During the entire period of evolution, the existence of the human population has depended on nature, i.e. on natural, and particularly, on artificial phytocoenoses. In the course of the development of agricultural systems, the species-varied composition of natural stands changed into intensively-cultivated monocultural plant communities. Through his purposeful activities, the farmer has brought these artificial agrophytocoenoses to a high productive efficiency, but also to a considerable breeding risk. Plant cultivars have lost their natural resistance of natural phytocoenoses against harmful factors. In agriculturally advanced countries, the uncertainty of yields was eliminated by rotating crops. From this point of view, the Cyclic sequence of various crops in the fields has become a stabilizing factor of every agricultural system. The criterion of the quality of the system of rotating crops is the level of production, as well as harmony with the landscape in which it is implemented.