• Authors:
    • Mauder, M.
    • MacPherson, J. I.
    • Srinivasan, R.
    • Grant, B.
    • Worth, D.
    • Smith, W. N.
    • Pattey, E.
    • Desjardins, R. L.
  • Source: Agricultural and Forest Meteorology
  • Volume: 150
  • Issue: 6
  • Year: 2010
  • Summary: Nitrous oxide (N2O) emissions are a large proportion of the agriculture sector's contribution to the greenhouse gas inventory of most developed countries. The spatial and temporal variability of N2O emissions from agricultural soils has long been considered the main factor limiting our ability to estimate N2O emissions, particularly the emissions associated with the spring snowmelt period. Tower and aircraft-based flux measurement systems and a process-based model were used to quantify N2O emissions for four years (2000, 2001, 2003 and 2004) in an agricultural area of eastern Canada, near Ottawa, where a corn-soybean crop rotation dominates. A tower-based system, which relies on the flux gradient technique, provided diurnal N2O emissions at a field scale. An aircraft-based system, which relies on the relaxed eddy accumulation technique, provided N2O emissions for two similar agricultural regions and the denitrification and decomposition (DNDC) model was used to estimate daily N2O emissions at a regional scale. In most cases, aircraft-based N2O emissions measurements were comparable for the two agricultural regions. Corresponding tower-based measurements which were collected over a field in the Ottawa area showed similar emission patterns to the aircraft-based measurements but in some cases the tower-based emissions were larger, as expected. This is because the footprint of aircraft-based measurements always incorporated a significant amount of crops such as soybean and other types of vegetation which do not receive additional nitrogen fertilization as well as waterlogged areas that do not emit N2O. While in three of the four years, the tower-based measurements were made over a tile drained field where nitrogen fertilizer had been applied the previous year. The N2O emissions patterns after planting were also similar for both aircraft and tower-based systems, but again they were slightly larger for the tower-based system. Aircraft-based N2O flux measurements are also compared to the N2O emissions obtained using the most recent version of the process-based model DNDC. Tests showed that DNDC gave comparable N2O emissions estimates for the measurement period as a whole, but was not always able to correctly predict the timing of peak emissions.
  • Authors:
    • Rosegrant, M.
    • Derner, J. D.
    • Schuman, G. E.
    • Verchot, L.
    • Steinfeld, H.
    • Gerber, P.
    • De Freitas, P. L.
    • Lal, R.
    • Desjardins, R. L.
    • Dumanski, J.
  • Source: Applied Agrometeorology
  • Year: 2010
  • Summary: Agriculture can make significant contributions to climate change mitigation by (a) increasing soil organic carbon (SOC) sinks, (b) reducing GHG emissions, and (c) off-setting fossil fuel by promoting biofuels. The latter has the potential to counter-balance fossil fuel emissions to some degree, but the overall impact is still uncertain compared to emissions of non-CO2 GHGs, which are likely to increase as production systems intensify. Agricultural lands also remove CH4 from the atmosphere by oxidation, though less than forestlands (Tate et al. 2006; Verchot et al. 2000), but this effect is small compared to other GHG fluxes (Smith and Conen 2004).
  • Authors:
    • Franzluebbers, A. J.
  • Source: Soil Organic Matter and Nutrient Cycling to Sustain Agriculture in the Southeastern USA
  • Year: 2010
  • Authors:
    • McDougal, R.
    • Pennock, D.
    • Badiou, P.
  • Year: 2010
  • Authors:
    • McKenzie, R. H.
    • Bremer, E.
    • Olson, B. M.
    • Bennett, D. R.
  • Source: Canadian Journal of Soil Science
  • Volume: 90
  • Issue: 2
  • Year: 2010
  • Summary: The risk of P leaching increases on land that receives manure at rates sufficient to meet crop N requirements, but calcareous subsoils may minimize P loss due to P adsorption. An 8-yr field experiment was conducted to determine the effects of different rates of manure on the accumulation and leaching of soil P in a coarse-textured (CT) soil and a medium-textured (MT) soil under typical irrigation management in southern Alberta. Treatments included a non-manured control and four rates of cattle ( Bos taurus) manure (20, 40, 60, and 120 Mg ha -1 yr -1, wet-weight basis). In manured treatments, P addition ranged from about 80 to 450 kg P ha -1 yr -1, while P removal by annual cereal silage crops ranged from 15 to 22 kg P ha -1 yr -1. High soil test P (STP) concentrations occurred to a depth of 0.6 m at the CT site and 0.3 m at the MT site. Increase in STP concentration to 0.6 m was equivalent to 43% of net P input, and increase in total soil P was equivalent to 78% of net P input. Non-recovery of net P input suggests that P loss by leaching occurred at these sites and that leaching was more prevalent at the CT site. These calcareous soils have considerable potential to hold surplus P, but may still allow P leaching.
  • Authors:
    • Larney, F. J.
    • McKenzie, R. H.
    • Olson, B. M.
    • Bremer, E.
  • Source: Canadian Journal of Soil Science
  • Volume: 90
  • Issue: 4
  • Year: 2010
  • Summary: Land application of livestock manure has caused concern about excess nutrients in soil and the potential risk to water quality. Application of manure based on crop-nutrient requirements is considered a beneficial management practice. A field study was conducted to assess the feasibility and impact of crop-based N and P application rates of cattle ( Bos taurus) manure and compost for crop productivity and accumulation of extractable soil N and P. The 6-yr (2002-2007), small-plot field study included 10 amendments: control (CONT), annual synthetic fertilizer N (F-N), annual synthetic fertilizer P (F-P), annual synthetic fertilizer N plus P (F-NP), annual N-based manure (M-N), annual P-based manure (M-P), three times the P-based manure once per 3 yr (M-3P), annual N-based compost (C-N), annual P-based compost (C-P), and three times the P-based compost once per 3 yr (C-3P). Amendments were arranged in randomized complete block design with five replicates and applied based on annual soil testing and nutrient recommendations. The test crops were triticale (* Triticosecale rimpaui Wittm.) and barley ( Hordeum vulgare L.) silage managed under irrigation. Dry matter yields for CONT and F-P were significantly smaller than for the other treatments. There were generally no significant differences among the six organic and F-NP amendments. Apparent N recovery (ANR) was greatest for F-NP (45%) and F-N (41%), followed by the P-based organic amendments (26-34%), M-N (15%), and smallest for C-N (10%). Apparent P recovery (APR) was greatest for F-NP (30%) and smallest for M-N (6%) and C-N (4%). The APR for the P-based organic amendments ranged from 14 to 22%. Application of the amendments did not result in the accumulation of excess nitrate N in the soil profile. The M-N and C-N amendments applied for 6 yr increased extractable P in the 0- to 0.15-m soil layer from 12 mg kg -1 to 121 and 156 mg kg -1, respectively. Crop productivity and soil nutrient responses indicated that assumptions made for P and N availability in manure and compost were reasonably accurate. Based on the results, P-based application of manure or compost can achieve optimum crop yield and prevent nutrient build-up in soil. Under the conditions of this study, the amount of land required to accommodate P-based application would be five to seven times more for manure and eight to ten times more for compost compared with N-based application.
  • Authors:
    • Hucl, P.
    • Matus-Cádiz, M. A.
  • Source: Crop Science
  • Volume: 50
  • Issue: 5
  • Year: 2010
  • Summary: Recent research has addressed the potential for gene flow in wheat (Triticum aestivum L.). However, there is scant information on the fate of introgressed genes in the subsequent crop rotation. The objective of this study was to quantify spring wheat volunteers potentially arising from gene flow. A total of 152 wheat fields that had been used to measure gene flow at distances of up to 10 km were surveyed for blue aleurone volunteers for 3 yr postharvest. No blue aleurone seed was detected in samples from the 152 fields surveyed. A single blue aleurone volunteer plant was detected in a pollen donor field subsequently sown to wheat in the third year postharvest. The absence of blue aleurone wheat volunteers in the postharvest crop rotation was not unexpected as only four of the original 152 fields had shown evidence of gene flow. Under the environmental and crop management practices encountered in this study, the risk of a gene flow-based adventitious event in spring wheat being detected at significant levels in subsequent crops appears low.
  • Authors:
    • Grant, C.
    • Khakbazan, M.
    • Mohr, R.
  • Source: López-Francos A. (comp.), López-Francos A. (collab.). Economics of drought and drought preparedness in a climate change context. Zaragoza : CIHEAM / FAO / ICARDA / GDAR / CEIGRAM / MARM, 2010 (Options Méditerranéennes : Série A. Séminaires Méditerranéens;
  • Issue: 95
  • Year: 2010
  • Summary: The objective of this paper was to study the impact of drought and adaptation measures on the economics of production for some major crops grown in Western Canada. Crop yields, yield variability, and crop losses were analyzed to quantify drought impacts and statistical models were developed to estimate the relationship between yield and growing season precipitation for wheat, canola, oats, and barley. The linear and quadratic precipitation terms were found to have the correct sign and to be significantly related to yield (p
  • Authors:
    • Ediriwickrema, J.
    • Shao, Y.
    • Lunetta, R. S.
    • Lyon, J. G.
  • Source: International Journal of Applied Earth Observation and Geoinformation
  • Volume: 12
  • Issue: 2
  • Year: 2010
  • Summary: The Moderate Resolution Imaging Spectrometer (MODIS) Normalized Difference Vegetation Index (NDVI) 16-day composite data product (MOD12Q) was used to develop annual cropland and crop-specific map products (corn, soybeans, and wheat) for the Laurentian Great Lakes Basin (GLB). The crop area distributions and changes in crop rotations were characterized by comparing annual crop map products for 2005, 2006, and 2007. The total acreages for corn and soybeans were relatively balanced for calendar years 2005 (31,462 km(2) and 31,283 km(2), respectively) and 2006 (30,766 km(2) and 30,972 km(2), respectively). Conversely, corn acreage increased approximately 21% from 2006 to 2007, while soybean and wheat acreage decreased approximately 9% and 21%, respectively. Two-year crop rotational change analyses were conducted for the 2005-2006 and 2006-2007 time periods. The large increase in corn acreages for 2007 introduced crop rotation changes across the GLB. Compared to 2005-2006, crop rotation patterns for 2006-2007 resulted in increased corn-corn, soybean-corn, and wheat-corn rotations. The increased corn acreages could have potential negative impacts on nutrient loadings, pesticide exposures, and sediment-mediated habitat degradation. Increased in US corn acreages in 2007 were related to new biofuel mandates, while Canadian increases were attributed to higher world-wide corn prices. Additional study is needed to determine the potential impacts of increases in corn-based ethanol agricultural production on watershed ecosystems and receiving waters. Published by Elsevier B.V.
  • Authors:
    • Holzapfel, C. B.
    • Kutcher, H. R.
    • Gan, Y.
    • Brandt, S. A.
    • May, W. E.
    • Lafond, G. P.
  • Source: Canadian Journal of Plant Science
  • Volume: 90
  • Issue: 5
  • Year: 2010
  • Summary: Differences in response to nitrogen (N) fertilizer will affect the production economics of field crops. Currently, there is limited information comparing the agronomic and economic performance of juncea canola (Brassica juncea L.) and sunflower (Helianthus annuus L.) to napus canola (Brassica napus L.) and flax (Limon ustitatissimum L.) in Saskatchewan under no-till practices. A study of these species was carried out at five Saskatchewan locations over 3 yr and included eight nitrogen rates. All four species had a curvilinear increase in grain yield as N rate increased with the largest yield response observed in napus canola to as much as 200 kg N ha I. The majority of the increase in flax grain yield occurred as the N rate increased from 10 to 90 kg ha(-1), while most of the increase in grain yield of juncea canola and sunflower occurred as N increased from 10 to 70 kg ha(-1). Biplot analysis indicated that grain yield variation was reduced at and above 50 kg N ha(-1) in flax, napus canola and juncea canola, but not in sunflower. Analysis indicated that a wide range of N rates would provide a similar adjusted gross return within each crop with the exact N range being determined by crop price and nitrogen cost. The N rate affected the kernel weight of sunflower but not the kernel weight of other crops. The protein concentration of all the species increased as N rate increased. Seed oil concentration tended to decrease as the N rate increased, but this was not consistent. In conclusion, higher yielding cultivars of sunflower and juncea canola are needed before they will replace a large acreage of flax or napus canola; however, in the drier regions of the Saskatchewan there is potential to expand sunflower production.