• Authors:
    • WCI
  • Volume: 2010
  • Year: 2010
  • Summary: Welcome to the Western Climate Initiative (WCI). The WCI is a collaboration of independent jurisdictions working together to identify, evaluate, and implement emissions trading policies to tackle climate change at a regional level. This is a comprehensive effort to reduce greenhouse gas pollution, spur investment in clean-energy technologies that create green jobs and reduce dependence on imported oil.
  • Authors:
    • Liu,C. W.
    • James,D. C.
    • Carter,M. R.
    • Cade-Menun,B. J.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 5
  • Year: 2010
  • Summary: In many regions, conservation tillage has replaced conventional tilling practices to reduce soil erosion, improve water conservation, and increase soil organic matter. However, tillage can have marked effects on soil properties, specifically nutrient redistribution or stratification in the soil profile. The objective of this research was to examine soil phosphorus (P) forms and concentrations in a long-term study comparing conservation tillage (direct drilling, "No Till") and conventional tillage (moldboard plowing to 20 cm depth, "Till") established on a fine sandy loam (Orthic Humo-Ferric Podzol) in Prince Edward Island, Canada. No significant differences in total carbon (C), total nitrogen (N), total P, or total organic P concentrations were detected between the tillage systems at any depth in the 0- to 60-cm depth range analyzed. However, analysis with phosphorus-31 nuclear magnetic resonance spectroscopy showed differences in P forms in the plow layer. In particular, the concentration of orthophosphate was significantly higher under No Till than Till at 5 to 10 cm, but the reverse was true at 10 to 20 cm. Mehlich 3-extractable P was also significantly higher in No Till at 5 to 10 cm and significantly higher in Till at 20 to 30 cm. This P stratification appears to be caused by a lack of mixing of applied fertilizer in No Till because the same trends were observed for pH and Mehlich 3-extractable Ca (significantly higher in the Till treatment at 20 to 30 cm), reflecting mixing of applied lime. The P saturation ratio was significantly higher under No Till at 0 to 5 cm and exceeded the recommended limits, suggesting that P stratification under No Till had increased the potential for P loss in runoff from these sites.
  • Authors:
    • Bertrand, N.
    • Parent, L. É.
    • MacDonald, J. D.
    • Chantigny, M. H.
    • Angers, D. A.
    • Fallon, E.
    • Tremblay, N.
    • Rochette, P.
  • Source: European Journal of Soil Science
  • Volume: 61
  • Issue: 2
  • Year: 2010
  • Summary: Drainage and cultivation of organic soils often result in large nitrous oxide (N2O) emissions. The objective of this study was to assess the impacts of nitrogen (N) fertilizer on N2O emissions from a cultivated organic soil located south of Montreal, QC, Canada, drained in 1930 and used since then for vegetable production. Fluxes of N2O were measured weekly from May 2004 to November 2005 when snow cover was absent in irrigated and non-irrigated plots receiving 0, 100 or 150 kg N ha(-1) as NH4NO3. Soil mineral N content, gas concentrations, temperature, water table height and water content were also measured to help explain variations in N2O emissions. Annual emissions during the experiment were large, ranging from 3.6 to 40.2 kg N2O-N ha(-1) year(-1). The N2O emissions were decreased by N fertilizer addition in the non-irrigated site but not in the irrigated site. The absence of a positive influence of soil mineral N content on N2O emissions was probably in part because up to 571 kg N ha(-1) were mineralized during the snow-free season. Emissions of N2O were positively correlated to soil CO2 emissions and to variables associated with the extent of soil aeration such as soil oxygen concentration, precipitation and soil water table height, thereby indicating that soil moisture/aeration and carbon bioavailability were the main controls of N2O emission. The large N2O emissions observed in this study indicate that drained cultivated organic soils in eastern Canada have a potential for N2O-N losses similar to, or greater than, organic soils located in northern Europe.
  • Authors:
    • Huffman, E. C.
    • Boles, S. H.
    • Li, C.
    • Worth, D.
    • Desjardins, R. L.
    • Grant, B. B.
    • Smith, W. N.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 136
  • Issue: 3-4
  • Year: 2010
  • Summary: Research is ongoing to develop ways to reduce emissions of greenhouse gases (GHGs) from agricultural sources. A convenient technique to estimate emissions is to develop emission factors for a wide range of management practices. Default emission factors such as those given in the Intergovernmental Panel on Climate Change Tier I methodology are often used but these can result in substantial errors when applied to specific geographical regions. In this paper an interface was developed to link soil, climate and agricultural activity data in Canada with the DeNitrification and DeComposition (DNDC) model to create a modeling tool for estimating emission factors for changes in agricultural management. This tool was also designed to calculate country-specific IPCC Tier II emission factors for comparison against modeled results. The DNDC-Management Factor Tool (DNDC-MFT) was developed to automatically generate soil, climate and agricultural management model input data from national databases for estimating emissions factors for any of 462 ecodistricts across Canada. Six ecodistricts were selected across the major climatic regions to test the tool. The emission factors generated by the DNDC model were significantly different from Tier II values. Much variability in N2O emission estimates exist, partly due to limitations in certain biophysical processes in the model and partly due to quality of input data. The DNDC model is very sensitive to climate, size of initial soil C levels, and fertilizer application rates. We should also keep in mind that there is uncertainly associated with Tier II emission factors. The combined N2O and soil C factors estimated by the DNDC model are generally comparable to values that are being used to estimate Canada's national inventory (Tier II/III) but only the tillage factor was found to be statistically similar. The DNDC-MFT will be useful for testing the ability of the DNDC model to generate GHG emission factors for many management scenarios across varying climatic regions in Canada. The framework can be extended to include improved versions of DNDC and other ecosystem models.
  • Authors:
    • van Groenigen, K. J.
    • van Kessel, C.
    • Oenema, O.
    • Velthof, G. L.
    • van Groenigen, J. W.
  • Source: European Journal of Soil Science
  • Volume: 61
  • Issue: 6
  • Year: 2010
  • Summary: Agricultural soils are the main anthropogenic source of nitrous oxide (N2O), largely because of nitrogen (N) fertilizer use. Commonly, N2O emissions are expressed as a function of N application rate. This suggests that smaller fertilizer applications always lead to smaller N2O emissions. Here we argue that, because of global demand for agricultural products, agronomic conditions should be included when assessing N2O emissions. Expressing N2O emissions in relation to crop productivity (expressed as above-ground N uptake: "yield-scaled N2O emissions") can express the N2O efficiency of a cropping system. We show how conventional relationships between N application rate, N uptake and N2O emissions can result in minimal yield-scaled N2O emissions at intermediate fertilizer-N rates. Key findings of a meta-analysis on yield-scaled N2O emissions by non-leguminous annual crops (19 independent studies and 147 data points) revealed that yield-scaled N2O emissions were smallest (8.4 g N2O-N kg-1N uptake) at application rates of approximately 180-190 kg Nha-1 and increased sharply after that (26.8 g N2O-N kg-1 N uptake at 301 kg N ha-1). If the above-ground N surplus was equal to or smaller than zero, yield-scaled N2O emissions remained stable and relatively small. At an N surplus of 90 kg N ha-1 yield-scaled emissions increased threefold. Furthermore, a negative relation between N use efficiency and yield-scaled N2O emissions was found. Therefore, we argue that agricultural management practices to reduce N2O emissions should focus on optimizing fertilizer-N use efficiency under median rates of N input, rather than on minimizing N application rates.
  • Authors:
    • Kutcher, H. R.
    • Kryzanowski, L. M.
  • Source: Recent Trends in Soil Science and Agronomy Research in the Northern Great Plains of North America
  • Year: 2010
  • Summary: Variability in soil and crop productivity in the Northern Great Plains is related to the pedogenic development of the parent glacial deposits, climate, native vegetation, and topography. Anthropogenic field management over the past 100 years has contributed to additional field variability through tillage erosion, crop-fallow rotations, fertilizer management, livestock manure management and crop residue management. Field topography influences microclimate and the hydrological conditions within a landscape by the redistribution of water and soil thermal dynamics. Water movement from upper to lower slope and depression areas either by runoff or through subsoil will result in the physical redistribution of surface soil (erosion), translocation of soluble nutrients or accumulation of salts. The end result of this redistribution is drier warmer upper slopes, and wetter cooler lower slopes and depressions. This influences soil biological, chemical and physical processes that impact crop growth. Often, the lowest crop yields are measured on the upper slopes and the highest yields on the lower slopes. Upper slopes are prone to erosion, shallow surface horizons, higher carbonate levels, lower organic matter levels and lower available water. The lower slopes have deposits of eroded surface material, deeper surface horizons, greater depth to carbonates, higher organic matter levels and higher available water. However, spatial relationships between productivity and landscape position are not always consistent. Higher productivity does not always occur in lower slopes because yield reductions can occur as a result of planting delays, poor crop germination, poor soil aeration, poor drainage, poor root development, foliar and root diseases, compaction, nutrient deficiencies, weed competition, limited root development, stunted crop development, acidic soil and salinity. Precision farming provides an opportunity to utilize technology to manage the topographical and spatial variability. Elevation and positioning data collected from global positioning systems can be managed by means of geographic information systems. Landform segmentation provides a fundamental basis for subdividing fields into landscape management units based on topography. Field sensors such as crop yield monitors along with remote sensing, aerial photography, soil sampling and weed populations provide additional data layers needed for site specific management. Variable rate controllers provide the technology for fertilizer, manure, lime and herbicide applications. Ultimately, economics will determine the adoption of precision farming technology and practices.
  • Authors:
    • Sun, O. J.
    • Wang, E.
    • Luo, Z.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 139
  • Issue: 1-2
  • Year: 2010
  • Summary: Adopting no-tillage in agro-ecosystems has been widely recommended as a means of enhancing carbon (C) sequestration in soils. However, study results are inconsistent and varying from significant increase to significant decrease. It is unclear whether this variability is caused by environmental, or management factors or by sampling errors and analysis methodology. Using meta-analysis, we assessed the response of soil organic carbon (SOC) to conversion of management practice from conventional tillage (CT) to no-tillage (NT) based on global data from 69 paired-experiments, where soil sampling extended deeper than 40 cm. We found that cultivation of natural soils for more than 5 years, on average, resulted in soil C loss of more than 20 t ha-1, with no significant difference between CT and NT. Conversion from CT to NT changed distribution of C in the soil profile significantly, but did not increase the total SOC except in double cropping systems. After adopting NT, soil C increased by 3.15 +- 2.42 t ha-1 (mean ± 95% confidence interval) in the surface 10 cm of soil, but declined by 3.30 ± 1.61 t ha-1 in the 20-40 cm soil layer. Overall, adopting NT did not enhance soil total C stock down to 40 cm. Increased number of crop species in rotation resulted in less C accumulation in the surface soil and greater C loss in deeper layer. Increased crop frequency seemed to have the opposite effect and significantly increased soil C by 11% in the 0-60 cm soil. Neither mean annual temperature and mean annual rainfall nor nitrogen fertilization and duration of adopting NT affected the response of soil C stock to the adoption of NT. Our results highlight that the role of adopting NT in sequestrating C is greatly regulated by cropping systems. Increasing cropping frequency might be a more efficient strategy to sequester C in agro-ecosystems. More information on the effects of increasing crop species and frequency on soil C input and decomposition processes is needed to further our understanding on the potential ability of C sequestration in agricultural soils.
  • Authors:
    • Stewart, G.
    • Gregorich, E. G.
    • McLaughlin, N. B.
    • Morrison, M. J.
    • Deen, W.
    • Tremblay, N.
    • Wu, T. Y.
    • Ma, B. L.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 1
  • Year: 2010
  • Summary: Nitrogen fertilization is considered as an important source of atmospheric N2O emission. A seven site-year on-farm field experiment was conducted at Ottawa and Guelph, ON and Saint-Valentin, QC, Canada to characterize the affect of the amount and timing of N fertilizer on N2O emission in corn (Zea mays L.) production. Using the static chamber method, gas samples were collected for 28-days after preplant and 28-days after sidedress fertilization at the seven site-year, resulting in 14 monitoring periods. For both methods of fertilization, peak N2O flux and cumulative emission increased with the amount of N applied, with rates ranging from 30 to 900 mu g N m(-2) h(-1). Depending on N amount and time of application, cumulative emission varied from 0.05 to 2.42 kg N ha(-1), equivalent to 0.03% to 1.45% of the N fertilizer applied. Differences in N2O emission peaks among fertilizer treatments were clearly separated in 13 out of 14 monitoring periods. Total N2O emissions may have been underestimated compared with annual monitoring in 10 out of the 49 cases because the monitoring period ended before N2O efflux returned to the baseline level. The flux of N2O was negligible when soil mineral N in the 0-15 cm layer was 15 degrees C was likely the driving force responsible for the higher levels of N2O found for sidedress than preplant application methods. However, caution must be taken when interpreting these later results as preplant fertilization may have continuously stimulated N2O emissions after the 28-days monitoring period, especially in situations where N2O effluxes have not fallen back to their baseline levels. Increasing fertilizer rates from 90 to 150 kg N ha(-1) resulted in slight increases in yields, but doubled cumulative N2O emissions.
  • Authors:
    • MDEQ
    • Midwestern GHG Reduction Accord
  • Volume: 2010
  • Year: 2010
  • Summary: The Midwest Greenhouse Gas Reduction Accord (MGGRA) was a commitment by the governors of six Midwestern states and the premier of one Canadian province to reduce greenhouse gas (GHG) emissions through a regional cap-and-trade program and other complementary policy measures. The Accord was signed in November 2007 as a part of the Midwestern Governors Association Energy Security and Climate Change Summit. Though MGGRA has not been formally suspended, participating states are no longer pursuing it.
  • Authors:
    • Bourbonniere, R. A.
    • Macrae, M. L.
    • DeSimone, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 138
  • Issue: 1-2
  • Year: 2010
  • Summary: Riparian zones often serve to buffer nutrient loading from agricultural uplands but may also release greenhouse gases such as nitrous oxide (N2O) to the atmosphere. Riparian zone topography, combined with lateral chemical inputs from fields, is expected to cause variable hydrochemical environments which may lead to spatially variable N2O emissions. We examined spatial patterns in the simultaneous measurements of subsurface nutrient supply in groundwater, subsurface N2O production and surface N2O fluxes along two transects across a forested riparian zone adjacent to an agricultural field. Although subsurface N2O concentrations and ground water nitrate (NO3-) concentrations displayed distinct spatial trends across the riparian zone, with larger concentrations near the riparian zone-field interface and smaller concentrations in the riparian zone interior, surface N2O fluxes did not reflect this pattern. Instantaneous N2O fluxes measured during this study ranged from -0.28 to 1.3 nmolm-2 s-1 and were as variable within a site as they were among sites. Surface N2O fluxes were most strongly correlated with air and soil temperatures and N2O concentrations in soil pores in the top 15 cm of the soil profile, and were generally not correlated with conditions found in deeper soil throughout the riparian zone, suggesting that lateral inputs in runoff from the agricultural uplands are not increasing N2O fluxes at this site. Further research and analysis is required for a better understanding of the production and consequent movement of N2O, as well as an improved understanding of the effects of agriculture on N2O emissions from riparian areas.