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Soil Salinity.pptx
- 2. SOIL SALINITY /SALT STRESS Muhammad Irfan IAE, IUB
- 3. Salinity Salinity isa condition where excessive salts in soil solution cause inhibition of plant growth or plant death. On a world scale, no toxic substance restricts plant growth more than does salts. Salt stress represents an increasing threat to plant agriculture.
- 4. Types of SaltAffected Soils Saline Soils Soil containing sufficient amount of soluble salts (Ca2+, Mg2+, Cl-, SO4 2-, CO3 2- HCO3 -,) to adversely affect the growth of most of crop plants. All these salts are white hence the saline soils exhibit white color. Also called white alkali soils.
- 6. Sodic Soils Soil containing sufficient amount of exchangeable Na to adversely affect the growth of most of crop plants. The pH of the soil usually high, often above 9. These soils have dispersed structure. Also called black alkali soils.
- 8. Saline SodicSoils Soil containing sufficient amount of soluble salts as well as exchangeable Na to adversely affect the growth of most of crop plants. These soils contain characters of both saline and sodic soils.
- 9. Characterization Of SaltAffected Soils Classification EC (ds/m) pH ESP Saline soils >4 <8.5 <15 Sodic soils <4 >8.5 >15 Saline sodic soils ≥4 ≥8.5 ≥15
- 10. Global Distribution OfSalt Affected Soils More than 800 million hectares of land throughout the world are salt affected, salinity (397 million hectare) sodicity (434 million hectare) This is over 6% of the world’s total land area.
- 11. National Distribution OfSalt Affected Soils In Pakistan, out of 20 million hectares of agriculture land 6.7 million hectares are salt affected Thousand hectare Province Saline Soils Saline-Sodic Sodic Total Punjab 504 2081 2586 Sindh 1342 950 28 2321 Kpk 501 14 515 Blochistan 175 129 304 Total 2523 3176 28
- 12. Effects Of SaltStress On Plants Evelin et al. 2009
- 13. Effects Of SaltStress On Plants Stunted growth Wilting Necrosis of leaf tips (form of cell injury which results in the premature death of cells in living tissue.) Drought stress symptoms Specific ion toxicities Nutrient imbalance Reduced water uptake
- 15. CROP ADAPTATIONS TOSALT STRESS Based on the responses to high concentration of salts, plants can be divided into two broad groups. 1) Halophytes 2) Glycophytes Halophyte ( salt tolerant crops) They are native to saline soils. Examples: Saltbush, Pickleweed, Lizard tail, Switchgrass Glycophytes Any halophyte that can only tolerate relatively low concentrations of salt.
- 16. Management of SaltAffected Soils Physical measures Chemical measures Soil management measures Biological measures
- 17. Physical Measures Leaching Inthis method, saline elements of the soil are transferred to lower levels after dissolving with water. Drainage • With drainage of additional water, the dissolved salts also drained out. • Drains may be constructed in the field so that excess water keeps on discharging. Regular irrigation and drainage provide successful reclamation of salt affected soils.
- 18. Chemical Measures Reclamationof sodic soils requires neutralization of alkalinity and replacement of most of the sodium ions by calcium ions. Chemical used: 1. Gypsum 2. Lime Stone 3. Sulphur, Acid of Sulphur Gypsum is the most commonly used chemical amendment.
- 19. Soil Management Measures Fields should be kept leveled for balanced distribution of irrigation water. Sowing of crop should be done on the slope by following furrow and basin method. Heavy irrigation prevents salt accumulation in the soil.
- 20. Biological Measures Thebiotic approach ‘plant-microbe interaction’ to overcome salt stress has recently received a considerable attention. Different branches of the Proteobacteria and Pseudomonas contain halophytic representatives. They are able to grow in up to 20 or 25% salts. Halophytes (Plants, Microbes) take excess of salts from the soil into their body.
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