In paper we consider the humus state of virgin chernozems in Southern Cisbaikalia and the degree of transformation under agrogenic and postagrogenic impacts. The weak humus layer with high humus concentration is characteristic for these soil covers specified by thermic soil regime. The humic state of virgin chernozems are better than agrogenically transformed ones. Intensive turning is promote considerable recession of humus layer and humus resources and decrease of soil humus state in whole. After passing to fallow land mode the topsoil is divided into upper and lower layers. The upper layer is swarding due to covering of perennial grasses, lack of turning and fertilizing whereas the lower one becomes more packed. The gradual recovering of humus state up to virgin chernozems is observing.