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This article in JEQ

  1. Vol. 30 No. 4, p. 1324-1330
     
    Received: Apr 21, 2000
    Published: July, 2001


    * Corresponding author(s): gmp@ksu.edu
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doi:10.2134/jeq2001.3041324x

Effects of Tillage and Phosphorus Placement on Phosphorus Runoff Losses in a Grain Sorghum–Soybean Rotation

  1. R.J. Kimmella,
  2. G.M. Pierzynski *a,
  3. K.A. Janssena and
  4. P.L. Barnesb
  1. a Dep. of Agronomy, 2004 Throckmorton Plant Science Center, Kansas State Univ., Manhattan, KS 66506
    b Dep. of Biological and Agricultural Engineering, Kansas State Univ., Manhattan, KS 66506

Abstract

Phosphorus enhances eutrophication of fresh water bodies. This study was conducted to determine the influence of tillage and P placement on P losses in runoff water from a somewhat poorly drained soil (Woodson silt loam [fine, smectitic, thermic Abruptic Argiaquoll], 1.0–1.5% slope) in a grain sorghum [Sorghum bicolor (L.) Moench]–soybean [Glycine max (L.) Merr] rotation. Chisel-disk-field cultivate (ChT), ridge-till (RT), and no-till (NT) in combination with 0 kg P ha−1 or 24 kg P ha−1 broadcast or knifed (applied prior to planting grain sorghum) were studied. Runoff volume and losses of sediment and P were summed over the growing season. Significant interactions between tillage and P placement for soluble P losses were found. For example, soluble P loss in 1999 for NT-broadcast in grain sorghum was 358 g ha−1; significantly greater than 31 g ha−1 for NT-knife or 23 g ha−1 for NT-check. Similar results were found for RT but no such differences were found for ChT. Bioavailable P losses were generally highest with broadcast P placement and for NT and RT. Total P losses were significantly higher at 959 g ha−1 with broadcast P on grain sorghum in 1998, compared with 521 g ha−1 for the check and 659 g ha−1 for the knifed P applications. Total P losses in 1999 for soybeans were only 18 g ha−1 for NT, which was significantly lower than 75 g ha−1 for ChT and 66 g ha−1 for RT. The results indicate that broadcast P applications on RT and NT will increase P losses, but the influence of tillage was not consistent.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:1324–1330.