Evaluating agrogenic structurization of soil variants under different application modes in the Forest-Steppe

Abstract

Aim. To develop the general normalized statistical model of organizing the structural state of the investigated soils, to determine the vector of direction and criteria of appraising structurization of soil variants in the Forest-Steppe on macro- and microaggregate levels of organization to obtain objective and integral information about the quality status of soil structure and to determine the critical level of degradation, when the residual resistance against the latter is lost. Methods. Field (investigated agrophysical properties of the most common variants in the Forest-Steppe of Ukraine: gray forest soil, meadow-chernozem soil, typical chernozem), laboratory (air-dried sieving of soil), statistical-analytical (fractal, factor, cluster, non-parametric statistics). Results. The combined study of the change in the state of soil structure in the most common soils in the Forest-Steppe on two hierarchy levels demonstrated the presence of soil-genetic interval in valuable structural units. The appraisal of several distribution series of structural soil units by dimensions in terms of stability using fractal indices and the structurization of agronomically non-valuable fraction of microaggregates of 0.7 and demonstrated the persistence and anti-persistence of the distribution series, namely, stability or trend. The re-grouping of soil structure constituents occurs by dimensions depending on the soil type, and microaggregates in the amount of 0.25 mm are mostly involved in structural aggregates of 1-0.25 mm and less so in more valuable structural units of >1 mm. Conclusions. It was determined that meadow-chernozem soil was the most resistant to anthropogenic impact (introduc- tion of mineral fertilizers and treatment methods). Its coeffi cient of macroaggregation was at a high level and in case of sowing perennial grasses with the introduction of fertilizers - at a very high level. Gray forest soil was found to be less resistant to the introduction of mineral fertilizers and typical chernozem was the most susceptible to agrophysical degra- dation: the macroaggregation coeffi cient was at a very low level. The microaggregation coeffi cient increased from typical chernozem to gray forest soil and meadow-chernozem which demonstrated the increase in humus content and biogenicity in the presented series of soil variants