Soil surface structure effect on isoproturon and diflufenican loss in runoff

Area of Science:

• Environmental Chemistry
• Soil Science
• Hydrology

Background:

• Soil surface structure critically influences water infiltration and runoff.
• Pesticide loss via runoff is a major environmental concern, impacting water quality.
• Understanding herbicide transport dynamics is crucial for effective agricultural management.

Purpose of the Study:

• To evaluate the impact of degraded soil surface structures on herbicide loss in runoff.
• To test the uniform mixing zone concept and two-site sorption kinetics for modeling herbicide transfer.
• To quantify the increased pesticide loss associated with altered soil surface conditions.

Main Methods:

• Field and laboratory experiments using simulated rainfall on treated plots.
• Surface application of isoproturon (IPU) and diflufenican (DFF).
• Analysis of herbicide concentrations in runoff under varying soil structural states.

Main Results:

• Herbicide concentrations in initial runoff were high (up to 60 mg L(-1) for IPU, 2 mg L(-1) for DFF).
• Degraded soil structures increased pesticide loss ratios significantly (e.g., IPU from 0.3% to 10%).
• Soil surface sealing limited soil-runoff interaction, influencing herbicide mobilization dynamics.

Conclusions:

• Soil surface structure degradation substantially enhances herbicide loss through runoff.
• The uniform mixing zone model with two-site sorption satisfactorily described IPU runoff concentrations.
• Effective management of soil structure is vital for mitigating pesticide runoff and environmental impact.