You can estimate carbohydrates by phenol-sulfuric acid method (Dubois et al, 1956) using glucose as standard.

In case of protein estimation, please follow Lowry's method of protein estimation (lowry et al, 1951) using BSA as standard.

Reference: Garcia-Rodriguez, F., Puerto, L. del, Venturini, N., Pita, A. L., Brugnoli, E., Burone, L., & Muniz, P. (2011). Diatoms, protein and carbohydrate sediment content as proxies for coastal eutrophication in Montevideo, Rio de la Plata Estuary, Uruguay. Brazilian Journal of Oceanography, 59(4), 293–310.

Thank's, I will try

Okay Joana Neves

I support Dr Shantanu Bhunia. Alternatively, Crude protein content in soil can be estimated by measuring Nitrogen and multiplying by a factor 6.25, fat could be estimated gravimetrically by extracting with methanol-chloroform mixture as solvent, carbohydrate = (100 - Protein% - moisture% - fat% -- ash%).