MAZHAR ABBAS 2004-ag-1536 7TH Agronomy University Of Agriculture Faisalabad

Salt Affected Soils

Salt Affected Soils Salt affected is a collective term which includes saline,sodic and saline sodic soils. Salt affected soils occur commonly in arid and semi arid regions where annual precipitation is less than evapotranspiration. Soil affected soils also occur in sub humid and humid regions under condition conducive to their development.

Soil Salinity Classification (WASID) Non Saline Soil 0.0 – 0.2% Soluble salts Slightly Saline Soil 0.2 – 0.5% Soluble salts Moderately Saline 0.5 – 1% Soluble salts Soil Strongly Saline Soil > 1% Soluble salts

Classification Of Salt Affected Soils Classification is based on ESP (Exchangeable Sodium Percentage) SAR (Sodium Adsorption Ratio) EC (Electrical Conductance) pH

Saline Soils Types of salts Neutral soluble salts: chlorides and sulphates of calcium, magnesium, potassium and sodium (calcium and magnesium dominant) Excess of TSS EC >=4.00 dS/m At 25 oC ESP <15 pH <8.5 SAR <15

Characteristics Plant growth is generally restricted by poor infiltration, stability and aeration of the soil. Usually, evaporation causes the formation of a white crust on the soil surface, known as white alkali, the name previously given to saline soils.

Sodic soils Types of salts Low concentration of neutral soluble salts, high concentration of sodium ions ESP > =15 EC < 4 dSm-1 SAR >=15 pH ranges b/w 8.5 -10

Characteristics This type of soil is the most affected and degraded by salinization. Soil particles are dispersed and soil pores become blocked. This worsens with depth. The reduced porosity leads to low permeability. The infiltration rate is reduced in such a way that water tends to form puddles. This type of soil is said to be waterlogged.

Saline Sodic Soils Types of Salts High concentration of neutral soluble salts and sodium ions ESP >=15 EC >=4 dSm-1 SAR >=15 Ph depends on dominance of either TSS or Na salt

Characteristics Plant growth in this type of soil can be affected by both excess soluble salts and excess sodium. Saline-sodic soils have characteristics between those of saline soils and sodic soils. If the soluble salts are leached out, and in particular if the ESP of the leaching water is high, the salinity level decreases, but ESP increases, transforming them into sodic soils.

Calcarious soils If there is excess of calcium salts

Salt Tolerant Crops Low salt tolerant crops Beans Mung Gram Pea Alfalfa Oranges Grape fruit Strawberry

Moderate Salt Tolerant Crops Rye Wheat Barley Paddy Maize Tomato Cabbage Potato Radish Carrots onion

High Salt Tolerant Crops Sugar beet Tobacco Turnip Cotton Palm Carrot

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