: Plants produce oxygen during the day via photosynthesis. At night, they consume oxygen and release carbon dioxide. Bacteria in the soil also consume oxygen to break down decaying organic matter, releasing the carbon dioxide the plants need to survive.
The Ultimate Bottle BiospBuild Your Own Self-Sustaining World Bottle Biosphere Guide
: As old leaves die and fall, microorganisms in the soil decompose them, returning vital nutrients to the earth to feed new growth. : Plants produce oxygen during the day via photosynthesis