Fertility reproduction features of southern carbonate chernozems in the conditions of the dry-steppe zone of Northern Kazakhstan (Shortandinsky district of Akmola region) are studied. We studied the changes of humus content in the model micro plot experience. Various variants of the experiment with non-fallow and dump steam without fertilizers, grain crops with different doses of mineral fertilizers, manure, as well as with straw and sideral crops (pea-oat mixture, Donnik) are laid down. The introduction of rotted manure in small doses of 20 t / ha did not provide an increase in humus during crop rotation. When adding 40 and 80 t / ha of manure to the fallow field, it allowed to increase the humus content by 0.24 and 0.18 % of the initial amount. The introduction of sideral steam and perennial grasses into crop rotation enhanced the processes of humification and provided a positive balance of humus. In this version of the experiment, the amount of humus increased by 0.10-0.13 %. The greatest accumulation of organic matter occurred when using melilot: the increase in humus was 0.39 %. Long-term cultivation of permanent wheat crop in one field, even with high doses of mineral fertilizers, does not provide significant reproduction of soil fertility. The application of mineral fertilizers does not contribute to the increase of humus in the soil. The greatest decrease in humus content in southern chernozems is observed in the permanent dump and waste-free pair-0.11 and 0.13% over a 6-year period of observations.
