HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Swensen, B. Articles by Singh, B. R. Search for Related Content PubMed Articles by Swensen, B. Articles by Singh, B. R. Agricola Articles by Swensen, B. Articles by Singh, B. R.

Transport and Transformation of Urea and Its Derivatives through a Mineral Subsoil

Agricultural University of Norway, Department of Soil and Water Sciences, P.O. Box 5028, N-1432 As, Norway.

^* Corresponding author (berit.swensen{at}ijvf.nlh.no).

ABSTRACT

The transport and transformation potential of N compounds derived from urea, applied as a deicing agent during the winter period, have been investigated in a coarse, heterogeneous glacial-contact deposit in southeast Norway. The hydrolysis of urea to ammonium-N (NH⁺₄-N) and subsequent oxidation to nitrate-N (NO^–₃-N) was monitored by extraction of soil water from five depths (from 70 to 220 cm) in a lysimeter trench. Urea transport through a soil profile is normally negligible, although urea is a hydrophilic, uncharged molecule. In this study, urea was rapidly transported to at least 220 cm. The measured urea-N concentrations varied from 2 to 50 mg L^–1 throughout the profile. This transport was explained by minimal hydrolytic activity because of soil temperatures close to 0°C, and by different preferential flow mechanisms being important during the snowmelt period. Urea hydrolysis occurred at all depths. The NH⁺₄-N formed in this in situ hydrolysis was oxidized to NO^–₃-N. The nitrification started immediately and was most rapid at the 70- and 105-cm depth, but was detectable at all depths down to 220 cm 120 d after solute application. Nitrification also occurred during the winter following the urea application. One year after the urea application, about 40% of the applied urea-N was recovered as NO^–₃-N in the unsaturated zone (0–450 cm), and it is estimated that at least 50% of the applied N will reach the groundwater as NO^–₃-N.