Analysis of Soil Biological Activity in the Surroundings of Sfântu Gheorghe in Covasna

Covasna County in Romania is regarded as an agricultural region due to the exceptionally high proportion of arable land. One of the most significant indicators of agricultural productivity is soil fertility, which is influenced by numerous factors. Among these, the most important is the biological condition of the soil.

In our research, we analyzed the biological activity of soils in the surroundings of Sfântu Gheorghe. Soil samples were collected from five different soil types (preluvosol, faeoziom, cambic faeoziom, aluviosol and gleysol) in autumn 2018 and spring 2019. For each field, 20 samples were collected and homogenized, and the biological activity was measured in three replications using the fluorescein diacetate (FDA) hydrolysis method.

The faeoziom soil type showed an enzymatic activity of 3.9631±0.1818 µg/g*h in autumn and 2.9788±0.3277 µg/g*h in spring; the cambic faeoziom soil type showed an activity of 4.0072±0.1145 µg/g*h in autumn and 3.0548±0.1621µg/g*h in spring; the gleysol type showed an activity of 3.2869±0.1817 µg/g*h in autumn and 2.9988±0.4679 µg/g*h in spring; the aluviosol soil type showed an activity of 2.4186±0.0616 µg/g*h in autumn and 1.3421±0.3779 µg/g*h in spring; and the preluvosol type recorded the highest values, with 5.4517±0.2609 µg/g*h in autumn and 5.3677±0.1548 µg/g*h in spring. For the faeoziom, cambic faeoziom, and aluviosol soil types, an approximately one-unit decrease was observed in spring due to the lower temperatures during the spring sampling period. For the gleysol soil type, the decrease was much smaller, and the differences between the values were not statistically significant. We attribute this to the application of manure by farmers after the autumn sampling, as manure contains a considerable number of microorganisms. For the preluvosol soil type, enzymatic activity also decreased slightly, which can be explained by the fact that this area is a pastureland with continuous vegetation cover and no soil disturbance, providing a stable habitat for microorganisms, andtherefore stable microbial activity.