Evaluating the effect of biological and organic fertilizers on metribuzine herbicide degradation and persistence in soil

In order to study the effect of some organic and bio-fertilizers on the analysis of metribuzine residue in soil, a Factorial experiment was conducted in a randomized complete block design with three replications at the Faculty of Agriculture, Shahrood University in 2011. Threatments included three levels of organic fertilizers (vermicompost, cow manure and control) and biological fertilizer in four levels (Pseudomonas putyda, Pseudomonas fluorescens, Azotobacter chrococcum and control). For determination of metribuzine residue, soil samples were taken from 0 to 15 cm soil depth, (2 hours), 3, 8, 32, 55 and 90 days after herbicide application. Then metribuzin residue was measured with HPLC. Results showed that, the bacteria population increased 86 percent by the interaction effects of vermicompost × Pseudomonas fluorescens than control treatment. The rate of herbicide degradation decreased 23 percent and the half-life of herbicide increased 26 percent with application of cow manure × Azotobacter chroococcum than control treatment. However, the application of vermicompost with Pseudomonas fluorescens increased the herbicide decay rate by 37 percent and decreased the half-life of herbicide by 52 percent compared to control treatment. Based on our results, organic and biological fertilizers by their synergistic effects can change the rate of metribuzine degradation and persistence in soil.