Optimizing potassium mining in rice-wheat system: Strategies for promoting sustainable soil health - A review

The rice-wheat system in the Indo-Gangetic Plain, often termed the ‘food basket’ of South Asia, has witnessed a concerning trend in its potassium balance over the past few decades. This negative trend stems from intensive and exhaustive agricultural practices, leading to 79% of the soil in the region falling into the low to medium potassium available category. Consequently, there has been a decline in soils with high potassium availability. Despite misconceptions about soil potassium sufficiency, abundant crop responses to potassium fertilization in alluvial soils, like those in the Indo-Gangetic Plain, have been observed. However, the current negative potassium balance exceeds acceptable levels, posing a significant threat to system sustainability. Soil deficient in potassium fails to yield optimal outputs without external potassium inputs. Thus, maintaining adequate potassium levels within the rice-wheat system is imperative for sustaining agricultural productivity, preserving soil health, ensuring food security, and mitigating associated environmental impacts. To address these challenges, this review provides a comprehensive understanding of the current nutrient balance, existing fertilizer application rates and methods, and various strategies to optimize potassium mining. These strategies include balanced fertilizer usage, crop residue recycling, minimizing potassium leaching losses, employing customized fertilizers and potassium-solubilizing microbes, establishing a national soil data repository, and implementing policy interventions. By synchronizing potassium application with crop requirements, these strategies aim to enhance potassium use efficiency and maximize return on investment, ensuring the long-term sustainability of the rice-wheat system in the Indo-Gangetic Plains.