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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.
0.2–0.5 Fully saturated soil, equivalent to effective porosity: Field capacity: θ fc: −33 0.1–0.35 Soil moisture 2–3 days after a rain or irrigation Permanent wilting point: θ pwp or θ wp: −1500 0.01–0.25 Minimum soil moisture at which a plant wilts Residual water content θ r: −∞ 0.001–0.1 Remaining water at high tension
The sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils.It is an indicator of the suitability of water for use in agricultural irrigation, as determined from the concentrations of the main alkaline and earth alkaline cations present in the water.
The residual sodium carbonate (RSC) index of irrigation water or soil water is used to indicate the alkalinity hazard for soil. The RSC index is used to find the suitability of the water for irrigation in clay soils which have a high cation exchange capacity .
The other soil forming factors are climate, organisms, relief and time. Parent materials that are not residual are classified by their mode of transport into a system. [ 1 ] These modes of transport are by wind ( aeloian ), water, gravity (colluvial), ice ( glacial till ), lakes ( lacustrine ), oceans ( marine ) or in place (non transported).
The nominal definition of field capacity (expressed symbolically as θ fc) is the bulk water content retained in soil at −33 kPa (or −0.33 bar) of hydraulic head or suction pressure. The term originated from Israelsen and West [1] and Frank Veihmeyer and Arthur Hendrickson. [2]
Moisture equivalent is proposed by Lyman Briggs and McLane (1910) as a measure of field capacity for fine-textured soil materials. Moisture equivalent is defined as the percentage of water which a soil can retain in opposition to a centrifugal force 1000 times that of gravity. It is measured by saturating sample of soil 1 cm thick, and ...
Soil deposits are affected by the mechanism of transport and deposition to their location. Soils that are not transported are called residual soils—they exist at the same location as the rock from which they were generated. Decomposed granite is a common example of a residual soil. The common mechanisms of transport are the actions of gravity ...