Plant spacing uniformity in corn

We set out last spring to investigate the uniformity of spacing between corn plants in local corn fields. To my knowledge, no counts have been done across Ontario in commercial corn fields. US surveys have found two-thirds of the corn fields in the Corn Belt could have improved planting accuracy.

US information suggests corn yields can be improved by reducing the variability of spacing between plants. Ontario research hasn't been as convincing but improving planter accuracy will at least help to attain your desired seeding rate.

Discussion- We found 37 % of the fields had SDs below the optimal 3 inches. Fourty-four per cent of fields were between 3 and 4 inches. These would benefit from some limited fine tuning of planters to reduce plant spacing variability. Fifteen per cent were between 4 and 5 inches and 4 per cent were above 5 inches. These plantings are the most concern. Consequently, efforts should be made to avoid variability at this level. These results are comparable to US studies.

Most planters had more doubles than skips with the exception of the Case Cyclo planter. Skips are more detrimental than doubles because skips or missing plants almost always result in lower yields usually related to lower plant populations. Doubles or extra plants don't hurt yield. In fact, if your plant population is lower than is optimal for field and weather conditions, then yields may increase from extra plants. If you are already seeding at 32,000 to 33,000 seeds/acre, doubles are increasing your seed costs.

There was very little difference between planter types in plant spacing variability, except that the Case Cyclo planted with most variability and lower plant populations. Within planter types, there was a range in numbers suggesting that all planters could perform better or worse depending on how they were operated.

Next month, we will look at ways of reducing plant spacing problems.