EVALUATION OF HERBICIDE RESIDUE LEVELS AND ASSOCIATED PHYSICOCHEMICAL PROPERTIES OF SOILS IN SELECTED AGRICULTURALLY INTENSIVE ZONES OF TARABA STATE, NIGERIA.

Abstract

Herbicide application is a common practice in intensive agriculture, yet its environmental persistence raises significant concerns regarding soil quality and ecosystem health. This study evaluates the levels of herbicide residues and associated physicochemical properties of soil in agriculturally intensive zones of Taraba state, Nigeria, specifically within Ardo-kola, Jalingo and Yorro Local Government Areas. Soil samples were collected and analyzed using Gas Chromatography-Mass Spectrophotometer (GC-MS) to detect and quantify
residues of selected herbicides, including glyphosate and
2,4-
Dichlorophenoxyacetic (2,4-D) as well as their degradation products. Concurrently, key soil parameters- pH, total organic carbon (TOC), particle size distribution and cation exchange capacity (CEC) were determined to assess their influence on herbicide persistence. Glyphosate was detected in significant concentration, averaging 1.68 mg/kg, while 2, 4-D was not detected in its parent form, however, its degradation product 2, 4- chlorophenol, was present at an average concentration of 0.65 mg/kg. Variations in residue distribution appeared correlated with organic carbon content and soil texture. The finding underscores the persistence and transformation of herbicides in soil with potential implication of groundwater contamination, crop safety, and human health. The study recommends the adoption of stricter regulatory controls and sustainable agricultural practices to mitigate herbicide- related environmental risks.