Long-term field study finds five pesticides near surface in conservation agriculture

A long-term field study found that chlorantraniliprole, metribuzin, pendimethalin, pretilachlor and tebuconazole primarily accumulated within the upper 5 centimeters of soil in conservation-agriculture fields used for a rice–wheat cropping system. The researchers also reported greater pesticide persistence during the Rabi season. These observations describe residue distribution in the studied agricultural soils; they do not establish that conservation agriculture caused the pattern or quantify the contribution of individual farming, seasonal or application conditions.

To examine the residues, the team developed and validated a liquid chromatography tandem mass spectrometry, or LC–MS/MS, method for the simultaneous detection of 93 pesticides in soil. Its extraction procedure was a modified QuEChERS approach adapted for the soil matrix. Soil samples were hydrated, residues were extracted with acetonitrile, buffering salts were added, and dispersive solid-phase extraction cleanup was performed before instrumental analysis.

The researchers optimized these steps and assessed the method under SANTE/11312/2021 guidelines before applying it to field samples. Validation results indicated satisfactory analytical performance across the tested parameters. Coefficients of determination for calibration lines exceeded 0.99, and measured recoveries fell within the accepted range of 70% to 120%.

Relative standard deviations were no greater than 20%, while HorRat values ranged from 0.15 to 2.0. Limits of quantification extended from 0.01 to 0.10 milligrams per kilogram, depending on the analyte, with measurement uncertainty of 50%. Specificity testing recorded interference levels of 0% to 26%.

Matrix effects varied among the pesticides, with most analytes showing medium suppression of 20% to 50%. The researchers used matrix-matched calibration for quantitative analysis and reported that the validation results met acceptable limits. Application of the method to long-term conservation-agriculture fields revealed the near-surface accumulation pattern for the five named pesticides at a depth of 0–5 centimeters.

The field results also showed that pesticide persistence was higher during the Rabi season than during the other part of the rice–wheat cycle. Together, the findings indicate that the monitored residues were distributed unevenly through the soil profile and persisted differently by season. The study’s scope was limited to pesticide-residue measurements in a rice–wheat conservation-agriculture setting, and the supplied findings do not isolate causal effects, establish human-health outcomes or demonstrate that the same distribution occurs in other soils, climates or farming systems.

Subject of Research: Pesticide residue distribution in long-term rice–wheat conservation-agriculture field soils

Article Title: Assessment of pesticide residues in rice–wheat based conservation agriculture fields using validated LC–MS/MS methodology

Article References: M, A., Shekhar, S., Raj, R., Saini, P., Gupta, S., & Banerjee, T. (2026). Assessment of pesticide residues in rice–wheat based conservation agriculture fields using validated LC–MS/MS methodology. Environmental Monitoring and Assessment, 198(11), 1243. https://doi.org/10.1007/s10661-026-16068-5

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16068-5

Keywords: pesticide residues, soil analysis, conservation agriculture, rice–wheat farming, LC–MS/MS, QuEChERS, environmental monitoring, chemical persistence, Assessment, pesticide, residues, rice