Dear Valery,

It will help if you specify the purpose of your investigation and especially the accuracy you need to achieve. Also, are you interested in mineral, or organic carbon, or both?

Once you have a clear idea of your needs, search the Web with the keywords "estimating soil carbon content": this will return over 8.9 million web pages... including many links to papers and documents on this topic. For instance, this site may provide a useful introduction to this topic:

http://soilcarboncoalition.org/measuring_soil_C

Best regards, Michel.

thak you Michel,

I need both mineral and organic carbon

Do you need to evaluate or estimate. Generally, if we already have one measurement we can evaluate against another measurements. For example, SMAP satellite level 4 produces soil organic carbon at 9 km spatial resolution which we evaluate using in situ observation. As Micheal said you have to specify the purpose of your investigations. As I said, if you just want to evaluate at regional or watershed you can use remotely sensed product, but for farm scale or plot scale you might need to collect sample and analyze in laboratory.

Dear Valery- Please refer to the pdf attached. You may find answer under ' Method'. 

The remote sensing images were used to predict the precise carbon content associated with organic matter in the soil using NDVI and related equations. A bulk density estimate is required to calculate soil organic carbon stocks in tonnes of carbon per hectare. You may consult the following publications:

1. Scientific Reports 6, Article No. 21842 (2016), doi: 10.1038/srep21842

2. Xu et al. in Soil Use and Management, doi: 10.1111/j.1475-2743.2011.00342.x

Hi Valery. I am sure the above replies are helpful already, especially Dr Verstraete and Dr DK Pal that contain the formulae for calculating it. Here is a contribution from my side with an example using those formulae. Firstly you would need a number for Total Org C of your experimental soil (e.g. 1.2% org C, as an example). Using this value and 10,000 m2 in one hectare x 0.1 m soil depth x 1.4 g/cm3 bulk density x 1.2 % = 16.8 t C/ha. Hope this helps you further. 

Dear Pal, I think his original question was how to estimate soil organic carbon in soil which you explained with an example (e.g. 1.2% org C which he does not have).

Thanks

Dear Naumi, you may consult the following two papers, probably that may serve your purpose.

1. Carbon stock and organic carbon dynamics in soils of Rajasthan, India by Singh et al. (2007). Journal of Arid environments 68, 408-421.

2. Depletion of organic carbon, phosphorus, potassium stock under a pearl millet based cropping system in the arid region of India by Singh et al. (2007) Arid Land Research and Management 21, 119-131.

Dear Dr Ray. I agree with what you said and I apologize I was not clear in my reply. As per your reply, I meant the same thing that Valery will need to get the value of Total Org C by analyzing his experimental soil. I provided a value of 1.2% as an example from my previous work. Thank you for drawing my attention to it.