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A xerophyte (from Greek ξηρός xeros 'dry' + φυτόν phuton 'plant') is a species of plant that has adaptations to survive in an environment with little liquid water. Examples of xerophytes include cacti, pineapple and some gymnosperm plants. The morphology and physiology of xerophytes are adapted to conserve water during dry periods.
For a given soil, the greater the void ratio, the higher the value of the coefficient of permeability. Here 'e' is the void ratio. Based on other concepts it has been established that the permeability of a soil varies as e2 or e3 / (1+e). Whatever may be the exact relationship, all soils have e versus log k plot as a straight line.
Permeability is a property of porous materials that is an indication of the ability for fluids (gas or liquid) to flow through them. Fluids can more easily flow through a material with high permeability than one with low permeability. [1] The permeability of a medium is related to the porosity, but also to the shapes of the pores in the medium ...
Soil texture determines total volume of the smallest pores; [56] clay soils have smaller pores, but more total pore space than sands, [57] despite a much lower permeability. [58] Soil structure has a strong influence on the larger pores that affect soil aeration, water infiltration and drainage. [59]
Sodium adsorption ratio. 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 Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt): If the ...
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. [1] Deserts and xeric (Ancient Greek ξηρός xērós 'dry') shrublands form the largest terrestrial biome, covering 19% of Earth 's land surface area. [2] Ecoregions in this habitat type vary greatly in the amount of annual rainfall they receive, usually less ...
The Richards equation represents the movement of water in unsaturated soils, and is attributed to Lorenzo A. Richards who published the equation in 1931. [1] It is a quasilinear partial differential equation; its analytical solution is often limited to specific initial and boundary conditions. [2] Proof of the existence and uniqueness of ...