There is too much premature praise for biochar and its products. There is virtually nothing extra to acive over a proper organic matter management with undigested plant residues or manues.

Dr.Ghafoor, good question but difficult to give definite answer. I agree to a greater extent with   the comments of Dr.Schnug .The role of composted manures in reclamation/amelioration of sodic soils is well documentated. What role the biochar plays in improving the sodic/saline sodic soils is not known. A major portion of added biochar is expected to remain in soils for centuries (as per some limited studies may be around 500 years).A small portion of some sort of labile biochar may play some role in nutrient retention and release,because of presence of  cation exchange sites.Also a small amount of biochar may participate in biological activity?What is the amount of basic cations like Ca and Mg present in biochar to play role in replacing Na from exchange complex?So let us hear from colleagues who have done some good work on biochar.We are majorly interested in mechanism  of action of biochar in sodic environment.

Thanks Dr. Rao and Schnug for sharing the question. Let us see urther.

 I am supplementing through one very good studies covering the subject , you have raised Dr Ghafoor. Remediating saline–sodic soils with organic amendments is increasingly seen as a cheaper and sustainable alternative to inorganic materials. The reclamation potential of biochar, biosolids and greenwaste composts applied to a saline–sodic soil was evaluated in a laboratory leaching experiment using moderate SAR reclaimed water. Treatments included biochar, biosolids co-compost, greenwaste compost (all applied at a 75 t ha−1 rate), gypsum (50% soil gypsum requirement), biochar + gypsum, biosolids + gypsum, greenwaste + gypsum and a non-amended control ( Chaganti et a. 2015, Agricultural Water Management  158: 255-265).l  All treatments were subjected to a one month incubation after which, soils were filled in columns and leached using reclaimed water until 7 PV of water had passed. Cumulative leachate losses of Na+, Ca2+, and Mg2+ were evaluated in addition to soil properties after leaching. Results show that leaching with moderate SAR water was effective in reducing the soil salinity and sodicity of all soils, irrespective of amendment application. However, incorporating biochar and composts significantly enhanced this effect. Salt leaching was higher in soils treated with organic amendments. Cumulative leachate losses of cations were significantly higher from biochar and compost treated soils compared to gypsum and unamended controls. 

Enclosed below two very interesting PDFs highlighting the role of biochars in remediation of sodic soils.

Dr.Ghafoor, I have come across a good review article where it was highlighted that the biochars are neutral to basic in pH  and provide some sort of liming effect and may have undesirable effect in alkaline soils.I am providing the details of the publication. Biochar application to soils A critical scientific review of effects on soil properties, processes and functions .F.Verheijen,S. and others.EUR24099EN,office of the official publications of the European Communities Luxembourg 149pp 2010

Biochar application to soils-European Soil Portal- Europa eusoils. irc. ec. europa eu7 EUR 24099.

Thanks dear colleagues for participating the discussion. Let us listen more from others.

Thanks dear Dr. Anoop Kumar Srivastava.

The soil used in studies "RECLAMATION OF SALINE SODIC SOILs UNDER SEMIARID CONDITION: COMPARATIVE EFFECTS OF DIFFERENT CHEMICAL,

ORGANIC AND INDUSTRIAL AMENDMENTS" b E.F. Aboukila, , P.D. Stahl, C.F. Strom, and S.J. Da is actually slightly saline-sodic. The levels of EC (6-& dS/m) and ESP of 23 is not a big problem for major agri crops (except some vegetables) and crops can be managed without reclamation. Again the authors have not computed economics of treatments.

However, the second paper is review and includes different aspects of biochar uses but yet inconclusive.. 

Dear Dr. Rao . Thanks for providing input. The paper by "F.Verheijen,S. and others.EUR24099EN,office of the official publications of the European Communities Luxembourg 149pp 2010" contains review but minor benefits (non-significant) have attributed to the application of biochar.

Dear Dr.Ghafoor I agree with your comprehension of the review article. We may be able to increase the carbon stocks in saline sodic soils with application of biochars of woody plants but the carbon stocks may not have  much reclamation effect or amelioration of those soils.

Dear Dr. Rao  you are perfectly correct. 

It is very well known that reclamation of saline-sodic soils (with pH > 8.5) with dominant carbonate and bicarbonate ions in soil solutions is fully successful with the addition of gypsum and rice as the first crops in rainy season. Use of other material like rice husk etc that remain inert  chemically  do not help in reducing  soil pH. Biochar being  a charred material would remain also chemically inert and expected to have any impact in reducing pH of the sodic soils. However their physical presence would show show a bit high amount of OC. For better information one can go through the 1970-1980's publications of the ICAR-CSSRIpublications.

also in this context I cant see any use from biochar. better think about a proper organic management through residues from your crop rotation!

dear colleagues, I am thankful for your experts contributions on the subject. I wonder the investigation work has to be fair, environment friendly and thus indirectly health friendly. Lot of sympathies for the indiscriminate use of biochar may not yield results as ware being expected and postulated.

There is a recent experimental literature examining biochar as a means of sorbing NaCl to mitigate salt impacts.  Most chars do sorb Na+ and Cl-; however, one would expect  gradual leaching of ionic species from chars.  If there is pulsed additions of salts, chars could serve to buffer the system, potentially keeping concentrations sufficiently low to avoid adverse effects. 

Enclosed is a publication that demonstrates dramatic results along these lines for simulated road salt additions.

Article Biochar mitigates negative effects of salt additions on two ...

Incidentally leaching of  sodic soils (pH >8.5, ESP>15, ECe> 4 m mhos/cm) does not help in reducing the pH. because of large amount of CO3 and HCO3 salts of Na, which would cause dispersion of clay particles even in presence of any chemically inert material including bio-char.

 Dr.Thomas,I have quickly gone through your paper.Plants survived with biochar and salt additions  but soil properties deteriorated.Simple addition of  50 t/ha biochar increased the soil pH from 7.49 to 8.04 but EC increase  was not much(120 uS/cm to 171 uS/cm).But with salt and biochar additions(50 t /ha)pH increased from 7.32 to 8.29  and EC increased from 1171uS/cm to 5331um/cm.That means normal soil with neutral pH and non-saline became moderately alkaline and saline. Now the problem is,how to ameliorate the soil? what could be the long term effects if the practice is continued?

Dear colleagues very interesting and debatable discussion. I must appreciate the contributions. But still I feel specifically designed studies are required to investigate the role of biochar(s) in amelioration of saline-sodic soils. My second point is about fresh plant materials, e.g. in paper attached by Dr. Thomas, how much plant material will be required to obtain 59 tons biochar per hectare but with minor soil improvement as indicated by Dr. AS Rao.

Thank you for raising such a great issue needing explicit implications. I agreed with the previous suggestions and wonderful discussion. I may add a few points regarding biochar applications to sodic soils:

1. biochar cannot be treated as 'on-size fits all' system as identified by several researchers.

2. biochar role in soil depends on its pyrolysis conditions, and the soil basic properties where it will be applied.

3. for a sodic soil having alkaline soil pH, low temperature biochar can be a good option which have higher labile organic C and slightly acidic pH. 

4. Biochar derived from wood or manure can be used for this purpose.

5. More important, complementary biochar addition along with organic amendment or gypsum may further improve the soil system to regain the viability.

One can go through the publication and find the related references from there:

http://www.sciencedirect.com/science/article/pii/S0925857415000129

Thanking you.

Rishikesh Singh

Dr. Rishikesh Singh has indicated good points for discussion and for further research planning..

Good suggestions by Dr.Singh but points  need research and scientific validation before actual use for reclamation of sodic or saline sodic soils.