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Soil samples were taken from plots at 3 different experimental sites that had received different fertilizer applications for more than 20 years. Denitrification capacity (DC) and denitrification potential (DP), defined as the amount of N 2 O released from the soils amended with KNO 3 and KNO 3 + glucose, respectively, and incubated anaerobically in the presence of 10 kPa acetylene...
The large temporal variation in nitrous oxide (N 2 O), methane (CH 4 ) and carbon dioxide (CO 2 ) flux rates is a major source of error when estimating cumulative fluxes of these radiative active trace gases. We developed an automated system for near-continuous, long-term measurements of N 2 O, CH 4 and CO 2 fluxes from cropland soils and used it to...
The amount, quality and bioavailability of organic matter stored in permafrost soils are important factors determining the response of high-latitude soils to climate warming. In this study, we investigated the storage and composition (isotopic composition, lignin, pyrogenic carbon) of organic matter in mineral soils which are differently affected by permafrost, and we determined the potential CO ...
In this paper we use regression kriging to improve predictions of a hard-to-measure soil variable based on an established process model. In our case study the target variable is the rate of nitrous oxide (N 2 O) emission from soil. We used three different process models that each have the same soil properties as input variables, but make different assumptions about the kinetics of denitrification...
Uneven distribution of resources in reclaimed mine land could translate in heterogeneous gas fluxes in these ecosystems, but few studies have examined this linkage. In this study, the spatial variability of CO 2 , CH 4 and N 2 O fluxes and soil properties was investigated at (i) a hay field (90 kg urea–N ha −1 y −1 ), and (ii) a meadow (without any grazing and...
Rice (Oryza sativa L.) paddy soils have the potential to emit both of the greenhouse gases methane (CH 4 ) and nitrous oxide (N 2 O), depending on redox potential. Results from incubation studies with homogenized soil led to a proposed “healthy redox potential” range that minimizes both CH 4 and N 2 O emission. We examined whether controlled irrigation with the water-saving...
Models are increasingly used to examine the potential impacts of management and climate change in agriculture. Our aim in this paper was to assess the applicability of the field-DeNitrification DeComposition (DNDC) model in Irish agriculture. This study provides the results of that evaluation, which is a prerequisite for using the model for assessing management impacts in the future. The DNDC model...
Geostatistical prediction of soil properties depends on the assumption of stationarity in the covariance, but this is often implausible, which implies that predictions may be suboptimal, and their computed variances will be unreliable. There have been attempts in the statistical literature to tackle this problem, and in this paper we discuss, develop and evaluate one approach. This is spectral tempering,...
The characteristic feature of the Prairie Pothole Region is a complex assemblage of mineral soil wetlands embedded in the dominantly agricultural landscape. Soils in these wetlands are loci of high potential greenhouse gas (GHG) emissions, and our objective was to provide estimates of greenhouse gas emissions and the controls on these emissions for typical wetlands of this region. Three years (2004–06)...
The rate of nitrous oxide emissions was measured from 276 soil cores on a 7.5-km transect, and then a subset of these data was used to compute geostatistical models in which land categories (land-use and soil type) were fixed effects. In one model the random effects were assumed to be second-order stationary. In the other models non-stationary random variation was modelled independently for the autocorrelation...
The effect of nitrogen addition, through deposition or fertilization, on ecosystem processes responsible for storing and releasing greenhouse gasses (GHG) CO 2 , CH 4 and N 2 O are poorly understood. We measured the effects of winter application of 200kgNha −1 to a near-end-of-rotation coastal Douglas-fir stand on soil CH 4 and N 2 O fluxes, soil and...
Atmospheric concentrations of nitrous oxide (N 2 O) have been increasing over the last century with much of this increase from agricultural soils, fertilized with nitrogen. To understand the N 2 O emissions from terrestrial ecosystems (e.g. grassland soils) it is necessary to understand the processes leading to N 2 O production. From February to August in 2010, we conducted...
There is a high spatial variation in N 2 O emission from agricultural fields and N 2 O emissions from fields cultivated with stalk-crops was generally measured in the interrow area. The aim of this study was to evaluate the difference in seasonal N 2 O emissions between interrow soil and interrow+row soil, and to understand the effect of different fertilizers on N 2 ...
The daily mean riverine N 2 O flux at a field site is often assumed to be equivalent to the magnitude of occasional once-per-day measurements made using the chamber method. The resulting time series data set therefore has a low temporal resolution. However, significant temporal variations in the N 2 O fluxes are typically found in streams and rivers, and high-frequency sampling is...
Urban landscapes often have altered soil–atmosphere fluxes of major greenhouse gases (GHGs) including carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) when compared to their rural counterparts. It is unclear to what degree soil disturbance during urbanization contributes to these altered emissions. In addition, rehabilitation of degraded urban soils through deep tillage and organic amendment...
Hydroxylamine (HA) is a crucial intermediate in the first step of nitrification, i.e., the oxidation of ammonium to nitrite. Due to its reactivity, HA may play a key role in soil N2O emission. To determine soil HA concentrations and to explore the correlation between soil HA concentrations and N2O emission rates, we developed a novel, extremely sensitive method based on fast extraction of HA from...
Soil salinity negatively affects the mineralization and nitrification processes of the N cycle and may also affect the production of nitrous oxide (N 2 O) and N 2 to N 2 O–N ratios. Application of organic amendments such as manures and composts improves soil physical, chemical, and biological properties of salt-affected soils. However, because these materials both mineralize...
Rice fields in the tropics can vary in water regime before production of rice on flooded soil, but relatively little is known about the effects of soil water regime and crop residue management between rice crops (i.e., fallow period) on methane (CH 4 ) and nitrous oxide (N 2 O) emissions during a subsequent rice crop. We measured CH 4 and N 2 O emissions during two...
Urea deep placement (UDP) increases nitrogen use efficiency (NUE) in lowland rice fields by reducing ammonia volatilization, surface runoff and increasing nitrogen uptake. However, its effects on N losses as nitrous oxide (N2O) and nitric oxide (NO) are not yet clear. We conducted field experiments at two locations of Bangladesh — Bangladesh Agricultural University (BAU) and Bangladesh Rice Research...
The effect of elevated CO2 (eCO2) on nitrous oxide (N2O) emissions is important as it could negate some of the potential benefits of eCO2 on carbon sink activity and thus affect the concentration of greenhouse gases in the atmosphere. Grazed grassland is a significant source of N2O but no studies have so far measured eCO2 effects on processes related to N2O production in grassland grazed by animals...
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