Solubility of the labile forms of soil carbon and nitrogen in K2SO4 of different concentrations

The general pattern of the changes in the solubility of the labile carbon and nitrogen compounds with the changes in the concentration of the salt extractant (0.05 and 0.5 M K2SO4) has been determined for soils differing in their acidity and in their contents of organic matter and nitrogen. Different forms of extracted compounds react differently to changes in the salt concentration. The solubility of inorganic nitrogen compounds (NH 4 + and NO 3 − ) does not depend on the concentration of K2SO4. In most cases, the carbon and nitrogen of the microbial biomass manifest a tendency for increasing extractability with an increase in the concentration of the K2SO4 solution. A fundamental difference is characteristic of the organic carbon and nitrogen compounds, the solubility of which in 0.5 M K2SO4 increases in different soils by 1.5–3.9 times in comparison with their solubility in 0.05 M K2SO4.