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This article in JEQ

  1. Vol. 30 No. 2, p. 617-624
     
    Received: Mar 13, 2000


    * Corresponding author(s): lorenz@tifton.cpes.peachnet.edu
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doi:10.2134/jeq2001.302617x

Denitrification from a Swine Lagoon Overland Flow Treatment System at a Pasture–Riparian Zone Interface

  1. Richard Lowrance * and
  2. Robert K. Hubbard
  1. Southeast Watershed Research Lab., USDA-ARS, P.O. Box 946, Tifton, GA 31793

Abstract

In manure disposal systems, denitrification is a major pathway for N loss and to reduce N transport to surface and ground water. We measured denitrification and the changes in soil N pools in a liquid manure disposal system at the interface of a pasture and a riparian forest. Liquid swine manure was applied weekly at two rates (approximately 800 and 1600 kg N ha−1 yr−1) to triplicate plots of overland flow treatment systems with three different vegetation treatments. Denitrification (acetylene block technique on intact cores) and soil N pools were determined bimonthly for 3 yr. The higher rate of manure application had higher denitrification rates and higher soil nitrate. Depth 1 soil (0–6 cm) had higher denitrification, nitrate, and ammonium than depth 2 soil (6–12 cm). The vegetation treatment consisting of 20 m of grass and 10 m of forest had lower denitrification. Denitrification did not vary significantly with position in the plot (7, 14, 21, and 28 m downslope), but nitrate decreased in the downslope direction while ammonium increased downslope. Denitrification ranged from 4 to 12% of total N applied in the manure. Denitrification rates were similar to those from a nearby dairy manure irrigation site, but were generally a lower percent of N applied, especially at the high swine effluent rate. Denitrification rates for these soils range from 40 to 200 kg N ha−1 yr−1 for the top 12 cm of soil treated with typical liquid manure that is high in ammonium and low in nitrate.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:617–624.