Topic 5: Soil texture and Structure

 What is meant by a soil crumb?

Soil crumbs are referred to as the large pieces of aggregated soil present as lumps.

. They need to be crushed and grounded and this is done while ploughing and tilling of land before land is prepared for sowing. 

.This is done with the help of iron leveller or wooden plank in smaller areas or power tillers in large areas. 

.This is done so that there is proper space for roots to penetrate, for better air circulation and good germination of seedlings.

                       Soil crumb sample

Importance of forming a good crumb structure for optimum plant growth

1. Conducive to air circulation

The larger pores between the granules are conducive to air circulation. The internal pores of the granules are dominated by water-holding pores. This kind of pore creates favorable conditions for the coordination of soil water, fertilizer, gas, and heat.

2. As a small reservoir of crop roots.

The water-holding pores in the granules can retain moisture, and the water infiltrated into the soil layer is held by capillary forces and held in the water-holding pores. The excess water penetrates the lower soil layer under the action of gravity.

In the sunny or dry season after the rain, the surface granules shrink due to water loss, and the upper and lower capillary connections are cut off, forming a separation layer and weakening the evaporation of soil moisture.

3. As a small fertilizer storehouse for crop growth

The water pores inside the crumb structure have less air, so the organic matter is decomposed slowly, which is beneficial to the synthesis of humus, this is beneficial to the accumulation of nutrients and plays a role in maintaining fertilizer.

The air in the gas-filled pores between the particles is suitable for the activities of aerobic microorganisms, the organic matter decomposes quickly, the available nutrients are more, and the fertilizer supply performance is good.

4. Loose soil make seeds germinated

The loose soil crumb structure is conducive to the long-term cultivation of crops, it can ensure that the seeds are easy to germinate, the highly developed roots, and the neat seedlings.

5. Maintain high soil biodiversity.

The large and small pore structures in soil particles provide a good living space for microorganisms. A balanced microbial state is an important guarantee for soil physical, chemical, and biological fertility.

How to build soil crumb structure 

1. Intensive cultivation

Intensive cultivation makes the topsoil lose. Although the formed granules are not water-stable, they also play a role in regulating soil porosity.

The continuous application of organic fertilizer can promote the formation of water-stable aggregate structure, form a high degree of agglomeration of aggregates, and various reasonably distributed pores.

2. Rotational grazing

The robust growth and well-developed root systems of leguminous crops, whether annual or perennial, can aid in the development of soil aggregates. The production of soil crumb structure can be aided by crop rotation, returning straw to the soil, preparing manure with microbes, and rotating paddy crops.