Corn Grows From Thin Air

Summary

Corn plants derive their carbon from atmospheric CO2, not soil, through a process akin to the Earth "breathing" in sync with the seasons.

Abstract

The article "Corn Grows From Thin Air" explains the counterintuitive process by which corn obtains its carbon. Contrary to the common belief that plants draw their substance from the soil, the author, a farmer's son, elucidates that the carbon in corn is sourced from the air. This is made possible by the leaves, which act as biological solar panels, converting carbon dioxide, water, and sunlight into sugars and oxygen through photosynthesis. The roots' primary role is to absorb moisture and nutrients from the soil, not to uptake carbon. A simple experiment is proposed to demonstrate that the increase in weight of a potted plant comes from the atmosphere, not the soil. The Earth's seasonal cycle of carbon dioxide absorption by plants in spring and summer, and its release by microbes in fall and winter, is likened to the planet breathing, emphasizing the dynamic and interconnected nature of the carbon cycle.

Opinions

The author challenges the traditional view of plant growth, emphasizing the role of atmospheric carbon in the development of corn.
The article suggests that the soil's function in plant growth is primarily as a medium for moisture and nutrients, akin to a damp paper towel used for sprouting seeds.
The author expresses a personal connection to the subject, recalling childhood memories of farming and the curiosity they inspired.
The author advocates for a hands-on approach to understanding this natural phenomenon, proposing a science fair project to empirically demonstrate the atmospheric origin of plant carbon.
There is an underlying appreciation for the elegance and efficiency of the natural processes involved in plant growth and the Earth's carbon cycle.

why all the carbon in corn comes from the atmosphere

I come from a long line of farmers who feed the nation, forming the backbone of America. I vividly remember spending my childhood years riding with my dad in his combine as he harvested corn. But where exactly did this 8-foot stalk of corn come from? The obvious answer is from the soil. However, there is one not-so-obvious, but more intriguing answer. Corn grows from the ocean-of-air that surrounds us.

Moisture was all they needed

Before planting season, my dad used to test his seeds by sprouting them in a damp paper towel. In a few days, the seeds would sprout roots. This is interesting, this means the soil is not needed to sprout roots, only moisture is necessary. After testing the seeds, he would plant thousands of them a few inches below the soil in straight lines. A few weeks later, thousands of leaves would emerge from the soil in perfect rows.

The biological solar panel

The leaf is a very efficient biological solar panel turning CO2, water, and sunlight into sugars and oxygen, and this is where our story gets interesting. The leaves that emerge have little holes — stomata — that let CO2 from the air into the plant. Like a garden hose, the xylem brings water from the roots to the leaf. Last, the leaf contains a solar receptor — chlorophyll — which captures sunlight. This light provides the energy needed to rearrange atoms in the CO2 and water into oxygen, which is released back to the atmosphere, and sugar, which is the plant’s food. The sugars are then used in different downstream processes, allowing the plant to form other building blocks and grow. These processes require nutrients, such as nitrogen and phosphorus, which the roots get from the soil.

The roots of the plant hook into the soil to suck out the moisture, but the roots are not sucking up the soil itself. If they did, a sinkhole would form under every tree on the planet. So, are plants growing from the soil or the air? In my mind, the soil simply replaces the paper towel as a medium for moisture and nutrients.

A simple experiment showing plants take up CO2

A simple experiment, which would make a great science fair project, can show plants are actually taking up carbon from the atmosphere. The experiment would start with two pots: a control pot with only soil and a second identical pot of soil planted with seeds. Each day, you water each pot with the same amount of water. Then record the weight of each pot every day. While the pot without seeds might show minor changes, the major weight increase will be in the pot sown with seeds. The only explanation for the weight increase is that it must come from the atmosphere. Please let me know if you build a project around this idea, as I would be interested in seeing the results.

Earth is breathing

One of the most exciting discoveries made by Charles Keeling, when he started measuring CO2 in our atmosphere in 1958, was that in some sense the Earth is breathing. In Spring and Summer, plants “breathe in” carbon dioxide from the atmosphere. In Autumn and Winter, microbes on the ground consume the fallen leaves, and in return, “exhale” CO2 back to the atmosphere. [Data source: NOAA-ESRL]

By now it should be clear that the carbon in a blade of grass, a tree, and a stalk of corn all came from the atmosphere. Our Earth inhales in the spring and summer and exhales in the fall and winter. These are the thoughts that go through my mind when I’m driving down a Minnesota country road during harvest season. That, and, “sweet corn sounds good for dinner.”

Editor: Dr. Rachana Maniyar

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