The microbiome is an incredibly complex microbial community which has evolved uniques symbiotic relationships with plants.
There are two fundamentally different types of digestive processes occurring in soil systems.
In a bacterially dominated soils the rapid digestion and release of nutrients is referred to as mineralization. In the mineralization process bacteria digest root exudates and carbon crop residues which have a narrow nitrogen carbon ratio. In this digestive process they extract minerals from the soil mineral matrix and utilize them to build their own bodies. As their bodies are recycled the minerals are released for plant absorption.
In a fungal dominated soil, saprophytic fungi decompose crop residues and complex organic material. Fungi are the primary microbes which have the capacity to digest lipids. This fungal digestive process is referred to as humification. The humification process is how we can build soil organic matter quickly and efficiently on a large scale.