Academic Research Journal of Agricultural Science and Research
 

Academic Research Journal of Agricultural Science and Research  Vol. 2(3), pp. 34-46, July, 2014.

 DOI: 10.14662/ARJASR2014.016.  ISSN: 2360-7874 ©2014 Academic Research Journals

Full Length Research

Design and Testing of a Novel Gas Exchange Chamber

¹John T. Murphy, ²Jay M. Ham, and ³Clenton E. Owensby.

¹Professor of Biology, Southwest Baptist University, Bolivar, MO 65613, jmurphy@sbuniv.edu;

²Professor of Environmental Physics and Micrometeorology, Department of Soil and Crop Sciences, Colorado State University, Ft. Collins, CO 80523, jay.ham@colostate.edu;

³Professor of  Range Management, Department of Agronomy , Kansas State University, Manhattan, KS, 66506, owensby@ksu.edu.

Corresponding author: Clenton E. Owensby, Kansas State University, Department of Agronomy, Throckmorton Hall, Manhattan, KS 66506-5501, e-mail: owensby@ksu.edu,  ph. 785-532-7232.

Accepted 8 July 2014

A transparent closed-system, non-steady-state chamber was developed that allowed measurements of net carbon exchange (NCE). The chamber was 0.85-m x 0.85-m with a height of 0.25-m and total weight of 10.9 kg. The sides were constructed of clear Plexiglas while the top of the chamber was Propafilm-C. Minimizing alterations to the chamber microclimate were of primary concern. To quantify alterations to the microclimate, the chamber was tested for two years over a range of climatic, leaf area, and biomass levels on an ungrazed tallgrass prairie near Manhattan, KS. The chamber had a minimal effect on microclimate; average chamber air temperature increased 2.9° C over 40 s, while chamber pressure increased only 0.3 Pa, and photosynthetically active radiation attenuation was 10%. Also, a method for selecting the appropriate model (linear or quadratic) to calculate the rate change of CO2 and water vapor from time-series data collected by the chamber was developed. The method utilized a computer program that determined whether the quadratic model, based on shape of the CO2 vs. time curve. Using this method, the quadratic flux estimate was utilized for 80.1% of all NCE flux calculations, 14.2% of the RE flux calculations, and 99.5% of water vapor flux calculations.

Key words: Key Words: Net Carbon Flux, Closed Gas Exchange Chamber, Water Vapor Flux, Tallgrass, Prairie


 

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