Be glad this spring provided better planting conditions for many people than last year. Early summer offers opportunities to look at the 2020 season. While there may still be some spots to replant or a field that needed more time before it was dry enough for planting, now you can think about other things. Concentrate on sidedressing nitrogen, scouting and the sun.
Yes, the sun. Consider the work the sun does for you. July and August are the sunniest months of the year in Indiana, with 20 to 22 days per month where the sun is shining in skies with 30% or less cloud cover throughout the day. Months like November and December hover around 10 days of sun. And what is crop production at its core? Basically, farming the sun and harvesting sunshine.
The most basic building blocks of everything living on Earth come from sunshine. When a plant photosynthesizes, carbon is converted from a gas to a solid — from carbon dioxide gas to glucose and other carbon-based compounds. Yet the crux of the entire photosynthesis equation boils down to these five words: “in the presence of sunlight.”
So, the process of photosynthesis goes like this: Carbon dioxide and water are pulled into the leaf tissue of a plant and, in the presence of sunlight, a chemical reaction occurs that converts the carbon dioxide to glucose, which is a complex sugar compound, and two oxygen molecules. The oxygen is released from the plant for man and animals to breathe. The glucose is put to work in the plant a variety of ways. Oxygen, considered a byproduct of photosynthesis, is probably one of the most important byproducts of any process ever.
Value of glucose
As for glucose, the primary product of photosynthesis, carbon is now “fixed” in a nongaseous form, and the plant can use it. Two important uses of carbon in a plant are for plant biomass and the commonly forgotten root exudates.
In fact, when a seed germinates and a seedling begins growing, up to 80% of the carbon fixed from photosynthesis is exuded out of the plant roots and into the soil surrounding it. This is because plants are dependent on microorganisms in the soil to help them survive.
As a plant grows, the percentage of carbon exuded out the root into the soil reduces, but typically is still around 50% until a plant gets to reproduction and pod fill. At that time in the plant growth cycle, more carbon is put into grain to guarantee successful future generations. So sunshine flows through and into the plant to feed itself, and out into the soil to feed the microbes that support it.
Someone may wonder if reducing the amount of root exudates would increase the amount of plant biomass. Research shows that it doesn’t. You can’t have one without the other! If the plant is bred to exude less carbon in the soil, photosynthesis overall becomes less efficient.
Photosynthesis is a miracle of nature. It’s what helps you convert plant materials into glucose, which the plant needs both aboveground and belowground. Whatever you can do to promote healthy plants with leaves that capture maximum sunlight promotes grain production.
McLain is the state soil health specialist with the Natural Resources Conservation Service. She writes on behalf of the Indiana Conservation Partnership.