Effects of Soybean–Corn Rotation on Crop Yield, Economic Benefits, and Water Productivity in the Corn Belt of Northeast China

Abstract

The Corn Belt of Northeast China (CBNC) is the most important commercial grain base in China. However, long-term intensive cultivation has caused the productivity of black soil to decline. The sustainable development of corn and soybean is seriously threatened. Field experiments of a corn–soybean rotation were conducted to evaluate the crop yields, economic returns, and water productivity in the CBNC from 2017 to 2020. The field treatments included continuous soybean (CS), continuous corn (CC), soybean–corn (SC), and soybean–corn–corn (SCC). The total yield for 2017–2020 is compared using the equivalent yield of corn, indicating that the crop yield of the CC treatment was the highest and that of the CS treatment was the lowest. The crop yield of the CS treatment was 0.58-fold lower than that of the CC treatment. The 4-year total income of the treatments showed that the total and net revenue of the CC treatment was the highest. The 4-year total net income of the CS treatment was 0.66- and 0.72-fold lower compared with those of the SC and SCC treatments, respectively. There was no significant difference between the treatments of rotation. The crop water productivity (WPC) and biomass water productivity (WPB) of the CS treatment were the lowest, at 0.30- and 0.54-fold lower than those of the CC treatment in 2017–2020, respectively. The WPC and WPB of the CC treatment were the largest. If soybean–corn rotation was implemented in the CBNC, the SC treatment would be a better choice than the SCC treatment for the CBNC, and farmers would need to be subsidized at least USD 1047.5 ha−1 to equal the income from growing corn. In considering production, financial gains, and water productivity, the CC treatment was, as a result, still the best planting pattern for the CBNC under the test site’s conditions.