The rhizosphere is a layer of soil that is directly connected with the roots of the plants.  Being directly connected with the root of a plant this layer of soil is directly affected by the microorganisms, microbiomes, secretions of the roots. The layer is the habitat for many bacteria and other microorganisms who depend on the plant roots for food. The rhizosphere is the layer from where the plants collect water and other necessary nutrients from the soil. The layer not only provides a habitat for microorganisms, but also provides them with the necessary food and other nutrients, hence it is necessary for the pressure and other physical factors to be in proper balance for the healthy growth of the plant.