• Authors:
    • Deen, W.
    • Janovicek, K.
    • Meyer-Aurich, A.
    • Weersink, A.
  • Source: Agronomy Journal
  • Volume: 98
  • Issue: 5
  • Year: 2006
  • Summary: The objective of our research was to identify economically efficient corn (Zea mays L.) based tillage-rotation combinations using a 20-yr data set from a long-term experiment in Ontario, Canada. Seven rotations in two tillage systems (moldboard and chisel plow) were analyzed. We found multiple benefits associated with diversifying rotations in both tillage systems The integration of soybean [Glycine mar (L.) Merr.] or soybean and wheat (Triticum aestivum L.) resulted in 7 to 11% higher corn yields in the chisel tillage system. In the plow tillage system corn yield in rotation with soybean and wheat increased by 5%, when wheat was underseeded with red clover (Trifolium pratense L.). These diversified rotations resulted in an increase in yearly net returns of $51 to $64 in the moldboard tillage system and $96 to $108 in the chisel tillage system. The diversification of rotations reduces variance of net return and thus makes the rotations attractive to risk averse producers. Furthermore diversified rotations showed less response to price changes. Diversified rotations evaluated in this study also proved to be less affected by increasing energy costs. Red clover seeded into wheat resulted in 5% higher yields for the following corn crop in the moldboard system. Rotations that included red clover cover lowered production risk but did not have higher net returns than comparable rotations without red clover. However, the potential for red clover to reduce N fertilization requirements for the following corn, was not considered in this study. Yield penalties due to chisel plowing with financial consequences were only observed in continuous corn. In all other rotations the effect of tillage was negligible. An increase in energy costs forces farmers to switch to crops with lower inputs rather than switch to reduced tillage.
  • Authors:
    • Kevan, P. G.
    • Belaoussoff, S.
    • Clements, D. R.
    • Murphy, S. D.
    • Swanton, C. J.
  • Source: Weed Science
  • Volume: 54
  • Issue: 1
  • Year: 2006
  • Summary: In a 6-yr study on four farms (36 fields) in Ontario, Canada, we tested the effects of tillage (moldboard, chisel plow, no tillage) and crop rotations (continuous corn, corn-soybean, corn-soybean-winter wheat) on emerged and seedbank weed species diversity and density Aside from the imposed experimental treatments, all other management was generally consistent among farms. Tillage had the largest effect on weed diversity and density. No tillage promoted the highest weed species diversity, chisel plow was intermediate, and moldboard plow resulted in the lowest species diversity. These results are consistent with ecological succession theory. The increase in weed species diversity resulted from 20 species being associated with no tillage systems, 15 of which were winter annuals, biennials, or perennials. Emerged weed density was affected only by tillage. Over 6 yr, seedbank declined in no-tillage systems from 41,000 to 8,000 seeds m(-3). Crop yields were not affected by tillage or crop rotation. In practical terms, reduced tillage in combination with a good crop rotation may reduce weed density and expenditures on weed management.
  • Authors:
    • Harker, K. N.
    • Beckie, H. J.
    • Blackshaw, R. E.
    • Upadhyay, B. M.
    • Smith, E. G.
    • Clayton, G. W.
  • Source: Canadian Journal of Plant Science
  • Volume: 86
  • Issue: 4
  • Year: 2006
  • Summary: Integrated weed management (IWM) systems that combine seeding date, seeding rate, herbicide rate, and timing of nitrogen (N) fertilizer application were assessed for their economic performance in the Dark Brown and Black soil zones. A barley-field pea IWM system in the Black soil zone at Lacombe, Alberta, and a wheat-canola IWM system in the Dark Brown soil zone at Lethbridge, Alberta, and Scott, Saskatchewan, were used to assess contributions of seeding date (April or May), seeding rate (recommended or 150% of recommended), fertilizer timing (fall or spring), and in-crop herbicide rate (50% or 100% of recommended). The factorial set of treatments was applied in 4 consecutive years at each site. For barley-field pea production, the highest contribution margin (CM) (returns over variable production costs) was earned with 50% of the recommended herbicide rate, spring application of N fertilizer, seeding barley later at the high seeding rate, and seeding field pea early at the recommended seeding rate. This IWM system had a CM benefit of at least $51 ha(-1) compared with current common practices. The wheat-canola system results were site specific. At Lethbridge, it was more profitable to use 50% of recommended herbicide rates and to seed both crops early, with an early seeding date being very important for canola. The CM of this IWM system was $48 ha(-1) higher than current common practices. At Scott, the wheat-canola system was more profitable with spring fertilizer application, 50% of the recommended herbicide rate, and an early seeding date for canola. The best IWM system had a CM $15 to $75 ha-1 higher, depending on the year, than common practices. Our results confirmed the economic merits of using IWM practices for cereal-oilseed and cereal-pulse cropping systems in these regions of western Canada.
  • Authors:
    • Vyn, T.
    • Janovicek, K.
    • Deen, B.
    • Lapen, D.
  • Source: ADVANCES IN GEOECOLOGY
  • Volume: 38
  • Year: 2006
  • Summary: In corn/soybean/wheat rotations in Ontario, Canada, tillage is often conducted intermittently to remediate compaction, address residues, incorporate nutrients or to level the surface. To determine the impact of intermittent tillage on no-till soil structure and crop yield, a 10-year study was initiated in 1995 at the Woodstock Research Station, University of Guelph. Specific objectives were (1) to compare the yield potential of corn, soyabean and wheat under short term and long-term no-till, and (2) to determine the best time to conduct intermittent tillage in a corn/soybean/wheat rotation. Tillage increased corn, soyabean and wheat yields in comparison to both short-term and long-term no-till. No-till soyabean yields did not improve with increasing years under no-till. Corn yields were reduced under first year no-till, but by the second year of no-till, corn yields were equal to long term no-till yields. In a corn/soybean/wheat rotation occasional tillage should be conducted in advance of corn.
  • Authors:
    • Meyer-Aurich, A.
    • Fulton, M.
    • Pannell, D.
    • Weersink, A.
  • Source: Canadian Journal of Agricultural Economics -- Revue Canadienne D'Agroeconomie
  • Volume: 53
  • Issue: 4
  • Year: 2005
  • Summary: Voluntary adoption of beneficial management practices will be the primary means by which farmers cat net greenhouse gas (GHG) emissions. The offset system will not be a major driver clue to (a) the relatively low prices likely to be offered by large final emitters facing an emission cap, (b) discounts applied to those prices for temporary sequestration, (c) the transaction costs and risk premiums associated with signing carbon contracts, and (d) the low elasticity of supply CO2 abatement. Although Canadian farmers are likely to participate to only a limited extent in the carbon-offset market, many will find it profitable to adopt one or more of the BMPs for reducing net GHG emissions. Canadian agriculture is likely to contribution significantly to net emission on reductions by voluntarily sequestering carbon due to the adoption of zero till in the last decade, and possibly by cutting fertilizer levels in the next decade. The contribution will be mainly a response to meeting personal economic objectives rather than being induced by direct incentives through the offset Program.
  • Authors:
    • Desjardins, R. L.
    • Trzcinski, M. K.
    • Pattey, E.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 72
  • Issue: 2
  • Year: 2005
  • Summary: Greenhouse gas emissions from the agricultural sector can be reduced through implementation of improved management practices. For example, the choice of manure storage method should be based on environmental decision criteria, as well as production capacity. In this study, greenhouse gas emissions from three methods of storing dairy and beef cattle manure were compared during the summer period. The emissions of CH4,N2O and CO2 from manure stored as slurry, stockpile, and compost were measured using a flow-through closed chamber. The largest combined N2O-CH4 emissions in CO2 equivalent were observed from the slurry storage, followed by the stockpile and lastly the passively aerated compost. This ranking was governed by CH4 emissions in relation to the degree of aerobic conditions within the manure. The radiative forcing in CO2 equivalent from the stockpiled manure was 1.46 times higher than from the compost for both types of cattle manure. It was almost twice as high from the dairy cattle manure slurry and four to seven times higher from the beef cattle manure slurry than from the compost. The potential reduction of GHG was estimated, by extrapolating the results of the study to all of Canada. By composting all the cattle manure stored as slurry and stockpile, a reduction of 0.70 Tg CO2-eq year-1 would be achieved. Similarly, by collecting and burning CH4 emissions from existing slurry facilities, a reduction of 0.76 Tg CO2-eq year-1 would be achieved. New CH4 emission factors were estimated based on these results and incorporated into the IPCC methodology. For North America under cool conditions, the CH4 emission factors would be 45 kg CH4 hd-1 year-1for dairy cattle manure rather than 36 kg CH4 hd-1 year-1, and 3kgCH4 hd-1 year-1 for beef cattle manure rather than 1 kg CH4 hd-1 year-1.
  • Authors:
    • Pennock,D. J.
    • Farrell,R.
    • Desjardins,R. L.
    • Pattey,E.
    • MacPherson,J. I.
  • Source: Canadian Journal of Soil Science
  • Volume: 85
  • Issue: 1
  • Year: 2005
  • Summary: One impediment to accurate national estimation of N2O is the difficulty in upscaling N2O measurements made at discrete points to larger field and regional scales. Our objective was to estimate N2O emissions during snowmelt in 2002 for a township (approximately 92 km2) near Laird, Saskatchewan. Chamber measurements were made at 12 sites in the township: four fields with canola (Brassica napus L.) residues, four with pea (Pisum sativum L.) residues, three with wheat (Triticum aestivum L.) residues, and one field that received cattle manure. Ten sampling chambers were used at each site, and N2O samples were made on 7 d during the snowmelt period (from 2002 Apr. 03 to Apr. 17). Cumulative N2O emissions during the 14 days of the snowmelt period differed between crop residue types: cumulative emissions from sites with wheat residues were 105.6 g N2O-N ha-1 and were significantly higher (P < 0.1) than those from fields with pea and canola residues (79.6 and 75.2 g N2O-N ha-1 respectively). The single manured site assessed had the highest cumulative emissions of 330.7 g N2O-N ha-1. The crop-specific emissions from the chamber-based measurements were multiplied by the area of each crop type in the township to calculate an area-weighted value for emissions. Cumulative emissions were 93.4 g N2O-N ha-1 for the chamber-based measurements. Water-filled pore space and soil temperature were not significantly correlated with cumulative emissions. Cumulative emissions from sites with fall nitrate levels below 8.0 kg ha-1 were consistently lower than those above this threshold. The emissions for the Laird township were well below the emissions calculated for most other studies in the Prairies and in central Canada. The lower emissions were probably due to low soil water contents and soil nitrate levels in the fall of 2001 and below normal snowfall in the winter of 2001–2002. This reinforces the importance in antecedent moisture conditions and soil N levels for modeling of emissions at snowmelt.
  • Authors:
    • Schuman, G. E.
    • Gollany, H. T.
    • Ellert, B. H.
    • Reeder, J. D.
    • Morgan, J. A.
    • Liebig, M. A.
  • Source: Soil & Tillage Research
  • Volume: 83
  • Issue: 1
  • Year: 2005
  • Summary: Concern over human impact on the global environment has generated increased interest in quantifying agricultural contributions to greenhouse gas fluxes. As part of a research effort called GRACEnet (Greenhouse Gas Reduction through Agricultural Carbon Enhancement Network), this paper summarizes available information concerning management effects on soil organic carbon (SOC) and carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes in cropland and rangeland in northwestern USA and western Canada, a region characterized by its inherently productive soils and highly variable climate. Continuous cropping under no-tillage in the region increased SOC by 0.27 ± 0.19 Mg C ha-1 yr-1, which is similar to the Intergovernmental Panel on Climate Change (IPCC) estimate for net annual change in C stocks from improved cropland management. Soil organic C sequestration potential for rangelands was highly variable due to the diversity of plant communities, soils, and landscapes, underscoring the need for additional long-term C cycling research on rangeland. Despite high variability, grazing increased SOC by 0.16 ± 0.12 Mg C ha-1 yr-1 and converting cropland or reclaimed mineland to grass increased SOC by 0.94 ± 0.86 Mg C ha-1 yr-1. Although there was generally poor geographical coverage throughout the region with respect to estimates of N2O and CH4 flux, emission of N2O was greatest in irrigated cropland, followed by non-irrigated cropland, and rangeland. Rangeland and non-irrigated cropland appeared to be a sink for atmospheric CH4, but the size of this sink was difficult to determine given the few studies conducted. Researchers in the region are challenged to fill the large voids of knowledge regarding CO2, N2O, and CH4 flux from cropland and rangeland in the northwestern USA and western Canada, as well as integrate such data to determine the net effect of agricultural management on radiative forcing of the atmosphere.
  • Authors:
    • Martin, R. C.
    • Patterson, G.
    • Fredeen, A.
    • Cohen, R. D. H.
    • Lynch, D. H.
  • Source: Canadian Journal of Soil Science
  • Volume: 85
  • Issue: 2
  • Year: 2005
  • Summary: The GrassGro model (a computer simulation of management-induced changes in range and pasture forage and livestock productivity) was combined with spreadsheet analyses to estimate the influence of improved grazing practices on soil organic carbon (SOC), and farm profitability, across native rangelands and tame pastures of the southern Canadian Prairies. Improved practices included complementary grazing (CG) and reduced stocking density (RSD) on rangeland; and N fertilization (FERT), seeded grass/legumes grazed continuously (GLGC) or rotationally (GLGR), and RSD on tame pastures. The analysis was stratified into three ecoregions on the basis of similarities in climate and soil type. Averaged over 30 yr and ecoregions, SOC rates of gain through improved management were 5 (RSD) to 26 (CG) kg C ha(-1) yr(-1) for rangelands, and 86 (RSD), 75 (GLGC), 62 (GLGR) and 222 (FERT) kg C ha(-1) yr(-1) for tame pastures. Gains with FERT were considered largely negated by associated energy (C) costs, N2O emissions, and shifts in grassland species. The CG system alone improved net returns to the producer. The estimated potential combined SOC gain on prairie grazinglands (11.5 Mha) was 1.63 MMT CO2 yr(-1) (or 0.465 MMT C yr(-1)), slightly less than the 1.70 MMT CO2 yr(-1) currently emitted from agricultural soils in Canada.
  • Authors:
    • Johnson, D. W.
    • Moeltner, K.
    • van Kooten, G. C.
    • Manley, J.
  • Source: Climatic Change
  • Volume: 68
  • Issue: 1-2
  • Year: 2005
  • Summary: Carbon terrestrial sinks are often seen as a low-cost alternative to fuel switching and reduced fossil fuel use for lowering atmospheric CO2. To determine whether this is true for agriculture, one meta-regression analysis (52 studies, 536 observations) examines the costs of switching from conventional tillage to no-till, while another (51 studies, 374 observations) compares carbon accumulation under the two practices. Costs per ton of carbon uptake are determined by combining the two results. The viability of agricultural carbon sinks is found to vary by region and crop, with no-till representing a low-cost option in some regions (costs of less than $10 per tC), but a high-cost option in others (costs of $100-$400 per tC). A particularly important finding is that no-till cultivation may store no carbon at all if measurements are taken at sufficient depth. In some circumstances no-till cultivation may yield a triple dividend of carbon storage, increased returns and reduced soil erosion, but in many others creating carbon offset credits in agricultural soils is not cost effective because reduced tillage practices store little or no carbon.