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

This Article Full Text (PDF) An erratum has been published An erratum has been published 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Denmead, O. T. Articles by Simpson, J. R. Search for Related Content PubMed Articles by Denmead, O. T. Articles by Simpson, J. R. Agricola Articles by Denmead, O. T. Articles by Simpson, J. R.

Dynamics of Ammonia Volatilization during Furrow Irrigation of Maize¹

ABSTRACT

In irrigated agriculture, supplemental nitrogen (N) is commonly applied by dissolving ammonia (NH₃) gas in the irrigation water. The operation is convenient and labor-saving, but because NH₃ is volatile, the potential for loss is high.

A micrometeorological method was used to measure losses of NH₃ gas during applications of water-run NH₃ to short (0.9 m) and tall (2.1 m) maize crops. The equilibrium NH₃ vapor pressure of the irrigation water and wind speed both affected the loss, but the influence of the latter was very marked, volatilization increasing with the approximate square of the wind speed.

Average volatilization losses were 7% of the N present in the irrigation water per hour from the short crop, and 1% from the tall crop, the difference arising from the greater attenuation of wind in the tall crop. Results for both crops were reconciled by considering transfer through an air layer close to the ground. Volatilization rate could then be expressed as the product of a wind-dependent exchange coefficient and the NH₃ vapor pressure difference between the water surface and 0.3 m.

Volatilization losses resulted in very uneven applications of N. The nitrogen content of the irrigation water decreased by 84% over a distance of 400 m along the furrow in the short crop, and by 59% in the tall crop. Some practical remedies are suggested, including irrigating at night. In these experiments, night-time volatilization rates were only one-half those observed by day for similar aqueous NH₃ concentrations.

Key Words: nitrogen loss • fertilizer efficiency • vapor transfer.

¹ Contribution from CSIRO, Australia.

² Senior Principal Research Scientists, CSIRO Divisions of Environmental Mechanics, P.O. Box 821, Canberra City, A.C.T. 2601, and Plant Industry, P.O. Box 1600, Canberra City, A.C.T. 2601, Australia.

Received for publication January 26, 1981. Accepted for publication August 21, 1981.

This article has been cited by other articles:

				R. R. Sherlock, S. G. Sommer, R. Z. Khan, C. W. Wood, E. A. Guertal, J. R. Freney, C. O. Dawson, and K. C. Cameron Ammonia, Methane, and Nitrous Oxide Emission from Pig Slurry Applied to a Pasture in New Zealand J. Environ. Qual., September 1, 2002; 31(5): 1491 - 1501. [Abstract] [Full Text] [PDF]

				A. O. LANGFORD and F. C. FEHSENFELD Natural Vegetation as a Source or Sink for Atmospheric Ammonia: A Case Study Science, January 31, 1992; 255(5044): 581 - 583. [Abstract] [PDF]