Study on the impact of different soybean-maize strip intercropping patterns on the spatio-temporal dynamics of water and heat in maize strips and on maize yield and economic returns

To identify the optimal intercropping pattern of soybean and maize in the black soil region of Northeast Inner Mongolia, a systematic field study was conducted in 2023 and 2024 in Arong Banner, located at the eastern foothills of the Greater Xing’an Range, using maize and soybean as experimental crops. The study examined the spatiotemporal dynamics of soil moisture and temperature within maize strips and assessed yield differences across various intercropping configurations: 2 rows of maize ‖ 2 rows of soybean (M2S2), 4 rows of maize ‖ 4 rows of soybean (M4S4), 4 rows of maize ‖ 2 rows of soybean (M4S2), 6 rows of maize ‖ 6 rows of soybean (M6S6), 6 rows of maize ‖ 4 rows of soybean (M6S4), and 6 rows of maize ‖ 2 rows of soybean (M6S2). The results showed that: (1) The soil moisture in M4S4 and M2S2 treatments was generally higher than in the other configurations during critical growth stages, while surface soil temperature was significantly lower. Compared with other treatments, M2S2 increased soil moisture by 1.59% to 16.85% during the tasseling-silking stage and by 1.89% to 14.82% during the grain-filling stage, with no significant difference from M4S4. Both treatments also exhibited relatively uniform water distribution throughout the growth period. (2) Maize in the M2S2 treatment achieved the highest single-plant yield and water use efficiency, followed by M4S4. M4S4 recorded the highest land equivalent ratio, reaching 1.61 and 1.60 in 2023 and 2024, respectively. Furthermore, M4S4 exhibited the highest input-output ratio of the intercropping systems, reaching 6.61, 7.39% to 32.28% higher than in other treatments. In conclusion, the M4S4 strip intercropping layout is identified as the most suitable pattern for soybean-maize intercropping in the black soil region of Northeast Inner Mongolia.