Measuring atrazine degradation and PRZM-2 testing under two water regimes

Abstract

In this study temporal variation of atrazine concentration andits downward movement in the corn root zone under two waterregimes in Daneshkadeh soil series (Fine, mixed, mesic,Calcixerollic Xerochrepts) were investigated. We also assessedthe risk of soil and water contamination due to this herbicideapplication. Atrazine application rate was 3.5 kg a.i./hafollowed by two irrigation treatments (high and normalirrigation) with three replications in a completely randomizeddesign. Atrazine concentrations during the growing season weremeasured by obtaining soil samples from each plot through 1 msoil depth. Atrazine transport simulation in the root zone bythe PRZM-2 model was checked using our observed field data. Theobserved data showed temporal reduction of atrazineconcentrations in the soil profile down to a maximum depth of 50cm. Statistical parameters ME (maximum error), RMSE (relativemean square error), EF (efficiency), and CRM (coefficient ofresidual mass) were obtained to compare predicted and observedatrazine soil residue concentrations. These parameters were5.22 mg/kg soil, 67.87 mg/kg soil, 0.60, and 0.46,respectively for high irrigation (ATA) treatment, and 6.02 mg/kgsoil, 93.89 mg/kg soil, 0.41, and 0.35, respectively fornormal irrigation (ATB) treatment. Based on this study, in general,the PRZM-2 simulation results were similar to the observeddata in the ATA treatment rather than the ATB treatment.