Below-ground connections underlying above-ground food production: a framework for optimising ecological connections in the rhizosphere

1. Healthy soils that contain an active microbiome and food web are critical to sustainably produce food for a growing global human population. Many studies have focussed on the role of microbial species diversity and the presence of key functional groups as important controls on the many functions that a sustainable food system relies on. 2. Here, we synthesise recent ecological empirical evidence and theory to propose that the interactions between organisms in the soil food web are the critical determinant of soil function. 3. We propose the Rhizosphere Interactions for Sustainable Agriculture Model, in which crop roots recruit small, modular, highly connected soil rhizosphere networks from large, static, relatively unconnected and diverse bulk soil networks. We argue that conventional agricultural management disrupts the connections between rhizosphere and bulk soil networks. 4. Synthesis. We identify future research directions for optimising ecological connections between roots and rhizosphere microbial and faunal networks, and between rhizosphere networks and bulk soil networks in agricultural production systems. Knowledge on these connections can be applied in agricultural systems to sustainability produce food for a growing global population.