A number of studies across sub-Saharan Africa have recently reported poor crop responses and low agronomic use efficiencies of applied nitrogen (AEN), phosphorus (AEP) and potassium (AEK). However, the conditions under which non-responsiveness occurs, its underlying causes and its probability of occurrence on different soil types are not well understood. Using data from 542 sites and 14 soil types in 23 African countries, we provide novel insights into the linkage between lack of response to applied N, P and K, the mineralogy of soils and their resilience to erosion. We estimated mean responses as well as the probabilities (ϕ) of no response in terms of response ratio (RR), yield gain (YG) and agronomic efficiency. Here we defined ‘no response’ as zero agronomic response to fertilizer inputs in a given site and year indexed by either RR ≤ 1, AEN ≤ 0, AEP ≤ 0 or AEK ≤ 0. The highest risks of no response were recorded on the iron-rich Plinthosols (ϕ = 0.26) followed by the aluminium-rich Alisols (ϕ = 0.16) and the erosion-prone Lixisols (ϕ = 0.16) and Leptosols (ϕ = 0.13). In terms of yield gains, the highest risk of low response (i.e., YG ≤ 0.5) was recorded on Alisols (ϕ = 0.47) and the lowest on Fluvisols (ϕ = 0.05). Cambisols, Fluvisols, Luvisols and Nitisols were deemed highly responsive to NPK fertilizer. The risks of no response were significantly higher on soils derived from siliceous than mafic parent materials, soil types with low resilience to erosion, soils with low-activity clays and high P fixation capacity. It is concluded that maize grain yields can exceed 3 t ha-1 with high probability (ϕ > 0.80) on Andosols, Nitisols and Vertisols, but with very low probability (ϕ < 0.30) on Alisols and Arenosols. It is also concluded that across soil types and agroecological zones, the risk of no response is up to two times more on farmers’ fields than on research stations. Here, we discuss the implications of these finding for the design and location of future agronomic trials. We also provide insights to guide the targeting of fertilizer subsidies where nutrients can be more efficiently used.

撒哈拉以南非洲地区的一些研究最近报告了作物反应不佳和施氮 (AEN)、磷 (AEP) 和钾 (AEK) 的农艺利用效率低。然而，不响应发生的条件、其根本原因以及在不同土壤类型上发生的概率尚不清楚。利用来自 23 个非洲国家的 542 个地点和 14 种土壤类型的数据，我们提供了关于对施用的 N、P 和 K 缺乏反应、土壤矿物学及其对侵蚀的恢复力之间的联系的新见解。我们根据响应比 (RR)、产量增益 (YG) 和农艺效率估计了平均响应以及无响应的概率 (φ)。在这里，我们将“无响应”定义为对给定地点和年份中的肥料投入的零农艺响应，索引为 RR ≤ 1，AEN ≤ 0，AEP ≤ 0 或 AEK ≤ 0。无反应的最高风险记录在富含铁的 Plinthosols (φ = 0.26) 上，其次是富含铝的 Alisols (φ = 0.16) 和易侵蚀的 Lixisols ( φ = 0.16) 和 Leptosols (φ = 0.13)。在增产方面，低响应风险（即 YG ≤ 0.5）在 Alisols（φ = 0.47）和 Fluvisols 最低（φ = 0.05）。Cambisols、Fluvisols、Luvisols 和 Nitisols 被认为对 NPK 肥料高度敏感。硅质土壤的无响应风险显着高于镁铁质母质土壤、抗侵蚀能力低的土壤类型、低活性粘土和高固磷能力的土壤。得出的结论是，在 Andosols、Nitisols 和 Vertisols 上，玉米籽粒产量很可能超过 3 t ha-1（φ > 0.80），但在 Alisols 和 Arenosols 上的概率非常低（φ < 0.30）。还得出结论，在不同的土壤类型和农业生态区，农民田间没有反应的风险是研究站的两倍。在这里，我们讨论了这些发现对未来农艺试验的设计和定位的影响。我们还提供见解，以指导肥料补贴的目标可以更有效地利用养分。