May 11, 2021

Trends in Corn Plant Populations

by Michael Langemeier

Trends in seed costs are driven by both changes in seed prices and changes in corn plant populations.  This article examines trends in corn plant populations in Iowa, Illinois, and Indiana.  In addition, this article examines the proportion of seed costs per acre that are explained by changes in seed prices and plant populations.  FINBIN data was used to represent seed cost per acre.  Seed price and corn plant population data were obtained from USDA-NASS.

Corn Plant Populations

Figure 1 presents corn plant populations in Iowa, Illinois, and Indiana from 1996 to 2020.  The annual growth rate in plant populations ranged from 0.99 percent in Iowa to 1.09 percent in Illinois over the study period.  Annual increases in plant populations ranged from 280 plants per acre in Iowa to 306 plants per acre in Illinois.

Figure 1.  Corn Plant Populations in Iowa, Illinois, and Indiana Source: USDA-NASS

Figure 1. Corn Plant Populations in Iowa, Illinois, and Indiana

The three trends lines illustrated in figure 1 are highly correlated, but obviously are not identical.  In 1996, the corn plant population in Iowa, Illinois, and Indiana were 24,950; 24,200; and 23,500 plants per acre; respectively.  Projected plant populations in 2021 are 32,410 in Iowa, 32,570 in Illinois, and 31,287 in Indiana.

Relationship between Seed Cost, Seed Prices, and Plant Populations

To examine the relative importance of changes in seed price and plant population to changes in seed costs, we developed indices for all three of these measures.  Figure 2 presents indices for seed cost, seed price, and plant population in the three states represented in figure 1 (i.e., Iowa, Illinois, and Indiana) from 1996 to 2020.  The base year for each measure was 2011.

Figure 2.  Seed Cost, Seed Price, and Plant Population Indices for Corn

Figure 2. Seed Cost, Seed Price, and Plant Population Indices for Corn

It is obvious from figure 2 that there is a closer link between the seed cost and the seed price indices than there is between these two indices and the plant population index.  To examine the relationship between the three measures, we regressed the seed price and plant population indices on the seed cost index.  The regression coefficients for both the seed price index and the plant population index were significant.  Results indicated that a 1 percent change in the seed price index resulted in a 0.86 percent change in the seed cost index, while a 1 percent change in the plant population resulted in a 1.41 percent change in the seed cost index.  Though the seed cost index was more sensitive to changes in plant population, given the relatively larger change in the seed price index during the study period, as illustrated in figure 2, the seed price index had a larger impact on the seed cost index over the study period.  To more fully understand the impact of the seed price index and the plant population index on seed costs, we computed coefficients of separate determination (Langemeier et al., 1992).  These coefficients can be used to measure the influence of each independent variable upon the dependent variable.  The sum of the coefficients of determination for each variable equal the R-square goodness of fit measure, which was 0.993 for the seed cost regression.  Seed price explained approximately 81.6 percent of the variation in seed cost and plant population explained approximately 17.7 percent of the variation.

Concluding Comments

This article discussed trends in corn plant populations for three Corn Belt states, and examined the relationship between seed cost, seed price, and plant populations for corn.  Plant populations for corn increased approximately 1 percent per year for Iowa, Illinois, and Indiana from 1996 to 2020.  For Illinois, the state with highest projected plant population in 2021, corn plant population increased from 24,200 plants per acre in 1996 to 30,400 plants per acre in 2020.  A vast majority of the change in seed costs since 1996 can be explained by changes in seed prices.  However, approximately 18 percent of the variation in seed costs since 1996 was explained by changes in corn plant population.  Thus, when developing crop budgets, it is important to account for current seed prices and trends in corn plant population in seed cost estimates.

Obviously, increases in corn plant populations have also impacted trends in corn yield since 1996.  Though an important topic, it was beyond the scope of this short article to examine the relationship between corn plant population and corn yield.  We will leave this topic for future article.

 


Citations

Center for Farm Financial Management, University of Minnesota, FINBIN web site, accessed on April 9, 2021.  https://finbin.umn.edu/

Langemeier, M., T. Schroeder, and J. Mintert.  “Determinants of Cattle Finishing Profitability.”  Southern Journal of Agricultural Economics. 24(December 1993):41-47.

USDA-NASS.  Quick Stats, accessed on April 9, 2021.  https://quickstats.nass.usda.gov/

TAGS:

TEAM LINKS:

RELATED RESOURCES

Corn & Soybean Basis Steady to Stronger in Most Locations, Weaker at Ohio River Terminals

February 12, 2024

After starting the year weaker than normal, corn and soybean basis has been steadily increasing since harvest ended last fall. In recent weeks, many eastern Corn Belt locations have seen steady to slightly stronger corn and soybean basis levels.

READ MORE

The Outlook for Corn & Soybeans

January 17, 2024

Host Brady Brewer provides a recap of Dr. Chad Hart’s presentation on the 2024 agricultural crop market outlook at the Purdue Top Farmer Conference on the latest episode of the Purdue Commercial AgCast. Dr. Hart, a professor and crop marketing specialist at Iowa State University, explores the shift to “normalcy” for crop prices and farm incomes in 2024.

READ MORE

International Benchmarks for Corn Production

January 11, 2024

Examined yield, gross revenue, and cost for farms in the agri benchmark network from Argentina, Brazil, Canada, the Ukraine, and the United States.

READ MORE

UPCOMING EVENTS

Commodity Classic 2024

The Purdue University Center for Commercial Agriculture will present a Learning Center Session on Thursday, February 29 entitled Positioning Your Farm for Long-Term Success during Commodity Classic in Houston, Texas.

Read More

2024 Crop Cost and Return Guide

November 22, 2023

The Purdue Crop Cost and Return Guide offers farmers a resource to project financials for the coming cropping year. These are the December 2023 crop budget estimations for 2024.

READ MORE

(Part 2) Indiana Farmland Cash Rental Rates 2023 Update

August 7, 2023

Purdue ag economists Todd Kuethe, James Mintert and Michael Langemeier discuss cash rental rates for Indiana farmland in this, the second of two AgCast episodes discussing the 2023 Purdue Farmland Values and Cash Rents Survey results.

READ MORE

(Part 1) Indiana Farmland Values 2023 Update

August 6, 2023

Purdue ag economists Todd Kuethe, James Mintert and Michael Langemeier discuss Indiana farmland values on this, the first of two AgCast episodes discussing the 2023 Purdue Farmland Values and Cash Rents Survey results. Each June, the department of agricultural economics surveys knowledgeable professionals regarding Indiana’s farmland and cash rental market.

READ MORE