Mixed Sowing of Feed Rape and Vicia Villosa Can Substitute Nitrogen Fertilizer to Improve Soil Multifunctionality in the Hetao Irrigation District

Abstract

Soil multifunctionality (SMF) and crop production of continuous green manure returning is crucial for sustainable agricultural development. Multiple cropping of green manure after wheat is a typical planting pattern in the Hetao Irrigation District, and maybe substitute the use of nitrogen (N) fertilizer. However, information is scarce about how the green manure affected SMF and crop production under limited nitrogen inputs. A 7-year field experiment was conducted to investigate the effects of green manure types (Feed Rape (FR), Vicia Villosa (VV), Feed Rape, and Vicia Villosa mixed sowing (FR+VV)) on soil properties, enzyme activities, SMF, and rotated spring wheat yield under different N application rates (150 kg N ha−1, N; no nitrogen, N0). The results showed that FR and FR+VV increased soil active carbon (C) and N fractions by 4.0%-499.3% and 11.3%-147.8% compared to VV. Enzyme activities with FR+VV were significantly increased by 13.7-82.9%. SMF and CCI were significantly affected by N fertilizer and green manure types, with N0 higher than N application by two times and FR+VV higher than FR by 1.4-4.3 times and VV by 1.0-6.6 times in 0-20 cm soil layer. Spring wheat yield was significantly affected by nitrogen fertilizer and green manure types, with N0 application higher than N application by 5.8% and FR and FR+VV higher than VV by 8.0% and 12.5% under N application (p < 0.05). Partial least squares path model detected that mixed green manure had a significant positive and indirect effect on SMF through regulating soil enzyme activities, and ultimately contribute to the improvement in spring wheat yield. In conclusion, the mixed sowing of Feed Rape and Vicia Villosa increases soil active C and N fractions and associated enzyme activities, and has the potential to improve the SMF and rotated wheat yield, thereby providing an effective approach to reduce N fertilizer.

Keywords: green manure types, nitrogen fertilizer, soil multifunctionality, yield