Rapeseed-maize double-cropping with high biomass and high economic benefits is a soil environment-friendly forage production mode in the Yangtze River Basin

Abstract

The problem of the large area of winter abandoned fields in the Yangtze River Basin (YRB) has gotten worse. Moreover, there was no suitable annual forage crop planting pattern to fulfilling the annual forage needs of livestock and poultry production in the YRB region. Utilizing the abandoned field to develop high-quality and efficient forage crop planting patterns is significant. Herein as a first-time study, two growing seasons of five different double-cropping modes field experiments were performed with ryegrass-maize (RM), hairy vetch-maize (HM), rapeseed-maize (BM), milk vetch-maize (MM), and abandoned-maize (AM) to study their effects on forage production, soil properties, latter maize performance, and economic benefits. Rapeseed-maize double-cropping mode achieved the maximum annual biomass yield (37.0 Mg ha−1) and net profit value (33563 CNY ha−1), which is the most productive among the five double-cropping modes. The soil available phosphorus content after planting rapeseed was significantly higher than other modes, which was 65.6%, 37.0%, 1.5%, and 12.2% higher than abandoned field, ryegrass, hairy vetch, and milk vetch, respectively. There was a non-significant difference in soil penetration resistance (PR) between after planting rapeseed, hairy vetch, and milk vetch at the soil depth of 5–27.5 cm; whereas, the PR was reduced by 24.7% and 34.8% after planting rapeseed compared to abandoned field and planting ryegrass, respectively. Compared to the abandoned field, planting hairy vetch and milk vetch showed highly significant effects on suppression of weeds biomass and density in maize field followed by rapeseed, while planting ryegrass significantly increased the weeds biomass and density by 61.6% and 62.3%, respectively. The principal component analysis results indicated that the PR was negatively correlated to the soil fertility and maize growth traits, while positively correlated with weeds occurrence. Besides, the root activity, and root, shoot biomass of maize were significantly positively correlated with the soil fertility after harvesting winter crops. Therefore, rapeseed-maize double-cropping may be a productive pattern to promote annual forage production and enhance the agricultural economy in the Yangtze River Basin region.