Comparison on annual crop yields, soil physicochemical properties, and system energy flow characteristics among different multiple cropping patterns in double-cropping paddy fields

As a core crop, rice is crucial for both global and national food security in China, and suffers from continuous cropping obstacles due to long-term continuous monoculture. This phenomenon not only poses potential threats to soil ecological health but also endangers the sustainability of grain production. The paddy-upland multiple cropping system serves as an effective measure to mitigate the challenges associated with continuous rice monoculture. However, the regulatory mechanisms of water-drought rotational cropping on soil physicochemical properties and energy flow characteristics in farmland ecosystems remain unclear. This study established five treatments: Chinese milk vetch-early rice-late rice (CK), Chinese milk vetch-early rice-maize‖soybean (MRCB), oilseed rape-early rice-maize‖soybean (RRCB), oilseed rape-early rice-late rice (RRR), and potato-early rice-late rice (PRR). By measuring soil physicochemical properties, annual crop yields, and energy flow, we analyzed the key physicochemical factors affecting crop productivity and energy flow characteristics under different multiple cropping patterns. Our results showed that, compared with CK, PRR significantly increased soil available potassium content by 156.71%−300.00%. In addition, MRCB and RRCB showed higher available potassium content than CK in the winter cropping season and late rice season. Notably, RRCB had the highest rice actual yield which reached (20 868.52±633.57) kg·hm⁻² among all the five treatments. Correlation analysis indicated a highly significant positive relationship between rice yield and soil available potassium content in RRCB. In terms of energy flow characteristics, the total primary productivity of RRCB increased by 568.58% compared with that of CK. The energy flow circulation indexes of MRCB, RRCB, and PRR were 0.247, 0.228, and 0.388, respectively, all of which surpassed that of CK. Furthermore, RRCB exhibited the highest light energy utilization efficiency, which was 2.42 times than that of CK. Therefore, it can be concluded that RRCB has the potential to elevate the content of available potassium, thereby increasing the annual crop yields.