Impact of Atrazine and Biochar Pre-treatment on Soil and Leachate Properties

Abstract

Atrazine is a widely used herbicide in agriculture, but its persistence and mobility in soils and water pose ecological and health risks, however, biochar a carbon rich solid product of biomass pyrolysis, has been proposed as a strategy to reduce herbicide leaching and improve soil quality. This study
assessed the effects of atrazine application (at manufacturers, adjusted lower and higher rates of 3.0, 1.5 and 4.5 kg of the active ingredients ha⁻¹ and biochar pre-treatment (Tithonia diversifolia, TD and TD + bonemeal, applied at 3 t ha⁻¹) on soil and leachate properties in soils with contrasting organic
carbon contents. A factorial leaching column experiment was conducted with 72 experimental units, using 250 g soil columns under screen-house conditions. Results revealed that , Nitrate leaching reached 9.7 mg L⁻¹ in LOC compared to 8.9 mg L⁻¹ in high organic carbon (HOC) soils, while phosphate losses ranged from 0.00 to 0.35 mg L⁻¹. Biochar amendments enhanced soil quality by increasing organic carbon (up to 3.32%) and available phosphorus (up to 105.3 mg kg⁻¹), but this led to short-term nutrient leaching, with leachate electrical conductivity (EC) rising to 1780 µS cm⁻¹ in
amended HOC soils compared to 664 µS cm⁻¹ in the control. Overall, biochar, particularly TD + m bonemeal, reduced atrazine mobility and improved soil fertility, though its effectiveness was soildependent and required careful rate management to minimize leaching risks.