Salinity and Sodicity are the most common problems found in the soil of arid and semiarid regions. They are well studied and have been treated with many soil chemistry solutions.
Salinity resists the production of corps through the layers of salt accumulated to levels due to lack of leaching in arid and semiarid areas. Main sources of salts in soils included precipitation, fertilizers, applications of amendments, waters containing dissolved salts, weathering products of parent minerals etc. Other reasons of decreased productivity of crop may include reduced infiltration because of the soil dispersion, decreased water availability, accumulations of toxic ions etc.
Both sodium and salts interact with soil in opposite ways. Salt in high concentration causes flocculation and permeability while dispersion is caused by the sodium due to which infiltration becomes very slow. There are some basic facts observed by formers like salty water gives good infiltration in a field. Such facts are very helpful in deciding the correct treatment of soil.
Most often irrigation waters disturb the growth of crop by accumulating sodium Na and salts into the soil. This may happen even under an excellent soil management. In such cases water amendments are more effective than simple soil management as they reduce the Na and salts from the soil. Water amendments change the properties of soil and chemistry of water at the point of soil-water interface.
However, they are not applied in sufficient quantities which can results in rapid reclamation.
There are many remedies known from a long time for the sodic and saline soils. Leaching is well known amongst all used for solving the salinity problem. Sodium (Na) is displaced with other beneficial ion like Ca. If soluble ion is not present after the leacing, it may result in sodic soil. CaCO3 makes the reclamation process slower by dissolving of lime into the water and provide Ca. Here, to increase the rate of dissolution of CaCO3 sulphur containing compounds are used. Thus sulphur helps in providing Ca to replace the Na with. These sulphur containing compounds add soluble Ca to CaCO3 either through neutral salts like gypsum which is directly added to it or by reaction of acid forming compounds with CaCO3 in the soil.
Leaching brings many improvements in the conditions of soil management like reduction in ion toxicity. Also it caused the degradation of osmotic potential.
Main Sulphur materials suitable for water treatment and soil amendments are chosen as per their usability to soil, neutrality, acid forming ability and ability to generating soluble Ca. Following is the table containing some sulphur materials along with their formulas, their common form used in reaction and suitability-
|Material||Formula||Commonly Used form-Reaction||Suitability|
|sulphuric acid||H2SO4||Liquid-acid||Soil and water|
|Ammonium polysulfide||(NH4)XSY||Liquid-alkaline||Water and soil|
|Lime sulphur||CaxSy||Liquid-alkaline||Water and soil|
|sulphur Dioxide||SO2||Gas||Water and soil|
|Elemental sulphur||S0||Solid-insoluble in water||Soil|
|Ammonium thiosulfate||(NH4)2S2O3||Liquid||Water and Soil|