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Journal of Thermal Analysis and Calorimetry
Authors:
Lisardo Núñez-Regueira
,
J. Proupín-Castiñeiras
,
J. Rodríguez-Añón
,
Maria Villanueva-López
, and
O. Núñez-Fernández

Abstract  

The design of a rigorous experimental procedure is the basis for any environmental study. In this work, the basic criteria are established for determination of soil health using microcalorimetry as the main technique complemented by the study of physical (temperature, moisture, porosity, hydraulic conductivity, density and plasticity), chemical (pH and C to N ratio) and biological features (most probable number of microorganisms and organic matter content), and also environmental properties in the form of bioclimatic diagrams. The design was elaborated using as a reference a humic eutrophic-Cambisol subjected to afforestation with P. pinaster Aiton situated in Viveiro (Galicia, NW Spain). Main results of this study refer to total heat evolved during the processes (2.65 to 3.81 J g–1), time to reach the maximum of the peak from 16.17 to 19.29 h, and microbial growth rate constant from 0.0732 to 0.1043 h–1. These results change over the year as they are influenced by the action of environmental parameters over soil microbial activity. The results are in close agreement with some others previously reported using different experimental techniques.

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Journal of Thermal Analysis and Calorimetry
Authors:
Lisardo Núñez-Regueira
,
J. Rodríguez-Añón
,
J. Proupín-Castiñeiras
,
Maria Villanueva-López
, and
O. Núñez-Fernández

Abstract  

Microcalorimetry was used to study the seasonal evolution over one year of the microbial activity in a humic-eutrophic Cambisol soil as a function of its forest cover. The study was carried out on three soils with identical origin but covered with different forest species: pine, eucalyptus, and a typical Atlantic-humid riverside forest. Some other physical, chemical and biological properties and environmental parameters, mainly humidity and environmental temperature, were considered to analyze their influence on soil microbial activity. The study was performed using a microcalorimeter Thermal Analysis Monitor 2277 in which the experiments were carried out with 1 g soil samples treated with 1.25 mg glucose g–1 soil. From the measured results it follows that pine forest soil is the least productive of the three, as it generates an average heat of 2.7 vs. 5.9 J g–1 generated by the eucalyptus forest soil and 3.1 J g–1 generated by the riverside forest soil. These results are dependent on the remaining physical, chemical and biological features analysed and because of this, pine forest soil, with a pH value 3.3 in spring, shows a small capacity to maintain a stable microbial population which is the lowest of the three (0.079108 to 0.46108 microorganisms g–1 soil) while riverside soil microbial population is in the range from 7.9108 to 17108 microorganisms g–1 soil.

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