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Sunflower District


Best Management Practices for Planting Corn

Corn planting is right around the corner! While planning for the next crop begins as we are harvesting, there are several best management practices to keep in mind.

1. Proactively manage soil water
Many times successful dryland corn production relies heavily on off-season moisture collection. Therefore, catching snow and minimizing evaporation are important factors.

Research to show the relation between wheat stubble height and subsequent corn and sorghum yields has been conducted on the K-State Research and Extension Center in Tribune. In 2016, corn yields were 10 bu/ac greater in stripper stubble and tall cut stubble than short cut stubble. This is consistent with long term averages of the study. Here is the complete research report on this study from 2007-2016: http://bit.ly/2F2YI0j

2. Optimize agronomic and economic fertilizer rates
There are many resources to assist with calculating fertilizer rates. A great starting place is the K-State Soil Testing Lab's website: http://bit.ly/2FBZWnG

There are two useful resources: an excel workbook and publication with charts. The 'Fertilizer Recommendation Program' excel workbook allows you to enter your soil test data to generate recommendations. The publication is 'Soil Test Interpretations and Recommendations' MF-2586. It has easy to use charts to quickly determine fertilizer rates, based on soil organic matter and yield goal.

3. Create a season-long weed management plan
Getting a season-long spraying schedule assembled, allows you to rotate herbicides and modes-of-action. This will help minimize reliance on one or two herbicides and help with prevention of resistant weeds.

A good K-State source for this is the K-State Chemical Weed Control Guide. This book lists herbicides labeled for use in Kansas and has a handy chart at the beginning of each crop. This chart rates the efficacy of a specific herbicide on a specific weed. For example, Dual II Magnum is F-G (fair to good) on pigweed species, while Lumax is E (excellent).

Pick up your copy of the K-State Chemical Weed Control Guide at your local Extension Office or get it online at http://bit.ly/2o5WdmK

4. Plant into optimal planting conditions
Corn kernels need a soil that is warm, moist, well supplied with air and fine enough to give good contact between seed and soil for rapid germination.
Planting corn early is important to use the growing season and maximize yield. Recommended planting dates for our area are April 25 to May 15.

Avoiding too wet conditions are important for a couple of reasons. First, if it is important to get the seed slot closed for good seed-to-soil contact and prevent the seed/seedling/roots from drying out. Second, if the soil conditions are too wet, it will cause sidewall smearing. This can cause problems all growing season because the root growth will be severely restricted to the seed slot.

Planting when the soil temperature reaches 55 degrees at 2" at mid-day is an excellent guide early in the planting season. This is especially true if the weather outlook for the following days is favorable.

If during the planting window, there are cold temperatures or snow predicted you may need to stop planting to avoid cold injury to the seed. If the seed imbibes (takes in) cold water, it can damage cell membranes. This results in reduced growth rate and can interfere with emerging seedlings growth.
If soil temperatures are in the high 40s and the weather forecast calls for cold wet conditions within the next 48 hours — that will likely reduce soil temperatures, so refrain from planting.

Additional information on chilling damage in corn is available from University of Nebraska's CropWatch newsletter: http://bit.ly/2IunfxR

The K-State corn production handbook is available: http://www.agronomy.k-state.edu/documents/extension/corn-book.pdf

Links for all publications listed are available at www.sunflower.ksu.edu/agronomy

Do you use the K-State Soil Testing Lab?

  • Your own account with log-in to track your samples
  • Flat fee shipping service (UPS shipping-$6 for 15 lbs)
  • Sources to generate your fertilizer recommendations

   Costs: (soil prep-$1.25/sample)

  • Pkg 1       $5.75        pH, buffer pH, P, K
  • Pkg 2       $11.50      Pkg 1 + OM + Zn
  • Profile      $8.25        NO3, S, Cl (0-24")
  • Additional packages available.

K-State Soil Testing Lab: http://bit.ly/2G17sYQ


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Calculating Corn Yield Estimates

Yield estimates can be made using the yield component method. This method uses a combination of known and projected yield components of corn to calculate an estimate of the potential yield. It is "potential" yield because one of the critical yield components, kernel size, will not be known until physiological maturity. Before then, one can use only an estimate of predicted yield based on what you think the grain filling period might be like (e.g. favorable, average, or poor).

Estimating potential corn yield using yield components is accomplished using the following elements:

Ears per acre: This is determined by counting the number of ears in a known area.

With 30-inch rows, 17.4 feet of row = 1,000 of an acre. This is probably the minimum area that should be used. The number of ears in 17.4 feet of row x 1,000 = the number of ears per acre. Counting a longer length of row is fine, just be sure to convert it to the correct portion of an acre when determining the number of ears per acre.

Make ear counts in 10 to 15 representative parts of the field or management zone to get a good average estimate. The more ear counts you make (assuming they accurately represent the field or zone of interest), the more confidence you have in your yield estimate.

Kernels per ear: This is determined by counting the number of ear rows and number of kernels in each row. Multiply those two items to arrive at kernels per ear (number of rows x kernels per row).

Do not count aborted kernels or the kernels on the butt of the ear; count only kernels that are in complete rings around the ear. Do this for every 5th or 6th plant in each of your ear count areas. Avoid odd, non-representative ears.

Kernels per acre = Ears per acre x kernels per ear

Kernels per bushel: This will have to be estimated until the plants reach physiological maturity.

Common values range from 75,000 to 80,000 for excellent, 85,000 to 90,000 for average, and 95,000 to 105,000 for poor grain filling conditions. The best you can do at this point is estimate a range of potential yields depending on expectations for the rest of the season.

Ears per acre = average of 22.5 ears in 17.4 ft of row (1/1000 acre).
22.5 x 1,000 = 22,500 ears per acre

Kernels per ear = average of 14 rows x 27 kernels per row.
14 x 27 = 378 kernels per ear

Kernels per bushel = estimating 105,000 kernels per bushel, based on poor growing conditions.

Calculation:   Ears per acre x Kernels per ear = Bushels per acre
                    Kernels per bushel

22,500 ears per acre x 378 kernels per ear = about 81 bushels per acre
105,000 kernels per bushel


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