Crumb structure is a type of soil structure in which the structural units or peds have a spheroidal or crumb shape. Crumb structure is often found in more porous than granular organo-mineral surface soil horizons and provides optimal pore space for soil fertility and reduce soil problems for agricultural cultivation.
The soil is a porous structure system. It consists of three-phase substances solid, liquid, and gas. The solid material in the soil includes both mineral and organic matter. The liquid part refers to the moisture of the soil, which is preserved and moved between the pores of the soil and is the most active part of the soil.
The gas part refers to the air of the soil, and it is filled with pores that are not occupied by moisture. The pores are divided into three types: large, medium, and small. Among them, the large pores are called gas-filled pores. Large pores should not be too much, water is easy to run off if too much, and the small pores is not conducive to the breathability and rooting of plants.
Medium pores are also called water-holding pores. The more medium pores are more suitable for the growth of crops. Just like our human skin, the better the water retention and air permeability, the healthier it is.
Advantages of Soil Crumb Structure
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.
Usually, the air-filled pores are often filled with air, and the water-holding pores are often filled with moisture, which harmonizes the contradiction between moisture and air. Because water and gas are coordinated, thermal properties such as soil heat capacity generated by water and gas are moderate, so the soil temperature can also be stabilized.
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.
In short, soil with crumb structure has good water vapor circulation, sufficient nutrient supply, good cultivability, and promotion of root growth, which is an important guarantee for stability and high yield. Therefore, it is the most ideal soil structure.
How to Build Soil Crumb Structure
1. Intensive cultivation, increase the use of organic fertilizer
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. Rational rotation
Annual or perennial grasses or leguminous crops, which grow robustly and have developed strong root systems, they can promote the formation of soil aggregates.
Returning straw to the soil, making manure with microbes, crop rotation, and paddy crop rotation are all beneficial to the formation of soil crumb structure.
3. Reasonable irrigation, timely cultivation
Flood irrigation can easily damage the soil structure, so that the soil is compacted, cultivating tillage timely after irrigation is necessary to prevent compaction.
Timely cultivating, and fully play the role of alternating wet and dry and freeze-thaw cycles, it is conducive to the formation of a large number of water instability aggregates, regulate soil structure.