E.F. Gilman, T.H. Yeager and D. Weigle
Nitrogen leaching from cypress wood chips
HortScience 25 (11): 1388-1391
Columns (4 x 15 cm) of incubated (25C, 7% volumetric moisture) milled cypress [Taxodium distichum (L.) L. Rich] wood chips received 180 mg of each ionic form of N applied to the surface from dry NH4NO3, KNO3, or (NH4)2SO4 and were leached daily with 16 ml deionized water (pH 5.5). After 10 days, >85% of applied N leached from the columns in all treatment. After 25 days, all N leached from the NH4NO3 and KNO3 treatment, and 93% leached from the (NH4)2SO4 treatment. In subsequent experiments, columns received 360 mg N from NH4NO3 and were leached daily with either 16, 32, 48, or 64 ml of deionized water for 50 days. The rate of N leaching increased with increasing water application rate, although total N leached per column was similar for all water rates after 25 days. Columns that received 45, 90, 180, or 360 mg N/column were leached daily with 16 ml of deionized water. Nitrogen concentrations in the leachate ranged from 3406 ppm NO3--N and 2965 ppm NH4+-N at day 5 for the 360-mg rate to 3 and 5 ppm, respectively, at day 35 for the 45-mg rate. In all experiments with NH4NO3, more NO3- -N leached than NH4+-N and more NO3- -N leached than applied, indicating nitrification occurred. NH4+-N and NO3--N broadcast over cypress wood chips in the landscape would leach quickly into the soil.
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