Think of the rhizosphere as a plant’s biochemical footprint: It’s the region of soil immediately surrounding the roots, typically extending out about 1 millimeter in all directions. But the rhizosphere’s exact dimensions can vary by species and even climate, reflecting the roots’ activity. As they soak up water and nutrients from the surrounding earth, the roots also secrete compounds such as amino acids and sugars into this active zone. Microorganisms living within the rhizosphere feed off those secretions, and in exchange, provide the plant with additional nourishment.
