Mulching Practice Regulates the Soil Hydrothermal Regime to Improve Crop Productivity in the Rainfed Agroecosystem of the Loess Plateau in China

Mulching practices have demonstrated the potential to increase crop yields and resource utilization efficiency. However, the response of different crops with various growth stages to different mulching practices remains unclear, particularly in the rainfed agroecosystem. Therefore, a two-year field experiment (2013–2015) of different crops (wheat, maize, and potato) was conducted to evaluate the effects of three different mulching treatments: straw strip mulching (SM), plastic film mulching (PM), and conventional planting without mulching as the control (CK), on soil moisture and temperature, evapotranspiration (ET), water use efficiency (WUE), crop yield and economic benefits on the Loess Plateau. The results indicated that both mulching practices significantly increased the soil water content (SM: 4.3% and PM: 3.6%) compared to CK. However, the effects on soil temperature varied between mulching practices, PM increased soil temperature by 4.9% compared to CK, while SM decreased it by 6.3%. The improved soil hydrothermal conditions, characterized by favorable temperatures and higher soil water status would lead to a higher crop daily growth rate (5.3–49.8%), as well as greater dry matter accumulation (4.7–36.7%). Furthermore, mulching practice (SM and PM) has a significant influence on crop yield and its components of various crops, as well as WUE. The mean grain yield of SM and PM was, respectively, increased by 11.4% and 27.1% for winter wheat, compared to CK, 1.8% and 24.3% for spring maize, and 23.0% and 13.9% for potato, respectively. Compared to CK, PM yielded a higher net economic benefit and WUE for winter wheat and spring maize, while SM presented the best economic benefit and WUE for potato. In conclusion, a comprehensive analysis of crop yield, economic benefits, and resource utilization efficiency suggests that straw strip mulching for potato is a more sustainable environmentally friendly mulching practice, recommended for rainfed farming systems on the Loess Plateau and areas with similar climatic conditions.