Root traits regulate the capacity of the rhizosphere to support multiple ecosystem services under intercropping and phosphorus fertilization

Crop rhizospheres are the foundational support for multiple ecosystem services, ranging from food production to carbon sequestration and soil fertility. Land use intensification is known to impact these fundamental ecosystem services. However, little is known about how root traits regulate the responses of rhizosphere ecosystem services to land use intensification. Here, we conducted a field experiment to explore the responses of rhizosphere ecosystem services to phosphorus (P) fertilization and maize-alfalfa intercropping, and specifically evaluated how root traits drive these responses. Results showed that unfertilized intercropping treatments produced the highest values of rhizosphere ecosystem services, including enhanced plant-soil mutualism, and the greatest abundance of soil decomposers. Unfertilized intercropped alfalfa increased nutrient cycling, soil carbon storage, and soil microbial diversity. Crop-specific root traits such as exudation and morphology are critical in explaining the responses of the rhizosphere. The exudation traits of alfalfa, and morphological traits of maize in unfertilized intercropping treatments were most important for the increases in ecosystem services. Our results highlight the importance of root traits in promoting rhizosphere ecosystem services under land use intensification. Intercropping supported rhizosphere multiservices under the more sustainable low-input system through plant-specific root trait complementarity. This is critical for developing management policies to promote the far-reaching development of agroecosystems.