Herbicidal activity of atrazine to barnyard grass depends upon soil characteristics

BACKGROUND The efficacy of a herbicide as soil treatment agent may be largely affected by soil characteristics. Understanding the relationship between herbicide efficacy and soil characteristics can provide decision basis for herbicide application according to local conditions. This study was aimed towards exploring the effect of soil characteristics on herbicidal activity of atrazine as a model herbicide to barnyard grass and thus to find an indicator for the herbicidal activity assessment of a herbicide against weeds. RESULTS The herbicidal activity of atrazine to barnyard grass varied greatly among the tested soils with the medium inhibition concentration (IC50), based on the amended concentration, ranging from 1.07 to 10.91 mg kg(-1). Uptake of atrazine by barnyard grass was negatively correlated with its adsorption onto soils, whereas it was positively related to the concentration of the herbicide in in situ pore water (C-IPW). Comparable IC50 values ranging from 1.14 to 1.38 were obtained from C-IPW in the tested soils with much smaller variation coefficient compared to those based on the traditional concentration (C-soil) of this herbicide in soils determined by extraction with organic solvents. CONCLUSION The concentration of atrazine in in situ pore water could be reliable to evaluate its bioavailability and herbicidal activity to barnyard grass. C-IPW of a herbicide in soil could be an indicator for guiding the practical application rate. (c) 2022 Society of Chemical Industry.