Posts tagged ‘corn seeding rates’

Current OSU Recommendations for Corn Seeding Rates in Ohio

Corn seeding rates continues to be a topic of interest. Several seed companies are moving growers in the direction to increase seeding rates to 35,000-40,000 seeds per acre. Research from Ohio State University and Dr. Peter Thomison indicates that recommended plant populations at harvest can range from 20,000 to 30,000+ plants/acre for maximizing yield, depending on the hybrid and production environment.

According to the Ohio Agronomy Guide, final stands of 30,000 plants per acre are recommended for soils with high yield potential (>175 bushel/acre) that have high soil fertility levels and exceptional water holding capacity. On soils averaging 150 bushels/acre, final stands of 26,000 to 28,000 plants/acre may be all that is necessary to optimize yield. Finally, on soils that average 120 bushel/acre or less, final stands of 22,000 plants/acre may be adequate for optimal yields.

In a recent OSU study conducted by Dr. Thomison, effects of early (late April) and late plantings (early to mid June planting dates) on corn response to population (24,000, 30,000, 36,000 and 42,000 plants/acre) were investigated at three locations. Results suggested that final stands of 30,000 to 36,000 plants/acre were required for optimal yield for the late April plantings. However, for the early to mid June planting dates, the results indicated little benefit from increasing seeding rate and a significant yield loss was noted at plant populations above 30,000 plants/acre.

If a grower is allowing their corn to dry as much as possible in-field, which can delay harvest, the grower will have to weigh the benefit from using plant populations above 30,000 plants/acre. Although hybrids may exhibit similar yield potential when harvested early (early/mid October), differences in yield become evident with harvest delays, which can be attributed to differences in stalk quality. With harvest delays, yield losses can occur at the higher plant populations, especially 42,000 plants/acre, due to increased stalk lodging.

Final stands are always less than the number of seeds planted per acre. Cool, wet soil conditions may reduce germination and emergence. Generally, you can expect from 10 to 20 percent fewer plants at harvest than seeds planted. As such, you need to plant more seed than the desired population at harvest to achieve the target harvest population. To determine a corn planting rate, use the following formula: Planting Rate = Desired Population per Acre ÷ (Germination x Expected Survival). Germination is shown on the seed tag (convert to decimal form). Expected survival is the percent of seedlings that emerge and reach harvest maturity under normal conditions (convert to decimal form). Ninety percent survival (or 10% plant mortality) is about average. If you are planting early and the soil is cool and expected to remain cool for several days following planting, you may want to reduce expected survival by 5%. Also, many no-till farmers will recommend reducing expected survival rates by 5% when planting corn in to a true no-till field.

March 9, 2009 at 7:00 am

Corn Seeding Rates: To Increase or Not to Increase

A few seed companies have been discussing with farmers the idea of increasing their corn seeding rates in 2009 from 30,000-32,000 seeds/acre to nearly 40,000 seeds/acre with the idea that this increase in seeding rate will maximize potential corn yield. In 2008, a research trial was conducted at Farm Focus to look at this very issue. This one year trial examined corn yield differences at two different seeding rates, 30,000 and 40,000 seeds/A, as well at the influence of nitrogen and foliar fungicide.

In a head-to-head comparison of 30,000 seeds/acre and 40,000 seeds/acre with equivalent inputs and OSU recommended nitrogen rates, the 30,000 seeds/acre seeding rate showed a statistically significant yield advantage as well as nearly a $70/acre increase in net revenue based on OSU crop budgets. In the same study we also looked at a comparison of 30,000 seeds/acre and 40,000 seeds/acre with a higher than recommended rate of nitrogen, so as to rule out nitrogen as a limiting factor for the higher seeding rate. Again, the 30,000 seeds/acre corn seeding rate showed a statistically significant yield advantage over the 40,000 seeds/acre seeding rate. In this high nitrogen rate comparison, the economic benefit of using the lower seeding rate provided a net revenue increase of over $80/A compared to the higher seeding rate.

This study at Farm Focus does have a few limitations. First, the data is from one-year only. Second, the planting date was May 23 and a May planting date may not react to increasing corn seeding rate as much as an April planting date.

This research study is available in its’ entirety here:

Full podcast here:

EDIT 02/09/09

This study has generated a life of its’ own, and I need reinforce in this post some of the limitations of this study that are in the full reference above:

  • this data is from one year only
  • this corn study was planted May 23
  • this data comes from only one corn hybrid
  • budgets are based on generalized OSU crop budgets

    February 4, 2009 at 7:00 am


    This blog is no longer being maintained. Information on this blog may still be relevant, but for the latest agronomic information and farm management information please visit and, respectively.

    %d bloggers like this: