Productive moisture dynamics in sod-podzolic soil under spring barley cultivation

The article presents the results of a long-term two-factor stationary experiment in the conditions of the Republic of Mari El, which was conducted in 1996–2021 in two plots. The aim of the research was to study the dynamics of productive moisture in the 0–20 cm layer of sod-podzolic soil depending on the predecessors of spring barley in six-field crop rotations. The predecessors were potatoes with application of 60 t/ha of manure, spring grain crops (oats, spring wheat) and winter cereals (winter wheat and winter rye). In the course of study a correlation and regression data analysis was carried out between the corresponding hydrothermal coefficient of Selyaninov (HTC) and the reserves of available soil water in barley sowings during “shooting” and “wax ripeness” phases after various predecessors. As a result, it was found out that sowing barley after oats led to one unit increase of HTC, that raised the amount of soil water available to plants by 17.45±7.95 mm by the time of barley harvesting. Dead moisture reserves were possible at HTC less than 0.79 in this case. Correlation and regression analysis data for other predecessors were less evident, but retained the noted trend. It was established that the weather conditions of 1996-2021 in the Republic of Mari El to the time of spring barley sowing mainly provided "satisfactory" (20–30 mm) amount of productive soil moisture in the 0–20 cm soil layer. Potatoes were the best predecessors in the experiment. After that during the vegetation of barley the reserves of available water in the soil were least determined by the HTC – R-squared (R 2 ) was 0.306±0.096, the amount of productive moisture decreased by 34.6 % on average. After cereal crops, mainly oats, HTC affected significantly the variability of the “amount of productive moisture” indicator by the time of harvesting (R 2 up to 0.802±0.028) reducing the yield twice from the moment of sowing (up to 15.1±5.1 mm).