9 Main Factors Affecting Soil Structure

This article throws light upon the nine main factors affecting soil structure. The factors are: 1. Climate 2. Organic Matter 3. Adsorbed Cations 4. Tillage 5. Type of Vegetation 6. Plant Roots 7. Soil Organisms 8. Manurial Practices and Crop Rotation 9. Alternate Wetting and Drying.

Factor # 1. Climate:

Climate influences the degree of aggregation which in turn affects the different types of structure to a great extent. In arid regions, very little aggregation of primary particles is found. In semi-arid regions, the degree of aggregation is greater than arid regions.

Factor # 2. Organic Matter:

Organic matter is the major agent for the encouragement of granular- type aggregates in soils. During decomposition of organic matter, various organic compounds and other slimy materials having sticky, cementing and binding properties are produced and these compounds bind the soil separates together forming soil aggregates. Besides organic matter is of much importance in modifying the effects of clay.

Factor # 3. Adsorbed Cations:

Aggregate formation is certainly influenced by the nature of the cations adsorbed by soil colloids. As for example, if Na⁺ is a dominant adsorbed ion, then the particles are dispersed or deflocculated and a very undesirable soil structure is formed. On the other hand, when the dominant absorbed cation is Ca²⁺, then the soil particles will be flocculated and granulation will be encouraged and thereby good soil structure will form.

Factor # 4. Tillage:

Intensive cultivation increased infiltration capacity and penetrability, but spoiled the soil structure. For obtaining good soil structure tillage operation should be made at optimum moisture conditions.

Factor # 5. Type of Vegetation:

Grassland and forest soils have high stability of aggregates. Grasses and legumes improve the aggregation of soils as compared with crops like corn.

Factor # 6. Plant Roots:

Large number of granules remains attached to roots and root hairs which help to develop crumb structure. Secretary products from the roots of different plants may also act as cementing agents in binding the soil particles together and help for the formation of good soil structure. 

Factor # 7. Soil Organisms:

Intense microbial activity takes place after the incorporation of organic materials to the soil. The different soil organisms like earthworm, moles, insects etc. burrow the soil and take part in the aggregation of soil separates through their slimy and other secretary products.

Factor # 8. Manurial Practices and Crop Rotation:

The cultivation of green manuring and grass crops will improve the soil structure. In sandy loam soils, the crop rotations like wheat-jowar and wheat-maize were found to improve the soil structure.

Factor # 9. Alternate Wetting and Drying:

Variations in the moisture content of soils significantly affect the formation of aggregates and the development of different types of soil structure. The dehydration and re-wetting of a soil mass cannot be uniform, especially if the drying and wetting processes are rapid. Such unequal strains arise throughout the mass which will tend to form clods and granules of various sizes.