Linking glyphosate herbicide residues to degradation in Ultisols under chronosequences of oil palm plantations

Summary

This quantitative survey examined physicochemical soil properties and glyphosate persistence across oil palm plantation chronosequences in tropical Ultisols. Long-term monoculture cultivation significantly degraded soil structure (bulk density increased from 0.85 to 1.31 g cm⁻³ in young plantations), whilst glyphosate residues accumulated with plantation age, peaking at 18.07 mg kg⁻¹ in 10–15-year-old plantations and 16.94 mg kg⁻¹ in fruit from 15–20-year-old plantations. The findings suggest that plantation age, organic matter dynamics, and herbicide use intensity drive both soil degradation and herbicide persistence in tropical oil palm systems.

Regional applicability

This study was conducted in Indonesia and addresses tropical Ultisol degradation specific to Southeast Asian oil palm monocultures. Findings have limited direct applicability to United Kingdom agriculture, which operates under different soil types (Cambisols, Luvisols), climate, and cropping systems. However, the methodological framework for linking herbicide residues to soil degradation may inform UK soil monitoring practices, particularly for arable systems with high glyphosate use.

Key measures

Bulk density (g cm⁻³), porosity, water content, permeability, soil pH, glyphosate residue concentration (mg kg⁻¹ in soil and fruit), organic matter, nutrient retention properties

Outcomes reported

The study measured physicochemical properties of glyphosate-contaminated Ultisols and glyphosate residue concentrations across oil palm plantations of different ages. Soil bulk density, porosity, water content, permeability, pH, nutrient retention capacity, and glyphosate concentrations in soil and fruit were quantified.

Direct research

Oil-palm plantation soils and fruit glyphosate residues provide direct farming/soil evidence.

Limits: Chronosequence survey with random sampling does not randomise plantation age or herbicide exposure; confounding prevents simple causal attribution.

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