Ohio State University Extension
Department of Horticulture and Crop Science
2021 Coffey Road, Columbus, Ohio 43210-1044

Tips For Improving Seed Placement In Corn

AGF-120-90

When we discuss planting corn, attention is primarily given to optimizing seeding rates (plant population) and planting dates. The significance of uniform spacing within the row is sometimes overlooked and not given sufficient attention. However, corn seed needs to planted as uniformly as possible within the row to ensure maximum yields and optimal crop performance -- regardless of plant population and planting date.

What's the impact of irregular seed placement? It's well documented that corn plants next to a gap in the row may produce a larger ear or additional ears (if the hybrid has a prolific tendency) which compensates in part for missing plants. But these plants cannot make up for those which are crowded, i.e. plants spaced too closely together in the row that compete ineffectively for sunlight, water, and nutrients. Crowding often results in barren plants or ears too small to be harvested (nubbins), as well stalk lodging and ear disease problems.

Corn producers have not had much actual data to refer to that indicated the importance of uniform planting. In recent years research has been conducted at Purdue University to evaluate the effect of within-row spacing variability on corn grain yield. Commercial corn fields have also been sampled to establish a base line on plant spacing variability under "real world conditions."

Based on the Purdue studies, it appears that corn growers in Indiana could improve grain yield anywhere from 4 to 12 bushels per acre if within-row spacing were improved to the best possible uniformity (depending on how bad the spacing variability was to begin with). Ohio growers would probably observe similar responses for corn grain yields to within-row spacing variability because many of our production environments are similar to those in Indiana.

The most effective way to improve planter accuracy is to keep planting speed within the range specified in the planter's manual. The following are some additional points to consider for improving seed placement uniformity.

1. With plate-type planters, match the seed grade with the correct planter plate.
2. Planters with finger pick-ups should be checked for wear on the back plate and brush (use a feeler gauge to check tension on the fingers, then tighten them correctly).
3. Check for wear on double-disc openers and seed tubes.
4. Make sure the sprocket settings on the planter transmission are correct.
5. Check for worn chains, stiff chain links, and improper tire pressure.
6. Make sure seed drop tubes are clean and clear of any obstructions.
7. Clean seed tube sensors if you have a planter monitor.
8. Make sure coulters and disc openers are aligned properly.
9. With air planters, match the air pressure to the weight of the seed being planted.

Prepared by:
Peter R. Thomison
Extension Agronomist