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Journal of Environmental Quality Abstract - Landscape and Watershed Processes

Phosphorus Forms and Chemistry in the Soil Profile under Long-Term Conservation Tillage: A Phosphorus-31 Nuclear Magnetic Resonance Study


This article in JEQ

  1. Vol. 39 No. 5, p. 1647-1656
    Received: Dec 12, 2010

    * Corresponding author(s): Barbara.Cade-Menun@agr.gc.ca
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  1. Barbara J. Cade-Menun *a,
  2. Martin R. Carterb,
  3. Dean C. Jamesa and
  4. Corey W. Liuc
  1. a Agriculture and Agri-Food Canada, SPARC, Box 1030, Swift Current, SK S9H 3X2 Canada
    b Agriculture and Agri-Food Canada, Charlottetown, PEI C1A 4N6 Canada
    c Stanford Magnetic Resonance Laboratory, Stanford University, Stanford CA 94305-5126. Assigned to Associate Editor Katherine Knowlton


In many regions, conservation tillage has replaced conventional tilling practices to reduce soil erosion, improve water conservation, and increase soil organic matter. However, tillage can have marked effects on soil properties, specifically nutrient redistribution or stratification in the soil profile. The objective of this research was to examine soil phosphorus (P) forms and concentrations in a long-term study comparing conservation tillage (direct drilling, “No Till”) and conventional tillage (moldboard plowing to 20 cm depth, “Till”) established on a fine sandy loam (Orthic Humo-Ferric Podzol) in Prince Edward Island, Canada. No significant differences in total carbon (C), total nitrogen (N), total P, or total organic P concentrations were detected between the tillage systems at any depth in the 0- to 60-cm depth range analyzed. However, analysis with phosphorus-31 nuclear magnetic resonance spectroscopy showed differences in P forms in the plow layer. In particular, the concentration of orthophosphate was significantly higher under No Till than Till at 5 to 10 cm, but the reverse was true at 10 to 20 cm. Mehlich 3–extractable P was also significantly higher in No Till at 5 to 10 cm and significantly higher in Till at 20 to 30 cm. This P stratification appears to be caused by a lack of mixing of applied fertilizer in No Till because the same trends were observed for pH and Mehlich 3–extractable Ca (significantly higher in the Till treatment at 20 to 30 cm), reflecting mixing of applied lime. The P saturation ratio was significantly higher under No Till at 0 to 5 cm and exceeded the recommended limits, suggesting that P stratification under No Till had increased the potential for P loss in runoff from these sites.

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Copyright © 2010. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyAmerican Society of Agronomy, Crop Science Society of America, and Soil Science Society of America