Remember when a four-inch rainfall was a rarity in Iowa? No? That was Iowa farm life a century ago. In 1991, climate scientists predicted a wetter, warmer Midwest climate with warmer winters and more spring and early summer rain showers. We all know how that turned out. New climate predictions this week forecast a future with wetter harvests, and high humidity grain storage.
If you haven’t already heard, the fourth Climate Science Special Report is out. Climate predictions for the Midwest see more rainfall, higher humidity, hotter temperatures, and more extreme weather events in our future. This summer’s weather is the new normal for the Midwest, which presents challenges in the field and with stored grain.
Nitrogen loss from excessive rains is nearly the norm. Wet weather is making corn more susceptible to Physoderma brown spot and node rot, and gray leaf spot. Corn leaf aphids, bird cherry-oat aphids, and soybean cyst nematode are more common and making earlier appearances in the field.
These factors present challenges to grain condition, which in turn makes storing grain more challenging too.
Applying the Global Climate Report to the Midwest
Dr. Gene Takle, Nobel Prize-winning climate change panelist, emeritus ISU agronomy professor, and contributing author, tells Iowa farmers what else to expect. These are a few of his regional takeaways from the Special Report:
- Iowa’s annual five-day heat wave temperatures will likely rise 7° F by mid-century from late 20th century temperatures
- Heat waves will top out at 103 to 108 degrees about once per decade between now and 2050
- Daily total rainfall will double in intensity by mid-century with the greatest change coming before 2025
- Extreme weather events, which include flooding in typically dry seasons, will increase over the next 30 years
- Higher humidity will be the norm, promoting molds and grain quality deterioration
Making the Best of Midwest Climate Change
All is not gloomy on the weather front for Iowa though. Global climate change means winners and losers when it comes to regional climates. The Midwest, in one sense, has been winning, due largely to land use according to an MIT study.
The study shows increases in crop production lead to wetter, cooler conditions. In the Midwest, agricultural intensification is being credited with impacting the regional climate. Even though the number of planted acres hasn’t changed significantly, the number of plants per acre has increased dramatically over the last 40 years.
Here’s how the study says agricultural intensification may be affecting local climate.
Plant transpiration – plants releasing water into the atmosphere through photosynthesis – increases humidity and lowers temperature. Transpiration increases local moist static energy that leads to increased rainfall. Since rainfall uses lots of moist static energy, there’s little left for heating the air.
Dr. Takle says that the higher humidity makes it seem hotter, “even though in many cases the temperature is less than it was in the ‘50s or ‘60s.” The bigger worry for Iowans may be erratic rainfall and subsequent flooding.
Takle calls the new regional climate a “double-edged sword.” On one hand, the corn growing season is about three weeks longer now than it was 50 years ago due to warmer temperatures. (Corn has proven remarkably adaptable to climate change.) On the other hand, higher humidity is negatively impacting proper corn storage.
Dealing with High Humidity Grain Storage
According to Dr. Takle, “The higher humidity that leads to the growth of mold, aflatoxins, etc., is promoting more deterioration of the grain quality. And that’s just not something that was a factor a few decades ago.” With predictably higher humidity every summer, farmers will need to make adjustments to reduce high humidity grain storage.
Since high-moisture grain produces heat when put into confined storage like your grain bin, it’s important to deal with moisture before storing. Continuous flow dryers or batch drying are reliable ways to get grain to an acceptable moisture content level for storage.
But drying grain to an acceptable 18% to 15% won’t be enough to keep it in good condition while storing. Once it’s in the bin, it’s all about the temperature.
Taking the Guesswork out of Grain Temperature Monitoring
Once upon a time, when the average bin size was 2,500 bushels, managing grain temperature in the bin was more straightforward. These days 36 x 26 x 36 bins that hold 30,000 bushels with multiple loading ports are common. This can affect airflow. Since one field won’t fill one of these bins, you’re layering corn in different conditions from different fields in the same bin. This adds to the problem. (Blending, rather than layering can help here.)
It’s imperative to have in-bin temperature monitoring, because there’s no way you’ll know what’s going on in there without it.
The minute the grain comes into the bin, you should turn on the aeration fans to cool it down. On average, grain loses 1% of moisture for every 15 degrees of cooling. Conventional wisdom has been to run fans continuously, but that may be counter-productive in high humidity conditions.
For optimum drying, the absolute humidity of air outside the bin should be less than the absolute humidity inside the bin. This may require running fans at night instead of during the day for best results. During fall and spring, when the conditions cause condensation, leaving aeration fans off during the day protects grain from the outside air. Running them during high humidity introduces more moisture into the bin.
But why guess if you’re managing your grain effectively?
Combating Grain Temperature and Humidity
Monitoring grain storage temperature is essential when a total bin loss can start at $150,000. You’ll want to shoot for one temperature cable for 10 feet of air flow, so the larger the bin, the more temperature cables you’ll need to protect your grain from spoilage.
If you think you don’t have time to monitor the conditions inside your grain bin, you’re not using the right equipment.
With the GrainTrac temperature monitoring system, you’ll have all the temperature, relative humidity, and other data you need to operate your fans efficiently. And have it at your fingertips 24/7. You can monitor your grain’s temperature remotely on your smartphone from anywhere you have Internet.
Even better, you have the option of managing your fans remotely too. Plus, optional weather sensors give you the ability to monitor humidity, rain, and wind conditions outside your bin for the best decisions.
Preparing to deal with higher humidity during wet growing seasons, harvest times, and storage may mean the difference between healthy profits from your stored grain and catastrophic losses from out of condition grain.
(Sources: Iowa News Service and Fourth Climate Science Special Report)
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