The changing climate has spawned discussion and projections on how cropping patterns might change in the U.S. For example, a paper by Emily Burchfield of Emory University entitled Shifting cultivation geographies in the Central and Eastern U.S. projected the suitability for corn production under moderate greenhouse gas emissions would navigate north and be centered in Minnesota and Wisconsin by 2100. Burchfield also projected Nebraska would no longer be suitable for corn production and soybean production would move eastward in the state but would remain in counties bordering the Missouri River. Burchfield does note, though, that the projections assume no changes in technology in the future and that technological changes in the past have increased agricultural productivity.
Pondering crop patterns in the future makes one wonder about in the past. Have the centers of corn and soybean production in Nebraska changed over the past 50 years? Are there discernible trends in corn and soybean production given the changing climate? To investigate these questions, USDA National Agricultural Statistics Service corn and soybean production data by county was examined between 1970 and 2020. Each county’s share of state production in ten-year increments was calculated and counties with a production share of at least 2 percent was defined as a top-producing county. Maps were then developed for each 10-year increment highlighting the top-producing counties. The darker a county is colored, the greater the county’s share of state production. This week Tidbits highlights maps for corn production and next week soybeans will be featured.
Maps of the top corn-producing counties beginning in 1970 are shown in Figure 1. The first item which catches the eye is how stable geographically the top-producing corn counties were between 1970-2020. Corn production during the past 50 years has been centered in a corridor of counties along I-80 and the Platte River ranging from York and Fillmore Counties on the east to Dawson and Phelps Counties on the west. Custer County was the only county outside this corridor which consistently shows up as a top-producing county. Lincoln, Holt, Antelope, Platte, and Merrick Counties made multiple appearances as top corn producers but didn’t have the staying power of the other counties.
Total corn production in Nebraska in 1970 was 367 million bushels with 13 counties as top-producing counties. Collectively, these counties produced 39 percent of the state’s production. Hamilton and York Counties had the largest shares of state production at 4.1 percent and 3.6 percent respectively. By 1990, top-producing counties numbered 17 and accounted for 46 percent of the state’s production, suggesting production was becoming more concentrated. However, in 2020 the number of top-producing counties declined to 12 and accounted for just 28 percent of state production. In 2020, total state production had grown to 1.79 billion bushels, almost 5 times greater than 1970 production. York (2.79 percent), Hamilton (2.67 percent), and Custer (2.67 percent) Counties were the largest producers. In fact, the combined production of the top nine counties in 2020 exceeded the total state production in 1970 by 18 million bushels.
What explains the staying power of the counties in the I-80 and Platte River corridor as the state’s top corn producers? There could be many reasons. Access to water, the density of irrigation, soils, topography, local corn demand (ethanol facilities), easy access to major rail lines and I-80, could have all played a role. Climate change doesn’t appear to be significantly affecting crop suitability thus far, at least in terms of the top-corn-producing counties. Whatever the reasons for the stability in corn production in the state, it has lasted 50 years and is likely to do so for the foreseeable future.
Figure 1. Counties with At Least 2% of State’s Corn Production*
* Counties highlighted accounted for at least 2 percent of state’s total corn production in that year. The darker the county, the greater the share of production.
Source: NEFB graphics based on USDA NASS data