By using Walkley Black rapid titration method for analysing organic matter content, we are facing problem of no colour change of high turbidity of the solution. So what would be the appropriate method for calculating OM content of FYM. Is loss-on-ignition method can be a better alternative or something else which can be scientifically approved.
Hope for your suggestions for this query.
Regards,
Rishikesh
Thanks Dr. Rajendran. Yes, we tried it with 0.5 g sample and even 0.1 but faced the same problem. If you have some detailed protocol, you may share it with me.
Dr.Singh ,have tried the same method with small amount of sample and external heating for half an hour ?
Thank you Dr. Subba Rao sir,
I'll try this method of Nelson and Somners.
Let's hope that the problem of turbidity may not be a case.
Dr.Singh,probably it is better to go for ignition method.You can also compare the ignition with Nelson and Sommers method.You may go through the following paper to know the problems in estimating carbon in diverse manure samples especially wet samples.In dry manure samples ignition may be a better method,comparable combustion method.
Use of routine testing procedures to predict total carbon and C:N ratio of manure s By:Branden J. Furseth Advisor:Dr.Chris Baxter
https://www.uwplatt.edu/files/agriculture/furseth08.pdf
Walkley and Black method suugested by Dr Rajendran is appropriate. But, you have to take a small amount of sample. I think the dilution of sample will help you. Sometimes the turbidity is also because of the impurity of the Orthophosphoric acid used. So please check to that also.
Thank you once again Dr. Subba Rao sir for sharing the related paper.
Thank you Apurva, I'll follow these suggestions in re-analysis.
The best method would be loss on ignition , conventionally followed for determining the carbon content of any organic manure . Any wet digestion method will not be suitable for determining carbon content of organic manures.
Thank you all for your valuable suggestions and especially Dr. Rao sir and dear Apurva for their to the point suggestions.
I tried the method of Walkley and Black by taking sample of 0.1 g (instead of 1.0 g) and provided an extra heating of 30 mins at 150 C. And the resultant was less turbid, and therefore, was easy to identify the colour change.
Thank you once again for fruitful discussion and suggestions on my query.
Regards,
Rishikesh Singh
Walkley-Black or modified Walkley Black. I will send you a paper to the email address listed above.
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