Transformation of structural and aggregate composition parameters of fallow soils in the South-East of Western Siberia

The study of fallow lands is of great importance for sustainable development of agriculture. In addition, the materials presented in this work not only significantly complement the previously published works of the authors but also significantly replenish the knowledge of physical processes occurring in the fallow soils of the right bank of the Ob River in Novosibirsk Region. The aim of the study was to determine the structural and aggregate state of fallow soils of the right bank of the Ob River differentiated by age in the Novosibirsk Region by three parameters: structure coefficient, criterion of water stability of aggregates, and water resistance. For each age category of fallow lands (young, middle-aged, and old), the two most representative soil profiles were selected. The studies were carried out in accordance with generally accepted methods of selecting soil samples and chemical-analytical processing. To identify the reliability of the differences, the obtained data were analyzed by statistical analysis methods in Google Colab with the SciPy Python library. Statistical analysis of the results was carried out based on the non-parametric Kruskal — Wallis and Wilcoxon — Mann — Whitney tests. Regarding the structure coefficient within the arable horizon, the values of this indicator for fallow lands of all ages are at a good level, being in the range of 0.9…5.7. According to the water stability of the studied soils, it is evident that they are actually in the same group, with values ranging from good to excellent throughout the sampling depth. Changes in the water stability down the profile of the studied fallow soils have a similar character in the soils of middle-aged and old fallow lands, as well as virgin lands. According to the structure coefficient, water stability criterion, and water resistance, the studied soils of fallow lands of different ages exhibit generally good indicators of the structural-aggregate state, which is especially important in connection with the dissected relief of the Pre-Salair region. It can also be considered established that the structural and aggregate state of soils of fallow lands of different ages is determined primarily not by the age of the fallow land but by the state of its soils at the time of conversion of arable land into fallow land.