Co-incorporating rice straw and Chinese milk vetch (CMV) residues can enhance soil organic carbon (SOC) sequestration and productivity. However, limited information exists regarding its effects on SOC and nitrogen (N) pools as well as the sustainability of rice production in the middle and lower reaches of the Yangtze River Basin. A 3-year field experiment was conducted to assess the effects of co-incorporating rice and CMV residues into paddy soils with chemical-N reduction on SOC and total N (TN) sequestration, SOC and N fractions, grain yields and the sustainable yield index (SYI) in Ma’anshan City, Anhui Province. The treatments included winter fallow–rice rotation without or with both rice straw incorporation and fertilization, as the control (CK and WF-IF, respectively), and rice-CMV rotation with the co-incorporation of rice and CMV residues under 100%, 80%, and 70% recommended N fertilization (CMV-IF, CMV-MIF and CMV-LIF, respectively). Compared with the CK, the CMV-IF significantly increased the rice grain yield and the SYI by 82.1% and 90.4%, respectively. The SOC and TN stocks under CMV-IF were significantly enhanced by 6.3% and 26.4%, respectively, relative to the CK. The CMV-IF exhibited the highest soil active organic C (AOC) and active total N (ATN) contents, followed by CMV-MIF, CMV-LIF, WF-IF, and CK. Microbial biomass C and microbial biomass N were the primary components of soil AOC and ATN, respectively, and linked more explicitly to the SYI than other soil C and N parameters. Therefore, the co-incorporation of rice and CMV residues, coupled with 70~80% recommended N fertilization, might represent an environmentally friendly field management practice for rice production in the middle and lower reaches of the Yangtze River Basin.

Efficient allocation of climatic resources is essential for improving the sustainability and productivity of cropping systems under changing climate conditions. This study aimed to evaluate whether diversified grain–forage rotations could optimize inter-annual growth period configurations and improve annual thermal and radiation resource use in the North China Plain (NCP). A field experiment was conducted from 2023 to 2025 to compare five cropping systems: wheat–maize (W-M), wheat–silage maize (W-SM), wheat–sweet sorghum (W-SS), ryegrass–silage maize (R-SM), and ryegrass–sweet sorghum (R-SS). Growth period characteristics, annual thermal and radiation resource allocation, dry biomass yield, crude protein yield, resource use efficiency, and economic performance were evaluated. The results showed that alternative cropping systems extended annual resource use duration and altered seasonal resource allocation compared with W-M. R-SS exhibited the longest annual growth duration and the most balanced seasonal distribution of thermal and radiation resources, whereas R-SM achieved the highest annual biomass yield. All alternative systems improved thermal and radiation resource use efficiencies compared with W-M, with increases particularly evident during the summer–autumn season. Moreover, diversified systems reduced cultivation costs and improved economic returns. Overall, optimizing inter-annual growth period configurations might provide an effective strategy for enhancing the resource use efficiency, productivity, and economic sustainability of grain–forage cropping systems in the NCP and other regions with similar agro-meteorology in the world.