Search results for "nitrogen cycle"

Typology of exogenous organic matters based on chemical and biochemical composition to predict potential nitrogen mineralization

2010

Our aim was to develop a typology predicting potential N availability of exogenous organic matters (EOMs) in soil based on their chemical characteristics. A database of 273 EOMs was constructed including analytical data of biochemical fractionation, organic C and N, and results of N mineralization during incubation of soil–EOM mixtures in controlled conditions. Multiple factor analysis and hierarchical classification were performed to gather EOMs with similar composition and N mineralization behavior. A typology was then defined using composition criteria to predict potential N mineralization. Six classes of EOM potential N mineralization in soil were defined, from high potential N minerali…

Contribution of bacteria to initial input and cycling of nitrogen in soils

2005

Linking microbial diversity and ecosystem functioning: The nitrogen cycle example

2014

Microbial communities have a central role in ecosystem processes by driving the Earth’s biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. While functional trait-based approaches are commonly used for at least two decades in microbiology, most microbial diversity studies are still carried out with the rRNA genes. This talk will show how metagenomic approaches targeting microbial guilds involved in nitrogen cycling can help bridging microbial community ecology and ecosystem processes in terrestrial environments.

A core microbiota of plant and earthworm interaction? Phylogenetic and functional aspects

2017

International audience; The core microbiota concept has been proposed to describe the subset of a microbiota (e.g. the rhizosphere microbial community) associated with a given host (e.g. a plant) going beyond macroenvironment differences (e.g. soil type), and characterized by taxonomic markers (e.g. 16S rRNA gene sequences). Its existence has been questioned by geographical studies, showing the overruling soil type effect in shaping microbial communities. As far as biotic determinants are concerned, several “hosts” or macroorganisms are impacting a given habitat and its specific microbial community. In soils, there is an overlap between the so-called rhizosphere and the drilosphere, defined…

Spatial distribution of ammonia-oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning

2011

Characterization of spatial patterns of functional microbial communities could facilitate the understanding of the relationships between the ecology of microbial communities, the biogeochemical processes they perform and the corresponding ecosystem functions. Because of the important role the ammonia-oxidizing bacteria (AOB) and archaea (AOA) have in nitrogen cycling and nitrate leaching, we explored the spatial distribution of their activity, abundance and community composition across a 44-ha large farm divided into an organic and an integrated farming system. The spatial patterns were mapped by geostatistical modeling and correlations to soil properties and ecosystem functioning in terms …

Investigation on the Nitrogen Metabolism of Spruce Needles in Relation to the Occurrence of Novel Forest Decline

1988

Summary In order to obtain information on the nitrogen metabolism of undamaged and damaged spruce ( Picea abies ), investigations were performed in 1985 and 1986 on the activity of glutamine synthetase and on the content of free ammonium and soluble proteins in spruce needles. In addition, the chlorophyll content was determined. Needles from the second needle year and the seventh whorl were used. The investigations were carried out in pair comparison on a 20-year-old spruce plantation and in comparison with damage classes on an 80-year-old spruce plantation. Both the pair comparison and the contrasting of different damage groups show an unequivocal decrease of the chlorophyll content correl…

Integration of physically based distributed hydrological model with model of carbon and nitrogen cycle: Luquillo Critical Zone Observatory, Puerto Ri…

2015

The dynamics of carbon and nitrogen cycles, increasingly influenced by human activities, are the key to the functioning of ecosystems. These cycles are influenced by the composition of the substrate, availability of nitrogen, the population of microorganisms, and by environmental factors. Therefore, land management and use, climate change, and nitrogen deposition patterns influence the dynamics of these macronutrients at the landscape scale. In this work a physically based distributed hydrological model, the tRIBS model, is coupled with a process-based multi-compartment model of the biogeochemical cycle to simulate the dynamics of carbon and nitrogen (CN) in the Mameyes River basin, Puerto …

Effect of storage and composting on the properties and degradability of cattle manure

1995

Abstract Stockpiling or thermophilic composting of cattle manure resulted in significant carbon losses of 17% and 26.4% and relative nitrogen gains of 25% and 32.7% for stockpiled and composted manure, respectively. As a consequence, C/N ratios decreased with increasing time of storage or composting. However, neither the pH nor the mineral nitrogen and organic carbon contents of the 0–50 μm fractions were significant indicators of the transformations of these materials. The degradability of the manure was measured by incubation for 2 weeks in a brown calcareous soil, following 1 week of preincubation. The biodegradation index (BI) or the proportion of CO 2 released from the amended soil in …

Anaerobic batch degradation of solid poultry slaughterhouse waste

2000

We studied anaerobic batch degradation of solid poultry slaughterhouse wastes with different initial waste and inoculum concentrations and waste-to-inoculum ratios and simulated the dynamics of the process with a new generation <METHANE> model. Our modelling results suggest that inhibited propionate degradation by long-chain fatty acids (LCFA) and inhibited hydrolysis by a high propionate concentration constituted the rate-limiting step in the waste degradation. Palmitate was the most abundant LCFA in the assays. Within 27 days of incubation, up to 0.55 to 0.67 m3 of methane (STP)/kg VS added was produced under the studied conditions. Lower waste-to-inoculum ratios exhibited a…

Leaching of n and c from birch leaf litter and raw humus with special emphasis on the influence of soil fauna

1988

Abstract To examine the role of a community of soil animals in N-mineralization and C fluxes in dead organic matter, we established a microcosm system with substrates composed of: (a) birch leaf litter; (b) raw coniferous humus; and (c) litter on humus. Every 3–4 wks the substrates were irrigated with distilled water, and the amounts of NO5-N, NH4-N, total-N and total-C (as well as humic substances at one recording) in the leachates were analyzed. At the end of the experiment, water-soluble and exchangeable forms of N were measured in the test materials. The differences in the release of N were clear both between the replicates with and without soil animals and between the different forms o…