Effects of atrazine on the population of fungi and actinomycetes on a soil in Saldaña, Tolima

Abstract

We evaluated the effect of atrazine in the dynamics of microorganisms' populations of a soil in Saldana, Tolima. The groups of microorganisms studied were: Fungi in general, and actinomycetes (This group of organisms was analyzed and considered the total microbial population). We used a random design with five treatments and four repetitions. The results were studied with the variance analysis. Besides we compare the microorganism populations 60 days later in soil close to the rhizosphere (0.5 em and 1 em of the root distance) and the other one was taken to 8 em of the soil of the stem. When we applied substrate with atrazine the U.F.C / g. of soil increased t hrough the time, more than when the herbicide was added. When we only applied substrate, the populations showed an increase of U.F.C. / g. of soil through the time in similar way but in a lesser degree when we added atrazine and substrate. It happened in the soil next to the rhizosphere. In the soil analyzed to 8 em of distance the substrate, the atrazine and a mix of both, caused an adverse effect showed in a lower number of spores of MA in the soil taken at 8 em of distance from the stem. We observed an increase in the establishment of the following fungi Rhizopus sp, Mucor sp, Penicillium sp, Aspergillus sp and Cephalosporium sp. in the soil close to the rhizosphere as well as in the one obtained at 8 em from the stem. In relation with the groups of microorganisms, most of them were established next to the rhizosphere soil, excluding the fungi which were located in higher quantity in the soil studied to 8 em from stem