Effects of Soil Physicochemical Properties on Maize, Wheat, and Soybean Yields in Maize-Wheat and Maize-Soybean Intercropping Systems in China: a Meta-analysis

Intercropping has demonstrated its potential to boost crop yields and optimize land utilization in numerous instances. Yet, the specific mechanisms underlying the enhancement of intercropped plants’ relationships through improved crop management practices remain unclear. We conducted a comprehensive analysis of multiple studies across diverse regions to gain deeper insights into the impact of intercropping systems on crop yields. This investigation explored the influence of various factors, including different intercropping strategies, patterns of rainfall and temperature, and soil nutrient levels, on the production of maize, soybeans, and wheat crops. To quantify the magnitude of these effects, we employed the odds ratio as the effect size metric. Our findings reveal that, in regions with rainfall amounts of ≤ 200 mm, maize yields in both maize-wheat and maize-soybean intercropping systems were significantly affected (p = 0.0002) compared to regions with higher rainfall. This effect may be attributed to the substantial positive effect size observed when temperatures were below 11 °C, measuring 3037.55 with a 95% confidence interval ranging from 2347.71 to 3727.40, as opposed to temperatures above 11 °C, which had an effect size of 671.55 with a 95% confidence interval ranging from 241.40 to 1101.69. Additionally, maize yields were significantly higher (p = 0.0007) in sandy loam soils compared to silty clay loam and clay loam soils within the maize-wheat intercropping system, in contrast to maize monoculture. Furthermore, our study found that maize yields in a maize-wheat intercropping system significantly improved (p = 0.0008) in regions with soil bulk density ≤ 1.33 g cm−3 compared to regions with bulk density > 1.33 g cm−3. Notably, both the maize-wheat and maize-soybean intercropping systems exhibited significant yield advantages when compared to conventional monoculture of maize. This study underscores the optimum performance of the maize-wheat intercropping system, thus establishing it as a highly suitable agricultural approach. This innovative farming method contributes to sustainability, particularly in semiarid regions, and holds great promise for improving crop productivity.