Abstracts |
The agricultural use of biosolids has been stimulated, however, as the chemical
composition of these residues is varied, the agronomic value and effects on soil quality
characteristics need to be individually assessed in order to establish safety norms for their
application. The present work evaluated biological characteristics after the application for two
consecutive years of increasing doses (0, 6, 12, 18 and 24 t ha(-1) dry matter) of biosolid
generated by a PET fiber and resin industry. There was also a complete mineral fertilizer
treatment in corn cultivation in a Cambisol, compared to an adjacent area under Brachiaria sp.
Without cultivation for the last ten years. The microbial biomass C and N, basal respiration and
urease, beta-glucosidase and fluorescein diacetate hydrolysis activities were increased, while
the acid phosphatase activity was reduced with the increase of biosolid rates. The different
biosolid doses had no effect on the microbial metabolic quotient (qCO(2)). The decrease in
phosphatase activity was related to the increase in Phosphorus availability in soil rather than
representing an adverse effect to biosolid application. With the application of 12 Mg ha(-1)
biosolid (agronomic recommendation), the basal respiration and fluorescein diacetate hydrolysis
were higher and the phosphatase activity lower than in the soil that received mineral fertilizer,
while the other parameters were not affected by these treatments.. The mycorrhizal colonization
of Brachiaria sp. Did. Not differ among spontaneously growing plants in plots previously
cultivated with corn and those of adjacent area. In spite of the lower spore number, an
enrichment in the arbuscular mycorrhizal fungi species was observed in the cultivated plots.
Organic carbon and microbial biomass were highly correlated. With the other characteristics. This
indicates that the changes in the amount and quality of soil organic matter, as a result of
biosolid application, altered microbial dynamics and influenced the biological parameters of soil
quality positively.
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