What are the forms of soil moisture in farmland? What is the relationship between them

There are three forms of soil moisture in farmland:

1.Surface water: This is the water that exists on the surface of the earth, such as water in ditches, rivers, lakes, and swamps. Surface water can be formed by rain, snowmelt, etc., and its quantity and quality will vary depending on climate, soil type, topography, and other environmental conditions.

2.Soil water: Soil water is the water that exists on the surface of soil particles and is most closely related to crop growth.

Soil water can enter the soil by precipitation, irrigation, etc., and can be maintained in the soil for a period of time for plant roots to absorb and utilize. Soil water has an important impact on plant growth and development.

3.Groundwater: Groundwater is water that exists in soil pores and rock cracks below the water table. Groundwater can be formed by precipitation, surface water infiltrating subsoil, and rocks. Groundwater plays an important role in soil moisture cycling and plant growth.

There is a relationship between these three forms of soil moisture. For example, surface water can infiltrate to form soil water and groundwater, while groundwater can form soil water and surface water through evaporation, infiltration, etc. Therefore, these three forms of soil moisture affect each other in terms of quantity and quality, forming a complex soil moisture cycle.

The water in the farmland soil includes gravity water, capillary water and absorbent water, and only capillary water is the effective water.

Summary. Hello, "Soil refers to a layer of loose material on the surface of the earth, composed of various granular minerals, organic matter, water, air, microorganisms, etc., which can grow plants. Soil is composed of minerals weathered from rocks, organic matter produced by the decomposition of animal and plant and microbial residues, soil organisms (solid substances), water (liquid phase substances), air (gas phase substances), and oxidized humus.

2. Provide water resources and their purification energy.

3. Provide the function of various organisms and microorganisms in the soil, and provide the function of various nutrients in the soil and the transformation place of organic waste.

What are the basic components of soils and how do you see the relationship between them?

Hello, "Soil refers to a layer of loose material on the surface of the earth, composed of various granular minerals, organic matter, water, air, microorganisms, etc., which can grow plants. Soil is composed of minerals weathered from rocks, organic matter produced by the decomposition of animal and plant and microbial residues, soil organisms (solid substances), water (liquid phase substances), air (gas phase substances), and oxidized humus. Related Extensions:

1. The biggest function of soil is to allow the roots of plants to gain a foothold, support their underground parts and supply the nutrients, water and oxygen needed by plants or crops. 2. Provide water resources and their purification energy. 3. Provide the function of various organisms and microorganisms in the soil, and provide the function of various nutrients in the soil and the transformation place of organic waste.

How do you see the relationship between them?

Soil is composed of minerals, animals and plants weathered from rocks, organic matter produced by the decomposition of microbial residues, soil organisms (solid phase substances), water (liquid phase substances), air (gas phase substances), humus, etc. Solid matter includes soil minerals, organic matter, and microorganisms. Liquid matter mainly refers to soil moisture.

Gases are the air present in the pores of the soil. These three types of substances in the soil constitute a contradictory unity. They are interconnected, mutually restrictive, provide the necessary living conditions for crops, and are the material basis of soil fertility.

Soil minerals are mineral particles of different sizes (sand, soil and gum) formed by the weathering of rocks. There are many types of soil minerals, and the chemical composition is complex, which directly affects the physical and chemical properties of the soil, and is one of the important nutrients of crops.

Explain the concepts and meanings of soil bulk density, relative density, and porosity?

1. Moisture absorption.

Hygroscopic water is also known as absorbing water and tightly binding water. Under the action of molecular gravity, soil particles adsorb water molecules in the air on its surface and become hygroscopic water, which is a very thin water film attached to the surface of soil particles, and is polymerized by 15 20 layers of water molecules. Hygroscopic water is very strong by the soil particles, 10000-31 atmospheres, has the nature of solid water, can not move, density, 105 can be baked.

2. Membrane water:

It refers to the water layer maintained by the adsorption of the surface of soil particles, and its thickness can reach tens or hundreds of more than 100 water molecules. Similar in nature to liquid water, but with higher viscosity and less solubility, it can move, but very slowly.

3. Capillary water.

Capillary water is the water held by the capillary gravity generated by the capillary pores in the soil, which is called capillary water. Capillary water is subjected to suction pressure of one atmosphere, and can move up and down, left and right, and the speed is fast. It has the ability to dissolve nutrients and also has the effect of transporting nutrients to the roots of crops.

4. Gravity water.

When the water entering the soil exceeds the water holding capacity of the field, a part of the water leaks down along the macropores by gravity, and this part of the soil water subjected to gravity is called gravity water. Although gravity water can be absorbed by plants, it has very little chance of being used by plants because of its rapid infiltration.

1. Moisture absorption.

Features: Hygroscopic water is very strong by the soil particles, 10000-31 atmospheres, with the nature of solid water, the plate can not move, density, 105 can be baked out.

2. Membrane water:

Characteristics: Similar in properties to liquid water, but with higher viscosity and less solubility, it can move, but very slowly.

3. Capillary water.

Features: Capillary water is subjected to suction pressure, and can move up and down, left and right, and the speed is fast. It has the ability to dissolve nutrients and also has the effect of transporting nutrients to the roots of crops.

4. Gravity water.

When the soil moisture exceeds the water holding capacity of the field, the excess water will be moved down the macropores in the soil by gravity, and this gravity-supported water is called gravity water.

It is possible to measure it according to the specific soil.

Bai to be flexible

A variety of principles and schemes are selected, such as the use of time-domain reflectometer (internal TDR) to measure the water content of a certain volume of soil or other media. The Handi-Trase TDR soil moisture meter provided by Yunsheng Technology is a combination of a handheld Trase Time Domain Reflectometer (TDR) and a tablet PC. The Handi-Trase is a miniaturized product of the Trase and MiniTrase systems, which not only has all the advantages of the MiniTrase, such as a wide measurement range and high accuracy, but also has an instrument size that is only the size of the palm of your hand, making on-site measurement more convenient.

The binding of soil to water refers to the electrocuted molecules.

The source attraction adsorbs water in the soil on the surface of the soil particles. Because the surface of fine soil particles generally has a negative charge, an electric field is formed around the soil particles, and the water molecules in the electric field range and the cations in the aqueous solution are adsorbed on the surface of the soil particles. Because the water molecule is a polar molecule (its positive and negative charges are biased at both ends of the molecule and do not coincide), it is attracted by the surface charge of the soil particle or the solution charge and is arranged in a directional manner.

Bound water can be further divided into strongly bound water and weakly bound water. Strongly bound water is equivalent to water in the fixed layer, while weakly bound water is equivalent to water in the diffusion layer.

1) Strong binding water.

Close to the surface of the soil particles, it is most attractive. Its properties are: it shows the properties of a solid, has great viscosity, elasticity and shear strength, and does not transmit hydrostatic pressure.

Clay is solid and hard when it contains only strong water; The content of strongly bound water in sand is very small, and the sand containing only strong bound water is in a loose state.

2) Weakly bound water.

Close to the outside of the strongly bound water, the adsorption force is slightly lower and the thickness is slightly larger. Its characteristics are: it is in a viscous state, does not transmit hydrostatic pressure, and cannot flow freely, but has a certain ability to move.

Under the action of strong external electric field, the thin film water can flow slowly, and the self-thick part moves to the thin part, and the weakly bound water has the greatest influence on the properties of cohesive soil.

Water is affected by various forces in the soil, such as gravity, capillary gravity, water molecular gravity, and molecular gravity on the surface of soil particles, forming different types of water and reflecting different properties.

Solid water, ice crystals formed when soil water freezes.

Vapor water, which is present in the soil air.

Binding water, including hygroscopic and membranous water.

Free water, including capillary water, gravity water, and groundwater.

Hygroscopic waterThe water held by the dry soil by absorbing water vapor from the air is called hygroscopic water.

Membrane water (membrane water).

Membranous water refers to the layer of water held by the adsorption of the surface of soil particles, and its thickness can reach tens or hundreds of more than one water molecule.

Capillary water Capillary water is the water held by the capillary gravity generated by the capillary pores in the soil, which is called capillary water.

When the water entering the soil exceeds the water holding capacity of the field, a part of the water leaks down along the macropores by gravity, and this part of the soil water subjected to gravity is called gravity water. When gravity water seeps into the impervious layer below, it accumulates into groundwater. So gravity water is important for groundwater**.

The above types of water can be converted into each other under certain conditions, for example, the water that exceeds the membrane water becomes capillary water; The amount of water that exceeds the capillary water becomes gravity water; Gravity water infiltrates and accumulates groundwater; Groundwater rises and becomes capillary support water; When a large amount of soil moisture evaporates, there is only hygroscopic water in the soil.

Briefly describe the types of soil water and the availability of each type of water.

There are four types of soil water: hygroscopic water, membranous water, capillary water, and gravity water.

1) Hygroscopic water cannot move freely in liquid water, cannot be absorbed by plants, and is ineffective water.

2) Only a portion of the membranous water is effective.

3) The water that is kept in the pores of the soil capillary by the gravitational force of the soil capillary is called capillary water, which moves faster and is no longer affected by the gravitational force of soil particles, and is the free water that can be moved, and is the main water used by plants, so it is the most important for plants.

4) Gravity water can be absorbed by plants, but it will soon seep down, so it cannot be continuously absorbed and utilized by plants.

1. Moisture absorption.

Hygroscopic water is a thin layer of water formed by the surface molecules of solid particles in the soil directly absorbed by the water absorbed from the air. Its thickness and content depend on the saturation of water vapor in the air. In absolutely dry air, the amount of hygroscopic water is minimal, approximately zero.

Under saturated water vapor conditions, the hygroscopic water reaches its maximum. Hygroscopic water is greatly adsorbed by soil solid particles, so the content of hygroscopic water is related to soil texture, organic matter content and soil solute content. Because the hygroscopic water is tightly bound to the soil particles, it cannot move freely, and it is difficult to be absorbed and utilized by plants.

2. Thin film water.

After the adsorption of water vapor molecules by soil particles reaches the maximum moisture absorption, the soil particles adsorb more liquid water, and connect the water film between the particles to form a continuous water film, which is called membrane water wrapped in the outside of the hygroscopic water. The membrane water is adsorbed on the outside of the hygroscopic water, and is less adsorbed by the soil particles, so it can move freely between the membranes, and move from the place where the water film is thick to the place where the water film is thin. Membrane water is also known as the maximum molecular water holding capacity.

3. Capillary water.

When the soil water content reaches the maximum molecular water holding capacity, the soil moisture continues to increase and fill the capillary pores of the soil, and at the same time, it remains in the pores of the soil, becoming the soil moisture maintained by the capillary force, and is called capillary water. Capillary water is less stressed, has a strong ability to move freely, and can be absorbed and utilized by plants. At the same time, it has the ability to dissolve chemicals contained in the soil, so it is also a solvent and carrier for chemicals in the soil.

Depending on the degree of connection between soil moisture and groundwater, capillary water can be divided into capillary rising water and capillary hanging water.

When the groundwater is buried at a shallow depth, the groundwater can rise to a certain height along the capillary through the action of capillary force, and this soil moisture is called capillary rising water. Capillary rising water is a major form of groundwater replenishment of soil moisture. In the case of shallow groundwater, plants indirectly absorb and utilize groundwater through the action of capillary water lifting.

If the groundwater is buried at a large depth, the groundwater cannot rise to the surface through capillary action, and the water seeps down through the upper soil after rainfall or irrigation, and a part of the water moves from the macropores to the deep layer under the action of gravity, and a part of the water is maintained and suspended by the capillary force, which is called capillary hanging water.

4. Gravity water.

When the water in the soil exceeds the capillary force range, the excess water moves along the large capillary in the soil under the action of gravity. This moisture that moves under the force of gravity is called gravitational water. Gravity water has the basic characteristics of liquid water, so it can be absorbed and utilized by plants, but because it can move freely by gravity, it is not easy to remain in the root zone of crops, so most gravity water has no chance to be absorbed and utilized by plants.

Types of soil moisture: According to the force of soil moisture, soil moisture can be divided into three categories: one is adsorption water (binding water), which is maintained by soil adsorption, which can be divided into hygroscopic water and membrane water; the second is capillary water, which is maintained by the action of soil capillary force; The third is gravity water, which is dominated by gravity and can easily move further into the deep soil profile.