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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Lemon, E. Articles by Van Houtte, R. Search for Related Content PubMed Articles by Lemon, E. Articles by Van Houtte, R. Agricola Articles by Lemon, E. Articles by Van Houtte, R.

Ammonia Exchange at the Land Surface¹

Studies of NH₃ exchange between plant leaves and air have mostly been made in controlled chambers where the concentrations were far above the ambient atmospheric levels usually found in nature. Under such conditions leaves act as an infinite sink for NH₃. More recent controlled chamber studies, however, have shown NH₃ evolving from leaves when concentrations were nearer to those of the atmosphere. In this study we measured both NH₃ absorption and evolution by vegetation under field conditions using micrometeorological techniques where vertical profiles of wind and NH₃ are measured. Both evolution and absorption strongly suggest that plants have a compensation point for NH₃. Data are presented for fields of quackgrass (Agropyron repens L.), soybeans (Glycine max L. Merr.) and alfalfa (Medicago saliva L.). Computer simulation confirmed that vegetation exchange is concentration dependent. We speculate that plants (and soil) keep atmospheric NH₃ in check, at low concentrations, with winds moving it from N rich to N poor ecosystems. Dispersed sources of NH₃ from crop lands are probably increasing due to more fixed N in farming. Thus the added NH₃ due to man's activity probably increases the net global biosphere uptake of both N and C.

Key Words: NH₃ exchange • Atmospheric NH₃ • Plant NH₃ • Compensation point • Micro-meteorological measurement • Computer simulation • Global N and C budgets

² Dr. Lemon formerly held appointments as a soil scientist, USDA, and professor of agronomy, Cornell Univ. Present address is: P.O. Box 612, West End, Tortola, British Virgin Islands. Mr. Van Houtte is a former graduate assistant at Cornell Univ.

Received for publication July 21, 1980.

This article has been cited by other articles:

				C. A. Rotz, F. Taube, M. P. Russelle, J. Oenema, M. A. Sanderson, and M. Wachendorf Whole-Farm Perspectives of Nutrient Flows in Grassland Agriculture Crop Sci., September 23, 2005; 45(6): 2139 - 2159. [Abstract] [Full Text] [PDF]

				P. W. Hill, J. A. Raven, B. Loubet, D. Fowler, and M. A. Sutton Comparison of Gas Exchange and Bioassay Determinations of the Ammonia Compensation Point in Luzula sylvatica (Huds.) Gaud. Plant Physiology, January 1, 2001; 125(1): 476 - 487. [Abstract] [Full Text]

				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]