Measurement of aldicarb degradation and movement in upstate New York and Massachusetts potato fields (U.S.A.)

Abstract

The degradation and movement of aldicarb residues from an emergence application was measured in soil and groundwater beneath potato fields near Deerfield, Massachusetts, and Savannah, New York. Soil samples collected following the application showed that aldicarb residues degraded at a rate corresponding to a half-life of ∼1.1 months. This half-life is consistent with previous studies. At the Massachusetts location, residues in half of the plot were confined to the upper 1.2 m of soil. In the other half of the plot which was temporarily flooded due to an overflow of a nearby pond, residue movement exceeded 4.8 m and residues up to 21 μg L −1 were observed in the upper 1.5 m of the saturated zone. No residues were observed in wells installed farther than 40 m from the treated area and residues in all wells dropped below 10 μg L −1 within 16 months of the aldicarb application. At the New York site, aldicarb residues entered shallow groundwater after a period of heavy rainfall in late November and early December of 1986. During the study, aldicarb residues were confined to shallow groundwater directly beneath or within 5 m of the treatment area. Aldicarb residues in excess of 10 μg L −1 were not found deeper than ∼2.5 m below the water table. Aldicarb residues had declined to below 1 μg L −1 in all monitoring wells within 5 yr, implying an average half-life of aldicarb residues in groundwater of <1 yr.