Classification of Salt-Affected Soils (Arid Land Research and Management 19: 61–79, 2005,DOI: 10.1080/15324980590887344)

Irrigated agriculture in arid and semiarid regions of the world has resulted in salinity and waterlogging problems that are threatening the sustainability of our lands. Based on pH of the saturated paste, electrolytic conductivity of the saturated paste extract (ECe), and exchangeable sodium percentage (ESP), these soils have been classified as saline, alkali, and saline-alkali per the criteria of the U. S. Salinity Laboratory. Apart from textural B horizon, the Soil Taxonomy considers only ESP for defining a natric and ECe for defining a salic horizon. It does not consider pH and the nature of soluble salts as criteria for classifying these soils. All soils with high pH values (>8.5) as well as high ESP (>15) and high ECe (>4 dS m1 ) developed in situ, soils with high pH values (>8.5) as well as high sodium adsorption ratio (SAR >13) and high ECe (>4 dS m1 ) formed due to use of irrigation waters containing high residual sodium carbonate (RSC >2.5 mol m3 ), and those with moderate pH values (7 to 8.5) but high SAR (>13) and high ECe (>4 dS m1 ) formed due to shallow saline water table, are classified as saline-alkali soils. These are classified as Salidic Natrustalfs under Alfisols, since such soils contain both salic and natric horizons. Reclamation of such soils requires both leaching to remove soluble salts and application of amendments to lower ESP. This creates confusion in the mind of soil survey officials, planners, and development authorities. An examination of the composition of saturated paste extracts of these soils shows that these are either to be treated as saline or alkali for the purpose of adopting reclamation techniques. Soils that have the ratio of either ð2CO2 3 þ HCO 3 Þ=ðClþ2SO2 4 Þ and=or Naþ=ðCl þ 2SO2 4 Þ > 1, expressed in mol m3, should be treated as natric and require chemical amendments for reclamation. When soils have both these ratios

Classification of Salt-Affected Soils (Arid Land Research and Management 19: 61–79, 2005,DOI: 10.1080/15324980590887344)

Irrigated agriculture in arid and semiarid regions of the world has resulted in salinity and waterlogging problems that are threatening the sustainability of our lands. Based on pH of the saturated paste, electrolytic conductivity of the saturated paste extract (ECe), and exchangeable sodium percentage (ESP), these soils have been classified as saline, alkali, and saline-alkali per the criteria of the U. S. Salinity Laboratory. Apart from textural B horizon, the Soil Taxonomy considers only ESP for defining a natric and ECe for defining a salic horizon. It does not consider pH and the nature of soluble salts as criteria for classifying these soils. All soils with high pH values (>8.5) as well as high ESP (>15) and high ECe (>4 dS m1 ) developed in situ, soils with high pH values (>8.5) as well as high sodium adsorption ratio (SAR >13) and high ECe (>4 dS m1 ) formed due to use of irrigation waters containing high residual sodium carbonate (RSC >2.5 mol m3 ), and those with moderate pH values (7 to 8.5) but high SAR (>13) and high ECe (>4 dS m1 ) formed due to shallow saline water table, are classified as saline-alkali soils. These are classified as Salidic Natrustalfs under Alfisols, since such soils contain both salic and natric horizons. Reclamation of such soils requires both leaching to remove soluble salts and application of amendments to lower ESP. This creates confusion in the mind of soil survey officials, planners, and development authorities. An examination of the composition of saturated paste extracts of these soils shows that these are either to be treated as saline or alkali for the purpose of adopting reclamation techniques. Soils that have the ratio of either ð2CO2 3 þ HCO 3 Þ=ðClþ2SO2 4 Þ and=or Naþ=ðCl þ 2SO2 4 Þ > 1, expressed in mol m3, should be treated as natric and require chemical amendments for reclamation. When soils have both these ratios

According to broad classification of USDA Soil  Salinity Research 0 to 20 centimeter  surface soil  a soil may  be classified as saline soil   pH between 7 to 8.5 , soluble salt content is  above 4 dsm-1 and exchangeable sodium percent below 15 . Saline-alkali soil pH between 7 to 8.5 , soluble salt content is above 4 dsm-1 and exchangeable percentage is below 15 and alkali soil  pH  above 8.5 , soluble salt content below 4 dsm-1 ,exchangeable sodium percent above 15 of the saturation extract.

Above mentioned salt affected  soil may be generally reclaimed by  flashing of affected soil by  irrigation water and flooding of surface soil   by leching of salt to lower horizon of the  soil.  Application of gypsum as  calcium sulfate   @ 2.5 to 5 tons according to gypsum requirement of salt affected  soil. Application of  organic matter @ 10 tons per hectare or enriched organic matter like vermi-compost @ 5 tons per hectare to make complexes with the soluble salts in the soil. These sat affected soil generally contain soluble salt of  chloride,sulfate,carbonate,bicarbonate ions of calcium,magnesium,potassium ,sodium .  In strongly alkali  soil sodium of carbonate and bio-carbonate ions are serious problem for cultivation of crop.

Green manuring of legume  like Sesbenia aculeta from the on set of monsoon season may be recommended   for reclamation of salt affected soil. Green manuring plant may be burred in the salt affected soil by plowing below one to one and half month plant.

The concentration of salts at the surface layers of soils is a big issue. This is the result of the excessive evaporation compared to precipitation. The use of deep plowing and mixing could be recommended. In addition the use of water which is not excessive in salts is critical. To avoid the addition of salts in excess work with quality of irrigation water. In addition the use of drip irrigation with mulch could be recommended for high value crops. In terms of the remediation of alkali content the use of sulfur might be a good choice. Acids can be used in the drip irrigation system to clean the lines and to help remediate the soil reaction.  If the soil can be lowered to pH 7.3 or lower many of the issues will be resolved. In terms of benefits from organic amendment you might want to consider mature compost which has more longevity in the soil. There is some promising work on conditioning seeds and transplants so they respond better in alkali and saline environments. Some fertilizers and organic amendments can be sources of salinity issues. 

I assume this is a general discussion on soils impacted by salts. I feel when we do this we need to look at some history. Here in the US the salinity lab has been doing and continues to do extensive work in this area. I've attached a older handbook that still has great value USDA Handbook 60.  I believe each impacted field must be evaluated. Dr. Srivastava noted the use of saturated paste method for test, today many look for easier solutions. Most if not all of the plant effects (e.g. yield reductions) used analytical results utilizing the saturated paste preparation method.  We also need to be clear in differentiating between Gypsum and anhydrite. Gypsum (CaSO4.2H2O) and anhydrite (CaSO4).

I Have dealt with saline and sodic soil from spills of oil production 'produced' wastewater. The contamination areas have ECs of ~100+ dS and S.A.R. of ~100+. in reducing the Na contamination by addition of OM, Gypsum on will increase the EC. , we are now in our third year of recovery. 

All impacted fields need to be evaluated and treated as individual projects applying rules of thumb. 

Bob

In salt affected saline soil and saline and alkali soils  management I have  already discussed .  Suitable  crop should be selected like Field crops like Rice ( Oryza sativa), Barley( Hordium vulger), Sugarbit, Sugarcane (Saccharum officinarum), rape seed etc. Fodder crop like Salt  grass ,  Dubgrass( Cynodon decctylon), Rhodes grass ,Bermuda grass, Aromatic plant  plant like Cytronilla , Fruit like Date palm,Coconut, Falsa (Grewal asiatica).

This will help you.

Attached is a link to the USDA Salinity Lab's Plant Tolerance data base which should add to the discussion

https://www.ars.usda.gov/pacific-west-area/riverside-ca/us-salinity-laboratory/docs/research-databases/

The criteria of sodic soil classification has witnessed some changes of late.What are those, let's concentrate on this issue. Soil pH of 8.5 , ESP of 15 , SAR of 8 are no longer valid under soils of different mineralogies.

Furthermore, a lot of material can also be taken from following links

http://forages.oregonstate.edu/matchclover/soils

https://link.springer.com/chapter/10.1007/978-1-4612-3322-0_7

http://www.fao.org/docrep/x5871e/x5871e03.htm

Thanks!

In costal area sea water enundation is a serious problem for development of saline soil. In tropical and subtropical climate where evaporation from surface of the soil exceed preciptation alkali soil developed. In saline soil salt of chloride, sulfate of sodium, potassium, calcium,magnesium may increase salinity of soil. In alkali soil carbonate and bicarbonate of sodiim form alkali soil.