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Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation.
Water retention curve is the relationship between the water content, θ, and the soil water potential, ψ. The soil moisture curve is characteristic for different types of soil, and is also called the soil moisture characteristic. It is used to predict the soil water storage, water supply to the plants (field capacity) and soil aggregate stability.
Soil moisture is the water content of the soil. It can be expressed in terms of volume or weight. Soil moisture measurement can be based on in situ probes (e.g., capacitance probes, neutron probes) or remote sensing methods. [1] [2] Water that enters a field is removed from a field by runoff, drainage, evaporation or transpiration. [3]
Field capacity is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually occurs two to three days after rain or irrigation in pervious soils of uniform structure and texture.
Available water capacity is the amount of water that can be stored in a soil profile and be available for growing crops. [1] It is also known as available water content ( AWC ), profile available water ( PAW ) [ 2 ] or total available water ( TAW ).
The consistency index (Ic) indicates a soil's consistency (firmness). It is calculated as CI = (LL-W)/(LL-PL), where W is the existing water content. The soil at the liquid limit will have a consistency index of 0, the soil at the plastic limit will have a consistency index of 1, and if W > LL, Ic is negative.
Available water capacity is the amount of water held in a soil profile available to plants. As water content drops, plants have to work against increasing forces of adhesion and sorptivity to withdraw water. Irrigation scheduling avoids moisture stress by replenishing depleted water before stress is induced. [64] [65]
There are various factors that affect soil temperature, such as water content, [84] soil color, [85] and relief (slope, orientation, and elevation), [86] and soil cover (shading and insulation), in addition to air temperature. [87] The color of the ground cover and its insulating properties have a strong influence on soil temperature. [88]