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N.sub.2./sub.O and N.sub.2./sub. emissions, denitrification activity and the size of the denitrifying community in a pasture soil – what is the role of pH?
Čuhel, Jiří ; Šimek, Miloslav ; Laughlin, R.J. ; Chéneby, D. ; Bru, D. ; Philippot, L.
Denitrification and subsequent N emissions are significantly influenced by soil pH. Nevertheless, it is not clear, whether pH controls denitrification only due to the influence on kinetics of denitrification enzymes or also due to the different structure of denitrifiers. The objective of the present study was to compare results from N gas emissions and N.sub.2./sub.O molar ratio from soils with artificially changed pH, with those obtained from potential denitrification, and to find out whether there is a relationship between N fluxes and abundance of denitrifiers. The experimental site was located in a grassland area at Borová Farm near Český Krumlov, Czech Republic, and consisted of 12 plots (3x3 m) amended with KOH solution (pH alkaline), H.sub.2./sub.SO.sub.4./sub. solution (pH acidic) or with no amendments (pH natural). The .sup.15./sup.N gas flux method was used to quantify emissions of N.sub.2./sub.O and N.sub.2./sub. in situ at intervals over 74 H.
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Symptomes of nitrogen excess in soil
Hynšt, Jaroslav ; Šimek, Miloslav
Nitrogen cycling is one of the most important processes on the Earth. Most of N transformations run in soil. Nitrogen usually enters the soil as occasional input in concentrated forms which means that it is often in excess or in deficit. However, deficit and excess of N have different value in different soils and ecosystems. For example, amount of N which causes significant impact on ecosystem of spruce forest is insufficient for the maize field. This suggests, that the amount of N in soil must be evaluated in context of the whole ecosystem. In N-limited ecosystems, most of N is stored in plant biomass and litter characterized by slow transformations. Productivity of ecosystem is low, but N is utilized with high efficiency. On the other hand, in conditions of high availability of N, losses take place. These differences are reflected in content of different fractions of soluble N in soil and different rates of their transformations.
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Soil micromycetes - the potential source of N.sub.2./sub.O in soils
Jirout, Jiří ; Šimek, Miloslav ; Elhottová, Dana
The aim of this paper is to summarize knowledge on potential production of N.sub.2./sub.O by fungi. The processes involved in the global nitrogen cycle are suggested to have an important role in the global environmental changes. Nitrification and denitrification processes cotribute to the production of N.sub.2./sub.O, which belongs to the group of highly active greenhouse gases. Denitrification - the successive reduction of nitrate to N.sub.2./sub. - was supposed to occur only in prokaryotes, but recently the evidence for dissimilation of nitrates and formation of nitrogen oxides and N.sub.2./sub. was reported also in fungi. N.sub.2./sub.O of fungal origin is formed from nitrate or nitrite by reduction under anaerobic or microaerobic conditions. Since fungi showed the capability to use denitrification and oxygen respiration simultaneously under various pO.sub.2./sub. conditions, the N.sub.2./sub.O production by fungi is expected in a wide range of soils with different aeration status.
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The cultivation of bacteria originated in bat guano
Petrásek, Jiří ; Elhottová, Dana ; Krištůfek, Václav ; Kováč, L.
The bat guano represents an important source of organic matter in the oligotrophic caves. The high content of chitin from the remains of digested insect in bat diet causes the slow decomposition of the guano. The bat guano deposits can be auccumulated near the bat colonies during hundreds of years. The bat guano represents unique environment with specific conditions and appropriate composition of bacterial community. In this study, the bacterial communities of the guano from Domica and Ardovská Caves (NP Slovak Karst) were investigated using plate method with six different growing media. Total numbers of cultivable aerobic bacteria in guano were determined on the solid complex medium TSBA (Becton & Dickinson]. Total numbers of cultivable anaerobic bacteria were determined on the DifcoTM Anaerobic agar and blood agar (Schaedler agar with 5% sheep blood).
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Archaea – the important part of soil microbial community
Němcová, Anna ; Elhottová, Dana
Archaea is a very old group of prokaryotic microorganisms distinguished by unique characteristics from other procaryotic representatives. Archaea represent the third discrete domain of life. The recent research focused on biology and ecology of Archaea has brought quite new and fascinating information about these microorganisms as well as about the life evolution in general. By virtue of application of recent molecular methods, it is apparent that archaeal habitat is not limited only to extreme environments but it is a distributed group coexisting with other microorganisms in common environments. The study of archaeal role in processes of C and N transformation connected with production and emission of greenhouse gases belongs to important problematic of recent soil biology. From a point of view of the evolutionary relations among soil organisms or interaction with other representatives of edafon the study of Archaea represents other important tasks of soil biology.
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Methods for study of soil fungal communities - application on soils disturbed by outdoor cattle husbandry
Jirout, Jiří ; Elhottová, Dana
Fungal organisms comprise a physiologically and genetically diverse group of organisms with the key role in soil ecosystems. However, dynamics, structure, diversity and biomass of populations of soil fungi remain unclear and unknown. Conventional methods in microbiology provide only a glimpse view on the fungal diversity, but the last 15 years have brought many technological advances in community profiling and cultivation independent approaches to studying soil microorganisms. Changes in fungal diversity associated with agricultural management may affect the soil fertility and stability, but the effect of the agricultural practices on fungal complex community is still unclear. Conventional and modern methods in soil microbial ecology were used for study of microbial communities at the pasture used as a cattle overwintering area. Soil environment at this site is relevantly disturbed by cattle impact.
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Nitrogen and carbon transformation processes in soil in permanent grasslands - research in cattle overwintering area
Šimek, Miloslav ; Hynšt, Jaroslav ; Čuhel, Jiří ; Elhottová, Dana ; Chroňáková, Alica ; Němcová, Anna ; Jirout, Jiří ; Krištůfek, Václav
Agricultural soils represent a significant source of greenhouse gases (carbon dioxide, nitrous oxide and methane). Pasture soils and especially overwintering areas receive large amounts of nutrients as animal excrements. Together with other effects, this creates good conditions for high rates of nitrogen and carbon transformations, and also for substantial losses in the form of gaseous metabolites. This paper informs on research of a specific model ecosystem – the cattle overwintering area. Research is focused either on the structure of soil microbial community and on its activities including the formation of gases in, and their emission from the soil to atmosphere.
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