Characterization of nicosulfuron availability in aged soils

Area of Science:

• Environmental Chemistry
• Soil Science
• Agrochemicals

Background:

• Pesticide sorption-desorption in soil influences environmental fate.
• Soil properties and pesticide characteristics affect these interactions.
• Aging time impacts pesticide availability for transport, uptake, and degradation.

Purpose of the Study:

• To evaluate changes in nicosulfuron sorption and availability with soil aging.
• To assess the impact of aging on pesticide transport predictions.
• To understand the mechanisms behind increased sorption over time.

Main Methods:

• Utilized radiolabeled (14C) nicosulfuron tracer.
• Incubated herbicide in different soil types (Mollisols, Oxisols).
• Measured changes in sorption coefficients (Kd,app) after aging periods.

Main Results:

• Aging significantly increased nicosulfuron sorption across all tested soils.
• Kd,app values increased 2-3 fold in Mollisols and 5-9 fold in Oxisols after 41 days.
• Freshly treated soil Kd values overpredict nicosulfuron transport.

Conclusions:

• Pesticide aging substantially alters sorption behavior.
• Mathematical models for pesticide transport must incorporate aging effects.
• Understanding aging-dependent sorption is crucial for accurate environmental risk assessment.