Optimizing potassium management for enhanced cotton yields in China's diverse agro-ecological regions

Context

Potassium (K) plays a crucial role in the growth and yield of cotton. As the world's leading cotton-producing country, China faces challenges such as soil K depletion and rising costs of K fertilizers. Current research primarily focuses on K application at specific locations, which limits its applicability to broader agro-ecological regions. Therefore, there is an urgent need to conduct K fertilizer management research on a regional scale.

Objective

This study aims to employ a novel approach by integrating meta-analysis with K-yield relationship models to assess the effects of K fertilization in China's major cotton-growing areas from 1980 to 2024, and to combine this with an economic benefit model to determine the ideal K application rates (KR) for different ecological cotton-growing regions in China.

Methods

The study utilizes generalized additive models (GAM) to model seed cotton yield and economic benefits as functions of KR. Data from various studies were compiled to analyze the relationship between K application and cotton yield across different regions.

Results

The findings indicate that K fertilization enhances cotton yields by an average of 11.05 % in the Northwest Arid Zone (NW), 19.43 % in the Yellow River Basin (YR), and 20.36 % in the Yangtze River Basin (YT). K application significantly influences cotton yield, particularly in areas with mean annual temperatures (MAT) of 15–25°C, mean annual precipitation (MAP) of 600–1000 mm, low soil available K (SAK), high pH, and soil organic matter (SOM) content above 20 g/kg, especially in coarse soils.

Recommendations

For different cotton regions in China, ideal KR recommendations are 85.7–93.0 kg K₂O/ha for the NW, 117.5–121.5 kg K₂O/ha for the YR, and 163.1–172.1 kg K₂O/ha for the Yangtze River Basin. The corresponding planting densities are > 6 plants/m² for the NW, 0–4 plants/m² for the YR, and 4–6 plants/m² for the Yangtze River Basin.

Significance

This study offers important insights for creating effective K management strategies in China's various cotton regions, highlighting the importance of adjusting fertilization and planting density based on local soil and climate conditions to improve productivity and promote sustainable agriculture.