Crop Update: Soil type determined yield difference in corn; moisture conditions will dictate wheat acreage

Posted: Sep. 22, 2011 9:31 am Updated: Nov. 28, 2014 2:17 pm


Combines have been rolling for several weeks now, with at least one producer done with corn while others have yet to begin. And yields are a mixed bag, which I think we all knew.

Many are pleasantly surprised by some of the corn yields. It's not uncommon to find 150- to 160-bushel corn (or even better). Unfortunately we've also seen some less than 100-bushel corn.

Much of the yield difference can be determined by soil type. Among other things, soil type dictated:

º How early the corn could have been planted -- the earlier the better, since all corn died prematurely this year, and the further along the corn was the better the yield.

º Whether it had to be replanted -- replant corn won't be as good.

º How much subsoil moisture the plants had access to -- better moisture holding soils are going to yield better, although, clay soils hillsides really suffered this year.

Soybean harvest is very close. Most likely most corn harvest will be "downhill" by the time the peak of soybean harvest begins.

Soil moisture conditions will somewhat dictate wheat acres this fall. If our dry conditions persist into October, there will be even fewer wheat acres. We've experienced a downfall in acres over the past few years, due to higher corn and soybean prices in addition to lower wheat yields.

For those who will be seeding wheat, the fly free date for our area is approximately Oct. 1. Seeding at or close to that date, we would recommend 1.5 million seeds per acre. Consult the seed tag to determine seeds per pound on the variety you are seeding, and then determine how many pounds per acre is required to achieve this population. Each week that seeding is delayed you should increase the seeding rate by 10 percent to account for reduced tillering.

Wheat varieties are numerous. Utilizing yield trials to determine varieties gives better results. The University of Illinois variety trials are available online at

The research conducted in Illinois generally has shown that wheat sown after soybean has a higher yield versus after corn. This is due to better stands behind beans as well as less disease potential.

Tillage has increased yield compared to no till wheat after corn, but probably not to the extent that the extra cost of tillage would outweigh the better yield. However, wheat planted after corn has benefited from a tillage trip. The key would be the ability of the drill to place the seed through the residue into the soil. Regardless of the preceding crop, having the residue spread evenly behind the combine is essential. Tillage can also help reduce the amount of winter annual weeds found in wheat fields. Although, due to the dry soil conditions, I wouldn't expect many emerged winter annuals at this time.

Wheat seed treated with an insecticide seed treatment generally has yielded positive results at the Orr Research Center, and the further you head south in Illinois, the more positive the results.

Application of 20-30 pounds of nitrogen in the fall is recommend. One hundred and fifty pounds of DAP would provide this, as well as provide much needed phosphorus; 50 pounds of 0-0-60 would also be required. Both these application rates are based upon the amounts of fertility 75 bushels of wheat would remove from the field. If the soil is low in either nutrient, then additional fertilizer should be added. Remaining nitrogen should be applied in the spring, in a single application. And nitrogen recommendations for wheat have been modified recently based upon wheat and nitrogen price.



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