Enzymatic activity measured by microcalorimetry in soil amended with organic residues

• Published in: Revista Brasileira de Ciência do Solo 2011-08, Vol.35 (4), p.1167-1178
• Main Authors: Cenciani, Karina, Santos Freitas, Sueli dos, Critter, Silvana Auxiliadora Missola, Airoldi, Claudio
• Format: Article
• Language: English
• Subjects: efeito térmico; enzimas extracelulares; microrganismos do solo; SOIL SCIENCE
• ISSN: 0100-0683; 1806-9657; 0100-0683
• DOI: 10.1590/S0100-06832011000400010

Enzymatic activity is an important property for soil quality evaluation. Two sequences of experiments were carried out in order to evaluate the enzymatic activity in a soil (Rhodic Eutrudox) amended with cattle manure, earthworm casts, or sewage sludges from the municipalities of Barueri and Franca. The activity of commercial enzymes was measured by microcalorimetry in the same soil samples after sterilization. In the first experiment, the enzyme activities of cellulase, protease, and urease were determined in the soil samples during a three month period. In the second sequence of experiments, the thermal effect of the commercial enzymes cellulase, protease, and urease on sterilized soil samples under the same tretaments was monitored for a period of 46 days. The experimental design was randomized and arranged as factorial scheme in five treatments x seven samplings with five replications. The treatment effects were statistically evaluated by one-way analysis of variance. Tukey´s test was used to compare means at p < 0.05. The presence of different sources of organic residues increased the enzymatic activity in the sampling period. Cattle manure induced the highest enzymatic activity, followed by municipal sewage sludge, whereas earthworm casts induced the lowest activity, but differed from control treatment. The thermal effect on the enzyme activity of commercial cellulase, protease, and urease showed a variety of time peaks. These values probably oscillated due to soil physical-chemical factors affecting the enzyme activity on the residues. A atividade enzimática é uma propriedade importante para avaliação da qualidade do solo. Duas sequências de experimentos foram realizadas com o objetivo de avaliar a atividade enzimática em amostras de solo (Latossolo Vermelho eutroférrico típico), tratadas com esterco bovino, húmus de minhoca ou lodos de esgoto dos municípios de Barueri e Franca. A atividade de enzimas comerciais nas mesmas amostras de solo, após serem esterilizadas, foi medida por microcalorimetria. No primeiro experimento, a atividade das enzimas celulase, protease e urease foi determinada em amostras de solo durante um período de três meses. Na segunda sequência de experimentos, o efeito térmico das enzimas comerciais celulase, protease e urease em amostras de solo, esterilizadas sob os mesmos tratamentos, foi monitorado por um período de 46 dias. O delineamento experimental foi inteiramente casualizado, em esquema fatorial cinco tratamentos x set