ИСТИНА

While using polyelectrolytes as soil ameliorants, there are two main directions. The first is the use of linear polymers: when treating the surface of soils with their solutions, a protective polymer-soil cover is formed, which prevents the spread of dust by the wind, erosion by water flows and mechanical destruction of soils in general. However, linear polymers do not directly affect the water-holding capacity of soils. This is where the second direction takes place: the use of hydrophilic covalently crosslinked polymers with network structure, which, when swollen in an aqueous medium, form hydrogels capable of long-term moisture retention, and when mixed with soil, significantly increase soil moisture retention, prevent water evaporation. However, such ameliorants, in turn, do not have the ability to form protective polymer-soil compositions, and do not contribute to the improvement of mechanical stability of soils. It should be noted that there are almost no descriptions of complex acting polymeric soil conditioners that cope with both described tasks at once. This paper presents the results of the use of super-readily cross-linked hydrogel as a soil ameliorant with a complex action that has the ability to biodegradation. For this purpose, a crosslinked copolymer based on acrylamide, potassium acrylate and starch (biodegradable component) was obtained, hereinafter - AM-AKStarch #. N, N-methylene-bis-acrylamide was used as a crosslinking agent; its mass content in the monomer mixture was 0.036 wt%. After the synthesis of the polymer in the block, it was crushed and divided into two fractions: <0.25 mm and 0.25-0.5 mm. For comparison, we also used a commercial medium crosslinked hydrogel (SNF, France), a copolymer of acrylamide and sodium acrylate, which was ground and fractionated in a similar way. The maximum degree of swelling of AM-AK-Starch # is 2-3 times higher than that of commercial one, which is explained by a lower degree of crosslinking and a higher degree of ionization. However, in experiments with quartz sand and sandy loam soil, it was found that the sparsely cross-linked hydrogel is unable to resist the pressure of the outer layers of the soil. Therefore, its degree of swelling drops sharply compared to the average cross-linked commercial one. Nevertheless, AM-AK-Starch # showed decent indicators for improving the water-holding properties of soil/sand in the range of mass contents of 0.5-1 wt.%. In addition, it was further shown that the commercial hydrogel is not capable of forming a single polymer-soil composition resistant to mechanical stress, while AM-AK-Starch # formed a single stable polymer-soil crust. Thus, soil composites based on commercial sample were unable to withstand water and air flows, almost completely collapsing, and crusts based on AM-AK-Starch # retained their integrity even when exposed to wind up to 30 m/s. Keywords: soil erosion, water retention, hydrogels, soil amendments This work was supported by the Russian Foundation for Basic Research (grant number 19- 29-05036 MK)