Leaching model (soil) Leaching model (soil) A leaching model is a hydrological model by which the leaching with irrigation water of dissolved substances, notably salt, in the soil is described depending on the hydrological regime and the soil's properties. <br> The model may describe the process (1) in time and (2) as a function of amount of water applied. <br> Leaching is often done to "reclaim" saline soil or to "conserve" a favorable salt content of the soil of irrigated land as all irrigation water contains salts. The leaching process in a salty soil to be reclaimed is illustrated in the leaching curves
Soil reduced by the addition of gypsum (calcium sulphate) as calcium adheres to clay more tightly than does sodium causing sodium to be pushed into the soil water solution where it can be washed out by an abundance of water. There are acid-forming cations (hydrogen and aluminium) and there are base-forming cations. The fraction of the base-forming cations that occupy positions on the soil colloids is called the base saturation percentage. If a soil has a CEC of 20 meq and 5 meq are aluminium and hydrogen cations (acid-forming), the remainder of positions on the colloids (20-5 = 15 meq) are