Average corn yields topped 200 bushels per acre in more than one-third of the counties in Iowa last year, according to final estimates recently released by USDA. A total of 39 counties had average yields above 200 bushels per acre, led by Marshall County with 226 bushels. Grundy, Delaware, Tama and Ida counties rounded out the top five with yields over 222 bushels per acre.

The county with the lowest average yield in the state was Adair, with 149. Yields are derived from production divided by area harvested.

Persistently wet conditions in north-central Iowa resulted in corn yields averaging 160 bushels per acre or less in Dickinson, Emmet, Clay and Palo Alto counties. In the previous year, corn yields in each of those counties exceeded 195 bushels per acre for the county average. Statewide, the average corn yield for Iowa in 2018 was 196 bushels per acre. The state’s average for soybeans was 57 bushels per acre.

Sioux County soybean leader

For soybeans, 31 counties averaged at least 60 bushels per acre in 2018. Sioux County had the highest yield for the second year in a row with an average of 67 bushels per acre. Lee County (65.9), Cherokee (65.5), Delaware (65.3) and Ida (65.3) rounded out the top five. Lucas County recorded the lowest yield at 42.3 bushels per acre.

The highest crop reporting district in Iowa for corn grain production in 2018 was central Iowa with 384 million bushels. The west-central district had the second-highest production at 380 million bushels.

Kossuth County was the highest-ranking county for corn for grain production with 53.4 million bushels produced. Plymouth, Sioux, Crawford and Woodbury rounded out the top five. Other counties with production of more than 39 million bushels were Delaware, Benton, Franklin, Clinton and Hardin.

Northwest tops in corn for silage

The northwest Iowa crop reporting district led all Iowa districts last year with 1.69 million tons of corn silage produced, according to USDA. This accounted for 30% of the state’s total production. The northeast district produced 1.59 million tons of silage, representing 29% of the state total.

Iowa’s highest silage yields were recorded in the northeast district, where yields averaged 22.5 tons per acre. The northwest and east-central districts rounded out the top three yielding districts with 22 and 21 tons per acre, respectively, for their averages. The highest county yield average was Des Moines County with 20 tons per acre. Yields for silage are derived from production divided by area harvested.

For the maps in the slideshow, six counties didn’t have corn yield and other corn information reported due to insufficient data, according to USDA. For soybeans, there wasn’t sufficient data for three counties.