Yield Responses to Differing Corn Populations
Dordt College
2016 Growing Season
Author: Sam Roskamp
Introduction
A particular question that many farmers need to consider is what is the optimum population of corn that maximizes yield and income for their farm. Through a series of trials with different populations of corn being grown in different plots, one can determine the population of corn that can be grown that saves costs while also receiving the greatest yield possible. Growing too much corn within a given area risks exhausting the nutrients within the soil and can increase competition for nutrients within a higher concentration of corn. Growing too little corn logically does not utilize the full potential of the soil and in effect causes the farmer to receive a reduced yield as well. According to a study performed by Iowa State University in 2015, using seven corn trials, researchers found that the best corn yields fell between 35,000 and 37,000 seeds/acre. Dordt College continues this study regarding corn populations and the response seen through harvest yield.
Materials and Methods
Three different corn populations were tested: 28,000, 32,000, and 36,000 seeds per acre using the Pioneer® PO157R variety within ten acres in 30in rows. This trial was performed at the Dordt College Agricultural Stewardship Center in Sioux County, Iowa. The trials were planted on May 18, 2016 and were randomized and replicated five times within six row plots within a no-till field. Observed and maintained throughout the summer, the corn population trial was sprayed with pre-emergent Triple Flex®as well as managed to prevent the effects of weeds and pests on the field trial. The corn was machine harvested on October 25, 2016 with each replication having moisture and weight tests conducted. Using the moisture corrected yield formula, the calculations were able to be made.
Results and Discussion
After measuring the results, no significant difference was found between the three different populations. Where one population had a higher yield in one rep compared to the other two, it also had a lower yield than one or both different population groups. The corn populations were not statistically significant (p = 0.058), showing little difference in yields, as observed in Table 1.
Table 1 – Average Yield
Population / Average Yield*28K / 223.44
32K / 236.514
36K / 234.802
*Value is measured in bushels per acre
The results of the trial do not suggest a significantly stronger yield,demonstrating that planting one ofthese corn populations will not create a strong difference in yield. With this in mind, this study acknowledges that other varieties may react differently to the corn population. Since income and yield are two of the greatest factors for a farmer to consider, knowing that these three corn populations do not differ from one another in a distinct way, seed cost will have to be relied on in deciding the optimal planting population.This study shows that economic yield increased by $27.68 per acre by planting 28,000 instead of 36,000 seeds per acre.
Chart 1 – Yield
Acknowledgements
Mike Schouten – Agriculture Stewardship Center Manager
Iowa State University