Homecoming Field Day Follow Up

August 19, 2010
Author Dr. Tom

Thanks to everyone who turned out for our Homecoming Field Day last Thursday!  We had a great crowd, and I think everyone really enjoyed Elwynn Taylor’s climate/weather talk, as well as Curt Tomasevicz’s tale of becoming a bobsledder and winning the gold medal.  While it was a hot, humid day the air conditioners for both the warehouse and the big tent worked well, and it felt reasonably comfortable.

On my way to Hooper early Thursday, August 12th , I noticed that one of our seed fields was showing some yellow/gold leaves. I suspect that we will begin harvesting the seed crop in 10 days or so.  Look at the cottonwood/birch/aspen (they are all closely related) trees in your neighborhood—they are beginning to show some light green to yellow leaves, a sure sign that fall is approaching.  On my way home, I watched corn fields carefully.  You expect the dryland fields to show yellowing/drying spots where there is compaction or light soils.  But even irrigated corn fields are beginning to show lighter green color, and ears are beginning to lean away from the stalk, all indications of approaching maturity.

The USDA came out with their crop forcast, another binbuster.  My feeling is that they may be a little high.  I see lots of fields that look a bit uneven, more so than last year.  There is some great corn, but in some spots we lost nitrogen with all the rain.  Some fields have less even stands than last year—we just had some cold, wet weather this spring—and some areas of fields are late developing, and the heat likely affected them the last few weeks.  By my calculations we are about as far ahead of normal heat unit accumulation this year as we were behind last year.  We compacted the grain filling period by a week or so due to hot days and nights.  The relatively high night temperatures tend to drive a little more respiration, so a little more of the sugar manufactured by the leaves during the day is used up at night. (The highest yield areas of the world have warm to hot, bright sunny days and 50 to 55 degree nights.)  I think there will be some huge numbers on yield monitors, but also some lower yielding areas and fields compared to last year.

One of the perennial questions is when do I stop irrigating my corn? (I’d keep on watering beans until the leaves turn color!)  You and your agronomist have been watching your fields, but I’d still suggest an old rule of thumb:  you want two or three inches of water in the active root zone when the milk line is half way down the kernel.  “Black layer” is an artifact, and grain filling stops days before the conductive cells at the cob/kernel juncture turn brownish, and several more before the “black layer” forms.

I hope that the milder weather that showed up this weekend holds!

Until next time,


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