November 8, 2016
Some farmers are finished harvesting in Iowa, others are still trying to get their remaining corn and beans out of the field. Here’s a report from a couple of Iowa State University Extension field agronomists interviewed by Wallaces Farmer as we start the week of November 7, 2016.
CHECK SOIL TEMPERATURE: Farmers are reminded to wait until soil temperatures are below 50 degrees F before applying anhydrous ammonia fertilizer this fall. Soil temps have been slow to cool due to the unusually warm late fall weather.
“We started harvest this fall in late September in much of the state, but then had some rainy periods, even foggy humid days that slowed down progress,” says Paul Kassel, ISU agronomist located at Spencer in northwest Iowa. “We still have a few soybean fields and some corn yet to harvest here in northern Iowa. So that’s a little concern, especially with the beans, but the weather looks good here. We’re looking at pretty well wrapping up harvest this week.”
1) What’s the moisture content of corn coming out of the field? Is corn coming out pretty dry now? It’s a little bit slow to dry down in the field, says Kassel. “We’ve had some nice days, we’ve had some good temperatures. But we’ve had days with high humidity, too, on the warmer days this fall. We’re still looking at 16% to 17% moisture corn in the field, which isn’t bad. But we’ve had recent years where it was much less than that, which helps lower the drying bill and reduces total expenses. We like it to be a little drier but we really can’t complain.”
Talk about grain piled on the ground. Are the yellow mountains starting to grow larger in your neck of the woods? Yes, they are, he says. “We have a big crop in Iowa this fall and a lot of farmers are harvesting fields that average 200 bushel per acre or better. And we’ve also had a good soybean crop this fall in Iowa, so that takes some of the storage space. So there are more piles this fall than we had with last year’s crop. Outdoor grain piles will be persistent on the landscape into next spring for sure.”
2) Need to run your fans to cool grain in bins. In eastern and southeast Iowa, ISU Extension agronomist Virgil Schmitt also is seeing piles of corn outside a number of elevators, piles which are growing bigger as farmers are finishing harvest. The concern is with temperatures being too warm, and how the grain will keep.
Farmers who like to use natural air to dry corn in bins, instead of high temperature gas-fired drying systems, like to see fall temperatures that are warmer than normal. But as a reminder, people who’ve stored soybeans and corn in the bin earlier this fall and the grain went into the bin at a warm temperature, they need to run the fans at night a little bit to cool that grain down, says Schmitt. It needs to be cooled to between 30 and 40 degrees F for safe winter storage.
“Up here in northern Iowa we are now getting some nights with the air temperature down into the 40s, so we can cool grain down by running the bin fans on those nights,” says Kassel. If you’ve got corn dried down but it’s still warm in the bin, you needed to run those fans when air temperatures are cool enough. Eventually you want to get your stored corn and soybeans down to between the 30 to 40 degree range. But for the present time, if you can cool stored grain down into the 40 to 45 degree range, that’s good too.
The difficulty with that is it’s been so wet and foggy in some areas of Iowa this fall. The last thing you want to do is blow more moisture back into the grain. “The key concern with aerating grain is the temperature,” says Kassel. “We have really nice weather now, so with this current weather, we recommend getting the grain cooled down.”
3) Weed pressure showing up in fields this fall. Talking about weed pressure and weed resistance to herbicides, farmers saw a lot of weed escapes this year. “We have a lot of cover crops coming up now in fields, green is visible after harvest,” says Kassel. “We may also see weeds emerging and getting a toe-hold this fall. This is more of a concern in southern half of the state than in the northern half, since southern Iowa is a little warmer which favors weed germination and growth in the fall.”
Some farmers with no-till acres in southern and central Iowa are applying herbicide this fall after harvest, says Schmitt. We’ve seen some issues with marestail. We encourage farmers to keep an eye on fall weeds emerging and if they’re looking at no-tilling corn into soybean acres come spring, if they have a lot of winter annuals coming and weeds such as marestail, they may want to consider fall weed control on those fields. Particularly with this warm fall weather this year.
4) What about cover crops? Are you seeing a lot of cover crops being planted this fall? Or that were aerially seeded into standing corn and soybeans earlier this fall or in late summer? Both Kassel and Schmitt say cover crops look great. There was a lot of aerial seeding in late August and early September. “We had a lot of areas in north central and northeast Iowa this year with 10 to 12 or a few with even 15 inches of rain in several days in September,” notes Kassel. “But in general, cover crops really look good this fall and the warm weather has gotten them off to a good start. We know of a field where oats were drilled in the fall after corn silage was harvested and those oats are a foot tall already here on November 7. It’s been a great fall for cover crop growth.”
5) Nitrogen management with fall anhydrous application. Kassel and Schmitt shared some tips on managing nitrogen as we’re coming into manure application time? What should those farmers be thinking about now? This is the time of year when farmers decide whether to apply anhydrous in the fall or wait until spring, notes Kassel. The first week of November the soil temperatures are usually pretty cooperative. But this year they are not.
“I’m looking at the ISU Mesonet website and the soil temperature at the 4-inch depth is 53 degrees in Clay County and Palo Alto and Kossuth counties in recent days here in northern Iowa. In central and southern Iowa they are warmer than that,” notes Kassel. “But warm soils are a concern for applying anhydrous ammonia and also manure in the fall. We encourage farmers and fertilizer dealers to wait until the soil temperature gets down to 50 degrees and falling, and that may be awhile yet this year. With the forecast, we’re looking at some warm days and also some warm nights, warmer than normal for this time of the year.”
6) What about the N in liquid swine manure? That’s a concern going forward, notes Schmitt. It converts to ammonium in the soil and the warmer the soil is, the more that ammonium will convert to nitrate. And nitrate can leach from the soil in the spring if we have excess rain. Of course, we often do have rainy periods spring. So farmers should follow the “Don’t go until the soil temp is 50 degrees or below” guideline, to make the best use of nitrogen that we can, whether it’s anhydrous ammonia or manure that we’re knifing into the soil.”
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