THE CONTENT AND COMPOSITION OF ORGANIC-MATTER IN CHERNOZEMS AND ITS ROLE IN THE FORMATION OF A WATER-STABLE STRUCTURE

The composition of chernozem organic matter (at C(org)greater than or equal to 3% and Cha : Cfa greater than or equal to 1.5) favors the for mation of the optimum (above 40%) content of water-stable aggregates > 0.25 mm in diameter. When chernozems are plowed, organic matter is min eralized by 22-35%, and the content of water-stable aggregates >0.25 m m decreases by a similar extent. The most pronounced decreases are obs erved for the content of detritus and fulvic acids in organic matter a nd for the content of fractions >1 mm in diameter in the composition o f water-stable aggregates, which implies the involvement of detritus a nd fulvic acids along with humic acids in forming aggregates of this s ize.