Decomposition of Organic Residues: 7 Factors

This article throws light upon the seven main factors affecting the decomposition of organic residues. The factors are: 1. Temperature 2. Soil Moisture 3. Soil Reaction 4. Nutrients 5. Soil Texture 6. Type of Vegetation 7. Other Factors.

Factor # 1. Temperature:

The decomposition of organic residues is accelerated in warm temperature than that of cold climates. Continuous cold temperatures lower soil humus because of low rate of decomposition of fresh organic materials. Since biological activity depends on temperature and hence decomposition of organic materials—a biological process also are largely influenced by the variation of temperature.

Factor # 2. Soil Moisture:

Decomposition of organic matter at near or slightly wetter than field capacity moisture conditions are most favourable. Extremes of both dry (aerobic) and waterlogged (anaerobic) conditions retard the process of organic matter decom­position.

Factor # 3. Soil Reaction:

Soil reaction influences the activity of soil micro-organisms and hence influences the decomposition of organic residues. The optimum soil reaction for most of the organisms at a pH range between 6-8. The activity of most soil organisms are inhibited below pH 4.5 and above pH 8.5. Therefore, decomposition of organic matter will be very low under both strong acid and strong alkali soil conditions.

Factor # 4. Nutrients:

Inadequate amount of nitrogen in the soil slows down the decomposition of organic matter.

Factor # 5. Soil Texture:

Soil texture indirectly influences the rate of organic matter decom­position.

Clayey soil texture tends to bind larger amounts of humus. The many active bonding sites of minerals and humus include the = O, —OH, —A1—OH, —Fe—OH, and cation exchange sites of minerals and the —SH, —OH and —COOH groups of organic materials.

Factor # 6. Type of Vegetation:

Various types of vegetation also affect the rate of decomposition e.g. legumes are more easily decomposed than grasses.

Factor # 7. Other Factors:

There are various other factors like toxic effect of different elements such as aluminium, manganese, boron, chloride etc., excessive soluble salts and organic phyto-toxins etc.. also affect the decomposition of organic materials in soil. Crop cultivation and tillage operation in the soil also accelerate the rate of decomposition of organic materials through intimately mixing it with the soil.