Application of thermodynamic characteristics to the description of humus acids in soils

A new method of calculating the thermodynamic characteristics of humus subs tances on the basis of their elemental composition is suggested. It is suit able for all humus fractions, permitting the calculation of the following p arameters under the standard conditions: the heat capacity C-p, the absolut e entropy S-0, the entropy of formation Delta S-0, the free energy of forma tion Delta G(0), the heat of formation Delta H-0, and the heat of combustio n Q(0). It was established that the irrigation of chernozem and dark and light ches tnut soils alters the thermodynamic parameters of humic acids. There is an increase in the heat of combustion, the heat of formation, the free energy, and the entropy of formation.