Posted May 12, 2020
Use the following information to scout wheat fields and make your own yield estimates. To help, we have compiled the steps tour participants use to estimate yields so you too can participate. Justin Knopf, wheat farmer in Saline County, provided some helpful hints he and other farmers use when evaluating their fields.
What You Need:
- One yard stick (a ruler will work in a pinch).
- One writing utensil and notepad.
- One calculator (the one on the phone will suffice).
- The wheat yield formula (see below in the story).
- A pocket knife to slice open wheat in the boot stage to examine the wheat head.
- A camera to capture an overall view of the wheat field (the one on the phone is fine).
How to Estimate Wheat Yield and Conditions:
Step 1: Find a wheat field. If you are not a farmer or landowner, call a farmer friend. Above all else, be respectful of other people’s property.
Wheat Tour Tip: Do not enter a fenced field, just as you would not enter a fenced yard in town.
Step 2: Pick your scouting spot. Wheat farmer Justin Knopf suggested going further out in the field than the first few rows, called end rows. This is where equipment often overlaps and farmers load out their trucks near field entrances, both of which can affect tiller count.
Step 3: Observe general field conditions. Do you see weeds? Does the field have an odd color (yellow or blue)? Is the wheat stand uniform or are there bare patches in the field? How thick or thin is the canopy (where the leaves from one row touch the other, same as in a forest where the trees touch each other)?
Wheat Tour Tip: Old farmer’s scouting trick: Throw a hat into the field. If the wheat holds it up, it is generally a good, thick stand. Watch the wind!
Wheat Tour Tip: Color can be an indicator stress, which will reduce yield. A yellow cast can indicate a lack of nitrogen or drought stress. A blue cast indicates drought or heat stress.
Step 4: Measure the height of the wheat plant. By this time of year, wheat should be well above your knee.
Wheat Tour Tip: If the wheat is not taller than a rusty can you found in the ditch, it is abnormally short and will be very difficult to harvest.
Step 5: Examine the wheat head.
If the wheat head has emerged, count the rows of spikelets (covering of the wheat kernels). Knopf said he generally looks for 12 or more in a row for a good stand of wheat. Do not count the bottom or the top. This is the maximum potential the wheat plant has at this point of growth.
While the above steps help gauge the general health and conditions of the wheat field, the next steps will be how you formulated projected yield. So, get out your handy yardstick!
Step 6: Measure the distance between wheat rows in inches. Express any fractional parts of an inch as a decimal. Record on your yardstick or notepad.
Wheat Tour Tip: The most common spacing between rows is 7.5 or 10 inches.
Farmer Tip: Officially, all stalks should be counted. However, Knopf said that secondary tillers (short ones that will feel more like a blade of grass than solid like a tree trunk) are unlikely to mature in time to produce grain at harvest. You decide.
Step 8: Calculate yield, using one of two methods. (formulas below provided by USDA/NASS)
1) Late Season Formula (headed wheat)
- From the bottom of the head to the top, count the number of spikelets (usually 6-12). Spikelets are a V-shaped cover where the grain is produced and held until harvest.
- Count the number of kernels in each spikelet (usually 2-3).
- Calculate the yield using the formula below. Remember, the formula is just a guide. It does not take into consideration high test weight or low test weight.
2) Early Season Formula (pre-heading)
- Select the appropriate formula depending on whether you are in the western, central or eastern third of the state.
- Calculate heads per foot, per the formula.
- Multiply the number of heads per foot by the average weight per head, per the appropriate formula.
- Divide by row spacing.
- Multiple the result by 19.213.
- Congratulations! You have calculated projected wheat yield.
Step 9: Share your results!
Share your results straight from the field on Twitter using the hashtag #wheattour20.
Originally published May 4, 2015, Written by Julia Debes, Updated with 2020 formulas.