TY JOUR TI MOBILE HUMIC SUBSTANCES IN THE SPATIAL VARIABILITY OF THE CHERNOZEM STRUCTURAL ORGANIZATION AGGREGATE LEVEL KW soil KW humic substances KW structural composition KW aggregate composition JO Bulletin of KSAU AU Kurachenko, N.L. AU Alexandrova, S.V. PY 2012 IS PB Krasnoyarsk State Agrarian University