Potassium (K) has received little attention as a potential yield-limiting factor in cropping systems. Here we investigated the K status in intensive cereal cropping systems in Indonesia, which are representative of many other Southeast Asian countries. Our analysis included nutrient input–output balance, leaf nutrient status, long- and short-term fertilizer trials, and farmer surveys. We revealed that soil K levels alone are insufficient to meet plant requirements, and current fertilizer applications are inadequate to prevent K deficiencies and large negative annual soil K balances in farmer fields (average −62 kgK ha⁻¹). On-farm fertilizer trials indicated that nearly 80% of rice crops and 70% of maize crops achieved higher yields with the application of K fertilizer. Addressing K limitations will require an enhanced capacity to predict crop responses to K fertilizer, together with long-term, flexible fertilizer and crop residue management strategies. Furthermore, similar K limitations have probably emerged in other regions globally due to intensive cropping with insufficient K replenishment, which must be addressed to close yield gaps on existing farmland.

钾 （K） 作为种植系统中潜在的产量限制因素很少受到关注。在这里，我们调查了印度尼西亚集约化谷物种植系统的钾态，这是许多其他东南亚国家的代表。我们的分析包括养分投入产出平衡、叶片养分状况、长期和短期肥料试验以及农民调查。我们发现，仅靠土壤 K 水平不足以满足植物需求，而目前的肥料施用不足以防止农田缺钾和每年土壤钾平衡大幅负（平均 -62 kgK ^ha-1）。农场肥料试验表明，近 80% 的水稻作物和 70% 的玉米作物在施用钾肥后获得了更高的产量。解决钾肥限制问题需要增强预测作物对钾肥反应的能力，以及长期、灵活的肥料和作物残留物管理策略。此外，由于集约化种植和钾补充不足，全球其他地区可能也出现了类似的钾限制，必须解决这一问题以缩小现有农田的产量差距。