Herbicide Leaching in Soil with Different Properties: Perspectives from Commercial Formulations and Analytical Standards

Abstract

The leaching of herbicides into the soil is essential to control germinating seeds and parts of vegetative weeds. However, herbicide transportation to deeper soil layers can result in groundwater contamination and, consequently, environmental issues. In this research, our objective was to investigate differences in herbicide leaching between commercial formulations and analytical standards using three different soils. Leaching experiments were carried out for diuron, hexazinone, and sulfometuron-methyl herbicides isolated and in binary and ternary mixtures. The herbicide residue quantification was performed by ultra-high-performance liquid chromatography coupled to a mass spectrometer (LC-MS/MS). Diuron had less mobility in soils and was retained in the most superficial layers. Hexazinone and sulfometuron-methyl were more mobile and leached into deeper layers. The leaching process was more intense for hexazinone and sulfometuron-methyl. The additives present in the commercial formulation favored the leaching in soils of diuron, hexazinone, and sulfometuron-methyl herbicides isolated and mixture compared to the analytical standard. This fact highlights the importance of considering these effects for the positioning of herbicides in the field to increase the efficiency of weed control and minimize the potential for environmental contamination.

Keywords: herbicide behavior; herbicide leaching; herbicide–soil interaction.

Figure 1

X-ray diffractometry of the clay fraction from the A horizons of Haplic Cambisol (CX), Red Latosol (LV), and Quartzarenic Neosol (RQ). Ct: Kaolinite; Il: Illite; Mt: Montmorillonite; Gt: Goethite; Hm: Hematite; Gb: Gibbsite; and Qz: Quartz.

Figure 2

Pictorial diagram of the leaching column setup fabricated for the experiment.

Figure 3

MRM mode, total ion intensity chromatogram for the herbicides diuron, hexazinone, and sulfometuron-methyl (A), intensity of the daughter ions of diuron (B), hexazinone (C), and sulfumeturon-methyl (D).

Figure 4

Leaching (μg kg⁻¹) of diuron isolated and in binary and ternary mixtures for commercial and standard formulation in Red Latosol. Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). D + S (diuron + hexazinone), D + H + S (diuron + hexazinone + sulfometuron-methyl), D + H (diuron + hexazinone). D1 to D7 represent the soil depths.

Figure 5

Leaching (μg kg⁻¹) of diuron isolated and in binary and ternary mixtures for commercial and standard formulation in the Haplic Cambisol. Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). D + S (diuron + hexazinone), D + H + S (diuron + hexazinone + sulfometuron-methyl), D + H (diuron + hexazinone). D1 to D7 represent the soil depths.

Figure 6

Leaching (μg kg⁻¹) of diuron isolated and in binary and ternary mixtures for commercial and standard formulation in Quartzarenic Neosol. Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). D + S (diuron + hexazinone), D + H + S (diuron + hexazinone + sulfometuron-methyl), D + H (diuron + hexazinone). D1 to D7 represent the soil depths.

Figure 7

Leaching (μg kg⁻¹) of hexazinone, isolated and in binary and ternary mixtures, for commercial and standard formulation in Red Latosol. Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). H + S (hexazinone + sulfometuron-methyl), H + D + S (hexazinone + diuron + sulfometuron-methyl), H + D (hexazinone + diuron). D1 to D7 represent the soil depths.

Figure 8

Leaching (μg kg⁻¹) of hexazinone isolated and in binary and ternary mixtures for commercial and standard formulation in the Haplic Cambisol. Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). H + S (hexazinone + sulfometuron-methyl), H + D + S (hexazinone + diuron + sulfometuron-methyl), H + D (hexazinone + diuron). D1 to D7 represent the soil depths.

Figure 9

Leaching (μg kg⁻¹) of hexazinone isolated and in binary and ternary mixtures for commercial and standard formulation in Quartzarenic Neosol. Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). H + S (hexazinone + sulfometuron-methyl), H + D + S (hexazinone + diuron + sulfometuron-methyl), H + D (hexazinone + diuron). D1 to D7 represent the soil depths.

Figure 10

Leaching (μg kg⁻¹) of sulfometuron-methyl isolated and binary and ternary mixtures for commercial and standard formulation in Red Latosol. S + H (sulfometuron-methyl + hexazinone), S + D + H (sulfometuron-methyl + diuron + hexazinone), S + D (sulfometuron-methyl + diuron). Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). D1 to D7 represent the soil depths.

Figure 11

Leaching (μg kg⁻¹) of sulfometuron-methyl isolated and in binary and ternary mixtures for commercial and standard formulation in the Haplic Cambisol. S + H (sulfometuron-methyl + hexazinone), S + D + H (sulfometuron-methyl + diuron + hexazinone), S + D (sulfometuron-methyl + diuron). Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). D1 to D7 represent the soil depths.

Figure 12

Leaching (μg kg⁻¹) of sulfometuron-methyl, isolated and binary and in ternary mixtures, for commercial and standard formulation in Neosol. S + H (sulfometuron-methyl + hexazinone), S + D + H (sulfometuron-methyl + diuron + hexazinone), S + D (sulfometuron-methyl + diuron). Lowercase letters compare means between mixtures, and uppercase letters compare formulations (commercial and standard). Bars indicate the standard error of the mean (n = 3). D1 to D7 represent the soil depths.