Effects of Green Manure Intercropping on Soil Moisture, Nutrients, and Apple Yield in a Weibei Apple Orchard

［Objective］ We conducted a field experiment to investigate the effects of intercropping green manure crops and their combination with ground fabric mulching on soil moisture, fertility, and apple yield. ［Methods］ The main treatments included intercropping ryegrass (NGR), oilseed rape (NGO), and alfalfa (NGA), the sub-treatments included combining these intercropping modes with mulching ground fabric under apple trees (GR/GO/GA), and the control treatment was traditional clean tillage (CK). Additionally, 15N labeled microplots were set up within the main and control treatments. The responses of soil moisture, nutrients, and fruit yield were explored under the apple-green manure intercropping system. ［Results］ All treatments reduced soil water content (SWC) compared to CK, among which the decreasing range of GR (1.7%) was the smallest. Soil water difference ratio (SWDR) in the main treatments were all negative, among which NGR and NGA had the smallest (0.5%) and largest (4.7%) absolute value, respectively. All treatments increased evapotranspiration (ET) compared to CK, among which the increasing range of GR (0.3%) was the smallest. All treatments reduced soil nitrate-nitrogen (SNN) content, compared to CK. Compared to the sub-treatments, SNN and soil ammonium-nitrogen (SAN) contents in the main treatments increased by 6.8% and 5.4% on average. Intercropping green manure (NGR, NGO, and NGA) reduced 15N loss by an average of 56.4% (p<0.05), compared to CK, with alfalfa and ryegrass showing the highest (39.4%) and lowest (19.7%) 15N utilization efficiency, respectively. Compared to CK, ryegrass intercropping treatments (NGR and GR) increased SOM and TN contents by an average of 1.5% and 0.2%, respectively. In contrast, alfalfa (NGA and GA) intercropping treatments decreased SOM and TN contents by an average of 15.2% and 15.4%, compared to CK. Ryegrass intercropping treatments (NGR and GR) showed the highest fruit yield and water use efficiency, with an average increase of 12.1% in yield and 8.8% in water use efficiency, compared to CK (p<0.05). ［Conclusion］ Adopting the binary mulching pattern (ground fabric mulching under apple trees+ryegrass intercropping between rows) is beneficial to decreasing water consumption, nutrient loss, and increasing fruit yield and water use efficiency.