SODIC SOILS.pptx

The Problematic soils are major constrain for agriculture. Understanding their properties in important for providing solutions. Sodic soils are one of them mainly found in coastal areas and Arid climate conditions. Further knowledge about management of sodic soils is necessary.

1. SODIC SOILS K. Avinash I M.Sc. (Ag.) Soil Science Department of Soil Science and Agricultural Chemistry Tamil Nadu Agricultural University, Coimbatore SAC 511 MANAGEMENT OF PROBLEM SOILS AND WATER (2+1)

2. Characters of Sodic soil

3. A lkaline hydrolysis - e.g. sodium carbonate The surface is dry and hard EC = 4 dS /m at 25 °C pH = 8.2 to 10 ESP > 15

4. Low level of Ca & Mg Dispersed clay particles High level of sodium Absent of white surface Organic matter - Black sodic soils

5. Source: FAO 2015; Butcher et al. 2016; Zaman et al. 2018; Sahab et al. 2021 Global distribution of salt-affected land area

6. Source : Encyclopedia of the Environment (unknown date). https://www. encyclopedie-environnement.org/ en /zoom/land-salinization/ Global distribution of saline, sodic, and saline-sodic soils

7. Source: FAO 2015; Butcher et al. 2016; Zaman et al. 2018; Sahab et al. 2021 Distribution of salt-affected land area in India

8. Source: CSSRI database 2010

9. Tamil nadu These are essentially found in the central Tamil Nadu covering Ramanathapuram Cuddalore Kanchipuram Tirunelveli Thanjavur Pudukottai Madurai Tiruchirapalli Source: CSSRI database 2010

10. Parent material Genesis of Sodic soils Low rainfall

11. Soils formed from rocks having high proportion of bases are become saline / sodic in nature. eg. Basalt, Sand stone etc. Parent material Low rainfall High Evaporation Genesis of Sodic soils

12. One of the important reason for the development of Sodic soil is insufficient water to remove bases from soil horizon and thereby accumulation of salts in soil. This is more common in semi arid and arid regions where the rainfall is usually low. Parent material Low rainfall High Evaporation Poor drainage

13. Water along with salts reaches the surface from sub surface of the soil by capillary raise due to high evaporation in arid and semi arid regions. This results in accumulation of salt at surface of the soil while water alone moves to atmosphere. Parent material Low rainfall High Evaporation Poor drainage Poor quality irrigation waters

14. Water logged salinity / sodicity is a common seen in low-lying area of inlands particularly in high clay soils. Improper drainage leads to accumulation of salts at surface horizon and becomes reason for entry of sodium in clay complex. High Evaporation Poor drainage Poor quality irrigation waters High water table

15. Continuous use of poor quality sodic water for cultivation accumulates salts / sodium in the soils. Poor drainage Poor quality irrigation waters High water table Sea water intrusion

16. High water table at alluvial plains and other areas leads to improper drainage, which leads to accumulation of salts in soils. Poor quality irrigation waters High water table Sea water intrusion Base forming fertilizers

17. In coastal regions seawater intrudes into land and pollutes the soil as well as ground water of that locality. High water table Sea water intrusion Base forming fertilizers

18. Continuous application of base forming fertilizers for cultivation is also causes soil salinity / sodicity. eg. NaNO 3 Sea water intrusion Base forming fertilizers

19. Plant growth in Sodic soils Effect of excess exchangeable sodium

20. Graph showing relation between ESP and hydraulic conductivity I nfluence on the physical soil properties . Increase in exchangeable sodium – D ispersed soil - results - breakdown of soil aggregates. L owers the permeability of the soil to air and water. I mpermeable surface crusts that hinder the emergence of seedlings. Plant growth in Sodic soils Effect of excess exchangeable sodium

21. A ffects soil pH . lowering the availability of some essential plant nutrients. For example, the concentration of the elements calcium and magnesium in the soil solution is reduced as the pH increases due to formation of relatively insoluble calcium and magnesium carbonates by reaction with soluble carbonate of sodium, etc. and results in their deficiency for plant growth. pH Solubility of CaCO 3  me/l 6.21 19.3 6.50 14.4 7.12 7.1 7.85 2.7 8.60 1.1 9.20 0.8 10.12 0.4 Source: FAO

22. N Nitrogen in Sodic soils S odic soils are generally deficient in available nitrogen . N itrogen losses - highest under alternate aerobic and anaerobic conditions - sodic soils. L osses of N (ammonia) - volatilization - high pH . affect the transformations and availability of applied nitrogenous fertilizers . I ncreasing soil pH and sodicity - Increases the time for complete hydrolysis of urea. Reduced hydrolysis in soils of high sodicity was attributed to the possible effect of high pH on the activity of the enzyme urease or the direct effect of carbonate ions on the formation of ammonium carbonate .

23. In P otato crops - twice as much nitrogen was needed as when under conditions of good soil structure. C rops grown in sodic soils generally responded to higher levels of N application compared to crops grown in non-sodic soils but otherwise similar soil and climatic conditions. G enerally recommendation - sodic soils fertilized at 25% excess - recommendation for normal soils. (CSSRI, Karnal - Annual Reports 1980). A pplication of additional nitrogen compensated the yield reduction - increasing levels of ESP . Increased uptake of calcium and magnesium ; D ecreased uptake of sodium N P Phosphorous in Sodic soils Nitrogen in Sodic soils

24. P Phosphorous in Sodic soils General trend of phosphorus availability in relation to pH and degree of sodium saturation. B arren sodic soils has positive correlation between soluble P status and the EC of the soil. Due to presence of sodium carbonate - resulted formation of soluble sodium phosphates T he soil calcium - calcium carbonate form - not available to the plants. The crops grown in freshly reclaimed sodic soils did not respond to applied P fertilizers for 4-5 years because of their high available P status Source: Pratt and Thorne (1947) N Potassium in Sodic soils K

25. I ncreasing soil sodicity resulted in reduced uptake of potassium by most crops. Lack of response to applied K in sodic soils observed. It was attributed to the presence of K-bearing minerals in the soil which could supply sufficient K to meet the crop requirements. ESP K % in 30 day old plants Safflower Linseed Cowpeas Raya Sunflower 7.6 3.06 1.66 2.04 3.94 2.24 12.5 2.53 1.56 1.96 3.49 2.46 16.6 1.95 1.40 1.92 3.38 2.63 23.0 1.58 1.23 1.92 2.87 3.02 44.2 1.25 0.95 1.89 2.12 2.64 Source: Singh et al., 1979, 1980, 1981; Chhabra et al., 1979 K Calcium in Sodic soils Ca Potassium in Sodic soils

26. Ca Calcium in Sodic soils I ncreased uptake of sodium - decreased uptake of calcium by plants. I ncrease in ESP - I ncrease in Na concentration of plants > D ecrease in the Ca concentration . For this reason the plants often accumulate sodium in toxic quantities before the calcium becomes limiting for plant growth. However, when the exchangeable sodium levels are very high, calcium is often the first limiting nutrient, for example when the soils contain appreciable quantities of free sodium carbonate and the soil pH is high such that application of amendments is absolutely necessary. P M Micronutrients in Sodic soils

27. M Micronutrients in Sodic soils High pH, low organic matter content and presence of calcium carbonate strongly modify the availability of micronutrients to plants grown in sodic soils. Zn Zn in Sodic soils

28. M Micronutrients in Sodic soils Zinc deficiency has been widely reported for crops grown in sodic soils and is accentuated when an amendment is applied to a Zn-deficient sodic soil. Several field studies have shown significant increase in crop yields due to application of zinc. Field studies by showed that application of 10 kg ZnSO 4 /ha was sufficient to mitigate the deficiency of Zn in rice grown in an amended, highly sodic soil. Zn Zinc in Sodic soils Fe Iron in Sodic soils

29. Fe Iron in Sodic soils Iron is limited - D ue to high pH & calcium carbonate . Addition of iron salts to correct the deficiency was generally not useful unless it was accompanied by changes in the oxidation status of the soil brought about by prolonged submergence and addition of organic matter . There is increase in the extractable Fe and Mn status of a sodic soil upon submergence up to 60 days; more when organic materials ( rice husk or farmyard manure) were incorporated in the soil. Zn Zinc in Sodic soils B Boron in Sodic soils

30. B Boron in Sodic soils P resent in the toxic range. A positive correlation between water soluble boron and the pH and EC of soils. In a laboratory study - reduction in the water soluble boron content of a highly sodic soil upon addition of gypsum observed. At high pH and sodicity, boron - highly soluble sodium metaborate - G ypsum is converts it to relatively insoluble calcium metaborate . Reduced uptake of boron by grasses with decreasing ESP due to gypsum application. Fe Iron in Sodic soils Mo Molybdenum in Sodic soils

31. B Boron in Sodic soils Mo Molybdenum in Sodic soils solubility of Mo increases with pH and for this reason forage grown on sodic soils is likely to accumulate Mo in excessive quantities, which may prove toxic to the animals feeding on them F Fluoride in Sodic soils

32. B Boron in Sodic soils F Fluoride in Sodic soils Water extractable fluoride increased with increasing sodicity and pH . F content of plants i ncreased with increasing ESP and decreased with application of P fertilizer . Mo Molybdenum in Sodic soils

33. Reclamation of Sodic soils

34. Reclamation of Sodic soils G ypsum or calcium chloride - supply soluble calcium - replacement of exchangeable sodium, or other substances. Organic matter (i.e. straw, farm and green manures), decomposition and plant root action also help dissolve the calcium compounds found in most soils, thus promoting reclamation but this is relatively a slow process. The kind and quantity of a chemical amendment to be used for replacement of exchangeable sodium in the soils depend on t he soil characteristics including T he extent of soil deterioration, D esired level of soil improvement including crops intended to be grown and economic considerations.

35. Reclamation of Sodic soils Gypsum ( CaSO 4 .2H 2 O )

36. white mineral - occurs extensively in natural deposits. It must be ground before it is applied to the soil. S oluble in water. D irect source of soluble calcium . Gypsum reacts with both the Na 2 CO 3 , and the adsorbed sodium as follows: Gypsum ( CaSO 4 .2H 2 O ) Calcium chloride (CaCl 2  2H 2 O) Na 2 CO 3  + CaSO 4  -> CaSO 3  + Na 2 SO 4  (leachable)  + CaSO 4  <-> Clay micelle   + Na 2 SO 4  (leachable)    

37. H ighly soluble salt supplies soluble calcium directly. Its reactions in sodic soil are similar to those of gypsum: Calcium chloride (CaCl 2  2H 2 O) Gypsum ( CaSO 4 .2H 2 O ) Sulphuric acid (H 2 SO 4 ) Na 2 CO 3  + CaCl 2  -> CaCO 3  + Na Cl  (leachable)  + CaCl 2  <-> Clay micelle   + NaCl  (leachable)  

38. A luminium sulphate (Al 2 (SO 4 ) 3 .18H 2 O O ily corrosive liquid. Purity – 95%. C alcium carbonate reacts to form calcium sulphate and provides soluble calcium indirectly. Chemical reactions involved are: Sulphuric acid (H 2 SO 4 ) Calcium chloride (CaCl 2  2H 2 O) Iron sulphate FeSO 4 .7H 2 O A lum  + CaSO 4  <-> Clay micelle   + Na 2 SO 4  (leachable)   Na 2 CO 3  + H 2 SO 4 - > CO 2 + H 2 O   + Na 2 SO 4 (leachable) CaCO 3  + H 2 SO 4  -> CaSO 4  + H 2 O + CO 2

39. S olid granular materials. High degree of purity. soluble in water. D issolve in soil water and hydrolyse to form sulphuric acid, which in turn supplies soluble calcium through its reaction with lime present in sodic soils. A lum Iron sulphate FeSO 4 .7H 2 O A luminium sulphate (Al 2 (SO 4 ) 3 .18H 2 O Sulphuric acid (H 2 SO 4 ) Sulphur FeSO 4  + 2H 2 O -> H 2 SO 4  + Fe (OH) 2 H 2 SO 4  + CaCO 3  -> CaSO 4  + H 2 O + CO 2  + CaSO 4   <-> Clay micelle   + Na 2 SO 4  (leachable)  

40. yellow powder. P urity from 50 percent to more than 99 percent. N ot soluble in water S - undergo oxidation to form sulphuric acid which in turn reacts with lime present in the soil to form soluble calcium in the form of calcium sulphate: Sulphur A lum Iron sulphate FeSO 4 .7H 2 O A luminium sulphate (Al 2 (SO 4 ) 3 .18H 2 O SO 3  + H 2 O = H 2 SO 4 2 S + 3 O 2  -> 2 SO 3  (microbiological oxidation)  + CaSO 4  <-> Clay micelle   + Na 2 SO 4  (leachable)   CaCO 3  + H 2 SO 4  -> CaSO 4  + H 2 O + CO 2 Pyrite (FeS 2 )

41. O xidation of pyrite are complex and appear to consist of chemical as well as biological processes . The first step in the oxidation is nonbiological and iron II sulphate (ferrous) is formed B acterial oxidation of iron II sulphate - by  Thiobacillus ferrooxidans , Pyrite (FeS 2 ) 4 FeSO 4  + O 2  +2 H 2 SO 4  -> 2 Fe 2  (SO 4 ) 3  + 2 H 2 O 2 FeS 2  + 2 H 2 O + 7 O 2  -> 2 FeSO 4  + 2 H 2 SO 4 Subsequently iron III sulphate (ferric) is reduced and pyrite is oxidized by Chemical reaction . Elemental sulphur so produced may then be oxidized by  T. thiooxidans   and the acidity generated favours the continuation of the process. 4 FeS 2  + 2 H 2 O + 15 O 2  -> 2 Fe 2  (SO 4 ) 3  + 2 H 2 SO 4 2 S + 3 O 2  + 2 H 2 O -> 2 H 2 SO 4 Fe 2  (SO 4 ) 3  + FeS 2  -> 3 FeSO 4  +2 S Sulphur

42. Subsequently iron III sulphate (ferric) is reduced and pyrite is oxidized by C hemical reaction . Elemental sulphur so produced may then be oxidized by  T. thiooxidans   and the acidity generated favours the continuation of the process. Pyrite (FeS 2 ) 4 FeS 2  + 2 H 2 O + 15 O 2  -> 2 Fe 2  (SO 4 ) 3  + 2 H 2 SO 4 2 S + 3 O 2  + 2 H 2 O -> 2 H 2 SO 4 Fe 2  (SO 4 ) 3  + FeS 2  -> 3 FeSO 4  +2 S Oxidation of pyrite are complex and appear to consist of chemical as well as biological processes . The first step in the oxidation is nonbiological and iron II sulphate (ferrous) is formed Bacterial oxidation of iron II sulphate - by  Thiobacillus ferrooxidans , 4 FeSO 4  + O 2  +2 H 2 SO 4  -> 2 Fe 2  (SO 4 ) 3  + 2 H 2 O 2 FeS 2  + 2 H 2 O + 7 O 2  -> 2 FeSO 4  + 2 H 2 SO 4

43. Reference Somani , L.L. 2013, “Sodic soils: their reclamation and management” Agrotech Publishing Academy Udaipur – 313002. Bresler , Eshel , Brian L. McNeal, and David L. Carter.  Saline and sodic soils: principles-dynamics- modeling . Vol. 10. Springer Science & Business Media, 2012. Mandal, A. K., R. C. Sharma, G. Singh, and Ie Dagar . "Computerized Database On Salt Affected Soil In India, Technical Bulletin No. CSSRI/Karnal/2/2010." (2010): 28. https://www.fao.org/3/x5871e/x5871e05.htm#4.4%20Reclamation%20and%20management Sumner, Malcolm E. "Sodic soils-New perspectives."  Soil Research  31, no. 6 (1993): 683-750. Lal, F, P Lal, and M Singh, "Effect of Ca/B Ratios in Soil On the Yield of Bajra Grown On Saline-Sodic Soils" Journal of the Indian Society of Soil Science 27, no.1.(1979): 95-. Kumar, Parveen, Ram Kishor Fagodiya , Suresh Kumar Chaudhari, Rakesh Singh, Ajay Kumar Mishra, Kailash Singh, and Dinesh Kumar Sharma, "Effect of Different Nitrogen Management Options on Nutrient Uptake, Biomass Carbon Sequestration and Grain Yield of Maize-Wheat System in Reclaimed Sodic Soil" Journal of Plant Nutrition 45, no.8.(2022): 1240-1252. Gupta, Manjul, Pankaj Kumar Srivastava, Suman B Singh, Nandita Singh, and Shri Krishna Tewari, "Organic Amendments with Plant-Growth-Promoting Fungi Support Paddy Cultivation in Sodic Soil" Communications in Soil Science and Plant Analysis 46, no.18.(2015): 2332-2341. Mishra, V K, A K Nayak, C S Singh, S K Jha, Rahul Tripathi, Mohammad Shahid, R Raja, and D K Sharma, "Changes in Soil Aggregate-Associated Organic Carbon and Nitrogen after ten Years under Different Land-Use and Soil-Management Systems in Indo-Gangetic Sodic Soil" Communications in Soil Science and Plant Analysis 45, no.10.(2014): 1293-1304. Sharma, D. K., and Randhir Singh. "Salinity News 2010_2." (2010). Thank You

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