Clopyralid and imazamox are successfully used for weed control during the first years of regeneration of pedunculate oak forests. Hence, the question that arises is how these herbicides affect microorganisms, especially the activity of dehydrogenase enzyme, when they reach the soil. Two study sites were selected in regenerated pedunculate oak forests, and the two herbicides were applied in two doses that are used for weed control (clopyralid, 100 g a.i. ha⁻¹ and 120 g a.i. ha⁻¹; imazamox, 40 g a.i. ha⁻¹ and 48 g a.i. ha⁻¹). The effect of the herbicides was evaluated 7, 14, 21, 30, and 60 days after application. A significant reduction in dehydrogenase activity was found on days 7 and 14 at both sites. However, after 14 days there was a recovery of dehydrogenase activity for all treatments such that the values obtained on day 21 did not differ from the control values. The effect of clopyralid and imazamox on dehydrogenase activity was not dose-dependent. Dehydrogenase activity also depended on soil properties, soil sampling time and climatic conditions during the investigation years. The results show that clopyralid and imazamox can reduce soil dehydrogenase activity, but this effect is transient. This can be attributed to the ability of microorganisms to overcome the stress caused by the herbicide by developing the capability to utilize herbicides as a nutrient source and proliferating in such an environment.

This study reveals the mutual interaction of the abiotic (climate) and biotic (bacteria, actinomycetes and fungi) factors and their impact on dehydrogenase enzyme activity in the soil within the Quercetum montanum typicum forest community at the National Park “Frushka gora” in the Vojvodina Province of Serbia. A total of 32 field visits were conducted between 2014 and 2017 to obtain site-specific data on air and soil temperature and humidity, and soil sampling for further microorganisms’ abundance and dehydrogenase activity determination through lab analysis. The key findings indicate that climate conditions, particularly variations in air temperature and humidity, significantly impact dehydrogenases and are positively impacted by soil bacteria and actinomycetes, although the effect of fungi varies. Climate conditions, particularly variations in air temperature and humidity, significantly impact the abundance of soil microorganisms, and further positively impact the dehydrogenase activity. These findings underscore the importance of understanding the interplay between abiotic and biotic factors in soil ecosystems for sustainable environmental management and to support soil fertility and health.

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For an agricultural region such as the Vojvodina Province in northern Serbia, soil quality monitoring is very important. Enzymatic activities are proposed as good indicators as they respond to even the slightest changes in the soil. This study aimed to analyze the enzymatic activity levels across three different soil types in Vojvodina and to examine their connection to soil chemical properties and land use. All soil types (chernozem, vertisol, solonchak) were sampled at nine locations, each with 3 field plots. The activities of acid and alkaline phosphatase, β-glucosidase, dehydrogenase, and catalase were measured in samples, as well as the selected chemical properties. Results showed differences in enzymatic activity across different soil types and land use. The most active enzymes in vertisol were acid phosphatase and β-glucosidase; in solonchak, it was alkaline phosphatase; in chernozem, it was dehydrogenase. A high correlation between enzymatic activities and certain soil chemical properties (pH reaction, organic matter, organic carbon, total nitrogen) was also observed, underlining the existence of a relationship between different soil components. The highest determined correlation was between acid phosphatase and pH (r=-0.7), alkaline phosphatase and total nitrogen (r=0.7), and organic matter (r=0.72); the obtained correlations were found to be statistically significant.

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, the scientific journal of the Mendel University in Brno, Czech Republic