Mitigation of the Ratio of Soil Dissolved Organic Carbon to Available Phosphorus Effectively Improves Crop Productivity under Mulching Measures on the Loess Plateau

Soil erosion and extensive management, as key factors limiting the sustainability of the agroecosystem in the Loess Plateau, severely hamper the high-quality development of regional agriculture. Soil fertility and element synergy can be enhanced by applying mulching measures properly. However, there is a lack of systematic research into how soil stoichiometric characteristics under mulching affect crop productivity. This study focused on the agroecosystem of the Loess Plateau. Based on the 11-year field positioning experiment, the management measures of straw mulching (SM), plastic mulching (PM) and ridge-film mulching (RM) were selected to investigate the effects of long-term mulching measures on the stoichiometric characteristics of topsoil and the impact of crop productivity under the ecological stoichiometry theory. The findings revealed a significant increase in soil carbon, nitrogen and phosphorus contents and microbial biomass under mulching. SM and RM significantly decreased the stoichiometric ratio of soil available nutrients, whereas PM and RM had effective alleviating effects on C:N and C:P imbalance. The yield components of long-term SM and RM greatly increased and responded favorably to the synergy of soil carbon and phosphorus. This study provides theoretical guidance and technical support for the assessment of the effective and sustainable use of agricultural resources on the Loess Plateau.