Can soil type interfere in sorption-desorption, mobility, leaching, degradation, and microbial activity of the 14C-tebuthiuron herbicide?

Abstract

Understanding the behavior in soil of herbicides applied PRE-emergence, such as tebuthiuron, is essential for more accurate weed management and less environmental impact. Thus, the objective of this research was to evaluate the effect of the physicochemical attributes of soils in 14C-tebuthiuron behavior. All studies were carried out by radiometric technique. The Kf and Kd values of 14C-tebuthiuron sorption were 30% and 35% higher in clay soil (1.15 mg(1–1/n) L1/n Kg−1 and 1.32 L Kg−1) compared to loamy sand soil (0.80 mg(1-1/n) L1/n Kg−1 and 0.85 L Kg−1, respectively). The desorbed amount was ∼19% higher in loamy sand soil compared to loamy sand soil, and this process was influenced by OC and clay content. The 14C-tebuthiuron leaching in clay soil was up to 10 cm depth, while in loamy sand soil was higher, up to 25 cm, and this difference can be explained by high mobility and low sorption of herbicide in loamy sand soil. 14C-tebuthiuron had a long persistence in both soils (DT90 of ∼385 and 334 d in loamy sand and clay soil, respectively). Although, the microbiological activity in soils differed little in the presence and absence of herbicide. Soil type interfered in 14C-tebuthiuron behavior, and then the application recommendation of this herbicide as a function of the physicochemical attributes of the soil is an alternative to increase efficiency in weed control and reduce the risk of environmental contamination.