Influence of plant carbon on the mineralisation of atrazine residues in soils

The persistence of the s-triazine herbicides such as atrazine has led to increasing concern about environmental contamination by these compounds. A laboratory incubation experiment was carried out to determine the effects of plant residues on the mineralisation of atrazine residues in an agricultural soil with no recent history of atrazine application. The experiment further aimed to identify the importance of different fractions (water soluble and insoluble) of plant residues to the dynamics and extent of hydroxy-atrazine mineralisation. Hydroxy-atrazine mineralisation was initially (0 – 2 days) enhanced by the addition of water-insoluble plant (pea) fractions and inhibited by addition of water-soluble plant fractions. However, by the end of the incubation (10 days), only addition of unfractionated shoot material caused overall enhancement of hydroxy-atrazine degradation. Little or no lag in mineralisation in a soil which had not been exposed to the atrazine for 15 years demonstrated long-term maintenance of degradative capability.