Thursday, March 28, 2024
General Agriculture

Alkaline (Sodic) Soils and Saline-Alkaline Soils

These are soils in which the sodium content or Na saturation is greater than 15%. That is, if the exchange sites of the soil is occupied by sodium to the tune of 15%. The term “exchangeable sodium percentage” (ESP) or sodium adsorption ratio (SAR) is usually used and expressed as

ESP = ex Na meg/100g soil    x 100

C.E.C. meg/100g soil

For example, (i) if C.E.C. of a soil is 10meq/100g in which Mg = 2.5, Ca = 2.0, K =1.0

Na = 2.5 and A1 = 2.0 meq/100g soil

Then   % Na = 2.5 meq/100g x 100

10meq/100g

= 25% Na

(ii) if Na = 1.0meq/100g soil then   % Na = 1.0  x 100

   10

= 10% exchangeable sodium

Conclusion: Soil (i) is alkaline whereas solid (ii) is not.

Saline-Alkaline Soils

A soil which is both saline (electrical conductivity > 4mmhos/cm) and alkaline (ESP > 15%) is referred to as saline-alkali soil or saline-sodic soil.

Such a soil has pH value of less than 8.5: and if the salts are leached out, excess sodium reacts with carbon dioxide to form sodium carbonate and the pH of the soil may be as high as 9 or 10, thus turning the soil to pure sodic soil.

Read Also: Sources of Salt-Affected Soils

Agric4Profits

Benadine Nonye is an agricultural consultant and a writer with over 12 years of professional experience in the agriculture industry. - National Diploma in Agricultural Technology - Bachelor's Degree in Agricultural Science - Master's Degree in Science Education... Visit My Websites On: 1. Agric4Profits.com - Your Comprehensive Practical Agricultural Knowledge and Farmer’s Guide Website! 2. WealthinWastes.com - For Effective Environmental Management through Proper Waste Management and Recycling Practices! Join Me On: Twitter: @benadinenonye - Instagram: benadinenonye - LinkedIn: benadinenonye - YouTube: Agric4Profits TV and WealthInWastes TV - Pinterest: BenadineNonye4u - Facebook: BenadineNonye

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