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"

Types of soil

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.

Soils containing both soluble salts and exchangeable sodium 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                    

Comparisons of Salt-affected Soils

Sources contributing salinity Parent Material Irrigation water Ground water Flood water Sea water Salt loving vegetation Industrial wastage / sewage water Overuse of chemical Fertilizer

Effects on plant growth

Sub-soiling Deep ploughing Sanding Horizon mixing Profile inversion Reclamation of Salt- affected soils Physical Methods Sub-soiling Deep ploughing Sanding Horizon mixing Profile inversion

- Flooding - Growing of crops 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 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 Bean Sesame Carrot okra Onion Apple Apricot Grapefruit Lemon Lime Mango Orange Peach Pear Plum Strawberry

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