Movement and conversion of aldicarb and its oxidation products in columns of grassed and fallow soil

Abstract

Abstract Aldicarb was mixed into the top layer of columns of undisturbed soil 0.6 to 1 m long, which were then replaced in the soil and exposed to field conditions. During the growing season (15 May to 26 October, 30 cm total rainfall), the oxidation products of aldicarb were retained in the upper 20 cm of grassed soil. Similar results occurred with fallow loam soils. However with fallow humic sand soil, 2 to 15% of the dose was leached from columns 0.6 m long. After 5.5 months, aldicarb sulfoxide plus sulfone residues in grassed soil ranged from 4.2 to 7% and from 11 to 17% of the dose for two loam soils and a humic sand soil, respectively. Residues in fallow loam soil averaged 0.45 to 0.76 times those in the grassed ones. In the winter period the precipitation excess leached 0.48 to 2.2% of the dose from the 1 m long loam columns, while 2.4 to 3.4% was retained, mainly at the lower end of the columns. The residues were almost completely leached from columns of humic sand soil 0.8 m long.