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Initial experimental results from the Laboratory Biosphere closed ecological system facility.
M Nelson1, W F Dempster, A Alling
1Biosphere Foundation, Santa Fe, NM 87508, USA. nelson@biospheres.com
Advances in Space Research : the Official Journal of the Committee on Space Research (COSPAR)
|September 25, 2003
Summary
Soybean growth in a closed system showed reduced trace gas emissions over time. Photosynthesis rates were high, requiring carbon dioxide (CO2) injections for continued plant development.
Area of Science:
- Controlled environment agriculture
- Plant physiology
- Environmental science
Background:
- Biosphere experiments simulate closed ecological systems.
- Understanding trace gas dynamics is crucial for life support systems.
- Soybean cultivation in controlled environments requires monitoring of atmospheric conditions.
Purpose of the Study:
- To assess soybean growth and trace gas dynamics in a closed soil-based system.
- To quantify soil respiration and phytorespiration rates.
- To investigate the relationship between atmospheric CO2 concentration and photosynthesis.
Main Methods:
- A soil-based soybean crop (cultivar Hoyt) was grown in a Laboratory Biosphere facility.
- Light levels were maintained at 58 mol m-2 d-1 for 12 hours daily.
- Trace gas concentrations (methane, nitrous oxide, CO2, O2, ethylene) and respiration/photosynthesis rates were monitored.
Main Results:
- Aboveground soybean biomass reached 2510 grams.
- Methane and nitrous oxide concentrations decreased significantly over the experiment.
- Photosynthesis CO2 drawdown reached up to 3950 ppm d-1, necessitating CO2 injections.
- A positive correlation was found between atmospheric CO2 and fixation rates up to 8800 ppm.
Conclusions:
- Closed soil-based systems can reduce certain trace gas emissions.
- Soybean photosynthesis is strongly influenced by atmospheric CO2 levels.
- Optimizing CO2 concentrations is vital for maximizing plant productivity in closed environments.