Abstract

BARBERO, Florencia Magalí et al. MICROBIAL COMMUNITIES AFFECTED BY CAPTAN IN SOILS UNDER DIFFERENT MANAGEMENT PRACTICES. Cienc. suelo [online]. 2023, vol.41, n.1, pp.31-65.  Epub Nov 30, 2023. ISSN 1850-2067.

The application of fungicides has become a recurring method of modern agriculture. However, its frequent application could inhibit key processes in agroecosystems, particularly in the soil. Captan is a broad-spectrum, organochlorine, non-systemic fungicide widely used in agriculture. This study aimed to evaluate how different dosages of the fungicide captan affect the microbiota of soil subjected to different types of management and with a degradation gradient associated with the soil organic matter (SOM) content. The trial was conducted in a greenhouse and included soils with three types of management: pristine forest soil (L1), 2:1 rotation (soybean-corn) under no-tillage management (L2), and soybean monoculture under conventional tillage management (L3). The treatments were: control (0x), dosage 1.0 mg/kg soil (1x), and dosage 10 mg/kg soil (10x). Sampling was carried out 30 days after the application of captan. Enzymatic activities related to C, N, and P cycles, phospholipid fatty acid profiles (PLFA), and a quantification method for ribosomal RNA gene copy numbers (16S and 18S) were evaluated to assess the impact of captan on the structure and activities of microbial communities. Our results showed increases in enzyme activities and biomass in L1 soils at 1x doses compared to the control, except for gram-negative bacteria that increased at 10x dosages. However, the application of 10x dosages produced losses in activity and microbial biomass in the three types of soil. The lowest values of 16S and 18S rRNA copies were registered in the treatments with fungicide. The 16S bacterial rRNA did not present differences between the treatments in the L3 soils. In conclusion, the L1 soil presented greater sensitivity in its response to captan compared to the L2 and L3 soils under agricultural management.

Keywords : microbial community structure; enzyme activity; microbial abundance..

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