Your plants need oxygen to power the final step of respiration that makes most of their energy. Oxygen grabs electrons at the end of the chain to keep the whole thing moving. Without oxygen in plant respiration, your plants can only make a tiny bit of the ATP they need. Every root, stem, and leaf cell needs a steady supply of oxygen to work well.
When I first started growing tomatoes in heavy clay soil, I learned this lesson the hard way. My plants looked great for a few weeks after planting them in the garden. Then the leaves went yellow and the roots turned brown and mushy to the touch. The clay held too much water and pushed out all the air pockets around the roots. My plants drowned because their roots couldn't get the oxygen they needed to breathe and grow strong.
The process runs in the mitochondria of every cell in your plant. Aerobic respiration plants depend on takes place along the inner wall of these tiny power plants. Electrons flow down the chain like water over a dam and make energy along the way. Oxygen waits at the end to catch those electrons and combine with hydrogen to make water. This flow powers a pump that builds up ATP for your plant to use.
The numbers show just how much oxygen matters to your garden plants every day. With plenty of oxygen, your plant makes 27 to 28 ATP from each glucose it burns through aerobic respiration. Without oxygen, your plant can only run a backup system that makes just 2 ATP per glucose. That's a huge drop in energy output that your plant can't handle for long without showing signs of stress.
Your roots have the hardest time meeting plant oxygen requirements down in the soil. Roots can't reach into the air like leaves do to grab what they need. They must get oxygen from tiny air pockets between soil grains and bits of organic matter. Good soil structure keeps about 25% of its volume as air space for your roots to tap into all day and night long.
In my experience, most plant problems come from too much water rather than too little. Soggy soil fills those air pockets with water and cuts off the oxygen supply fast to your roots. Your roots can't respire right, so they can't take up water or nutrients no matter how much sits in the soil around them. The plant wilts even while sitting in wet ground because the roots have stopped working.
You can help your plants get the oxygen they need with some simple steps in your garden. Use raised beds or add compost to heavy soil to boost drainage and air flow through the root zone. Water deep but not too often so soil can dry a bit between drinks. Avoid walking on garden beds since your feet pack the soil tight and crush the air spaces your roots need.
Watch your plants for signs that their roots need more air around them in the soil. Yellow lower leaves, mushy roots, and slow growth all point to oxygen problems in the root zone. Dig up a small plant to check the roots if you're not sure what's wrong with it. White firm roots mean good oxygen flow, while brown mushy roots mean you need to fix your soil drainage fast.
Read the full article: Respiration in Plants: The Complete Process Guide
