ socio-economic conditions.

中文翻译：

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为什么萨赫勒地区农场层面的小米产量空间变异性高？对研究和开发的影响

摘要 即使在萨赫勒的同一农场内，小米的产量也存在很大差异。设计了该现象的概念模型，并根据现有的已发表研究对关键关系进行了定量分析。我们发现小米产量的高空间变异性归因于两个主要土壤因素：土壤肥力特性和可用水量。目前尚不清楚这两个主要因素的空间变异性是否是萨赫勒土壤固有的。然而，一些生物和非生物因素诱发甚至维持了主要因素的变异性。生物因素包括树木的存在、白蚁的活动、生育管理实践、病虫害。非生物因素包括降雨量（数量、强度和分布）和风蚀。强烈影响空间产量变异性的主要土壤化学性质包括有机碳、pH、铝饱和度和有效磷。小米产量与 P 呈正相关（r2=0.80，p < 0.001），与 pH 呈中度相关（r2=0.30，p < 0.001），但与铝饱和度的对数呈强烈负相关（r2=0.54，p < 0.001） ）。可用水量主要受土壤物理特性的影响，土壤物理特性通过渗透率和保水能力强烈影响小米产量的变异性。基本特性是土壤结构、质地和土壤表面条件。对土壤异质性考虑不足也可以解释农民对基于实验研究或决策支持的土壤肥力改善建议的采纳率低的原因。