Nitrate-N movement in a fine-textured vadose zone

M.W. Bobier; K.D. Frank; R.F. Spalding

ABSTRACT:

Nitrate transport rates were measured in the fine-textured vadose zone of eight irrigated research plots fertilized at rates of O, 336 (300), and 448 kg N/ha (400 lbs N/ac). Five years earlier nitrate loading in the vadose zone of these plots was positively associated with a long-term history of N-fertilizer applications. Lag correlations between the 1985 and 1990 NO₃-N data confirmed that NO₃-N beneath four of the five fertilized plots moved as identifiable zones. The vertical transport rate of the NO₃-N was ∼76 cm/yr (30 in/yr). These estimates compare favorably previously reported rates for fine-textured sediments from dryland fields Precipitation, which annually amounts to 66 cm/yr (26n/yr), appears to have been the driving force for the vertical NO₃-N transport.

Footnotes

M.W. Bobier is a geologist with Walsh and Associates, Inc., Omaha. NE 68237; K.D. Frank is associate professor of Agronomy, University of. Nebraska, Lincoln 68583-0916; and K.F Spalding is associate director of the Water Center and Professor of Agronom): University of Nebraska, Lincoln CS58.3-0844. This paper is Journal Series No. 9968 Agricultural Research Division, University of Nebraska, Lincoln. The authors am grateful for the support of a USEPA 329 grant. The authors also thank Drs. Power and Schepers. for their helpful comments and suggestions in their review of this paper.
Copyright 1993 by the Soil and Water Conservation Society

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