• 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:
    • 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:
    • Mrabet, R.
    • Ibno-Namr, K.
    • Bessam, F.
    • Saber, N.
  • Source: Land Degradation & Development
  • Volume: 12
  • Issue: 6
  • Year: 2001
  • Summary: A long-term experiment comparing no-till with conventional tillage systems across five rotations was evaluated 11 years after initiation. The objectives of the present paper are (1) to report differences in soil chemical properties (namely soil organic matter, total nitrogen, phosphorus, potassium and pH) that have resulted by converting from conventional to no-till under contrasting cropping systems and (2) to draw tentative conclusions and recommendations on fertility status and fertilizer use and management. Soil in the no-till system had increased surface soil organic C levels relative to conventional tillage regardless of rotation. In addition, depending on the rotation, the N and P content of the soil improved with no-till compared with conventional tillage. In other words, no-till has helped to retain soil organic matter (SOM), conserved more N, and resulted in increased extractable P and exchangeable K concentrations in the upper root-zone. Hence, wheat produced in a no-till system may receive more nutrients from decomposition of SOM and acidification of the seed zone. It is possible that lesser amounts of fertilizer nutrients will be needed because of the greater efficiency of nutrient cycling in no-till systems relative to conventional systems. Copyright (C) 2001 John Wiley & Sons, Ltd.
  • Authors:
    • Barrett, D. J.
    • Galbally, I. E.
    • Graetz, R. D.
  • Source: Global Change Biology
  • Volume: 7
  • Issue: 8
  • Year: 2001
  • Authors:
    • Cochran,V. L.
    • Thorn,R. G.
    • Shelver,W. L.
    • Caesar-Tonthat,T. C.
  • Source: Applied Soil Ecology
  • Volume: 18
  • Issue: 2
  • Year: 2001
  • Summary: Polyclonal antisera were raised against cell walls of a soil aggregating basidiomycete isolated in eastern Montana (isolate BB1) which has been identified as a member of the russuloid clade using molecular genetic techniques. In cross-reactivity tests using quantitative enzyme-linked immunosorbent assay (ELISA), polyclonal antisera to BB I cross-reacted significantly with fungal species representative of the russuloid clade and little or no reactivity was observed with fungal species of the polyporoid, euagaric, hymenochaetoid, bolete and gomphoid-phalloid clades of the Homobasidiomycetes. These results suggested that the cell walls of fungal species from the russuloid clade share common antigenic binding sites that are recognizable by the polyclonal antibodies and that these sites were not found or were present in small amounts in fungal species from the other clades. Experiments on the water stability of artificial aggregates amended with fungal species representative of these six homobasidiomycete clades indicated that many species of the russuloid clade were very efficient soil stabilizers. Fungal species from the other clades vary in their ability to aggregate soil particles but cross-react weakly with the antibodies. ELISA was used on water stable aggregates (WSA) from soil samples of three dryland locations under conventional tillage, no tillage and fallow management practices and on WSA from soil samples from grass barrier strips that were undisturbed for 30 years. Greater antigenic response was observed from WSA of undisturbed soils compared to cultivated soils and from WSA of soils under no till compared to till or fallow management practices. These results suggested that specific soil aggregating russuloids in WSA are sensitive to soil disturbance such as tillage. To our knowledge, this study is the first report of the detection and quantification of a taxonomic group of specific soil aggregating Homobasidiomycetes in dryland soils under diverse agricultural systems.
  • Authors:
    • Skaggs, R. K.
  • Source: Agricultural Water Management
  • Volume: 51
  • Issue: 2
  • Year: 2001
  • Summary: The possibility that drip irrigation technology could increase yields, reduce the incidence of crop diseases, and improve fruit quality has been identified as a critical research issue for the New Mexico chile pepper industry. Numerous hypotheses have been expressed regarding the low incidence of drip irrigation usage among New Mexico farmers. A survey of farmers was conducted in 1999 to assess commercial chile pepper producers' attitudes toward and knowledge of drip irrigation technology. The survey data were used in logistic regression models that predict current high-tech irrigation system usage, drip irrigation usage, and plans for future drip irrigation adoption by chile pepper producers. The results of this research provide information useful to extension personnel, other researchers, and chile industry members. Results also raise questions about the impact of widespread drip irrigation adoption on multi-user irrigation systems, such as those found in New Mexico.
  • Authors:
    • Follett, R. F.
  • Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
  • Year: 2001
  • Summary: This book chapter examines the organic carbon pools in grazing land soils.
  • Authors:
    • Lal, R.
    • Kimble, J. M.
    • Follett, R. F.
  • Year: 2001
  • Summary: Grazing lands represent the largest and most diverse land resource-taking up over half the earth's land surface. The large area grazing land occupies, its diversity of climates and soils, and the potential to improve its use and productivity all contribute to its importance for sequestering C and mitigating the greenhouse effect and other conditions brought about by climate change. The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect gives you an in-depth look at this possibility.
  • Authors:
    • Ruiz-Suárez, L. G.
    • González-Avalos, E.
  • Source: Bioresource Technology
  • Volume: 80
  • Issue: 1
  • Year: 2001
  • Authors:
    • Ellert, B. H.
    • Janzen, H. H.
    • Carefoot, J. M.
    • Chang, C.
    • Hao, X.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 60
  • Issue: 1
  • Year: 2001
  • Summary: Nitrous oxide (N2O) emission from farmland is a concern for both environmental quality and agricultural productivity. Field experiments were conducted in 1996-1997 to assess soil N2O emissions as affected by timing of N fertilizer application and straw/tillage practices for crop production under irrigation in southern Alberta. The crops were soft wheat (Triticum aestivum L.) in 1996 and canola (Brassica napus L.) in 1997. Nitrous oxide flux from soil was measured using a vented chamber technique and calculated from the increase in concentration with time. Nitrous oxide fluxes for all treatments varied greatly during the year, with the greatest fluxes occurring in association with freeze-thaw events during March and April. Emissions were greater when N fertilizer (100 kg N ha-1) was applied in the fall compared to spring application. Straw removal at harvest in the fall increased N2O emissions when N fertilizer was applied in the fall, but decreased emissions when no fertilizer was applied. Fall plowing also increased N2O emissions compared to spring plowing or direct seeding. The study showed that N2O emissions may be minimized by applying N fertilizer in spring, retaining straw, and incorporating it in spring. The estimates of regional N2O emissions based on a fixed proportion of applied N may be tenuous since N2O emission varied widely depending on straw and fertilizer management practices.