The influence of irrigation with mineralized waters and agro-ameliorative measures on the gross and mineralogical composition of chornozems of Transdniester region

Goal. To establish the patterns of the influence of irrigation with mineralized waters, the application of organic and mineral fertilizers on the gross composition and composition of clay minerals of the silty fraction of southern and typical chornozems of Transdniester region. Methods. Field — to study the influence of irrigation and agro-ameliorative measures on soil properties; laboratory-analytical — to determine the indicators of the gross and mineralogical composition of soils; mathematical-statistical — to assess the reliability of the research results. The researches were carried out in the Odesa oblast on the territory of the Danube-Dniester Irrigation System (DDIS) within the modern Bilhorod-Dniester (former Tatarbunar) administrative district on the territory of the Tatarbunar territorial community (TC) in a field stationary multi-year experiment (Biloliskyi stationary), and on the territory of the Divisiina TC in a small-plot field stationary multi-year experiment (Zhovtoiarskyi stationary) in 2003–2018. The research was based on the methodology of ecological and agro-reclamation surveys of irrigated lands [20]. Results. Irrigation with mineralized water led to an increase in the Na2O content in the studied soils. A tendency to increase the content of CaO and MgO in the 25–50 cm layer was noted in the variants with the introduction of phosphogypsum into irrigation water and soil. The silty fraction of the studied chornozems in the arable layer was represented mainly by minerals of the montmorillonite (smectite) group, mixed-layered (in soil samples that were under anthropogenic factors), hydromicas, and in much smaller quantities — kaolinite and chlorite. As a result of irrigation with mineralized water, the appearance of mixed-layered formations of the hydromica-montmorillonite type was observed. The introduction of phosphogypsum, and organic and mineral fertilizers caused a redistribution of clay minerals towards an increase in the content of hydromica material. Conclusions. Irrigation with mineralized water of southern and typical chornozems of the Transdniester region influenced their gross and mineralogical composition. In the subsoil layer, a narrowing of the SiO2/R2O3 ratio was observed due to an increase in the content of Fe2O3 and Al2O3. In the silty fraction of the arable layer of soils, mixed-layered minerals of the hydromica type — montmorillonite appeared. With the use of agro-reclamation measures, the crystallization of minerals with mobile crystal lattices decreased due to the formation of organomineral complexes.