Now showing 1 - 3 of 3
  • Publication
    Soil-Atmosphere Exchange of NH3 and NOx in Differently Managed Vegetation Types of Southern Germany
    Ammonia (NH3) and Nitrogen Oxides (NOx = NO + NO2) emissions from soils and vegetation, and their subsequent deposition are key factors in global Nitrogen (N) cycling and have important functions in atmospheric and ecosystem degradation processes. To better understand their contribution, NH3 and NOx gases were simultaneously measured from differently managed vegetation types using a dynamic-chamber method. Biomass and N yields were higher from unfertilized clover-grass than fertilized oilseed radish. Summer cuts of clover-grass resulted in 137% higher biomass and 2.7-3.7% N concentrations than autumn cuts. Mulching reduced the re-growth and biomass production in clover-grass by 16% compared to cutting. The relative loss of NH3 through mulching was higher from the clover-grass (2.18%) than in the oilseed radish (0.08%). The total NH3 release over the four cuts of the clover-grass was 0.58% of the N removed. The influence of biomass-N, either mulched or cut, on the total NOx emission was temporary, resulted in net deposition (0.02-0.15% of the added/removed biomass-N). The ecosystems acted as sources for NH3, with the rate being weakly related to the added biomass-N, air temperature and humidity (R2 = 0.58, p<0.07), and sinks for NOx, with the rate influenced significantly by sunshine hours, precipitation and amount of biomass-N added (R2 = 0.87, p<0.001). We conclude that cutting clover-grass multiple times could be a good option to reduce the emissions of reactive N species and increase fodder yields with moderate N. Additionally, clover-grass could be superior for soil conservation measures over oilseed radish. Results imply further studies on the annual exchanges of gaseous N between the ecosystems and the atmosphere through long-term measurements.
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  • Publication
    Variations in Soil Properties and CO2 Emissions of a Temperate Forest Gully Soil along a Topographical Gradient
    Although forest soils play an important role in the carbon cycle, the influence of topography has received little attention. Since the topographical gradient may affect CO2 emissions and C sequestration, the aims of the study were: (1) to identify the basic physicochemical and microbial parameters of the top, mid-slope, and bottom of a forest gully; (2) to carry out a quantitative assessment of CO2 emission from these soils incubated at different moisture conditions (9% and 12% v/v) and controlled temperature (25 °C); and (3) to evaluate the interdependence between the examined parameters. We analyzed the physicochemical (content of total N, organic C, pH, clay, silt, and sand) and microbial (enzymatic activity, basal respiration, and soil microbial biomass) parameters of the gully upper, mid-slope, and bottom soil. The Fourier Transformed Infrared spectroscopy (FTIR) method was used to measure CO2 emitted from soils. The position in the forest gully had a significant effect on all soil variables with the gully bottom having the highest pH, C, N concentration, microbial biomass, catalase activity, and CO2 emissions. The sand content decreased as follows: top > bottom > mid-slope and the upper area had significantly lower clay content. Dehydrogenase activity was the lowest in the mid-slope, probably due to the lower pH values. All samples showed higher CO2 emissions at higher moisture conditions, and this decreased as follows: bottom > top > mid-slope. There was a positive correlation between soil CO2 emissions and soil microbial biomass, pH, C, and N concentration, and a positive relationship with catalase activity, suggesting that the activity of aerobic microorganisms was the main driver of soil respiration. Whilst the general applicability of these results to other gully systems is uncertain, the identification of the slope-related movement of water and inorganic/organic materials as a significant driver of location-dependent differences in soil respiration, may result in some commonality in the changes observed across different gully systems.
    Scopus© Citations 3  17
  • Publication
    Contrasting Effects of Forest Type and Stand Age on Soil Microbial Activities: An Analysis of Local Scale Variability
    Understanding the functioning of different forest ecosystems is important due to their key role in strategies for climate change mitigation, especially through soil C sequestration. In controlled laboratory conditions, we conducted a preliminary study on six different forest soils (two coniferous, two deciduous, and two mixed sites comprising trees of different ages) collected from the same region. The aim was to explore any differences and assess seasonal changes in soil microbial parameters (basal respiration BR, microbial biomass Cmic, metabolic quotient qCO2, dehydrogenase activity DHA, and Cmic:Corg ratio). Indicator- and forest-specific seasonality was assessed. In addition to litter input, soil parameters (pH, nutrient content, texture and moisture) strongly regulated the analyzed microbial indicators. PCA analysis indicated similarity between mature mixed and deciduous forests. Among annual mean values, high Cmic and DHA with simultaneously low qCO2 suggest that the mature deciduous stand was the most sustainable in microbial activities among the investigated forest soils. Research on the interrelationship between soil parameters and forest types with different tree ages needs to be continued and extended to analyze a greater number of forest and soil types.
    Scopus© Citations 5  71