After a season of variable weather conditions, corn yield in Wisconsin reached a record 148 bushels per acre, an increase of 5 bushels over the old record set in 1999. Corn acreage planted for all purposes was 3.80 million acres. Acres harvested for grain were 2.90 million acres. Production was 429 million bushels, the second highest production on record. Corn silage production set a new record of 15.0 million tons. Silage acreage harvested was 880,000 acres.

Jeff Mezera, of Bagley in Grant County, became the first farmer in Wisconsin to break the 300 bu/A yield barrier. He had set the previous record of 296 bu/A in 2004. In 2005, he had three 10-acre fields produce over 300 bushels per acre (303, 307 and 323 bu/A).

In Wisconsin, both the National Corn Growers Yield Contest and the PEPS Program (Profit through Efficient Production Systems) measure yield on 10-acre fields. Sixteen counties set new corn yield records in 2005.