2005 Year in Review

From the Fields

Source: Jim Morrison, Extension Educator, Crop Systems, Rockford Extension Center, University of Illinois, Phone 815-397-7714, FAX 815-397-8620, Email morrison@uiuc.edu

The focus of this column is on two unrelated topics, but topics that have generated discussion and questions. “Do high corn populations require higher nitrogen rates?” and “What is the typical wheat straw yield in northern Illinois?”

In an attempt to explain why “higher than expected” nitrogen rates were needed in some cornfields, the contention by some has been that high corn plant populations require higher nitrogen rates. As Emerson Nafziger and Robert Hoeft, University of Illinois Department of Crop Sciences indicated in the recent Pest Management & Crop Development Bulletin, the only way to test such a theory is to grow a corn hybrid at different populations and at different nitrogen rates in the same field. The Department of Crop Sciences conducted such a study and averaged over 9 site-years, there was no difference in the optimum nitrogen rate among populations ranging from 25 to 40 thousand plants per acre.

Other researchers have had similar results, notes Nafziger and Hoeft, and they know of no published information that supports the contention that high plant populations need higher nitrogen rates. In summary, Nafziger and Hoeft say the false belief that high corn populations need more nitrogen only encourages over-application of nitrogen.

“What is a typical yield of wheat straw in northern Illinois?” To help answer that question, a study was initiated in 2004 at the Northern Illinois Agronomy Research Center, Shabbona.

Straw yield was calculated from these six winter wheat varieties grown at the Center as part of the University of Illinois wheat variety trial: Cardinal, Growmark FS 634, Kaskaskia, Madison, Pioneer 25R47, and Roane. Yield data averaged from 2004 and 2005 were:

- 2.6 tons of straw per acre (100% dry matter basis)

- 82 bushels of grain per acre

- 1 pound straw per pound of grain

The above results are an average of 3 replications in each of the two years. Statistical analysis of the data has not been completed. Details of the study are available from Jim Morrison, Extension Crops Educator at the Rockford Extension Center, phone 815-397-7714.

by  Editor, theCity1.com
October 4, 2005