Small‐Scale Spatial Variability of Atrazine and Dinoseb Adsorption Parameters in an Alluvial Soil

Abstract

Soil sorption processes largely control the environmental fate of herbicides. Therefore, accuracy of sorption parameters is crucial for accurate prediction of herbicide mobility in agricultural soils. A combined experimental and statistical study was performed to investigate the small-scale spatial variability of sorption parameters for atrazine and dinoseb in soils and to establish the number of samples needed to provide a value of the distribution coefficient (K(d)) next to the mean, with a given precision. The study explored sorption properties of the two herbicides in subsurface samples collected from four pits distributed along a transect of an alluvial soil; two to four samples were taken at about 30 cm apart at each sampling location. When considering all the data, the distribution coefficients were found to be normally and log-normally distributed for atrazine and dinoseb, respectively; the CVs were relatively high (close to 50% for dinoseb and 40% for atrazine). When analyzed horizon by horizon, the data revealed distribution coefficients normally distributed for both herbicides, whatever the soil layer, with lower CVs. The K(d) values were shown to vary considerably between samples collected at very short distance (a few centimeters), suggesting that taking a single soil sample to determine sorption properties through batch experiments can lead to highly unrepresentative results and to poor sorption/mobility predictions.

To Identify the Important Soil Properties Affecting Dinoseb Adsorption with Statistical Analysis

“…Contrast to that, the correlation coefficient shows that Clay has a positive relationship with K f . Dinoseb is a weak acid with a pH of 4.4–4.62 [20] and is mainly in anionic form at the pH of the studied soils [34]. Therefore, it is more reasonable that its affinity to soil was negatively correlated with the content of the negatively charged clays.…”

Fate of Pesticides in Soils: Toward an Integrated Approach of Influential Factors

“…It seems mainly due to the variation of organic carbon content (Coquet & Barriuso, 2002). But, the variability of pesticides adsorption is high even at smaller scales (cm to m) (Mermoud et al, 2008, Vieublé-Gonod et al, 2009). The adsorption of pesticides also varies with soil depth: in general, the adsorption decreases because of a decrease in the organic carbon content (Mamy & Barriuso, 2005).…”