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This article in JEQ

  1. Vol. 17 No. 4, p. 729-734
    Received: Dec 21, 1987

    * Corresponding author(s):
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Groundwater and Soil Leachate Inorganic Nitrogen in a Wisconsin Red Pine Plantation Amended with Paper Industry Sludge

  1. J. G. Bockheim *,
  2. T. C. Benzel,
  3. Rui-Lin Lu and
  4. D. A. Thiel
  1. Dep. of Soil Science, 1525 Observatory Dr., Univ. of Wisconsin, Madison, WI 53706;
    Aspen Services, Inc., 6510 W. Forest Home Ave., Milwaukee, WI 53220;
    Environ. & Applied Mathematics Res., Nekoosa Papers Inc., Port Edwards, WI 54469.



In late August 1984, a 2.5:1 primary/secondary paper industry sludge was applied to a row-thinned, 27-yr-old red pine (Pinus resinosa Ait.) plantation in central Wisconsin at levels of 32, 63, and 94 dry Mg ha−1 (550, 1120, and 1670 kg N ha−1, respectively). There were positive treatment effects on NO3-N and NH4-N in soil leachates and groundwater, but because of sample variability, few of these differences were significant at the p ≤ 0.05 level. Nitrate-N concentrations exceeded 10 mg L−1 for all treatments at the 10-, 45-, and 75-cm depths, but the potability standard was exceeded at the 165-cm depth and in groundwater only on plots receiving the medium and heavy applications. Nitrate-N concentrations generally were greater in the upper 30 cm of the saturated zone than at 60 and 90 cm, suggesting a lack of vertical mixing. Whereas the maximum NO3-N concentration decreased with depth, the time required for NO3-N concentrations to exceed 10 mg L−1 for a given treatment and the duration of the period when NO3-N concentrations exceeded 10 mg L−1 increased with depth. The seasonal trends in inorganic N concentrations in soil water collected at the 10- and 45-cm depths could be explained on the basis of N mineralization as derived from field incubation studies. A regression equation relating maximum NO3-N in groundwater to N content of the applied sludge indicates that little groundwater degradation will occur at depths of ≥ 5.2 m in central Wisconsin when the N application to pole-sized red pine is ≤800 kg ha−1 (≤46 dry Mg sludge ha−1).

Research funded by Nekoosa Papers Inc. and supported by the College of Agricultural & Life Sciences and the School of Natural Resources, Univ. of Wisconsin, Madison.

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