- Climate: Temperature and rainfall exert a dominant influence on the amounts of nutrients and Organic matter found in soils.
- Temperature: The Organic Matter content of comparable soils tend to increase if one moves from warmer to cooler areas. The decomposition of Organic matter is accelerated in warm climates as compared to cooler climates. For each 10 C decline in mean annual temperature, the total Organic matter and nutrients increases by two to three times.
- Rainfall: There is an increase in Organic Matter with an increase in rainfall. Under comparable conditions, the Organic matter increase as the effective moisture becomes greater.
- Nature of Vegetation: The total organic matters is higher in soils developed under grasslands than those under forests.
- Soil texture: Fine textured soils are generally higher in Organic matter than coarse textured soils
- Drainage: Poorly drained soils because of their high moisture content and relatively poor aeration are much higher in Organic matter than well drained soils.
- Cropping and Tillage: The cropped lands have much low N and Organic matter than comparable virgin soils. Modern conservation tillage practices helps to maintain high Organic matter levels as compared to conventional tillage.
- Rotations, residues and plant nutrients: Crop rotations of cereals with legumes results in higher soil Organic matter. Higher Organic matter levels, preferably where a crop rotation is followed.