What is the difference between alkalinity and salinity

Acidic soils have pH less than 7 while basic soils have pH greater than 7. Meanwhile, neutral soils have pH 7. Alkaline soils and saline soils are two types of basic soils. Saline soil has pH in between 7 to 8. Overview and Key Difference 2. What are Saline Soils 3. What are Alkaline Soils 4. Similarities Between Saline and Alkaline Soils 5. Saline soil contains high contents of soluble salts. Sodium salts are predominant in the saline soil. Hence, it has a basic pH range; 7 — 8. The salinity of the soil increases due to various reasons such as mineral weathering, excessive irrigation and the use of fertilizers and animal wastes, etc.

Soil salinity does not favour plant growth. Thus, it negatively affects crop yield. Furthermore, salinity also causes necrosis of leaf margins, stunted plants, wilting and plant death under severe conditions. The leaching requirement is the ratio of the salt content of the irrigation water to that of the soil.

To help determine crop water needs, see Chapter 5 on water management. Reclaiming Non-Saline Alkali Soils Sodic-Soils Leaching alone won't remove the adsorbed sodium and insoluble sodium carbonate and bicarbonate.

This also results in a lowering of soil pH after leaching. The gypsom needs to be finely ground and should be hoed oe harrowed into the surface rather than turned under with a moldboard plow. The turning action of a moldboard ends up leaving the gypsum poorly distributed in slots.

The soil should be kept moist to promote the reaction of the gypsum and soil. On those sodic soils containing calcium carbonate lime , sulfur can be used instead of gypsum. The soil bacteria convert it to sulfate which then reacts with the calcium carbonate in the soil to form gypsum.

Much less sulfur than gypsum is needed kg of sulfur have the effect of kg of gypsum. Allow months between sulfur application and leaching to allow the conversion to gypsum. The presence of calcium carbonate can be detected by adding several drops of sulfuric or hydrochloric acid to a small amount of soil. If fizzing occurs, this indicates calcium carbonate. An alternative to soil amendments: Recent research by the USDA has shown that sorghum-sudangrass hybrids can be effective in freeing adsorbed sodium on sodic soils containing calcium carbonate.

Sorghum-sudangrass often called sordan roots release unusually high amounts of carbon dioxide; the CO2 dissolves soil calcium which can then displace the adsorbed sodium ions. Heavy irrigation is needed to flush away the freed sodium.

Where suited, the use of sordan is much cheaper than gypsum and reclaims a greater depth of soil; it is also a nutritious cattle feed. However, plants less than 45 cm tall or those that have been drought-stricken or frosted contain toxic levels of hydrocyanic acid prussic acid.

Reclaiming Saline-Alkali Soils Saline-Sodic Soils As with sodic soils, leaching alone isn't effective on saline-sodic soils, because it removes only the soluble salts, leaving behind the adsorbed sodium.

Free fro. In other words, leaching, by itself, converts a salinesodic soil into a sodic soil! In a few cases, leaching without using gypsum or sulfur may be effective when the soil contains a large amount of soluble calcium or magnesium which can displace the adsorbed sodium. Controlling the Buildup of Salinity and Alkalinity It's seldom possible to permanently rid an affected soil of salinity and alkalinity, especially if the irrigation water is one of the causes. The beat strategy is to use management practices that favor crop growth on these soils and help keep salt content at tolerable levels.

Automatic gypsum metering devices can be bought or built, or a sack of gypsum placed in the irrigation ditch. Boron tolerance may be an important consideration too.

Tables at the end of this chapter list co on crops and their tolerances. Leaching assures that the soil salt content will never be higher than that of the irrigation water. The problems connected with soil salinity in these low-lying areas are of major importance in highly developed agriculture in desert regions.

The degree of alkalinity of a soil is conveniently expressed in terms of pH values. The pH scale is divided into 14 divisions or pH units numbered from 1 to Soils with a pH of 7 are neutral. A pH of 9 is ten times more alkaline than a pH of 8 and a pH of 10 is ten times more alkaline than a pH of 9. Unable to display preview. Download preview PDF. Skip to main content. This service is more advanced with JavaScript available.