Microbial Interactions in Soil Formation and Nutrient Cycling

Abstract

Mineralization by soil micro-organisms plays an important role in the environment as it releases trapped mineral nutrients (phosphorus, potassium, magnesium, calcium, and iron) required for plant growth. Ectomycorrhizosphere hosts diverse microorganisms (bacteria and fungi) that can stimulate each other forming specific interface between soil and trees. Fungi are known to cause geochemical changes and have a major role in the plant-root region, soil and in rock and mineral habitats. Therefore they have different roles in nutrient cycling that keeps the soil in good condition for plant growth. Majority of ectomycorrhizal root tips occur in mineral horizons exploiting the nutrient-rich substrates and helps to assimilate and translocate the nutrients. The extramatrical mycelia of ectomycorrhizal fungi acquire carbon from the soil through the enzymatic breakdown of organic matter and from tree photosynthates. This contributes to the association between weathering of minerals in the soil and photosynthetically-assimilated carbon acquired from trees. The microorganisms residing at mycorrhizosphere are capable of solubilizing the organic phosphate and other organic nutrients and can also mobilize iron. The structure and functions of the bacterial community involved in the mineral weathering are also determined by ectomycorrhizosphere. Plants, in turn, alter the soil structure through their root exudates favoring the activity of microbial communities. This chapter addresses the significance of mineral weathering by microbial interactions and the contribution of plant-microbial communities on soil formation through nutrient cycling which further improves the soil functionality.