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This article in CS

  1. Vol. 43 No. 1, p. 272-281
    Received: Aug 27, 2001

    * Corresponding author(s): karl.guillard@uconn.edu
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Extractable Soil Phosphorus Concentrations and Creeping Bentgrass Response on Sand Greens

  1. Karl Guillard * and
  2. William M. Dest
  1. Dep. of Plant Science, Univ. of Connecticut, 1376 Storrs Road, Unit-4067, Storrs, CT 06269-4067


Few studies have directly related turfgrass growth and quality responses to extractable soil P concentrations in sand greens. A 3-yr field experiment was conducted on a sand-based putting green to determine creeping bentgrass (Agrostis stolonifera L.) growth and quality responses to extractable soil P. Extractable soil P concentrations were obtained by using the modified-Morgan, Mehlich-1, and Bray-1 extractants. Critical extractable P concentrations (above which there is a low probability of response to increasing soil P concentrations) for shoot counts, thatch thickness, relative clipping yields, quality ratings, P deficiency ratings, tissue P concentrations, and root weights were determined using Cate-Nelson (CN) and quadratic response and plateau (QRP) models. Both models fit the data relatively well in most cases (R 2 values from 0.12 to 0.89), and critical concentrations for the QRP models were always greater than the CN models. Critical extractable P concentrations were lowest for the modified-Morgan extractant (1.4 to 12.0 mg kg−1) and greatest for the Mehlich-1 extractant (14.1 to 63.6 mg kg−1). Application of estimated critical extractable P concentrations in this study could be used to substantiate observed responses or explain lack of responses in other previously reported creeping bentgrass P studies. We found better model fits with modified-Morgan extractable P for bentgrass quality ratings, deficiency ratings, and tissue P concentrations than with P extracted by the Mehlich or Bray methods. This suggests that the modified-Morgan extractant may have advantages over stronger-acid extractants when used on sand-based media. The results can be used to revise or update existing P fertilization recommendations for bentgrass grown on sand-based media.

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Copyright © 2003. Crop Science Society of AmericaPublished in Crop Sci.43:272–281.