TY JOUR TI CONTENT AND RESERVES OF ORGANIC MATTER CARBON IN FALLOW AND ARABLE SOILS OF THE OMSK IRTYSH REGION KW carbon KW organic matter KW subtaiga KW forest-steppe KW steppe KW fallow land KW arable land KW omsk irtysh region JO Vestnik of Omsk SAU AU AZARENKO, Y.A. PY 2024 IS 56 PB FSBEI HE Omsk SAU