Influence of soil properties on ¹⁴C-Saflufenacil behavior: Sorption and mobility study

Abstract:

Background:

Knowing the relationships between the soil's physical-chemical properties and herbicide behavior in the soil allows establishing strategies for the efficient control of weeds with less environmental risk.

Objective:

It carried this study to investigate the role of physical-chemical properties of Brazilian soils in the sorption-desorption and mobility of the herbicide saflufenacil.

Methods:

We used nine soils from different regions of Brazil in the study of sorption-desorption and mobility of ¹⁴C-saflufenacil. The herbicide sorption-desorption estimate was performed using the batch equilibrium method and mobility using soil thin-layer chromatography. Principal component analysis (PCA) and clustering were performed to evaluate the impact of soil properties on the sorption-desorption behavior of saflufenacil.

Results:

The results indicated that saflufenacil was weakly sorbed in different types of tropical soils, and the sorption process is reversible, with its mobility varied from mobile (R_f = 0.70) to very mobile (R_f = 0.99) in the different soils and indicates that the herbicide has leaching potential in these types of soils. The sorption-desorption capacity and mobility of saflufenacil depend mainly on pH, CEC, clay, and OC content, and therefore it is vital to analyze them to predict the impacts of herbicide application on the environment. The PCA is an essential tool that helps to clarify how the effects of soil properties influence herbicide behavior.

Conclusions:

The OC content in Brazilian soils has a direct role in saflufenacil sorption and desorption. BR3 soil (soil with highest organic carbon; OC = 2,1%) exhibits greater sorption (K_d = 1,85 L kg⁻¹), value 5.5 times greater than the BR1 (soil with lower sorption; with OC = 0,6%). Therefore, the application of saflufenacil to tropical soils, especially those with low levels of CO (< 1%), may result in a greater potential risk of contamination of surface and groundwater in neighbouring agricultural and non-agricultural areas, particularly those with intensive use and ineffectiveness of saflufenacil. Future investigations could focus on integrating modeling approaches that incorporate soil variability to predict saflufenacil behavior accurately in diverse soil types, aiding in decision-making for sustainable herbicide use.

Keywords:
Sorption; Herbicide; Transport; Environmental contamination