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The maximum amount of water that a given soil can retain is called field capacity, whereas a soil so dry that plants cannot liberate the remaining moisture from the soil particles is said to be at wilting point. [2] Available water is that which the plants can utilize from the soil within the range between field capacity and wilting point.
Water retention curve is the relationship between the water content, θ, and the soil water potential, ψ. This 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.
Field capacity. 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 takes place two to three days after rain or irrigation in pervious soils of uniform structure and texture. The physical definition of field capacity ...
Cross-section of a hillslope depicting the vadose zone, capillary fringe, water table, and phreatic or saturated zone. (Source: United States Geological Survey .) Infiltration is the process by which water on the ground surface enters the soil. It is commonly used in both hydrology and soil sciences. The infiltration capacity is defined as the ...
The specific heat of soil increases as water content increases, since the heat capacity of water is greater than that of dry soil. [89] The specific heat of pure water is ~ 1 calorie per gram, the specific heat of dry soil is ~ 0.2 calories per gram, hence, the specific heat of wet soil is ~ 0.2 to 1 calories per gram (0.8 to 4.2 kJ per ...
Percolation test. A percolation test (colloquially called a perc test) is a test to determine the water absorption rate of soil (that is, its capacity for percolation) in preparation for the building of a septic drain field (leach field) or infiltration basin. [ 1] The results of a percolation test are required to properly design a septic system.
Available water capacity. 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 concept, put forward by Frank Veihmeyer and Arthur Hendrickson, [3 ...
Cation-exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmol c /kg. Some texts use the older, equivalent units me/100g or meq/100g. CEC is measured in moles of electric charge, so a cation-exchange capacity of 10 cmol c /kg could hold 10 cmol of Na + cations (with 1 unit ...