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A simplified version of the Emerson soil dispersion test [3] can be completed in the field on a 20-minute to two-hour timescale. Laboratory tests used to diagnose a soil as dispersive focus on the cation exchange capacity of a soil sample and its cation breakdown. Soil cations are dominated by Ca 2+, Mg 2+, K +, and Na +, as well as H + in ...
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.
Since this shallow-water phase speed is independent of the wavelength, shallow water waves do not have frequency dispersion. Using another normalization for the same frequency dispersion relation, the figure on the right shows that for a fixed wavelength λ the phase speed c p increases with increasing water depth. [ 1 ]
Irrigation using water with high sodium adsorption ratio may require soil amendments to prevent long-term damage to the soil. [3] If irrigation water with a high SAR is applied to a soil for years, the sodium in the water can displace the calcium and magnesium in the soil.
The Universal Soil Loss Equation (USLE) is a widely used mathematical model that describes soil erosion processes. [1]Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sediment load assessment and inventory, conservation planning and design for sediment control, and for the advancement of scientific understanding.
The drainage formula can be amplified [10] to account for (see figure on the right): the additional energy associated with the incoming percolation water , see groundwater energy balance; multiple soil layers; anisotropic hydraulic conductivity, the vertical conductivity (Kv) being different from the horizontal (Kh)
The soil moisture velocity equation [1] describes the speed that water moves vertically through unsaturated soil under the combined actions of gravity and capillarity, a process known as infiltration. The equation is alternative form of the Richardson/Richards' equation.
Pores (the spaces that exist between soil particles) provide for the passage and/or retention of gasses and moisture within the soil profile.The soil's ability to retain water is strongly related to particle size; water molecules hold more tightly to the fine particles of a clay soil than to coarser particles of a sandy soil, so clays generally retain more water. [2]