Soil moisture and metolachlor volatilization observations over three years

Area of Science:

• Environmental Chemistry
• Soil Science
• Agricultural Science

Background:

• Metolachlor is a widely used herbicide.
• Herbicide volatilization can lead to environmental contamination and reduced efficacy.
• Understanding factors influencing metolachlor volatilization is crucial for sustainable agriculture.

Purpose of the Study:

• To investigate the impact of surface soil water content on metolachlor volatilization.
• To quantify the relationship between soil moisture regimes and metolachlor vapor flux.
• To explore the role of soil temperature in metolachlor volatilization under varying moisture conditions.

Main Methods:

• A 3-year field study was conducted with controlled surface soil water regimes.
• Metolachlor vapor fluxes were measured using flux chambers at two distinct locations.
• Soil moisture, temperature, and meteorological data were continuously monitored.

Main Results:

• Metolachlor volatilization was approximately halved at drier sites compared to wetter sites over two years.
• During a drought year, similar soil water content at both sites resulted in comparable volatilization losses.
• A strong positive correlation (r² = 0.995) was found between field-averaged metolachlor volatilization and surface soil water content.

Conclusions:

• Surface soil water content is a primary driver of metolachlor volatilization.
• Subsurface water flow significantly influences surface soil moisture and subsequent herbicide loss.
• Management practices affecting soil moisture can mitigate metolachlor volatilization.