Effects of salinity levels in microbial activity of a Yellow Argisol incubated with different organic residues

Abstract

Soil microbiata quantification is not a simple task as we have poor information about the nature and amount of the activity of soil edafic microorganisms. Basal respiration is a reasonable method of soil microbial activity evaluation. The objective of this work was to evaluate the behavior of soil basal respiration incubated with organic matter and submitted to six levels of salinity, was installed a respirometry assay. Samples of a Yellow Argisol were  used and collected at 0 – 20 cm depth, they were packaged to respirometric jars after the receiving different NaCl (0 mg; 20 mg; 40 mg; 60 mg; 80 mg and 100 mg). The soil was fertilized with two types of organic matter, dry coconut dust and organic compost, in proportion relating to 30t ha^-1 and added a non addiction control of organic matter. The respirometry assay was conducted to 30 days from incubation. Mineralized C values’ in fertilized soils with organic matter were bigger than control soils, with higher results in incubated soils with dry coconut dust. These values ranged from 42,4 mg cm^-3 of      C-CO₂, in the treatment received with 20 mg of NaCl, to 66,9 mg cm^-3 of C-CO₂, in the treatment with 100 mg NaCl. Organic fertilization increased microbial activity, reducing prejudicial effect of salinity in edafic microorganisms activity.