Transformation of soil fertility under long-term irrigation with mineralised water

Irrigation with saline water is a challenging yet necessary practice for maintaining sustainable crop production in arid and semi-arid regions, particularly under conditions of climate change and freshwater scarcity. Given the potentially harmful effects of saline water on soil properties, particularly fertility, the primary aim of this study was to determine the extent of impact effects on dark chestnut soils in southern Ukraine, resulting from continuous irrigation of croplands with mineralised water from the Inhulets irrigation system. The Inhulets irrigation water is characterised by a high sodium content (10.49-21.63 me/L), elevated levels of toxic ions (11.83 21.97 me/L), and a high total dissolved solids content (1489-2280 mg/L). The research was conducted between 2003 and 2018 in the Bilozerka District of the Kherson Region. Soil fertility was assessed using the following indicators: humus content and nitrogen, phosphorus, and potassium concentrations. Changes in soil traits were evaluated for statistical significance at P < 0.05 using the MannKendall trend test and cumulative sums of change methods. The findings revealed a statistically significant trend towards a decline in soil humus content (-0.73%; Z-statistic: 2.0381). Conversely, slight but statistically insignificant increasing trends were observed in nitrogen, phosphorus, and potassium concentrations (+9, +2, and +65 mg/kg, respectively; Z-statistics: 0.6794, 0, and 0, respectively). Notably, positive changes were primarily observed after 2013, whereas the earlier period was predominantly characterised by declining soil fertility across all studied indicators. The study’s outcomes hold significant practical value as they highlight the longterm effects of continuous irrigation with mineralised water on soil fertility. These findings provide crucial insights into land reclamation and agrochemical measures necessary to mitigate soil degradation and ensure sustainable agricultural practices in vulnerable agroecosystems