By Andy Westhoven, AgriGold Regional Agronomist, CPAg, CCA
Just when you thought 2019 was challenging…the year of 2020 has laughed in the face of last year! So far, this season is shaping up as the have and have nots in terms of moisture. At a recent training, attendees brought in samples showing our growth stages ranging from V5 (or shin-high) to pollinated corn from around the state. The variability is evident in the sizes of corn plants, but what we are also seeing below ground. Let us take a journey to investigate the variability of the corn roots and what stories we might learn.
In years of dry weather, I have a belief that subtle variations are exaggerated. What might only be a bushel swing never noticed on a yield monitor becomes a 10+ bushel swing (and usually blamed on the hybrid). Our own farm can provide a perfect example. I noticed a pattern that was roughly every 60 feet and did not match the planter or any other pass that we had made. I concluded that is was the coop floater that sprayed the field right before a heavy rain. Now the rain has little bearing here, but the weight from the sprayer added another layer of compaction and thus limited the corn roots ever so slightly. Those plants emerged slower, have been a few inches shorter all year, and are still lighter green in color. I would venture to guess that the tassels even emerged a day later than the rest of the field. By the way, this is a sandy field – just imagine if it was heavier soil! We typically would not see this “damage” in a wetter year.
To add a shameful plug for myself, it ties perfectly to my last article published in May, Avoid the knee jerk reaction. In the article, I discussed the Rule of May. The theory is that growers usually get away with mudding-in corn in April, but not in May. If planting in May is into less than ideal conditions, it usually backfires unless you get rain all season to mask the problems.
Another story evident across the eastern Corn Belt is soils that were worked too wet (most likely to aid in drying them out). Those fields have a horizontal layer about 2 to 3 inches deep — the depth of the tillage pass. When digging up the roots, you will clearly see the restrictive layer and the roots struggling to penetrate deeper. Due to this root struggle, plants are not reaching water, nutrients, etc. and exhibiting stress signs like rolled-up leaves and even some nutrient deficiencies. In contrast where neighbors waited to let the soils dry out naturally, those fields show less signs of stress.
Most will say the stress observed in the corn crop is from lack of water. It is hard to argue against this thought. However, most of the stress is exaggerated by lack of root depth caused by man-made issues. The best way to know for sure is to dig up the plant and investigate. I was told in my younger days that 90% of the problems can be found and/or answered below ground. I believe that with 100% conviction to be true. The corn plants can tell a story all season long and the roots are like the grandfathers in our lives that have all the stories and have seen it all.
As our corn crop hits the midway point of the season (tassel and pollination time), if you notice any variation in tassel emergence or any variation, I encourage you to dig up the roots on the “poorer” plants and investigate what is happening below ground for a little insight. I will agree that a rain would not only help improve the crop, it would also allow for ease in digging up roots! I hope you stay safe and have a long, cool, wet grain fill period for maximum yields.