Harvest to harvest
on Illinois fields, chlorophyll salvage, and the seasonal oscillations that tune attention and rest
It is harvest season in Illinois. About ninety percent of the corn is already cut and shelled, nearly the same for soybeans. Together they cover more than twenty-one million acres, roughly half the state’s arable ground. Wheat and oats occupy only a few hundred thousand acres, small pockets of diversity in a sea of grain. From the highway the pattern looks uniform, but close up the air trembles with dust and the steady rhythm of machinery. Warm soil exhales into the cooling sky. It is a choreography of withdrawal, a collective act of energy transfer.
Along the fencerows and creek beds, the trees are harvesting too. Around w.oodland, maples and oaks are drawing magnesium inward, chlorophyll retracting, light softening. What reads like an Instagram fall photo vibe from a distance is, up close, a molecular strategy. The leaf is unmaking its solar machine, reclaiming every atom it can before the dark arrives.
Each chlorophyll pigment is a ring of four nitrogen atoms surrounding one magnesium ion, a flat porphyrin tuned to catch red and blue light. When a photon strikes, an electron rises and moves through a chain of proteins: photosystem II, cytochrome b₆f, photosystem I, and ferredoxin–NADP⁺ reductase. Those steps produce ATP and NADPH, which feed the Calvin cycle, turning carbon dioxide into carbohydrates that become wood, starch, and stored potential.
As daylight shortens and air cools, the tree senses the change. Phytochromes read the shifting balance of red to far-red light, cryptochromes track the fading blue, and temperature-sensitive kinases in buds and bark slow their reactions. Inside each cell, circadian genes such as CCA1, LHY, and TOC1 maintain a looping rhythm of transcription and inhibition, a molecular clock that stays in step with the Sun. The tree listens not to hours but to amplitude, feeling the widening swing between light and dark.
Hormones follow that signal. Abscisic acid rises while auxin declines, and metabolism shifts from growth to recovery. Chlorophyllase clips the pigment’s tail, freeing it from the membrane. Mg-dechelatase removes the magnesium ion for storage. Pheophorbide A Oxygenase opens the ring itself, catalyzing:
Pheophorbide a + NADPH + H+ + O2 <=> red chlorophyll catabolite + NADP+
The reaction prevents the pigment from turning phototoxic under weak light and recycles its atoms for later use. Nitrogen, carbon, and magnesium travel through the phloem toward the trunk, stored for reconstruction. The leaf is harvesting itself.
As green drains away, carotenoids glow in gold and amber, and anthocyanins flare briefly at the edges to shield the last reactions from stray photons. The palette is functional, a closing act of metabolic precision. What we call beauty is an exact record of efficiency, a ledger balancing before the cold.
We experience these changes because of the Earth’s geometry. The planet leans 23.44 degrees from upright, and that small inclination shifts how sunlight meets this latitude. In midsummer about one kilowatt of radiant energy falls on each square meter of ground, by late October only six hundred watts remain. The light arrives through a thicker column of air, blue wavelengths scatter more readily, and longer reds slip through with ease. At the same time the air cools, humidity rises, and the chemistry of leaves changes. The color of the woods, the crispness of the wind, and the amber angle of afternoon are not separate events, they are one coincidence of physics, metabolism, and perception.
That tilt establishes a rhythm the whole biosphere follows. Trees feel it in photoreceptors and circadian feedback, birds schedule migration on its cues, and humans register it as shifts in sleep and alertness as serotonin and melatonin rebalance with day length. What the tree translates into hormones and enzymes, we translate into attention and rest. The same oscillation of light and temperature guides when to store energy and when to release it.
I have started to recognize that pattern in my own life, the crest of focused creation and the trough of quiet rebuilding. It feels less like opposition and more like resonance. The season teaches the motion itself: gather energy, let it settle, then begin again. Fields, forests, and thought move to the same slow metronome set by a tilted planet.
When spring returns, magnesium will find its ring again, electrons will climb their familiar ladders, and photons will resume their patient work of turning light into matter. The fields will green, the woods will breathe, and the pulse will start anew.
Life does not end, it modulates, and in that modulation is its proof of endurance.