Of all the components of soil, organic matter is the most important. Organic matter serves as a reservoir of nutrients and wtaer in the soil, aids in reducing compaction and surface crusting & incraeses water infiltration into the soil. Organic matter is stable in the soil. It is decomposed until is becomes resistant to futher decomposition. Only about 5% of it mineralizes yearly which occurs with excessive tillage.
Benefits of organic matter:
Nutrient Supply: Organic matter is a reservoir of nutrients that can be relaesed to the soil. Each percent of organic matter in the soil releases 20 to 30 pounds of nitrogen, 4.5 to 6.6 pounds of P2O5 and 2 to 3 pounds of sulphur per year. Nutrient relaese occurs in the spring and summer, so summer crops benefit more from organic-matter mineralization than winter crops.
Water-holding capacity: Organic matter behaves like a sponge, with the ability to absorb and hold up to 90% of its weight in water. An advantage of water-holding capacity of organic matter is that the matter will relaese most of the water that it absorbs to palnts. In contrast, clay holds great quantities of water but much of it is unavailable to plants.
Soil Structure Aggregation: Organic matter causes soil to clump and form soil aggregates, which improves soil structure. With better soil structure, permeability (infiltration of water through the soil) improves, in turn improving soil's ability to take up and hold water.
Erosion Prevention: Data used in universal soil loss equation indicate that increasing soil organic matter from 1% to 3% can reduce erosion by 20% to 33% because of increased water infiltration and stable soil aggregate formation caused by organic matter.