Spatial distribution of sorption and desorption process of ¹⁴C-radiolabelled hexazinone and tebuthiuron in tropical soil

The understanding of the interaction between soil physicochemical attributes and herbicide behavior is fundamental for optimizing the efficient use of PRE-emergence herbicides in a more sustainable approach. However, it is still a poorly studied area within precision agriculture. Thus, the objective of this research was to evaluate the correlation of soil physicochemical attributes with the sorption and desorption processes of hexazinone and tebuthiuron to support application maps considering the field level variability. Soil samples from an agricultural area had their physicochemical attributes analyzed and were submitted to sorption and desorption studies of ¹⁴C-tebuthiuron and ¹⁴C-hexazinone using the batch equilibrium method. The values of sorption and desorption apparent coefficients (K_d), sorption and desorption percentage and bioavailability were correlated with soil attributes by Pearson's correlation. The K_d values of tebuthiuron and hexazinone sorption ranged from 1.2 to 2.9 mL g^-1 and 0.4-0.6 mL g^-1, respectively. For desorption of tebuthiuron and hexazinone, K_d values ranged from 3.4 to 4.4 mL g^-1 and 2.6-3.0 mL g^-1, respectively. A positive correlation among clay content, soil organic matter (OM), and tebuthiuron and hexazinone sorption K_d values were found. Both herbicides had variable retention according to geographic position in the area. The recommendation of application of PRE herbicides, such as tebuthiuron and hexazinone, observing the physicochemical attributes of the soil is an alternative to increase efficiency in weed control and decrease the risk of environmental contamination.