Title: Adsorption Dynamics of Imidacloprid in Soil Amended with Biochar, Poultry Manure, and Cow Dung
Authors: Anyim P.B.
Tukura B.W.
Jayeoba O. J.
Volume: 9
Issue: 11
Pages: 1-8
Publication Date: 2025/11/28
Abstract:
The present study investigated the adsorption dynamics of imidacloprid in unamended and organically modified soils to assess the effects of biochar, poultry manure, and cow dung on pesticide retention and mobility. Surface soil samples (0-15 cm) were collected from the Lafia axis of Nasarawa State, Nigeria, air-dried, and amended with 10% (w/w) of each organic material. Batch equilibrium experiments were conducted by equilibrating 1.0 g of soil with imidacloprid solutions of varying initial concentrations (10-50 mg L?¹) in 0.01 M CaCl? for 24 h, followed by UV spectrophotometric determination at 280 nm. Adsorption parameters, including equilibrium concentration (Ce), adsorbed amount (qe), and distribution coefficient (Kd), were evaluated to determine the adsorption efficiency of each treatment. The results showed that all amendments improved imidacloprid adsorption compared to the unmodified soil, with biochar exhibiting the highest qe (0.496 mg g?¹) and Kd (1.232 L g?¹), followed by poultry manure and cow dung. Adsorption efficiency increased with rising initial concentrations, indicating concentration-dependent uptake. Although one-way ANOVA revealed no statistically significant differences (p > 0.05) among treatments, numerical improvements were evident, particularly in biochar-amended soils. Pearson and Spearman correlation analyses demonstrated strong positive relationships between C?, qe, and Kd (r > 0.87; p < 0.01), confirming consistent adsorption trends. The overall adsorption sequence followed the order biochar > poultry > cow dung > unamended soil. These findings emphasize the potential of organic amendments, especially biochar, to enhance soil retention of imidacloprid, reduce its mobility, and mitigate environmental contamination risks.