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Journal of Environmental Quality Abstract - Plant and Environment Interactions

Grazing and No-Till Cropping Impacts on Nitrogen Retention in Dryland Agroecosystems

 

This article in JEQ

  1. Vol. 43 No. 6, p. 1963-1971
    unlockOPEN ACCESS
     
    Received: Dec 31, 2013
    Published: November 10, 2014


    * Corresponding author(s): meg.mobley@alumni.duke.edu
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doi:10.2134/jeq2013.12.0530
  1. Megan L. Mobley *a,
  2. Rebecca L. McCulleyb,
  3. Ingrid C. Burkea,
  4. Gary Petersonc,
  5. David S. Schimeld,
  6. C. Vernon Coleef,
  7. Edward T. Elliotte and
  8. Dwayne G. Westfallc
  1. a Haub School of the Environment and Natural Resources, Dep. of Botany, Dep. of Ecosystem Science and Management, and Program in Ecology, Univ. of Wyoming, Laramie, WY 82071
    b Dep. of Plant & Soil Sciences, Univ. of Kentucky, Lexington, KY 40546-0091
    c Dep. of Soil and Crop Sciences, Colorado State Univ., Fort Collins, CO 80523
    d Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
    e Natural Resource Ecology Laboratory, Colorado State Univ., Fort Collins, CO 80523
    f USDA Agricultural Research Service, Fort Collins, CO 80521

Abstract

As the world’s population increases, marginal lands such as drylands are likely to become more important for food production. One proven strategy for improving crop production in drylands involves shifting from conventional tillage to no-till to increase water use efficiency, especially when this shift is coupled with more intensive crop rotations. Practices such as no-till that reduce soil disturbance and increase crop residues may promote C and N storage in soil organic matter, thus promoting N retention and reducing N losses. By sampling soils 15 yr after a 15N tracer addition, this study compared long-term soil N retention across several agricultural management strategies in current and converted shortgrass steppe ecosystems: grazed and ungrazed native grassland, occasionally mowed planted perennial grassland, and three cropping intensities of no-till dryland cropping. We also examined effects of the environmental variables site location and topography on N retention. Overall, the long-term soil N retention of >18% in these managed semiarid ecosystems was high compared with published values for other cropped or grassland ecosystems. Cropping practices strongly influenced long-term N retention, with planted perennial grass systems retaining >90% of 15N in soil compared with 30% for croplands. Grazing management, topography, and site location had smaller effects on long-term N retention. Estimated 15-yr N losses were low for intact and cropped systems. This work suggests that semiarid perennial grass ecosystems are highly N retentive and that increased intensity of semiarid land management can increase the amount of protein harvested without increasing N losses.

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