Optimized management stabilized crop yield and mitigated the risk of potassium loss across different rotations in the middle of Yangtze River basin in China

Potassium (K) loss from cropland is a significant concern in the middle of Yangtze River basin due to extensive K fertilizer application and heavy rainfall, leading to soil fertility degradation and reduced nutrient use efficiency. Despite this, there has been limited research assessing K loss across different crop rotations. In this study, A five-year experiment was conducted to figure out the characteristics of the K loss via surface runoff and leaching across different crop rotations, and to evaluate the impact of two management strategies, conventional treatment (CT) and optimized management (OPT), on crop yield and soil available K content. Our findings revealed significant differences in K loss, ranging from 2.4 kg ha−1 to 11.8 kg ha−1 across different rotations, with paddy rotation exhibiting higher K loss than upland rotation. Seasonally, K loss was predominantly observed during the summer planting season, accounting for approximately 77.5% of sites, and between 50.0% and 86.2% of total K loss during this period. The proportion of K loss relative K input significantly decreased from 3.25% (CT) to 1.78% (OPT). The SEM model suggested that both runoff water and leachate volume exerted positive and significant effects on K loss. And optimized management enhanced crop yield and soil available K. In summary, optimized management stabilized crop yield and mitigated the risk of K loss across different rotations, and thus primarily required focused field water management to reduce runoff or leaching, with some practices such as cover straw offering an effective strategy. Our research provided basic data for K loss under different crop rotation systems in the middle of the Yangtze River basin and the theoretical guidance for optimizing management strategies of soil K in farmland.