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Northern Illinois Agriculture

University of Illinois Extension
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Managing crop residue

Posted by Russel Higgins -

The middle of April and a weather influenced slowdown in field activities in northern Illinois. Don’t put the jackets away just yet! Over the weekend several fields did have anhydrous applied but any type of spraying was absolutely out of the question. At the end of last week daily maximum wind gusts recorded by the Illinois State Water Survey were 36.7 mph in DeKalb County and 53.7 mph in Stephenson County.

While reading about what is happening in our surrounding states I came across a report on residue research by Dr. Mahdi Al-Kaisi, Department of Agronomy at Iowa State University. In his report titled Myths and Facts about Residue Breakdown he tackled several assumptions that have been in place for a number of years. In his words; “there is a common belief among many farmers and agronomists that the physical change in crop residue structure or orientation in the field by tillage can accelerate residue breakdown by cutting crop residue into small pieces or burying residue by tillage. Also, there is the belief that the application of nitrogen fertilizer on crop residue (i.e., corn residue) after harvest can speed up the process of residue breakdown. Both assertions are not correct.”

In his research Dr. Al-Kaisi compared deep tillage, strip tillage and no-till on residue breakdown of both Bt and non-Bt corn residues. The results of this three-year field and laboratory incubation study show no signi?cant differences in the breakdown or percent of residue that remained among the three tillage systems of Bt and non-Bt corn hybrid decomposition. Corn residue decomposition was evaluated by applying three N rates 0, 30 and 60 lb N/acre to corn residue immediately after harvest, in which specific amounts of corn residue were weighed and placed in nylon mesh bags and left in the field immediately after harvest for decomposition evaluation. The rate of residue decomposition was evaluated every three months for the entire year (12 months). The results showed that corn residue decomposition increased with time with lesser amounts of residue remaining after each evaluation period. There were no differences in the rate of residue decomposition as a result of N application of different N rates. These results suggest that a fall application of nitrogen to enhance corn stalk degradation is ineffective.

So what does determine residue degradation? The decomposition of crop residue is highly controlled by soil moisture and temperature as essential factors driving microbial activity. A very interesting study, if it withstands academic and field verification it may change the way we manage crop residue in the future.

The article can be accessed in its entirety on the Iowa Crop Management Newsletter site

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