Why Sodicity is a problem?

Sodicity can cause toxicity to plants and create mineral nutrition problems such as Ca2+ deficiencies. In saline soils soluble ions such as Cl−, SO42−, HCO3−, Na+, Ca2+, Mg2+, and sometimes NO3− and K+ can harm plants by reducing the osmotic potential.

What is the difference between salinity and Sodicity?

While salinity can improve soil structure, it can also negatively affect plant growth and crop yields. Sodicity refers specifically to the amount of sodium present in irrigation water. Irrigating with water that has excess amounts of sodium can adversely impact soil structure, making plant growth difficult.

How is Sodicity measured?

Identifying sodic or dispersive soils

1. measure the exchangeable sodium percentage (ESP) as part of a standard soil test (measures sodicity)
2. use a simple soil dispersion test.
3. observe visual indicators of moderate or severely dispersive topsoils.

What is soil Sodicity?

Sodicity in soil is the presence of a high proportion of sodium ions relative to other cations. As sodium salts are leached through the soil, some sodium remains bound to clay particles—displacing other cations. Soils are often considered sodic when the amount of sodium impacts soil structure.

How does Sodicity cause dispersion?

The sodium weakens the bonds between soil particles when wetted resulting in the clay swelling and often becoming detached. When this happens the clay particles spread out or disperse making the soil water cloudy. This process is called dispersion and occurs in sodic soils without any disturbance of the soil.

What is SAR soil?

Sodium adsorption ratio is a measure of the amount of sodium (Na) relative to calcium (Ca) and magnesium (Mg) in the water extract from saturated soil paste. It is the ratio of the Na concentration divided by the square root of one-half of the Ca + Mg concentration.

What causes soil Sodicity?

Sodicity is caused by the presence of sodium attached to clay in soil. A soil is considered sodic when the sodium reaches a concentration where it starts to affect soil structure. The sodium weakens the bonds between soil particles when wetted resulting in the clay swelling and often becoming detached.

Which one is the most tolerant crop to soil Sodicity?

Some crops are more tolerant of sodicity and waterlogging than others:

• Wheat is moderately tolerant and can produce good yields at ESP values of 30% under suitable conditions.
• Lentil and chickpea yields are severely restricted by ESP values of 10%.

How do you manage Sodicity?

Managing dispersive (sodic) soils

1. Avoid disturbing already productive sodic soils.
2. Apply lime or gypsum.
3. Increase organic matter.
4. Use deep-ripping.
5. Use raised beds or deepened seedbeds.
6. Use alternative plant and land-use options.

How is ESP and SAR calculated?

ESP can be estimated by the following empirical formula: ESP =[100 (-0.0126 + 0.01475 x SAR) ] / [1 + (-0.0126 + 0.01475 x SAR)].

What causes Sodicity in soil?

What is SAR of irrigation water?

The Sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils. It is an indicator of the suitability of water for use in agricultural irrigation, as determined from the concentrations of the main alkaline and earth alkaline cations present in the water.