"Pushing to plant corn early just gives you more time to replant later."

That quote came from one of our WakeUP clients — one who usually gets everything done on time on 1,300 acres and yet has plenty of time to try a few new ideas every Spring. He plants corn by soil temperatures, realizing how critical uniform emergence is for uniformly high yields across the field. 

April 5, 2018 — Another client reminded us of that corn germination fact this week. He planted some "test tube" corn in 50-degree soil. It emerged three weeks later. We planted our test-tube kernels in 70-degree soil. The first shoots emerged five days later. (See our previous report on those tubes.)

Purdue University agronomist Bob Nielsen posted some planting temperature reminders at this link. His data dramatizes the relation between corn emergence time and varying soil temperatures.

See also Bob Nielsen's report on corn germination at the link above

As long as Midwest overnight temps and soils remain chilled, you may as well wait... and wait... until soils warm to near 50 degrees. Forcing corn to remain underground before germinating exposes seed to pathogens longer, before its own physiological immunity can kick in. 

Two management tools offer emergence advantages this spring:

— Strip tillers who last fall swept this spring's corn-on-corn rows free of trash gain better odds of warming the seed zone's darker soil exposed to sunshine, while trash covers row middles. 

— Growers who applied a strong microbial stalk residue digester blend early last fall will have darker, more crumbly cornstalks this spring. The proven classic stalk decomposer is AgriEnergy's Residuce.

A biological newcomer to the Midwest is Biodyne Midwest's Environoc 501, which several of our clients are watching closely this spring after applying it last fall. For years we've encouraged growers to shred stalks right behind the combine, and get them "down and dirty" on the ground, plus applying a spray of Residuce and its related "starter" nutrients.

When a partially decomposed stalk crumbles instead of hairpins under the planter coulter, that means more uniform planting depth and more uniform emergence.

Just a few days of variability in corn emergence within a field imposes a severe alleleopathic drag on the late-emerging sprouts, leading to a yield drag on that plant's potential. corn yield champion Randy Dowdy demonstrated that late emerging plants develop ears with a yield potential that's 40 bu. or so less than the first mergers. Many of the runts don't even set an ear.

This magazine report on Dowdy  dramatizes uniform emergence. It says he doesn't plant until soil is 56 degrees, a luxury available in Georgia's longer season but much less available in the upper Midwest. 

In Spring 2016, the Landus Cooperative in central Iowa launched a field trial to re-test Dowdy's observation that late-merging stalks are "worse than weeds," as many growers maintain. You can see a video of their field trial made in September 2016 at the link in this paragraph. Regional agronomist Dan Lemke tells us the trial was again verified in 2017. The data, estimated by kernel counts on ears which developed within 17.5 feet of row, showed:

Yield estimates, assuming the average if all ears in an acre were like the sample ones counted:

— First 11 seedlings to emerge: 230 bu. per acre.

— Second 10 seedlings spiking 3.5 days after the first: 194 bu. per acre.

— Third 6 seedlings spiking 9 days after the first: 174 bu. per acre.

— Final 4 laggards spiking 9 days after the first seedlings: only 131 bu. per acre.

That's virtually a 100-bu penalty on a corn plant for being 9 days late to spike out of the ground. As you know, this kind of yield variability is hard to "see" from a combine. But it's there.

Here's a still photo of the ears from that 2016 test by the Landus co-op, taken from a screen capture from the video linked above.

Incidentally, the Landus Cooperative website has a wide array of practical management ideas for uniform emergence and top yields.

Also, the April 2018 issue of Progressive Farmer has a cover story, "Eye on Emergence," which stresses uniform emergence and describes exactly how to to an emergence/yield relationship test in your field.