The soil is a porous system.It consists of solid,liquid and gas three-phase substances.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 pore size of small pores is too small,which is not conducive to the breathability and rooting of plants.Medium pores are also called water-holding pores.The more midium 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.
What’s the Crumb structure in soil?
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.
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,It is a small reservoir of crop roots.
The water-holding pores in the granules have the ability to 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 into the lower soil layer amoung the pores 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,It is 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,so it 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.Therefore,the contradiction between supply fertilizer and maintain fertilizer was coordinated and the nutrient status was good.
4,Soil loose,good plough
The soil structure of the granule structure is loose,easy to cultivate,it is suitable for long period of cultivation,the quality of cultivation is good,the seeds are easy to germinate,the root system is easy to stretch,and the emergence is neat and tidy.
5,Maintain high soil biodiversity.
Due to the presence of soil-sized pores in the granule structure,it provides a good living space for microorganism.This is an important guarantee for the physical,chemical and biological fertility of the soil due to its high biological diversity for agricultural production.
In short,the soil with crumb structure has the characteristics of water vapor,nutrient supply and accumulation coordination,good ploughability,and good root growth,and is an important guarantee for stable and high yields.Therefore,it is the most ideal structure of the soil and an important indicator of soil fertility.