Reclamation of salt- affected soils. Munwar Sultana Solangi Lady Instructor Agriculture Training Institute Sakrand. Soil.
Reclamation of salt- affected soils Munwar Sultana Solangi Lady Instructor Agriculture Training Institute Sakrand
Soil An agricultural definition of soil is "a dynamic natural body on the surface of the earth in which plants grow, composed of mineral and organic materials and living forms"
Salt- Affected soils • The soils contain excessive amounts of either soluble salts or exchangeable sodium or both.
Nature of salt- affected soils Saline soils: Soils containing sufficient amount of soluble salts to interfere with germination and growth of most crop plants are classified as saline.
Sodic soils • Soils containing sufficient exchangeable sodium to adversely affect their properties and plant growth.
Saline- sodic soils Soils containing both soluble salts and exchangeable sodium
Soil Properties 1. Saline (non sodic) soils • EC > 4 ds/m • SAR < 15 • pH < 8.5 • "neutral" salts • often calcareous (lime- containing) • pH = 8.2 - 8.5 • "white alkali" soils = white surface crust 2. Saline-Sodic soils • EC > 4 ds/m • ESP (SAR) > 15 • pH < 8.5 • controlled by salts and lime • pH> 8.5 • also called "white alkali“
3. Sodic (non-saline) soils • EC < 4 ds/m • ESP (SAR) > 15 • poor physical condition • pH > 8.5 • high pH disperses organic matter Þ dark color • = "black alkali" • worst soil of the salt-affected • high dispersion = water-logging • can result from leaching saline-sodic soil
Sources contributing salinity Parent Material Irrigation water Ground water Flood water Sea water Salt loving vegetation Industrial wastage / sewage water Overuse of chemical Fertilizer
Reclamation of Salt- affected soils Physical Methods Sub-soiling Deep ploughing Sanding Horizon mixing Profile inversion
Biological methods - Flooding - Growing of crops - Incorporation of organic matter
Chemical Methods • Gypsum (sodic & saline- sodic) • Sulfur • Sulfuric acid • Hydrochloric acid
Reclamation of Saline Soils Reclamation of saline soil is done by applying excess water to the soil surface. The removal of salts may be accomplished either by continuous ponding of water on soil surface or by intermittent leaching.
Crop during Reclamation Some kind of vegetation should be grown during reclamation, as they help reclamation and also provide some income to farmers. As, Rice Sesbania Sorghum Bermuda Grass Kallar Grass
Salt Tolerance of crops Tolerant Moderately Tolerant Wheat Sorghum Soybean Saf flower Oats Sweet Clover Rhodes Grass Sudan Grass Beet Fig Jujube Olive Papaya Pine apple Pomegranate • Barley • Cotton • Sugar beet • Kallar Grass • Wheat Grass (Tall) • Date palm • Asparagus
Moderately sensitive Sensitive Bean Sesame Carrot okra Onion Apple Apricot Grapefruit Lemon Lime Mango Orange Peach Pear Plum Strawberry • Maize • Millet • Groundnut • Rice • Sugarcane • Sunflower • Barseem • Sesbania • Cabbage • Cauliflower • Corn • Cucumber • Egg plant • Lettuce • Muskmelon • Potato • Pumpkin • Radish • Spinach • Sweet potato • Tomato • Turnip • Water melon • Grape
Reclamation of sodic and saline-sodic soil Reclamation of sodic and saline-sodic soil is more difficult, time consuming and expensive. It involves not only leaching a soluble salts but also the replacement of exchangeable sodium with calcium and the improvement of physical properties of soil. The two most difficult aspects of the reclamation process are - Provision of source for replacement of sodium with calcium - Water for leaching
Management of salt affected soils • Crop selection • Variety selection • Irrigation practices • Ridge sowing • Proper fertilizer and fertilizer use • Green manuring • Organic manures on sodic-soils • Sub-soiling and deep tillage • Mulching