In the Chirchik oasis and Almalyk region of Uzbekistan, industrial activities and intensive agriculture have led to considerable contamination of irrigated soils with toxic elements. The presented study aimed to evaluate the agrochemical state of irrigated serozem and irrigated meadow soils under the influence of the JSC Maksam-Chirchik and the Almalyk Mining and Metallurgical Complex, respectively. For restoring soil fertility, a biological remediation technology including plowed-in tree leaf litter, inoculation with actinomycete strains, and introduction of earthworms took place through lysimetric experiment. Laboratory analyses over spring and autumn showed remediation treatment increased soil nutrient availability. The nitrate nitrogen rose from 16.0 mg/kg (spring) to 22.0 mg/kg (autumn), and phosphorus also increased in treated soils. The mobile potassium level decreased by autumn, likely due to crop uptake and leaching. The contaminated soils contained aluminum (up to 72.4 mg/kg) and water-soluble fluorine (up to 64.3 mg/kg) in spring, exceeding permissible limits; however, these toxic elements declined by autumn after remediation. Heavy metals (chromium and nickel) with trace amounts manifested in spring and declined to safe thresholds in autumn in polluted sites. The biological remediation technology significantly improved the soil’s health by enhancing macronutrient content, promoting humus formation, and reducing the concentrations of toxic elements in the soil. The results demonstrate the technology’s effectiveness in rehabilitating polluted irrigated soils and improving their ecological state.
Irrigated serozem soils, irrigated meadow soils, toxic elements, trophic chain, humus, nutrient elements
The contaminated irrigated soils showed significant seasonal dynamics in nutrient content, with biological remediation increasing available nitrogen and phosphorus. The remediation technology effectively reduced the exchangeable aluminum and fluorine levels and accumulation of chromium, nickel, and persistent pesticides and improved soil fertility, demonstrating its potential for ecological restoration of irrigated soils.