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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 257-267 
    ISSN: 1573-0867
    Schlagwort(e): ammonium fertilizer ; application rate ; cattle slurry ; denitrification ; grassland ; nitrate fertilizer ; nitrous oxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Five field experiments and one greenhouse experiment were carried out to assess the effects of nitrogen (N) fertilizer type and the amount of applied N fertilizer on nitrous oxide (N2O) emission from grassland. During cold and dry conditions in early spring, emission of N2O from both ammonium (NH 4 + ) and nitrate (NO 3 − ) containing fertilizers applied to a clay soil were relatively small, i.e. less than 0.1% of the N applied. Emission of N2O and total denitrification losses from NO 3 − containing fertilizers were large after application to a poorly drained sand soil during a wet spring. A total of 5–12% and 8–14% of the applied N was lost as N2O and via denitrification, respectively. Emissions of N2O and total denitrification losses from NH 4 + fertilizers and cattle slurry were less than 2% of the N applied. Addition of the nitrification inhibitor dicyandiamide (DCD) reduced N2O fluxes from ammonium sulphate (AS). However, the effect of DCD to reduce total N2O emission from AS was much smaller than the effect of using NH 4 + fertilizer instead of NO 3 − fertilizer, during wet conditions. The greenhouse study showed that a high groundwater level favors production of N2O from NO 3 − fertilizers but not from NH 4 + fertilizers. Inereasing calcium ammonium nitrate (CAN) application increased the emitted N2O on grassland from 0.6% of the fertilizer application rate for a dressing of 50 kg N ha−1 to 3.1% for a dressing of 300 kg N ha−1. In another experiment, N2O emission increased proportionally with increasing N rate. The results indicate that there is scope for reducing N2O emission from grasslands by choosing the N fertilizer type depending on the soil moisture status. Avoiding excessive N application rates may also minimize N2O emission from intensively managed grasslands.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 52 (1998), S. 141-149 
    ISSN: 1573-0867
    Schlagwort(e): controls ; grassland ; management ; modelling ; nitrous oxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract There is growing awareness that grassland livestock production systems are major sources of nitrous oxide (N2O). Controlling these emissions requires a thorough understanding of all sources and controlling factors at the farm level. This paper examines the various controlling factors and proposes farm management measures to decrease N2O emissions from intensively managed grassland livestock farming systems. Two types of regulating mechanisms of N2O emissions can be distinguished, i.e. environmental regulators and farm management regulators. Both types of regulators may influence the number and size of N2O sources, and the timing of the emissions. At the field and farm scales, two clusters of environmental regulating factors have been identified, i.e. soil and climate, and three levels of management regulators, i.e. strategic, tactical and operational. Though the understanding of these controls is still incomplete, the available information suggests that there is large scope for diminishing N2O emissions at the farm scale, using strategies that have been identified already. For example, model calculations indicate that it may be possible to decrease total N2O emissions from intensively managed dairy farms in The Netherlands in the short term from a mean of about 19 to about 13 kg N per ha per year by more effective nutrient management, whilst maintaining productivity. There is scope for a further reduction to a level of about 6 kg N per ha per year. Advisory tools for controlling N2O emissions have to be developed for all three management levels, i.e. strategic, tactical and operational, to be able to effectively implement emission reduction options and strategies in practice. Some strategies and best management practices to decrease N2O emissions from grassland livestock farming systems are suggested.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 181 (1996), S. 263-274 
    ISSN: 1573-5036
    Schlagwort(e): grassland ; grazing ; groundwater level ; nitrogen fertilizer ; nitrous oxide ; seasonal variations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Seasonal and interannual variations in nitrous oxide (N2O) losses from agricultural soils hamper the accurate quantification of the N2O source strength of these soils. This study focuses on a quantification of seasonal and interannual variations in N2O losses from managed grasslands. Special attention was paid to N2O losses during the growing season and off-season as affected by grassland management. Fluxes of N2O from grasslands with three different types of management and on four different soil types in the Netherlands were measured weekly during two consecutive years, using flux chambers. There were distinct seasonal patterns in N2O losses, with large losses during spring, summer, and autumn but relatively small losses during the winter. These seasonal variations were related to fertilizer N application, grazing and weather conditions. Measurements of N2O concentrations in soil profiles showed that a rise in groundwater level was accompanied by increased N2O concentrations in the soil. Disregarding off-season losses would underestimate total annual losses by up to 20%, being largest for unfertilized grassland and smallest for N-fertilized grazed grassland. Total annual N2O losses ranged from 0.5 to 12.9 kg N ha-1 yr-1 for unfertilized grasslands to 7.3 to 42.0 kg N ha-1 yr-1 for N-fertilized grazed grasslands. Despite the considerable interannual variations in N2O losses, this study indicates that the results of measurements carried out in one year have predictive power for estimating N2O losses in other years.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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