The results of studies of humus dynamics under five-field field rotation (2013–2017) are presented. It was investigated that among four crop rotations, deficient humus balance for rotation was provided only by winter wheat and corn for grain in all three variants of fertilizing system. In the non-fertilizer version, winter wheat accumulated 7.27 t/ha of surface-root residues, which, in the process of humification, provided 1.45 t/ha of humus in the soil. Thus, humus supply exceeded the losses by 0.20 t/ha. In the version with applying only mineral fertilizers (N90P60K60), the excess of the humus yield over losses was 0.32 t/ha, and the additional by-products — 2.04 t/ha. Similar results were obtained for maize on grain. Humus deficiency is observed in all fertilizer variants for soybeans and sunflowers. The highest humus losses (–0.82 t/ha) of soybeans and (–1.06 t/ha) of sunflower are recorded in the version without fertilizer. Humus losses on the steam field variant averaged 2.0 t/ha and, when applying the sidereal crop (corn in the milky-waxy phase), they decreased to — 0.62 t/ha. Applying of mineral fertilizers contributed to a slight decrease in humus losses in both cultures, whereas when adding by-products, humus losses were at the level of error. In short field crop rotation with the cultivation of winter wheat, corn soybeans for grain, sunflower, and the inclusion of the steam field, a deficient humus balance is achieved only when optimal doses of fertilizers are applied to each crop, combined with by-product yield of each crop.