Organic matter in the soil ensures a continuous food source for soil microbes. As soil bacteria metabolize organic matter, they help maintain good soil structure by developing compounds that cement small soil particles together into aggregates, allowing for both increased drainage and moisture retention. Microbes also change the organic matter into inorganic nutrients that can be used by growing plants.

The physical properties of the soil are equally important. Space between soil particles can affect aeration and soil moisture both of which  affect root growth. In addition, space between soil particles and particle size directly affect microbial activity. As the physical properties and mineral structure of the soil improves,  run off lessens and erosion and nutrient loss is decreased.