Nonhydrolyzable residue in humus of chernozems

Mismanagement of chernozems results in a decreasing humus content at the expense of the carbon of the nonhydrolyzable residue (the humin fraction). This conclusion is proved by the original data obtained by the authors and by other scientists. It is also shown that the newly formed humus is dominated by the carbon of nonhydrolyzable residue. These facts attest to the presence of labile humus compounds subjected to mineralization in the humin fraction of chernozems.