• Authors:
    • Li, C.
    • Drury, C. F.
    • Rochette, P.
    • Desjardins, R. L.
    • Grant, B. B.
    • Smith, W. N.
  • Source: Canadian Journal of Soil Science
  • Volume: 88
  • Issue: 2
  • Year: 2008
  • Summary: Process-based models play an important role in the estimation of soil N2O emissions from regions with contrasting soil and climatic conditions. A study was performed to evaluate the ability of two process-based models, DAYCENT and DNDC, to estimate N2O emissions, soil nitrate- and ammonium-N levels, as well as soil temperature and water content. The measurement sites included a maize crop fertilized with pig slurry (Quebec) and a wheat-maize-soybean rotation as part of a tillage-fertilizer experiment (Ontario). At the Quebec site, both models accurately simulated soil temperature with an average relative error (ARE) ranging from 0 to 2%. The models underpredicted soil temperature at the Ontario site with ARE from -5 to -7% for DNDC and from -5 to -13% for DAYCENT. Both models underestimated soil water content particularly during the growing season. The DNDC model accurately predicted average seasonal N2O emissions across treatments at both sites whereas the DAYCENT model underpredicted N2O emissions by 32 to 58% for all treatments excluding the fertilizer treatment at the Quebec site. Both models had difficulty in simulating the timing of individual emission events. The hydrology and nitrogen transformation routines need to be improved in both models before further enhancements are made to the trace gas routines.
  • Authors:
    • Li, X.
    • Flesch, T. K.
    • Gao, Z.
    • Desjardins, R. L.
    • van Haarlem, R. P.
  • Source: Canadian Journal of Animal Science
  • Volume: 88
  • Issue: 4
  • Year: 2008
  • Summary: Methane and ammonia emissions from a beef feedlot in western Canada for a twelve-day period in the fall. Can. J. Anim. Sci. 88: 641649. Commercial feedlot operations are becoming a mainstay in the Canadian beef industry. These large operations that typically raise thousands of animals at a time represent a large localized source of methane (CH4) and of atmospheric pollutants such as ammonia (NH3) and particulate matter. An inverse dispersion model was utilized to calculate CH4 and NH3 emissions from a commercial cattle feedlot and an adjacent runoff retention pond. The feedlot measurements were collected within the interior of the feedlot enabling a near continuous emissions record over the 12 d of the study period. Average daily emission estimates of CH4 and NH3 were 323 and 318 g animal -1d-1, respectively. The CH4 emissions represent 4% of the gross energy intake (GEI) and NH3 emissions represent 72% of the total N intake. Emissions from the runoff retention pond associated directly with the feedlot operation were approximately 2.7 and 2% of the daily average feedlot emissions of CH4 and NH3, respectively.
  • Authors:
    • Worth, D.
    • Desjardins, R. L.
    • Dyer, J. A.
    • Vergé, X. P. C.
  • Source: Agricultural Systems
  • Volume: 98
  • Issue: 2
  • Year: 2008
  • Summary: Commodity-specific estimates of the greenhouse gas (GHG) emissions from Canadian agriculture are required in order to identify the most efficient GHG mitigation measures. In this paper, the methodology from the Intergovernmental Panel on Climate Change (IPCC) for estimating bovine GHG emissions, for census years from 1981 to 2001, was applied to the Canadian beef industry. This analysis, which is based on several adaptations of IPCC methodology already done for the Canadian dairy industry, includes the concept of a beef crop complex, the land base that feeds the beef population, and the use of recommendations for livestock feed rations and fertilizer application rates to down-scale the national area totals of each crop, regardless of the use of that crop, to the feed requirements of the Canada's beef population. It shows how high energy feeds are reducing enteric methane emissions by displacing high roughage diets. It also calculates an emissions intensity indicator based on the total weight of live beef cattle destined for market. While total GHG from Canadian beef production have increased from 25 to 32 Tg of CO2 equiv. between 1981 and 2001, this increase was mainly driven by expansion of the Canadian cattle industry. The emission intensity indicator showed that between 1981 and 2001, the Canadian beef industry GHG emissions per kg of live animal weight produced for market decreased from 16.4 to 10.4 kg of CO2 equiv.
  • Authors:
    • Furtan, W. H.
    • Davey, K. A.
  • Source: Canadian Journal of Agricultural Economics/Revue Canadienne D'Agroeconomie
  • Volume: 56
  • Issue: 3
  • Year: 2008
  • Summary: The adoption of conservation tillage technology since the 1970s has been one of the most remarkable changes in the production of crops on the Canadian Prairies. The decision whether to adopt conservation tillage technology or not requires the producer to go through a thorough decision-making process. In Canada, there has been little economic research on the question of what farm, regional, and environmental characteristics affect the adoption decision. Using 1991, 1996, and 2001 Census of Agriculture data together with other data sources we estimate a probit model explaining the adoption decision. We find that important variables include farm size, proximity to a research station, type of soil, and weather conditions.
  • Authors:
    • McLaughlin, N. B.
    • Reynolds, W. D.
    • Yang, X. M.
    • Drury, C. F.
  • Source: Canadian Journal of Soil Science
  • Volume: 88
  • Issue: 2
  • Year: 2008
  • Summary: t is well established that nitrous oxide (N2O) and carbon dioxide (CO2) emissions from agricultural land are influenced by the type of crop grown, the form and amount of nitrogen (N) applied, and the soil and climatic conditions under which the crop is grown. Crop rotation adds another dimension that is often overlooked, however, as the crop residue being decomposed and supplying soluble carbon to soil biota is usually from a different crop than the crop that is currently growing. Hence, the objective of this study was to compare the influence of both the crop grown and the residues from the preceding crop on N2O and CO2 emissions from soil. In particular, N2O and CO2 emissions from monoculture cropping of corn, soybean and winter wheat were compared with 2-yr and 3-yr crop rotations (corn-soybean or corn-soybean-winter wheat). Each phase of the rotation was measured each year. Averaged over three growing seasons (from April to October), annual N2O emissions were about 3.1 to 5.1 times greater in monoculture corn (2.62 kg N ha-1 ) compared with either monoculture soybean (0.84 kg N ha-1) or monoculture winter wheat (0.51 kg N ha-1). This was due in part to the higher inorganic N levels in the soil resulting from the higher N application rate with corn (170 kg N ha-1) than winter wheat (83 kg N ha-1) or soybean (no N applied). Further, the previous crop also influenced the extent of N2O emissions in the current crop year. When corn followed corn, the average N2O emissions (2.62 kg N ha1 ) were about twice as high as when corn followed soybean (1.34 kg N ha-1) and about 60% greater than when corn followed winter wheat (1.64 kg N ha-1). Monoculture winter wheat had about 45% greater CO2 emissions than monoculture corn or 51% greater emissions than monoculture soybean. In the corn phase, CO2 emissions were greater when the previous crop was winter wheat (5.03 t C ha-1) than when it was soybean (4.20 t C ha-1) or corn (3.91 t C ha-1). Hence, N2O and CO2 emissions from agricultural fields are influenced by both the current crop and the previous crop, and this should be accounted for in both estimates and forecasts of the emissions of these important greenhouse gases.
  • Authors:
    • Worth, D.
    • Desjardins, R. L.
    • Verge´, X. P. C.
    • Dyer, J. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 88
  • Issue: 5
  • Year: 2008
  • Summary: Estimates of the efficiency of mitigation measures on reducing greenhouse gas (GHG) emissions from the agricultural sector are required. In this paper, recently calculated dairy GHG emissions for 2001 were extrapolated back to 1981 for census years using an index. The index was verified by comparing it with estimates based on the Intergovernmental Panel on Climate Change (IPCC) methodology for 1991. The index agreed with the IPCC estimates within 1% for methane and 4% for nitrous oxide on a national scale with no region having a difference of more than 5% for methane. For nitrous oxide, all regions were within 10%, except British Columbia, where the index was 19% too high. The index indicates that GHG emissions from primary milk production within the Canadian dairy industry have decreased by about 49% since 1981, mainly due to a 57% reduction in the dairy cow population during that period. The GHG emissions per kilogram of milk decreased by 35%, that is from 1.22 kg CO2eq kg-1 milk to 0.91 kg CO2eq kg-1 milk. Because this study took into account the energy-related CO2 emissions from all the major farm inputs (fertilizer and fossil fuel), there was little risk of hidden GHG emissions in the emission intensity calculation. This study demonstrates that where lack of input data restricts historical application of simulation models, a semi-empirical index approach can yield valuable results. Key words: Greenhouse gas, dairy industry, index, intensity indicator
  • Authors:
    • Janzen, H. H.
    • Ellert, B. H.
  • Source: Canadian Journal of Soil Science
  • Volume: 88
  • Issue: 2
  • Year: 2008
  • Summary: Irrigated land in southern Alberta is intensively managed, producing high yields but also requiring higher inputs, notably of nitrogen (N), than adjacent rainfed lands. The higher N inputs, combined with enhanced soil moisture, might stimulate nitrous oxide (N2O) emissions, but the influence of management on these emissions has not been widely studied. Our objective was to assess soil N2O emissions, along with those of carbon dioxide (CO2) and of methane (CH4), from irrigated cropping systems as influenced by source of N. We used a chamber technique to measure year-round emissions for 3 yr in long-term irrigated crop rotations receiving N as legume crop residues, non-legume crop residues, livestock manure or ammonium nitrate fertilizer. Unlike CO2 fluxes, which peaked during the growing season, those of N2O showed no consistent seasonal trends; emissions occurred sporadically in bursts throughout the year. Depending on management practices, 0.4 to 4.0 kg N2O-N ha(-1) yr(-1) was emitted to the atmosphere. The amount of N2O emitted from the alfalfa system, averaged over all manure and fertilizer N amendments, was more than twofold that emitted from the corn system. The proportions of fertilizer-N released as N2O were 0.95% for the alfalfa system and 1.30% for the corn system. After livestock manure or legume residues were incorporated, soil CO2 and N2O emissions appeared to be intertwined, but during the early spring N2O emissions were decoupled from CO2. Furthermore, N2O emissions were highly variable in space; at three of 54 chambers, N2O fluxes were consistently 12 to 55 times greater than those for other chambers in the same treatment. Such complexity conceals the underlying processes of net N2O production and transport to the soil surface.
  • Authors:
    • Alberta Environment and Water
  • Year: 2008
  • Authors:
    • Alberta Environment
  • Year: 2008