Agroecological soil properties changes and treated wastewater management in arid regions: A case study from the Kyzylorda Region, Kazakhstan

This study comprehensively assessed the agroecological characteristics and dynamics of soil cover in an experimental plot within the Syrdarya Delta's lower reaches in Kyzylorda Region, Kazakhstan, aiming to provide scientific data for developing sustainable cultivation practices for woody and forage crops amidst escalating water scarcity and soil degradation due to climate change and intensive agriculture. The methodology involved detailed physicochemical analyses of soil samples collected from upper (0-40 cm) and lower (below 40 cm) tiers of an experimental site in Tasboget village, specifically prepared with land leveling and irrigated using treated wastewater, with samples taken initially and after a vegetation period following GOST standards. Key analytical findings revealed significant and detrimental alterations in soil properties, particularly in the vital upper layers, including a shift in mechanical composition, a notable increase in pH (from 8.10 to 8.60), an alarming 1100% rise in sodium (Na⁺) content, dramatic increases in sulfate (SO₄²⁻), and a significant decrease in crucial humus content (up to 58.70%). These adverse changes profoundly undermined the soil's capacity to support plant life, evidenced by a very low (39.20%) survival rate of tree plantations, while lower tiers also exhibited persistent alkalinity and humus depletion alongside chloride and sodium accumulation; field observations further highlighted that higher irrigation volumes led to salt leaching and secondary salinization risks. In conclusion, intensive land leveling and inappropriate irrigation practices in this arid region severely degrade soil health, leading to increased alkalinity, salinity, and crucial humus depletion, creating a highly challenging environment for agricultural sustainability and plant establishment, thus underscoring the critical need for integrated and adaptive soil management strategies, including judicious irrigation, targeted agro-meliorative methods, and the responsible utilization of treated wastewater, which collectively offer an empirically-supported scientific foundation for effective land reclamation and optimized irrigation regimes to enhance the long-term productivity and sustainability of agricultural lands in Kazakhstan's challenging arid environments.