Battle for the Belt: Season 3, Episode 13 – Corn & Soybean Stand Counts

In Episode 13, we joined graduate students Diego Miranda, Taylor Dill, and Maria Kessler in the field for a demonstration on corn and soybean stand counts.

Season 3, Episode 13 of Battle for the Belt is now available:

https://www.youtube.com/watch?v=cXWCcFLAdMM

Stand counts are a useful tool to determine the overall plant population of a field. Stand counts can show us potential issues that may have been caused by planter problems, insects, disease, and environmental conditions. If areas have lower stands than we want or uneven emergence, understanding the cause is important for making management decisions. If damaged seedlings are present, dig up a few plants and look for the cause of damage. Biotic factors, such as diseases, insects, and slugs, and abiotic factors, like flooding, freeze damage, or soil crusting, may reduce plant population. Planter-related issues involving seed depth, compaction, and seed spacing can cause low stands, too. Identifying the cause of stand loss can assist you in preventing problems in future field seasons.

To get a good estimate of the plant population for an entire field, sampling a few areas of the field is necessary. Pick areas that are a good representation of the field. Row spacing determines the length of the area that you will need to count. The goal is to count 1/1000^th of an acre for stand count estimates. Therefore, if you count 38 corn plants in the area, the population is estimated at 38,000 plants per acre. See Table 1 to determine the area that you will need to count based on your crop’s row spacing.

The average corn field in Ohio is planted in 30-inch rows, therefore we can use a measuring tape and pull it to 17 feet, 5 inches and place it between two rows. Counting one row is 1/1000^th of an acre, however, you can count both sides to get a better average of the field. If one side has 36 plants and the other has 34, then the average population is 35,000 plants per acre.

In Ohio, a typical soybean field is planted in 15-inch rows. This means that you need to count 34 feet, 10 inches in total length, but you can use the 17 feet, 5 inches and count both rows to reach the total length. Pull the measuring tape out to 17 feet, 5 inches, and place it between two rows, then count both sides of the measuring tape. The total number of plants you count between both rows is then the population. Therefore, if you count 148 plants, the population would be estimated at 148,000 plants per acre.

Stand counts are a useful and easy evaluation to do in the field to help make field specific management decisions.

What is happening in the field?

The past week brought precipitation to all three locations, resulting in a delay in the final planting date. However, with the heat wave that began over the weekend, the soil may be dry enough to put these planting dates in at the beginning of this week. On June 13^th, the Western location was able to plant its fourth planting date (Table 2). Each location now has one planting date left!

At the Western location, the crops are quickly taking off with the first planting date of soybeans (4/18) at R1 (beginning flowering) for the past week (Figure 1). The early flowering of the early planting dates gives the plant the opportunity to have longer flowering and pod-setting periods. Planting date two (5/12) is at V3, planting date three is at V1, and the fourth planting date has not emerged yet. The corn stages are as follows: V8, V6, and V4 (Table 3). There has been no symptomology of disease at this location so far (Figure 2).

The Wooster location has the first two planting dates of soybean (3/27, 4/18) entering the reproductive stages. The third and fourth (5/12, 6/2) planting dates are at V2 and VC, respectively. The corn planting dates are as follows: V8, V7, V5, and V3. The only disease here has been anthracnose on young corn, which causes the first leaves to fall off but does not translate to a decrease in yield.

The Northwest location is no-till for both crops, which has contributed to the slightly delayed crop growth. The first soybean planting date (3/27) entered the reproductive stages last week. Planting dates two, three, and four are at V4, V2, and VC, respectively.

The corn in the first three planting dates at the Northwest location shows purple leaf edges (Figure 3). The purple edges show a buildup of anthocyanins or sugars, which can happen when the corn faces cooler nights. Purpling can also occur when the soil is saturated, and this location has been consistently wet this spring and early summer. Overall, this symptomology should resolve on its own and not cause a decrease in yield.

If you would like to learn more, check out our research updates through C.O.R.N. article updates and YouTube Videos this growing season! You can find the full video playlist of Battle for the Belt on the Ohio State Agronomy YouTube channel.