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This article in SSSAJ

  1. Vol. 58 No. 5, p. 1476-1483
     
    Received: July 2, 1993


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doi:10.2136/sssaj1994.03615995005800050029x

Nitrate Leaching as Influenced by Cover Cropping and Nitrogen Source

  1. Daniel V. McCracken ,
  2. M. Scott Smith,
  3. John H. Grove,
  4. Robert L. Blevins and
  5. Charles T. MacKown
  1. Dep. of Crop and Soil Sciences, Univ. of Georgia, Georgia Station, Griffin, GA 30223-1797
    Dep. of Agronomy
    USDA-ARS and Dep. of Agronomy, Univ. of Kentucky, Lexington, KY 40546-0091

Abstract

Abstract

To minimize groundwater contamination by NO3 and to maximize efficient crop N use, it is necessary to better characterize NO3 leaching in various cropping systems. Our objectives were to compare the contributions of hairy vetch (Vicia villosa Roth) and NH+4 N sources to NO3 leaching in corn (Zea mays L.) production, and to compare NO3 leaching losses in a corn production system utilizing hairy vetch as a N source and winter cover crop with leaching losses in one utilizing an NH+4 N source and a rye (Secale cereale L.) cover crop. Nitrogen, sometimes enriched with 15N, was applied to corn grown on a Maury silt loam (fine, mixed, mesic Typic Paleudalf) in lysimeters as vetch- or NH+4-N at rates between 10.5 and 14.0 g N m−2 yr−1. Treatments (N source/cover crop) were: NH+4-N/fallow, vetch-N/fallow, NH+4-N/rye, and vetch-N/vetch; mean 3-yr cumulative NO3 leaching losses were 6.11, 4.85, 0.35, and 2.51 g N m−2, respectively. Total recovery of added 15N in leachate was <5% for all treatments, and the percentage of leached NO3 derived from labeled N sources was generally <15%. In the winter-fallow lysimeters, effects of N source on the fraction of water input discharged, concentration of NO3, and quantity of NO3 leached varied with year and time of year; differences in N-source availability and mulch effects were sometimes indicated. Generally, cover crop effects were larger than N-source effects. The NH+4 N source/rye cover system leached consistently less NO3 than the vetch N source/vetch cover system, even though the fraction of water discharged was not consistently different.

Contribution no. 93-3-82 of the Kentucky Agric. Exp. Stn.

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