March 2018

USDA NASS county yield results from 2017

The 2017 average corn and soybean yields for counties and districts in Iowa were released in late February 2018 (Figure 1). This information is collected by USDA’s National Agricultural Statistics Service (NASS) each year using the December Agricultural Survey and County Agricultural Production Survey.

Through the Ag Decision Maker website, we provide this data in Information Files A1-12 and A1-13, Historical Yields by County, which show county averages from 2008 through 2017. This information is helpful for seeing trends in yields over the past ten years. Information File A1-14, Iowa Corn and Soybean Yields, also shows the ten-year average yield, as well as the year and yield results for the highest and lowest years for each county in the past ten years.

Yield data is helpful in developing corn and soybean budgets, cash-flow projections, flexible lease payments, or other types of analysis for producers in which the actual production history is not available. Note that the crop yields are reported in bushels per harvested acre; Farm Bill programs such as Agricultural Risk Coverage (ARC) use bushels per planted acre.

Forty-five counties reported their highest yield for corn in 2017, and 12 counties reported the highest soybean yield in 2017. Marshall County had the highest corn yield at 222.4 bushels/acre, and Sioux County reported the highest soybean yield at 64.6 bushels/acre. The state average corn yield was 202.0 bushels/acre, the second year in a row with a state average over 200 bushels/acre. The state average soybean yield was 56.5 bushels/acre. A slight decline from the record high achieved in 2016, but still in the top three statewide yields seen in the past ten years.

At the District level, four areas, North Central, Northeast, East Central, and Southwest all reported record corn yields in 2017. The remaining Districts in the state achieved a record high in 2016. Yields ranged from a high of 214.9 bushels/acre in the East Central District to 159.9 bushels/acre in the South Central part of the state. All Districts in the state had a record high soybean yield in 2016, and none topped this in 2017. The highest yielding region for 2017 in the state was the Northwest at 59.6 bushels/acre, and lowest was South Central, at 48.0 bushels/acre.

Each year, randomly selected operators in Iowa are interviewed for these surveys. The operator reports the whole farm’s planted and harvested acreage, yield and production for corn, soybeans, and hay. They also are asked to report acres rented from someone else. Other crops such as wheat and oats are collected earlier in the year. The data are collected using several methods: mail, telephone interview, personal interview or the operator can even report electronically. Data collection begins in late fall and continues through mid-January. Trained enumerators or census takers collect the data. Strict guidelines are followed in all states to ensure comparable results on a national level. Participation in agricultural surveys such as these is critical for the results to be published across the state.

In 2017, there were four counties in South Central Iowa lacking corn yield information and three counties with no soybean yield reported. This is the second time since 2015 that yield information has not been reported for both major crops in all 99 counties in Iowa. Results in these counties were suppressed due to not enough usable responses. If county yield data is used in a lease or other component on a farm operation, it might be necessary to agree upon a secondary source for yield information if the county yield is not released by NASS in a given year.

Summarized yield information is available on the Ag Decision Maker website. For other county estimates, including other crops, livestock, and farm numbers, visit the USDA NASS website for Iowa.

Ann M. Johanns, extension program specialist, 515-337-27664,


Ann M. Johanns

extension program specialist
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