• Authors:
    • Ulrich, D.
    • Brandt, S. A.
    • Malhi, S. S.
    • Lemke, R.
    • Gill, K. S.
  • Source: Journal of Plant Nutrition
  • Volume: 25
  • Issue: 11
  • Year: 2002
  • Summary: Cropping systems can influence the accumulation and distribution of plant nutrients in the soil profile, which can affect their utilization efficiency by crops and pollution potential in the environment. A field experiment was conducted on a Dark Brown loam soil at Scott, Saskatchewan, Canada to assess the effects of input level, cropping diversity and crop phase on the accumulation and distribution of nitrate-nitrogen (N) and extractable phosphorus (P) in the soil profile at the end of 1995 to 2000 growing seasons. The 54 treatments were combinations of three input levels (organic-ORG, reduced-RED and high-HIGH), three cropping diversities (low diversity-LOW, diversified annual grains-DAG, and diversified annual and perennials-DAP), and six crop phases chosen from fallow (tillage-fallow or chemfallow), green manure [lentil-Lens culinaris Medicus or sweet clover-Melilotus officinalis (L.) Lam], spring wheat (Triticum aestivum L.), canola (Brassica napus L. and Brassica rapa L.), fall rye (Secale cereale L.), field pea (Pisum sativum L.), spring barley (Hordeum vulgare L.), flax (Linum usitatissimum L.), oats (Avena sativa L.), and bromegrass (Bromus inermis Leyss), alfalfa (Medicago sativa Leyss) mixture hay. Soil was sampled from the 0-15, 15-30, 30-60, and 60-90cm depths in each crop phase from 1995 to 2000, with additional depths 90-120, 120-150, 150-180, 180-210, and 210-240cm taken from the wheat phase in 2000. In general, there were greater amounts of nitrate-N with HIGH input compared to ORG or BID inputs, especially under LOW diversity. The nitrate-N in various soil depths suggested some downward movement of nitrate-N to the deeper soil depths when HIGH input was compared to ORG input. In LOW cropping diversity, green manure or fallow usually had more nitrate-N in soil than other crop phases. In DAG and DAP cropping diversities, nitrate-N varied with crops and on average it had maximum concentration after wheat or canola in DAG and after hay followed closely by wheat in DAP. The ORG input level had greater nitrate-N than RED or HIGH inputs in some instances, most likely due to relatively low extractable P in soil for optimum crop growth under ORG input. Extractable P in the 0-15 and 15-30 cm soil depths tended to be greater under HIGH or RED inputs compared to the ORG input level in many cases. In summary there was no consistent effect of cropping diversity on extractable P in soil under ORG input, but LOW diversity tended to show more extractable 13 compared to DAG and DAP diversities in some cases of RED and HIGH inputs. The green manure/fallow, HIGH input and LOW diversity treatments tended to result in higher nitrate-N and extractable P levels compared to the corresponding treatments, and the effects were more pronounced on nitrate-N than extractable P and in shallow compared to deeper soil layers.
  • Authors:
    • Chanasyk, D. S.
    • Mathison, M. N.
    • Naeth, M. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 82
  • Issue: 2
  • Year: 2002
  • Summary: The longevity of deep ripping effects on Solonetzic soils was investigated at 11 field sites in east-central Alberta after a period of 15 to 20 yr. Select soil properties and crop yield of deep-ripped and non-ripped control plots were analyzed. Dryland yield data of wheat, barley, oats and canola were assessed for 10 of the 11 sites over a 16-yr time period. Select soil properties were analyzed once in 1998 with penetration resistance (PR) evaluated again in 1999. A significant difference in penetration resistance was found between the deep ripped versus control treatments ( P≤0.05). There were no significant treatment differences for soil texture, bulk density (Db), pH, electrical conductivity (EC) or sodium adsorption ratio (SAR). A significant yield difference between the deep ripping and control treatments (for all crop species) was found for 6 of 10 sites ( P≤0.10), with all sites having an increase in mean yield for the majority of years evaluated. Generally, sites in the drier ecoregions had smaller yield increases than those in the wetter ones. Hence some beneficial effects from deep ripping remain for a long time period.
  • Authors:
    • Nielsen, G.
    • Mortensen, D.
    • McGinn, S.
    • Coen, G.
    • Caprio, J.
    • Waltman, S.
    • Padbury, G.
    • Sinclair, R.
  • Source: Agronomy Journal
  • Volume: 94
  • Issue: 2
  • Year: 2002
  • Summary: The northern Great Plains have long been dominated by conventional tillage systems and cereal-based rotations including summer fallow. Over the last decade, however, the use of conservation tillage systems has markedly increased and, through improved moisture storage, has provided an opportunity for more diversified extended rotations including oilseed, pulse, and forage crops throughout the region. Considerable research is being carried out to assess the adaptability of these new crops and to develop appropriate management strategies. Typically, this type of agronomic research is carried out at plot-sized research sites, with the findings then being extrapolated to surrounding regions where growing conditions are thought to be reasonably similar. Because the environment itself largely dictates the success of a particular cropping system, extrapolation requires knowledge of the environmental conditions of the region and, in particular, the interaction of environmental components of soil and climate in relation to specific crop requirements. This paper describes 14 agroecoregions in the northern Great Plains and provides an initial framework for extrapolating agronomic information at broad regional scales. Because climate is the dominant crop production factor in the region, most of the agroecosystems represent broad climatic zones. Each agroecoregion is described in terms of its soil and landscape characteristics, with a particular focus being given to likely key environmental parameters related to the production of the new oilseed, pulse, and forage crops being introduced in the region.
  • Authors:
    • Krishnappan, B. G.
    • Stone, M.
  • Source: Water Research
  • Volume: 36
  • Issue: 14
  • Year: 2002
  • Summary: A field-scale no-till corn plot (120 m * 90 m) located on a tile drained silt loam soil near Kintore, Ontario was irrigated with 2.5 cm of water over a 3 h period to examine the effects of irrigation on tile sediment transport in a headwater stream. Flow characteristics and the composition, concentration and size distribution of suspended solids were measured at the tile outlet, an upstream reference site and three sites located downstream of the tile drain. Results show that tile sediments at the study site are fine-grained ( D50=5.0 m) and consist primarily of quartz, anorthite/albite, dolomite and calcite. Sediment concentrations in tile effluent increased from 8 to 57 mg L -1 after 1.5 h of irrigation and reached a maximum of 72 mg L -1. The sediment yield from the tile drain for the irrigation event was 4.6 kg ha -1. An unsteady, mobile boundary flow model (MOBED) was used to predict flow characteristics in the stream. According to the MOBED model, bed shear stress in the stream was approximately 6 N m -2. This value is significantly greater than the critical shear stress for complete suspension of 1 N m -2 for tile sediments as determined from laboratory experiments using a rotating circular flume. Grain size distributions of suspended solids in the stream were close to the dispersed size distribution because of the high shear stress in the receiving stream.
  • Authors:
    • Beckie, H. J.
    • Zand, E.
  • Source: Canadian Journal of Plant Science
  • Volume: 82
  • Issue: 2
  • Year: 2002
  • Summary: The competitiveness of three hybrid and three open-pollinated canola cultivars against two wild oat populations was determined under controlled environment conditions at two plant densities and five canola:wild oat ratios (100:0, 75:25, 50:50, 25:75, 0:100). Analysis of replacement series and derivation of relative crowding coefficients (RCC), based on shoot dry weight or leaf area, indicated that hybrid canola cultivars were twice as competitive than open-pollinated cultivars when weed interference was relatively high (i.e., high plant density and vigorous wild oat growth). Little difference in competitiveness among cultivar types was apparent when weed interference was lower. The results of this study suggest that hybrid canola cultivars may be best suited for use in an integrated weed management program, particularly for farmers of organic or low input cropping systems.
  • Authors:
    • Carlyle, W. J.
  • Source: The Geographical Journal
  • Volume: 168
  • Issue: 2
  • Year: 2002
  • Summary: Changes in cropping patterns in the Canadian Prairies are examined from the early 1960s to the mid-1990s using census data. Patterns of change within the region are mapped by census division using averaged proportions of land in crops occupied by the main crops for three pairs of census years. Spring wheat and oat have undergone the most significant relative declines. Canola increased dramatically from being the sixth-ranked crop by area in the early 1960s to the third-ranked crop by area by the 1990s. The main change in the Brown soil zone has been a large decline in spring wheat and a compensatory gain in durum wheat. Increases in special crops, especially pulse crops, canola and durum wheat have offset a substantial decline in spring wheat in the Dark Brown soil zone. Barley, tame hay and especially canola have increased at the expense of spring wheat, oat and flaxseed in the Black and Gray soil zones. Prices, transportation costs, changing export markets, crop breeding and local processing all have contributed to these changes.
  • Authors:
    • Samson, R. A.
    • Girouard, P.
    • Fyles, J. W.
    • Zan, C. S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 86
  • Issue: 2
  • Year: 2001
  • Summary: The conversion of relatively undisturbed ecosystems such as forests and grasslands to intensively managed agroecosystems has had major impacts on global carbon (C) cycling largely as a result of land clearing, cultivation, and replacement of perennial vegetation by annual crops. Numerous studies have demonstrated the ability of fast-growing perennial plant species dedicated to bioenergy production to sequester substantial amounts of C. Thus, the conversion of conventionally managed agricultural land to perennial bioenergy crops can be expected to increase C stored in above- and belowground biomass and in soil organic matter because of their perennial nature and greater root biomass. In this study, C storage was compared among five ecosystems in southwestern Quebec including two perennial crops, switchgrass (Panicum virgatum L.), and willow (Salixalbaxglatfelteri L.), and an annual corn (Zea mays L.) crop at two sites of differing soil fertility, a 20-year-old abandoned field, and a mature hardwood forest. After 4 years of production, corn had significantly higher levels of aboveground C than willow at the less fertile site, but no significant differences were detected at the more fertile site. Both perennial systems had significantly higher root C than the corn system but switchgrass had significantly higher root C levels below 30 cm compared with willow and corn. Soil organic C under willow at the more fertile site was higher than under the other managed or unmanaged systems, including willow at the less fertile site. The results of this study suggest that perennial energy crops grown on relatively fertile soils, have the potential to increase substantially soil C levels compared with conventional agricultural systems or unmanaged systems.
  • Authors:
    • Grant, B.
    • Desjardins, R. L.
    • Smith, W. N.
  • Source: Canadian Journal of Soil Science
  • Volume: 81
  • Issue: 2
  • Year: 2001
  • Summary: The Century model was used to estimate the influence of changing agricultural practices on C levels in seven major soil groups in Canada for the years from 2000 to 2010. Conversion of arable land to permanent cover, and inclusion of forages in crop rotations would result in the greatest sequestration of C, averaging 0.62 and 0.44 Mg C ha-1 yr-1, respectively. The increase in soil C when conventional-tillage is converted to no-tillage management was estimated to average about 0.13 Mg C ha-1 yr-1. Reduction of summerfallow (wheat-fallow to wheat-wheat-fallow) in the arid and semi-arid chernozems of Western Canada would reduce C losses by about 0.03 Mg C ha-1 yr-1. If fertilizer use efficiency was increased by 50%, 0.04 Mg C ha-1 yr-1 would be sequestered, whereas a decrease of 50% in fertilizer use efficiency would result in a loss of 0.05 Mg C ha-1 yr-1. Timing of N application (fall vs. spring) had little effect on C change. This study indicates that there are several feasible techniques that could be adopted by agricultural producers in Canada that would significantly increase CO2 uptake from the atmosphere. Although our estimates are based on changes in individual management options, we recognize that producers are likely to adopt several options at the same time. Any interactions resulting from such a move have not been assessed in this analysis, in particular the impact on N2O emissions. Key words: Soil carbon, CO2, C sequestration, Century model, soil, tillage, agricultural practices, nitrous oxide emissions, crop rotations
  • Authors:
    • Janzen, H. H.
  • Source: Soil Science
  • Volume: 81
  • Issue: 4
  • Year: 2001
  • Authors:
    • Boehm, M.
    • Grant, B.
    • Smith, W.
    • Junkins, B.
    • Kulshreshtha, S. N.
    • Desjardins, R. L.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 60
  • Issue: 1-3
  • Year: 2001
  • Summary: In 1991, on farm management practices contributed 57.6 Tg CO2 equivalent in greenhouse gas emissions, that is, about 10% of the anthropogenic GHG emissions in Canada. Approximately 11% of these emissions were in the form of CO2, 36% in the form of CH4 and 53% in the form of N2O. The CO2 emissions were from soils; CH4 emissions were from enteric fermentation and manure, and N2O emissions were primarily a function of cropping practices and manure management. With the emissions from all other agricultural practices included, such as the emissions from fossil fuels used for transportation, manufacturing, food processing etc., the agricultural sector's contributions were about 15% of Canada's emissions. In this publication, several options are examined as to their potential for reducing greenhouse gas emissions. These involve soil and crop management, soil nutrient management, improved feeding strategies, and carbon storage in industrial by-products. The Canadian Economic Emissions Model for Agriculture (CEEMA) was used to predict the greenhouse gas emissions for the year 2010, as well as the impact of mitigation options on greenhouse gas emissions from the agricultural sector. This model incorporates the Canadian Regional Agricultural sub-Model (CRAM), which predicts the activities related to agriculture in Canada up to 2010, as well as a Greenhouse Gas Emissions sub-Model (GGEM), which estimates the greenhouse gas emissions associated with the various agricultural activities. The greenhouse gas emissions from all agricultural sources were 90.5 Tg CO2 equivalent in 1991. Estimates based on CEEMA for the year 2010 indicate emissions are expected to be 98.0 Tg CO2 equivalent under a business as usual scenario, which assumes that the present trends in management practices will continue. The agricultural sector will then need to reduce its emissions by about 12.9 Tg CO2 equivalent below 2010 forecasted emissions, if it is to attain its part of the Canadian government commitment made in Kyoto. Technologies focusing on increasing the soil carbon sink, reducing greenhouse gas emissions and improving the overall farming efficiency, need to be refined and developed as best management practices. The soils carbon sink can be increased through reduced tillage, reduced summer fallowing, increased use of grasslands and forage crops, etc. Key areas for the possible reduction of greenhouse gas emissions are improved soil nutrient management, improved manure storage and handling, better livestock grazing and feeding strategies, etc. The overall impact of these options is dependent on the adoption rate. Agriculture's greenhouse gas reduction commitment could probably be met if soils are recognized as a carbon sink under the Kyoto Accord and if a wide range of management practices are adopted on a large scale. None of these options can currently be recommended as measures because their socio-economic aspects have not been fully evaluated and there are still too many uncertainties in the emission estimates.