Reclamation of salt affected soils
- 2. Types of salt affected soils Sodic soils Saline sodic Saline soils
- 3. contain large amounts of water-soluble salts The salts are white, chemically neutral and include the chlorides, sulfates and sometimes nitrates of calcium, magnesium, sodium, and potassium Saline soil
- 5. •.. Sodic soils Soil which have high amount of exchangeable Na Water intake usually is poor especially in soils high in silt and clay. The pH (acidity-alkalinity value) of the soil usually is high, often above nine plant nutritional imbalances may occur
- 7. Reclamation of saline soils Saline soils cannot be reclaimed by any chemical amendment, conditioner or fertilize . Only leaching can remove salts from the plant root zone . The amount of water necessary is related to the initial salt level in the soil , final salt level desired and the quality of the irrigation water.
- 8. CONTI… Adequate drainage prevents salts leached from the surface by irrigation from returning to the plant root zone by upward capillary action . Regular irrigation and drainage provide successful reclamation of this type of soil
- 9. Reclamation of sodic soils . Sodic soils are treated by replacing adsorbed sodium with a soluble source of calcium. Native gypsum, calcium in irrigation water or commercial amendments can supply the calcium. Adequate drainage also must be present
- 10. Purpose of amendment The purpose of an amendment is to provide soluble calcium to replace exchangeable sodium adsorbed on clay surfaces.
- 11. Types of amendment .. There are two main types of amendments: those that add calcium directly to the soil and those that dissolve calcium from calcium carbonate (CaCO3) already present in the soil
- 12. Conti.. Calcium amendments include gypsum (hydrated calcium sulfate) and calcium chloride . Gypsum is moderately soluble in water Good land management methods prevent salt buildup. Leveling the land and using heavy irrigation prevents salt accumulation in high spots
- 13. Conti.. Acid-forming or acidic amendments include sulfuric acid, elemental sulfur and calcium carbonate-sulfur. Sulfuric acid reacts immediately with the soil calcium carbonate to release soluble calcium for exchange with sodium.
- 14. Conti… Elemental sulfur must be oxidized by soil bacteria and react with water to form sulfuric acid . The formation of appreciable amounts of sulfuric acid from elemental sulfur may take several months to several years