Soil Organic Carbon in Alley Cropping Systems: A Meta-Analysis

Population growth and an increasing demand for food cause the intensification of agriculture leading to soil degradation and a decrease in the soil organic carbon (SOC) stock. Agroforestry systems such as alley cropping are gaining more and more attention as a practice to maintain and/or increase SOC in agroecosystems. The aim of this study was to add to the knowledge on SOC in alley cropping systems and to evaluate the contribution of introducing trees into agricultural landscapes by conducting a meta-analysis of the available data. The soil carbon (C) input will increase with time. Our findings suggest that a beneficial effect on SOC occurs after approximately a decade of alley cropping practice adoption. Furthermore, the effect of alley cropping is more beneficial in regions with lower initial SOC concentration compared to that in regions rich in SOC. Higher relative SOC is observed in the tropical region compared to that in the temperate climate zone. The establishment of alley cropping systems on agricultural land needs to consider several parameters such as alley width and tree species when designing such systems to achieve the highest possible tree and crop productivity while increasing SOC.