Saline soils

Saline soils

Soils having higher proportion of soluble salts affect adversely the growth of plants. The salt level in saline soils exceeds a limit of 4.0 dSm-1. Mostly these soils are dominant with chloride and sulphate salts. These salts are neutral salts and hence the pH of these soils may not round 8.5. Saline soils are formed through a soil forming process called salinization in semi arid and arid zones. Salinization refers to accumulation of soluble salts in the soil surface horizons.

Effects of soil salinity

The characteristics feature of saline soil in white encrustation on surface of soils due to evaporation of water to atmosphere leaving the salts on surface of soils presence of salts leach to alteration of osmotic potential of the soil solution. Consequently water intake by plants restricted and there by nutrients uptake by plants are also reduced. In these soils due to high salt levels microbial activity is reduced. Redirect microbial activity result in slow decomposition or organic matter. Slow decomposition leads to slow nutrient availability particularly nitrogen and sulphur. Due to osmotic potential alteration water from plants cells moves to soil and plants are affected due to dehydration. As a result drying of leaves and finally death of plants common seen in saline soils. Apart from above effects specific ion effects on plants are also seen due to toxicity of ions like chloride, sulphate etc.

Reclamation

All saline soils can be reclaimed easily of good quality water is available. Since the salts in this soils are soluble in nature using quality water they can be solubilized and leached off from the field. In the absence of good quality water in becomes necessary to manage saline soils for better growth of plants.

Management of saline soils

1. Crop management

Growing crops that are tolerate high level soil salinity e.g.: Cotton, Ragi, Barley, sugar beat,

Crops that are tolerant to soil salinity at medium level are paddy, wheat, onion, maize, sunflower, castor, grape, pomegranate, tomato, cabbage and potato. Crops that are tolerant to low level of soil salinity are garden beans, Reddish, lime etc. Black gram, green gram are sensitive to soil salinity. Crops are to be chosen based on the soil salinity level.

2. Soil / cultural management

Growing crops in raised beds will reduce accumulation of salt a around root zone. Planting seedlings / sowing seeds on slopry ridges slecreases accumulation salts around root zone. Mulching soil prevents evaporation which reduces accumulation of salts due to capillary rise of water ate surface of soils. Providing drainage in water lugged areas also helps to reduce salt accumulation.

3. Fertilizer Management

Addition of extra dose of nitrogen to the tune of 20 – 25% of recommended level will compensate the low availability of N in these soils. Addition of organic manures like, FYM, compost, etc helps in reducing the ill effect of salinity due to release of organic acids produced during decomposition. Green manuring (sun hemp, Daincha , Kolingi) and / or green leaf manuring also counteracts the effects of salinity.

4. Irrigation management

Proportional mixing of good quality (if available) water with salin water and then using for irrigation reduces effect of salinity. Alternate furrow irrigation favours growth of plant than flooding. Drip and sparkler irrigation systems aim are reduced use of water which is favorable for growth of plant since slat accumulation also reduced with low usage of water.

All the above four management practices suitably integrated to reduce the soil salinity which in favorable for better growth of plants and ultimately for better yields management of saline soils becomes essentials and unavoidable particularly in areas where both soil as well as irrigation water are saline in nature.