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Yields through knowledge

After harvest and planting, June is our third busiest time in the fields, except when we’re still planting in June. Scouting fields, spraying pesticides and sidedressing fertilizer consume the majority of our time.

My guess is most of you only read “spraying pesticides” in that last sentence. Many growers utilize crop scouts, and sidedressing corn has gone by the wayside a bit, even though it is a great practice for corn in our lighter soils.

Growers who are serious about adding yield to their bottom line must make time to evaluate their own planting practices in order to determine which variables can be manipulated next year to increase yield. This evaluation is the first step in Peterson Farms Seed’s Plus 20 initiative — adding bushels to the bottom line by effectively manipulating those variables over which you have some control.

Key Points

• Corn offers clues now to what’s holding down yield.

• Check stand for population,even emergence and more.

• Doing homework now can add bushels in the future.

What to look for

When scouting in June, look for uniform emergence and spacing. Corn does not like competition, either from weeds or from another corn plant that is too close. First, evaluate the population. Count the number of plants in a thousandth of an acre (23 feet, 9 inches for corn in 22-inch-wide rows; 17 feet, 5 inches for corn in 30-inch-wide rows).

Do this in six to seven different spots in the field, and determine the average. Your actual results should be within 5% of what you planted. We get about 5 to 6 bushels per acre per 1,000 plants. Any reduction from this will dramatically reduce yield.

Check for stand uniformity

While determining plant population, also check stand uniformity. Take an average spacing in each of the six to seven locations. Ideally, 80% of the plants should be within 2 inches of the target spacing (9.5 inches in 22-inch rows; 7 inches in 30-inch rows with a stand of 30,000 plants).

Be sure to take the time to figure out why problems exist. Was there a metering problem in the planter leading to doubles or skips? Is emergence uneven due to cool soil temps or varied planting depths?

Corn plants should all germinate within a 48-hour window for uniformity. If a plant emerges outside the 48-hour window and grows one collar or more behind its neighbor, it probably will not produce an ear or will miss pollination.

Use tissue tests

If any visual symptoms are noticed, use tissue tests to help determine what is going on. Take samples in both the bad spot and a good spot within the field. While this test may not tell you that the deficient-looking plants needed 48 more pounds of potassium, it will tell you what nutrient may have been lacking and whether the deficiency is due to poor nutrition or poor uptake of the nutrient itself.

Always look below the soil surface when making your diagnosis. Restricted root mass from lodging or insect damage usually leads to aboveground symptoms. Also, if you planted some trial strips, take tissue samples on those now to determine where something may be lacking.

My message this month should be clear: Don’t miss this opportunity to advance your farm and your farming practices. Examine the agronomic variables in your cornfields now by taking the counts, measuring the uniformity, evaluating the situation and sending in the tissue tests.

Don’t cross your fingers and hope for higher yields next year. Instead, do your homework now in order to add bushels next year through knowledge.

Spelhaug is an agronomist with Peterson Farms Seeds, Harwood, N.D. Contact him at 866-481-7333 or

This article published in the June, 2010 edition of DAKOTA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.