Impact of Organic Wastes and Irrigation Water Quality on Copper and Cobalt Dynamics in Soil and Their Phytoremediation by Statice (Limonium sinuatum L.)

Abstract

This study was conducted during the 2025–2026 agricultural season under a shade net at Al-Imam Agricultural Nursery, Al-Imam Subdistrict, Al-Mahawil District, Babil Governorate, Iraq, to evaluate the effects of organic wastes, irrigation water sources, and statice cultivation (Limonium sinuatum L.) on copper and cobalt concentrations in soil and their accumulation in plant tissues. The experiment was conducted as a 3 × 3 × 2 factorial experiment arranged in a completely randomized design (CRD) with three replications. The studied factors included organic wastes (no addition, sewage sludge at 100 t ha⁻¹, and poultry manure at 40 t ha⁻¹), irrigation water sources (river water, well water, and sewage water), and cultivation (with or without statice). Copper and cobalt concentrations were determined in the soil and in the shoots and roots of statice plants. The results showed that sewage sludge produced the highest mean soil concentrations of copper and cobalt, reaching 8.33 and 5.35 mg kg⁻¹ soil, respectively, whereas the no-addition treatment recorded the lowest means. Sewage water also resulted in the highest mean soil concentrations of copper and cobalt, reaching 8.39 and 5.48 mg kg⁻¹ soil, respectively. Statice cultivation reduced soil copper concentration from 9.68 to 4.30 mg kg⁻¹ and soil cobalt concentration from 5.22 to 4.21 mg kg⁻¹ compared with non-cultivated soil. In plant tissues, the combined application of sewage sludge and sewage water resulted in the highest copper and cobalt concentrations in both shoots and roots.