Farmers feel many emotions regarding how well their crop will perform come harvest time and can hardly keep themselves out of the field trying to predict the yield. Corn is commonly estimated in the waning weeks of August by walking into the field and grabbing a few ears off to see how soon harvest will be and to project the size of the crop. Soybeans are a little harder to project, but August rains are hugely important to the success of the soybean crop.
Chris Kallal is the technical agronomist for the corn and soybean brand Dekalb/Asgrow covering West Central Illinois, with a territory extending from Sangamon County all the way to Quincy, and south to St. Louis. Many people who know a farmer will hear them gripe about too much rain, or too little rain, or whatever other weather conditions may be present. There are an inordinate amount of variables that play into the yield of a crop, but Kallal says that weather is the single most important factor. Coming off of a challenging 2023 crop production season, 2024 provided a significant amount of relief by allowing farmers to get into fields in early April and plant a large percentage of the crop.
There was quite a bit of rain in late April but not the heavy rains that oftentimes cause plants to drown or wash away. Corn and soybeans can each endure a significant amount of stress in the portion of their lives growing vegetatively, but struggle without rain when they enter the reproductive stages. Both corn and soybeans usually enter this reproductive period of their lives with the emergence of tassels on corn and flowers in soybeans in early July. Kallal commented on how beneficial some of the rains around the 4th of July were this year, which set the area crops up for a strong yield. Following these early July rains came a very beneficial time period for corn and soybeans with periodic moisture and cool nights. Similar to a human needing sleep, these plants need a break and cool nights allow them to essentially rest without being stressed by heat 24/7.
The good weather persisted from mid-July to late August, providing a boost to the grain fill period of corn. A good grain fill period can skew yield estimates to lower than actual because it takes fewer kernels to fill a bushel compared to what is commonly used to calculate the estimate. In good news for farmers across central Illinois, their estimates were commonly lower than the corn yields they are harvesting and that is because kernels continued to grow larger until maturity.
Weather plays heavily into the rate at which harvest can progress. Because of our recent dry weather and warm temperatures, both corn and soybeans have been drying to an adequate harvesting moisture, while simultaneously allowing fieldwork to continue. Kallal noted that “for most people harvest has progressed very quickly, with a big crop.” He also noted some of the abnormalities this year including a presence of stink bugs and aphids in corn that was planted in May that had massive effects of up to a 50 bushel per acre decrease in corn yield. With $4 corn per bushel, these insects rarely observed in Central Illinois caused up to $200 per acre worth of damage. The positive news is that aphids, which were the cause of a majority of the insect damage, do not overwinter in Illinois and are hypothesized to have been blown in with Hurricane Beryl earlier this year.
Given the significant effects of spring rains, summer rains, summer temperatures, and other abnormal weather conditions, it is evident that farmers do not worry about the weather without reason. Thankfully for producers in our area this year, sentiment is strong on the crop that is being stored and sold following a season of conducive weather for producing corn and soybeans.