Carbono da biomassa e atividade bioquímica em solos de Cerrado submetidos à aplicação do nematicida Cadusafós

Abstract

The cerrado is the second largest Brazilian biome and considered the last agricultural frontier of the planet. Its soils are predominantly latosols, devoid of nutrients and susceptible to erosion, but which were not obstacles to the occupation by modern agriculture, with applications of large quantities of chemicals. Without the use of these products, increased pests and diseases could lead to significant losses in agricultural production. The challenge is to avoid soil degradation and reduce environmental pollution by meeting the growing demand for food, fiber and energy. Soil microorganisms participate in almost all the processes that occur there, and are recognized as sensitive indicators of the health of natural and agricultural soils. Soil microbiota can be affected by the chemical pesticides used to combat pathogens of agricultural crops, since these products have low selectivity. The effects that the application of organophosphate pesticides cause on soil microflora are still little known and reported. The objective was to analyze the effect of the organophosphate nematicide Cadusafós on the soil microbial community, with the help of some microbiological parameters. For this, sandy and loamy soils representative of the Cerrado region of Minas Gerais State were collected. The cadusafos used was the Rugby 200 CS, at the concentration rate of 0.4 mg i.a. Kg-1 of soil, recommended for field application, and at higher doses to test the minimum inhibitory concentration. The parameters analyzed were basal respiration, biomass carbon and metabolic quotient, afterwards the induced response of the microbial community to the addition of glucose was evaluated through basal respiration, glucose consumption with time, enzyme activity dehydrogenase and metabolic yield, all in quadruplicate. Data were submitted to analysis of variance and normality, and the means tested at the 5% probability level, by Tukey and KruskalWallis test. For the two soils sampled and in all the attributes tested, no significant differences between the treatments that received cadusafós and the control were verified. The hypotheses are that the cadusafós was biodegraded, has no toxic effect on microorganisms, or that the molecule was not bioavailable by the various interacting forces that occur with the soil. Our results indicate that the Cadusafós molecule does not compromise edaphic functionality, maintaining the original quality of the soil under the conditions tested. Deeper structural and residual assessments should be performed to strengthen the data found here. Knowledge about the effects of pesticides on the activity of the soil microbial community can provide subsidies for planning the correct use of land.