Effect of application methods on movement and degradation of aldicarb residues in Maine potato fields

The effect of application methods on movement and degradation of aldicarb residues was studied in a typically stony, Maine potato field by comparing aldicarb applied in-furrow at planting with aldicarb top-dressed at emergence. At the end of the growing season, residues from the at-planting application were found primarily in the top 0.6 m of soil and the residues from the emergence application were found primarily in the top 0.3 m. One year later, the residues were dispersed throughout the top 1.5 m of soil and had been reduced to about 5% of the original application. This study supports other work that has demonstrated that in the northeastern United States and Wisconsin, early aldicarb at-planting applications generally result in greater aldicarb residue movement than do later emergence applications. The study is also useful in illustrating variability of soil samples, which exhibited an average coefficient of variation of 110%. The results indicate that little information is lost due to compositing samples, so that compositing samples appears to be an option for reducing analytical costs associated with soil studies.