The rhizosphere is that the narrow region of soil that's directly influenced by root secretions and associated soil microorganisms referred to as the basis microbiome. The rhizosphere contains many bacteria and other microorganisms that prey on sloughed-off plant cells, termed rhizodeposition, and therefore the proteins and sugars released by roots. This symbiosis leads to more complex interactions, influencing plant growth, and competition for resources. Much of the nutrient cycling and disease suppression needed by plants occurs immediately adjacent to roots thanks to root exudants and communities of microorganisms. The rhizosphere also provides space to produce allelochemicals to regulate neighbors and relatives. The plant-soil feedback circuit and other physical factors are important selective pressures for the communities and growth within the rhizosphere.