Overview of Soybean Experiment

Experiment Log

First Plant Experiment: Soybean Cultivar 'Hoyt'
18th May 2002 to 13th August 2002

Sally Silverstone, in charge of Sustainable Agricultural Systems, seen through the observation window, weeding the west-side soil bed to encourage maximally efficient soybean growth.

The first experiment with the Laboratory Biosphere Experimental Chamber began on May 17th, 2002 and ended on August 10th, 2002 - a total of 65 days in length. This 'shakedown' experiment used the sealed chamber to grow a dwarf soybean cultivar in both soil-beds, and continued to test and explore the various mechanical and data acquisition systems under actual experimental conditions.

The soybean crop was grown under a 12-hour per day light regime up to the eventual harvesting of the aboveground biomass - Average light input was 68 mol m-2 d-1 . The dynamics of a number of trace gases were carefully monitored, and the system demonstrated its ability to track in detail the atmospheric dynamics occasioned both by the phytorespiration of the soybean crop and additional soil respiration. At the height of plant growth, near the time of fruiting, the CO2 draw-down occasioned by photosynthetic activity during lighted hours was high, requiring the periodic injection of measured amounts of CO2 to maintain plant growth. CO2 draw-down was, on several occasions, allowed to continue to severely limiting lower levels and the overall experiment produced a strong positive correlation between atmospheric CO2 concentration and the rate of fixation.


Using LabVIEW Remote Panel technology the data acquired can be displayed anywhere in the world using a simple web browser, without scientists doing any additional programming. It is thus possible to take control of the presentation of data from the Soybean experiment and manipulate that data in various ways for analytical purposes.	A graph recording a two-week set of Temperature data showing the diurnal variation in Temperature inside the sealed chamber. Important markers showing entry into the chamber or injection of CO2 can be mapped by data-points linked to particular events, here seen as yellow and puce dots. (Visit NI's real-time graphical display of the data shown above.)

Reference:

M. Nelson, W.F. Dempster, A. Alling, J.P. Allen, R. Rasmussen, S. Silverstone, M. Van Thillo. 2003. Initial Experimental Results from the Laboratory Biosphere Closed Ecological System Facility. 2003. Advances in Space Research, Vol 31 No. 7, pp.1721-1730, 2003

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Abstract: An initial experiment in the Laboratory Biosphere facility, Santa Fe, New Mexico, was conducted May-August 2002 using a soil-based system with light levels (at 12 h per day) of 58-mol m-2 d-1. The crop tested was soybean, cultivar Hoyt, which produced an aboveground biomass of 2510 grams. Dynamics of a number of trace gases showed that methane, nitrous oxide, carbon monoxide, and hydrogen gas had initial increases that were substantially reduced in concentration by the end of the experiment. Methane was reduced from 209 ppm to 11 ppm, and nitrous oxide from 5 ppm to 1.4 ppm in the last 40 days of the closure experiment. Ethylene was at elevated levels compared to ambient during the flowering/fruiting phase of the crop. Soil respiration from the 5.37 m2 (1.46 m3) soil component was estimated at 23.4 ppm h-1 or 1.28 g CO2 h-1 or 5.7 g CO2 m-2 d-1. Phytorespiration peaked near the time of fruiting at about 160 ppm h-1. At the height of plant growth, photosynthesis CO2 draw down was as high as 3950 ppm d-1, and averaged 265 ppm h-1 (whole day averages) during lighted hours with a range of 156-390 ppm h-1. During this period, the chamber required injections of CO2 to continue plant growth. Oxygen levels rose along with the injections of carbon dioxide. Upon several occasions, CO2 was allowed to be drawn down to severely limiting levels, bottoming at around 150 ppm. A strong positive correlation (about 0.05 ppm h-1 ppm-1 with r2 about 0.9 for the range 1000-5000 ppm) was observed between atmospheric CO2 concentration and the rate of fixation up to concentrations of around 8800 ppm CO2.

©2003 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Dempster, W.F., Van Thillo, M., Alling, A., Allen, J.P., Silverstone, S., Nelson, M. 2004. Technical review of the laboratory biosphere closed ecological system. Published in Advances in Space Research (2004) 34, 1477-1482.

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Laboratory Biosphere is a 40 m3 closed life system that commenced operation in May 2002. Light is from 12,000 W of high pressure sodium lamps over planting beds with 5.37 m2 of soil. Water is 100% recycled by collecting condensate from the temperature and humidity control system and mixing with leachate collected from under the planting beds. Atmospheric leakage was estimated during the first closure experiment to be 0.5-1% per day in general plus about 1% for each usage of the airlock door. The first trial run of 94 days was with a soybean crop grown from seeds (May 17, 2002) to harvest (August 14, 2002) plus 5 days of post-harvest closure. The focus of this initial trial was system testing to confirm functionality and identify any necessary modifications or improvements. This paper describes the organizational and physical features of the Laboratory Biosphere.