Optimal potassium management strategy to enhance crop yield and soil potassium fertility under paddy‐upland rotation

Abstract

Abstract BACKGROUND An unbalanced application of potassium (K) fertilizer usually destabilizes crop yield and affects soil K fertility. Developing a sustainable K management strategy requires improvements in crop yield without reducing soil K supply capacity over the long term. A combination of field experiments of K fertilization and straw return using rice ( Oryza sativa L.)–oilseed rape ( Brassica napus L.) rotation was designed to develop an optimal K management strategy. RESULTS The results showed the best strategy to maintain yield was K G +S (input equivalent K removed by seed treatment and straw return), K S +K G (input equivalent K removed by straw and seed) and K C +S (conventional K fertilization and straw return) treatments, and the yield gap among different treatments expanded with the extension of planting years. There were significant differences present in rice and rape K uptake, although no differences in seed K uptake were observed under different K management strategies. The K balance was approximately maintained under K G +S and K S +K G treatments, and negative K balances were present for K N (no K application), K C (conventional fertilization), +S (straw return) and K S treatments (input equivalent K that removed by straw treatment). A positive balance was observed under K C +S treatment. Slight changes in soil exchangeable and nonexchangeable K were observed under K G +S and +S treatments. However, high inputs of K fertilizer prevented the improvement of agronomic efficiency and recovery efficiency of K. CONCLUSIONS In summary, the optimal K management strategy was K G +S, which stabilizes the crop yield, maintains soil K fertility and maximizes K use efficiency. © 2020 Society of Chemical Industry

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