Agroecological substantiation of the sustainable development of arable soil fertility of the Altai dry steppe

The soil resources of the Altai dry steppe (and their fertility in particular) degrade in their evolutionary anthropogenic development. Transformation of fertility is occurring due to a combination of phenomena, such as natural conditions, intensive use, farming system practiced in the absence of science-based regimes. It is established that the humus content and humus horizon thickness are statistically significantly reduced due to the activation of deflation and dehumification processes. More than that, areas of alkaline soils are increasing. The authors also point out to the degrading granulometric composition. Also, the amount of physical clay, silt fractions, cation exchange capacity, exchangeable calcium, potassium, and mobile phosphorus decreases. Statistical processing of fertility parameters of allowed us to develop a scale of process dynamism and establish the degree of dynamism in the considered soil properties, as well as to assess the rate of increasing adverse changes or their absence. Intensity of degradation processes and indicators determining it contributed to the development of levels of agro-ecological state, such as "Norma", "Risk", "Krizis" and "Bedstviye" (based on GIS).