Difference between Surface Soil and Sub-Soil

This article will help you to differentiate between surface soil and sub-soil.

Difference # Surface Soil:

1. Surface soil is defined as the immediate uppermost loose layer of the earth consisting of organic matter and soil organisms suitable for plant growth. It is generally called furrow slice soil layer (0-15 cm depth) and fertile soil.

2. It is completely weathered.

3. Surface soil is dominated by finer particles like silicate clays.

4. Surface soil is porous and friable.

5. Aeration status of surface soil is good and exchange of gasses between atmosphere and soil air takes place.

6. The number and activity of soil micro­organisms is very high.

7. Relatively higher organic matter content due to presence of higher biomass on the soil surface.

8. Due to presence of high organic matter content the colour of surface soil is deep brown or dark.

9. It is fertile. Most of the essential plant nutrients are present.

10. Surface soil has no hard pan.

11. It has good physical management condition because of surface soil.

12. Cation exchange capacity is very high.

Difference # Sub-Soil:

1. Sub-soil is defined as the compact soil below the furrow slice (0-15 cm depth) soil layer which cannot be cultivated by tillage operation. It is generally poor in nutrient status and organic matter and hence it is less fertile than that of surface soil.

Sometimes in the sub-soil there is a formation of hard pan that cannot allow water to move down below the hard layer formed either due to accumulation of clay particle or formation of insoluble CaCO₃ layer resulting stagnation of water on the soil surface that affects plant growth.

2. It is partially weathered.

3. Sub-soil is dominated by quartz particles and other coarse fragments of minerals.

4. The sub-soil is more massive and compact.

5. Aeration status of sub-soil is very poor and hence exchange of gases is very much limited.

6. The microbial population and their activity are very low.

7. Due to lack in plant and animal residues in the sub-soil, the amount of organic matter is very low.

8. The colour of sub-soil is light and sometimes may be light yellowish colour depending on the nature and kinds of un-weathered materials.

9. It is less fertile; very few essential plant nutrients are present.

10. Sub-soil sometimes has hard pan.

11. It has poor physical condition.

12. Cation exchange capacity is low.