A cuvette design for field and laboratory measurement of water and ammonia flux from soils in a short grass prairie

Abstract

Development of micro‐meteorological methods has made it possible to estimate ammonia (NH₃) volatilization in the field. However, this method requires field size plots which are not possible to use under many circumstances such as evaluation of volatile loss of NH₃ from urine patches. Cuvettes are the only alternative available for direct estimation of NH₃ flux from small sites. This work describes the use of evaporation of water from a freely evaporating surface as a method of developing a cuvette which can provide realistic estimates of NH₃ volatilization in the field. Nitrogen‐15 labeled urea solutions were used to evaluate the overall performance of the cuvette system. A number of design considerations are discussed. Using evaporation rates was found to be a satisfactory method to determine operating parameters of a cuvette in the field. Nighttime and daytime conditions varied in such a way that it was necessary to use difference conditions for each. It was necessary for daytime conditions to mix the air inside the cuvette. Recovery of labeled N averaged 70.7% in capped micro‐plots and 71.8% in uncapped micro‐plots. The cuvette system appeared to provide realistic estimates of NH₃ volatilization in the field.

Notes

W. J. Parton and S. R. Bennett located and research conducted at the Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado.