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Diversified cropping systems in semiarid Montana: Nitrogen use during drought
Soil and Tillage Research (2007)
  • Andrew W. Lenssen, United States Department of Agriculture
  • J. T. Waddell, United States Department of Agriculture
  • G. D. Johnson, Montana State University
  • G. R. Carlson, Montana State University

Improved nitrogen use efficiency would be beneficial to agroecosystem sustainability in the northern Great Plains of the USA. The most common rotation in the northern Great Plains is fallow–spring wheat. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and available nitrogen, decreasing the efficiency of fallow. Chemical fallow and zero tillage systems improve soil water conservation, and may improve nitrogen availability to subsequent crops. We conducted a field trial from 1998 through 2003 comparing nitrogen uptake and nitrogen use efficiency of crops in nine rotations under two tillage systems, conventional and no-till. All rotations included spring wheat, two rotations included field pea, while lentil, chickpea, yellow mustard, sunflower, and safflower were present in single rotations with wheat. Growing season precipitation was below average in 3 of 4 years, resulting in substantial drought stress to crops not following fallow. In general, rotation had a greater influence on spring wheat nitrogen accumulation and use efficiency than did tillage system. Spring wheat following fallow had substantially higher N accumulation in seed and biomass, N harvest index, and superior nitrogen use efficiency than wheat following pea, lentil, chickpea, yellow mustard, or wheat. Preplant nitrate-N varied widely among years and rotations, but overall, conventional tillage resulted in 9 kg ha−1 more nitrate-N (0–60 cm) for spring wheat than did zero tillage. However, zero tillage spring wheat averaged 11 kg ha−1 more N in biomass than wheat in conventional tillage. Nitrogen accumulation in pea seed, 45 kg ha−1, was superior to that of all alternate crops and spring wheat, 17 and 23 kg ha−1, respectively. Chickpea, lentil, yellow mustard, safflower, and sunflower did not perform well and were not adapted to this region during periods of below average precipitation. During periods of drought, field pea and wheat following fallow had greater nitrogen use efficiency than recropped wheat or other pulse and oilseed crops.

  • Spring wheat,
  • Field pea,
  • Chickpea,
  • Lentil,
  • Yellow mustard,
  • Safflower,
  • Sunflower,
  • Zero tillage,
  • Soil nitrate,
  • Nitrogen recovery index,
  • Nitrogen harvest index,
  • Crop yields
Publication Date
June, 2007
Publisher Statement
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Citation Information
Andrew W. Lenssen, J. T. Waddell, G. D. Johnson and G. R. Carlson. "Diversified cropping systems in semiarid Montana: Nitrogen use during drought" Soil and Tillage Research Vol. 94 Iss. 2 (2007)
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