OMAHA (DTN) Our Digital Yield Tour is based on high-tech yield models developed by Gro Intelligence. While such models help put a county, state and national look at corn and soybean yields, they won't say what is going on in your fields. The best way to do that is with yield checks and pod counts. Here's the method farmers are using who are submitting information to the 2018 tour.
WHAT YOU'LL NEED
Pen and pad (for recording counts).
Camera/phone for recording conditions, diseases, insects.
Bucket (for carrying equipment into the field and carrying ears out).
Small tape measure (for measuring ear length/plant height).
Large tape measure or 30-plus feet of rope (for marking off plots). If you want to check multiple fields, a rope is faster, and cheaper if you accidentally leave it in the field. Measure off 35 to 40 feet of rope, and make one good knot at one end and another knot at the 30-foot point.
3-foot by 3-foot wire or rod square (for measuring soybean plot) or use tape measure and wire survey flags to mark off square plot.
HOW TO TAKE CORN ESTIMATES
Walk into random area of field well past the end rows.
Walk 35 paces down the row middle (away from the end rows). Starting there, lay out a 30-foot plot with tape measure or rope. You'll be using both rows in that plot.
Measure and record row width in inches (if not known).
Count the number of ears, on both rows, that will make grain INSIDE your 30-foot plot. Record total number.
Pull the fifth, eighth and 11th ear from one row.
Count the number of kernel rows on each ear, average for three ears.
Measure the length of GRAIN on each ear, average.
Multiply: Number of ears found X average kernel rows X average inches of grain divided by row spacing.
Example: 53 ears X 16.6 kernel rows X 6.5 inches equals 5,718; divided by 30-inch row space equals 190.62 bushels per acre.
HOW TO TAKE SOYBEAN ESTIMATES
Go to a representative area of the field, away from end rows. Walk 35 steps down the row and lay out a 3-foot plot, using either 3X3 "frame" or tape measure and flags.
Count all the plants in that plot.
Pull three plants at random.
Count all pods per plant, record. Average for the three plants.
Multiply: Average number of pods X total number of plants.
To compare planted and drilled bean fields: Multiply total number of pods by 36 and divide by row width.
There is not reliable method to convert pod counts to bushels per acre, all "on the ground" plot tours compare pod counts across various years and then make an estimate of how yields will move accordingly.
The key to sampling is to be as random as possible. That's why going to a spot in the field, then walking 35 (or some other number) additional steps, is important. The extra steps adds randomness to a good or bad spot that you might have selected subconsciously. Of course, if you want to know the yields or pods in specific spots, by all means check there, too. If there is a lot of variability in the field, take multiple samples and average.
If you want to share your information, send to us at email@example.com. Include your county, state, whether dryland or irrigated, and any other information about crop conditions. We'll only share yields and county, not your name, in any results we publish.
Greg D. Horstmeier can be reached at firstname.lastname@example.org
Follow him on Twitter @greghorstmeier
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