Sorption and degradation of atrazine in middens formed by Lumbricus terrestris

Little information is available about the fate of herbicides in middens formed by Lumbricus terrestris. The midden and surrounding soil materials from no-till and conventionally tilled fields were measured for their ability to sorb and biodegrade atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. For samples from the conventional tillage system, atrazine sorption was similar in middens and in the surrounding soil, while under no-till atrazine sorption was higher in middens than in the surrounding soil. Atrazine degradation under no-till was slower in the middens than in the surrounding soil, consistent with a commonly observed inverse relationship of sorption and degradation. Under conventional tillage, however, atrazine degradation was greater in the middens than in the surrounding soil, despite little difference in sorption between the two treatments.