Plants obtain nutrients from two natural sources, minerals and organic matter. Organic matter includes any plant or animal material that returns to the soil and decomposes.
Organic matter is essential to the soil as it not only provides nutrients to the soil but also provides habitat to organisms living in the soil, binds soil particles into aggregates and improves the soil water holding capacity.
Most soils have 2-10 percent organic matter making them a living dynamic ecosystem. Soils convert dead and decaying matter into plant nutrients, an essential aspect in plant growth. Furthermore, biological activities of soils depend on the organic matter supply.
Nutrient exchange between soil, water and organic matter is essential to soil fertility. In circumstances where soil is exploited for crop production without restoring organic matter, nutrients cycle could be broken leading to a decline in soil fertility.
Soil organic matter affects both the physical and chemical properties of soil and it's overall health. It's composition and breakdown rate affect the soil structure and porosity, the water infiltration rate and moisture holding capacity.