Spatial distribution of sorption and desorption process of 14 C- radiolabelled hexazinone and tebuthiuron in tropical soil Kassio Ferreira Mendes a, * , Marcelo Chan Fu Wei b , Ivan Ferreira Furtado a , Vanessa Takeshita b , Jo ~ ao Pedro Pissolito b , Jose Paulo Molin b , Valdemar Luiz Tornisielo b a Federal University of Viçosa, Viçosa, Minas Gerais, Brazil b University of S~ ao Paulo, Piracicaba, S~ ao Paulo, Brazil highlights graphical abstract  Spatial distribution of retention pro- cess of hexazinone and tebuthiuron was monitored.  The K d values for tebuthiuron sorp- tion in the soil was higher than hexazinone.  The herbicides had variable retention according to geographic position in the area.  Both herbicides sorption K d was most influenced by soil OM and clay content. article info Article history: Received 19 August 2020 Received in revised form 27 September 2020 Accepted 28 September 2020 Available online 1 October 2020 Handling Editor: Willie Peijnenburg Keywords: Retention Pre-emergence herbicide Precision agriculture Variability mapping abstract 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 14 C-tebuthiuron and 14 C-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 0.4e0.6 mL g 1 , respectively. For desorption of tebuthiuron and hexazinone, K d values ranged from 3.4 to 4.4 mL g 1 and 2.6e3.0 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 ac- cording 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. © 2020 Elsevier Ltd. All rights reserved. 1. Introduction Chemical control is the main control method due to its * Corresponding author. E-mail addresses: kassio_mendes_06@hotmail.com, kfmendes@ufv.br (K.F. Mendes). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere https://doi.org/10.1016/j.chemosphere.2020.128494 0045-6535/© 2020 Elsevier Ltd. All rights reserved. Chemosphere 264 (2021) 128494