Assessing the effects of agricultural management on nitrous oxide emissions using flux measurements and the DNDC model

2015 ◽  
Vol 206 ◽  
pp. 71-83 ◽  
Author(s):  
Kingsley Chinyere Uzoma ◽  
Ward Smith ◽  
Brian Grant ◽  
Raymond L. Desjardins ◽  
Xiaopeng Gao ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Agricultural Management ◽  
Nitrous Oxide Emissions ◽  
Dndc Model ◽  
Flux Measurements

Improved Chamber Systems for Rapid, Real-Time Nitrous Oxide Emissions from Manure and Soil

2017 ◽  
Vol 60 (4) ◽  
pp. 1235-1258 ◽  
Author(s):  
David B. Parker ◽  
Kenneth D. Casey ◽  
Richard W. Todd ◽  
Heidi M. Waldrip ◽  
Gary M. Marek ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Greenhouse Gas ◽  
Real Time ◽  
Nitrous Oxide Emissions ◽  
Chamber System ◽  
Flux Chamber ◽  
Total N ◽  
Recirculating Flow ◽  
Flux Measurements ◽  
Flow Through

Abstract. Nitrous oxide (N2O) emission rates have traditionally been measured using non-flow-through (NFT), non-steady-state (NSS) chambers, which rely on measuring the increase in N2O concentration in the sealed chamber headspace over time. These flux measurements are very labor- and time-intensive, requiring three to four gas samples collected over a 30 to 60 min period, followed by laboratory N2O measurement with a gas chromatograph (GC) and subsequent flux rate calculation. The objective of this research was to develop and evaluate improved, real-time flux chamber designs that rapidly quantify N2O emissions from manure and soil. The first chamber system consisted of six square 0.95 m2 chamber pans. The chamber pans were mounted on a rail system to facilitate controlled indoor/outdoor laboratory research at a pilot scale. An aluminum lid was moved among the chamber pans. A second portable chamber system with a circular footprint (0.49 m internal dia.) was designed for use in field measurements. With both systems, N2O concentrations were measured each second with 0.1 ppb resolution by recirculating sample air through a real-time continuous N2O analyzer with return flow into the recirculating-flow-through (RFT-NSS) chamber. Performance and observational data are presented for different chamber vent designs, sealing mechanisms between the chamber pan and lid, recirculation pumps, and presence/absence of an internal fan that mixes headspace air within the sealed chamber. As examples of the repeatability and precision of the methodology, ten consecutive flux measurements were obtained using moist manure (32.6% wet basis water content, WCWB) within a 15 min period in which chamber pans were fitted with lids for 60 s and removed for 30 s. The mean calculated N2O flux was 43.08 ±0.89 mg N2O m-2 h-1. Using dry manure (WCWB = 10.8%), five consecutive flux measurements showed a very low, but consistent, flux that averaged 0.025 ±0.0016 mg N2O m-2 h-1. Five case study experiments demonstrate the usefulness of these chamber systems and highlight discoveries and lessons learned to enhance future research efforts. Major discoveries and observations include: (1) installation of a small internal fan within the chamber lids decreased N2O fluctuation over small time periods, allowing precise measurement of manure N2O fluxes as low as 0.0073 mg N2O m-2 h-1 during a 60 s measurement period; (2) two distinct N2O peaks were observed at 1 and 21 d following the addition of water to manure (initial WCWB = 32.6%), with the second peak accounting for 83% of the total N2O emitted over 45 d; and (3) there was notable diurnal variation in N2O fluxes due to temperature variation, even when the manure was dry (WCWB = 10.8%). These flux chamber systems proved to be more rapid, precise, and repeatable than traditional flux chamber methods and offer promise for future greenhouse gas emissions research on manure and soil. Keywords: Cattle, Chamber, Diurnal, Fan, Feedlot, Greenhouse gas, Manure, Precision.

scholarly journals Assessing the impacts of tillage and fertilization management on nitrous oxide emissions in a cornfield using the DNDC model

2016 ◽  
Vol 121 (2) ◽  
pp. 337-349 ◽  
Author(s):  
Qi Deng ◽  
Dafeng Hui ◽  
Junming Wang ◽  
Chih-Li Yu ◽  
Changsheng Li ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrous Oxide Emissions ◽  
Dndc Model

Estimates of direct nitrous oxide emissions from Canadian agroecosystems and their uncertainties

2007 ◽  
Vol 87 (Special Issue) ◽  
pp. 141-152 ◽  
Author(s):  
J J Hutchinson ◽  
B B Grant ◽  
W N Smith ◽  
R L Desjardins ◽  
C A Campbell ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Nitrous Oxide ◽  
Crop Residues ◽  
N Fertilizer ◽  
Sensitivity Analyses ◽  
Nitrous Oxide Emissions ◽  
Dndc Model ◽  
Intergovernmental Panel ◽  
Ipcc Methodology

Using a revised Intergovernmental Panel on Climate Change (IPCC) methodology and the process-based model DeNitrification and DeComposition (DNDC), we estimated N2O emissions from agroecosystems in Canada for each census year from 1981 to 2001. Based on the IPCC methodology, direct emissions of N2O ranged from 12.9 to 17.3 with an average of 15.1 Tg CO2 equivalents, while the DNDC model predicted values from 16.0 to 24.3 with an average of 20.8 Tg CO2 equivalents over the same period, and showed a large interannual variation reflecting weather variability. On a provincial basis, emissions estimated by IPCC and DNDC methods were highest in Alberta, Saskatchewan and Ontario, intermediate for Manitoba and Quebec and lowest in British Columbia and the Atlantic provinces. The greatest source of emissions estimated by the IPCC method was from N fertilizer (avg. 6.32 Tg CO2 equiv. in Canada), followed by crop residues (4.24), pasture range and paddocks (PRP) (2.77), and manure (1.65). All sources of emissions, but especially those from fertilizers, increased moderately over time. Monte Carlo Simulation was used to determine the uncertainty associated with the 2001 emission estimates for both IPCC and DNDC methodologies. The simulation generated most likely values of 19.2 and 16.0 Tg CO2 equivalents for IPCC and DNDC, respectively, with uncertainties of 37 and 41%, respectively. Values for the IPCC estimates varied between 28% for PRP and manure and 50% for N fertilizer and crop residues. At the provincial level, uncertainty ranged between 15 and 47% with higher values on the prairies. Sensitivity analyses for IPCC estimates showed crop residues as the most important source of uncertainty followed by synthetic N-fertilizers. Our analysis demonstrated that N2O emissions can be effectively estimated by both the DNDC and IPCC methods and that their uncertainties can be effectively estimated by Monte Carlo Simulation. Key words: Nitrous oxide, IPCC, DNDC model, Uncertainty analysis, Monte Carlo Simulation

scholarly journals Modeling Nitrous Oxide Emissions From Large-Scale Intensive Cropping Systems in the Southern Amazon

2021 ◽  
Vol 5 ◽  
Author(s):  
Ciniro Costa ◽  
Gillian L. Galford ◽  
Michael T. Coe ◽  
Marcia Macedo ◽  
KathiJo Jankowski ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Spatial Data ◽  
Crop Production ◽  
Large Scale ◽  
Cropping Systems ◽  
Field Measurements ◽  
N Fertilization ◽  
Nitrous Oxide Emissions ◽  
Dndc Model ◽  
Mato Grosso

Nitrogen (N) fertilizer use is rapidly intensifying on tropical croplands and has the potential to increase emissions of the greenhouse gas, nitrous oxide (N2O). Since about 2005 Mato Grosso (MT), Brazil has shifted from single-cropped soybeans to double-cropping soybeans with maize, and now produces 1.5% of the world's maize. This production shift required an increase in N fertilization, but the effects on N2O emissions are poorly known. We calibrated the process-oriented biogeochemical DeNitrification-DeComposition (DNDC) model to simulate N2O emissions and crop production from soybean and soybean-maize cropping systems in MT. After model validation with field measurements and adjustments for hydrological properties of tropical soils, regional simulations suggested N2O emissions from soybean-maize cropland increased almost fourfold during 2001–2010, from 1.1 ± 1.1 to 4.1 ± 3.2 Gg 1014 N-N2O. Model sensitivity tests showed that emissions were spatially and seasonably variable and especially sensitive to soil bulk density and carbon content. Meeting future demand for maize using current soybean area in MT might require either (a) intensifying 3.0 million ha of existing single soybean to soybean-maize or (b) increasing N fertilization to ~180 kg N ha−1 on existing 2.3 million ha of soybean-maize area. The latter strategy would release ~35% more N2O than the first. Our modifications of the DNDC model will improve estimates of N2O emissions from agricultural production in MT and other tropical areas, but narrowing model uncertainty will depend on more detailed field measurements and spatial data on soil and cropping management.

scholarly journals Nitrous oxide emissions from a commercial cornfield (<i>Zea mays</i>) measured using the eddy-covariance technique

2014 ◽  
Vol 14 (14) ◽  
pp. 20417-20460 ◽  
Author(s):  
H. Huang ◽  
J. Wang ◽  
D. Hui ◽  
D. R. Miller ◽  
S. Bhattarai ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Eddy Covariance ◽  
Growing Season ◽  
Fast Response ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
N2o Flux ◽  
Flux Measurements

Abstract. Increases in observed atmospheric concentrations of the long-lived greenhouse gas, nitrous oxide (N2O), have been well documented. However, information on event-related instantaneous emissions during fertilizer applications is lacking. With the development of fast-response N2O analyzers, the eddy covariance (EC) technique can be used to gather instantaneous measurements of N2O concentrations to quantify the exchange of nitrogen between the soil and atmosphere. The objectives of this study were to evaluate the performance of a new EC system, to measure the N2O flux with the system, and finally to examine relationships of the N2O flux with soil temperature, soil moisture, precipitation, and fertilization events. We assembled an EC system that included a sonic anemometer and a fast-response N2O analyzer (quantum cascade laser spectrometer) in a cornfield in Nolensville, Tennessee during the 2012 corn growing season (4 April–8 August). Fertilizer amounts totaling 217 kg N ha−1 were applied to the experimental site. The precision of the instrument was 0.066 ppbv for 10 Hz measurements. The seasonal mean detection limit of the N2O flux measurements was 2.10 ng N m−2 s−1. This EC system can be used to provide reliable N2O flux measurements. The cumulative emitted N2O for the entire growing season was 6.87 kg N2O-N ha−1. The 30 min average N2O emissions ranged from 0 to 11 100 μg N2O{-}N m−2 h−1 (mean = 257.5, standard deviation = 817.7). Average daytime emissions were much higher than night emissions (278.8 ± 865.8 vs. 100.0 ± 210.0 μg N2O-N m−2 h−1). Seasonal fluxes were highly dependent on soil moisture rather than soil temperature, although the diurnal flux was positively related to soil temperature. This study was one of the few experiments that continuously measured instantaneous, high-frequency N2O emissions in crop fields over a growing season of more than 100 days.

scholarly journals Low Nitrous Oxide Emissions in a Boreal Spruce Forest Soil, Despite Long-Term Fertilization

2021 ◽  
Vol 4 ◽  
Author(s):  
Tobias Rütting ◽  
Anna-Karin Björsne ◽  
Per Weslien ◽  
Åsa Kasimir ◽  
Leif Klemedtsson
Keyword(s):  
Nitrous Oxide ◽  
Boreal Forests ◽  
Global Scale ◽  
N Fertilization ◽  
Nitrous Oxide Emissions ◽  
Stem Wood ◽  
Environmental Consequences ◽  
Flux Measurements ◽  
Nitrogen Ratio

Nitrogen (N) fertilization can increase stem wood production by several hundred percent in boreal forests. At the same time, there are concerns about the environmental consequences of N fertilization, especially considering losses of the greenhouse gas nitrous oxide (N2O) to the atmosphere. Soils are a large contributor to N2O emissions on a global scale. The aim of this study was to investigate the consequences of long-term nutrient optimization fertilization on N2O emissions in a boreal forest in Northern Sweden. Field N2O flux measurements were conducted during 2 years with manual and automatic chambers, as well as gas probes in the snow. The N2O emissions were generally low during the whole period of measurements, both from the control and fertilized plots. The emissions were generally highest during the winters, as well as the variability in the observed values. Overall, N2O emissions from fertilized plots were about twice the control, which could be explained by changes in the soil carbon-to-nitrogen ratio.

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