Effects of Copper Oxide (CuO) and Zinc Oxide (ZnO) Nano and Bulk Forms to Soil Fungal Community

The effects of copper oxide (CuO) and zinc oxide (ZnO) in bulk and nano forms on soil fungal community was determined. Lipa clay loam soil collected from the University of the Philippines Los Banos were placed in polypropylene bags and amended with 300 mg/L of CuO or ZnO in either forms. Colony-forming units (CFU) as well as average well color development (AWCD), functional richness and stress index were determined on day 1, 8 and 15 via indirect viable plate count method and community - level physiological profiling (CLPP). Fungal isolates from the same soil samples were likewise identified and tested in vitro in terms of radial growth when treated with varying concentrations of the metal oxides. Results indicated no significant difference in CFU, AWCD, functional richness and stress index among treatments. In vitro, responses of fungal isolates differed. CuO was more toxic than ZnO. In both cases, the nature of the compound, not size, was the primary determinant of toxicity. It is recommended that the use of nanotechnology in agriculture be promoted with caution to limit the harmful effects to the soil microbiota and to the environment in general.