Crop Tour Insider

August 11, 2010 10:32 AM

 Each year, the biggest investigative effort Pro Farmer takes on is the Midwest Crop Tour. "Investigative" might not be the word some market-watchers would use to describe the Crop Tour, but that’s exactly what it is. And, as in any investigation, you don’t want to start with too many notions about what you’re going to find! Just gather the information... and trust what you find.


Keep the investigation consistent —

The Pro Farmer Midwest Crop Tour starts the third Sunday of every August. On Monday, scouts move into the field for the first day of sampling with the eastern leg of the Tour traveling from Columbus, Ohio, to Fishers, Indiana, (near Indianapolis). Out west, Day 1 will find scouts in fields between Sioux Falls, South Dakota, and Grand Island, Nebraska.

The remainder of the eastern leg of the Tour will take scouts to much-deserved overnight stops in Bloomington, Illinois, and Iowa City, Iowa, before wrapping up in Austin, Minnesota. After the overnight stop in Grand Island, western scouts will spend nights in Nebraska City, Nebraska, and Spencer, Iowa, before meeting up with the eastern gang in Austin.

This Crop Tour is not a "windshield tour."

Sure, scouts make crop observations while driving down the road, but this is a working, sampling Tour. Scouts stop every 15 to 20 miles where they can sample a corn and soybean field at the same time. This is when consistency is critical. With each team of scouts sampling each field the same way, we can compare yield potential in Nebraska to yield potential in Ohio.
In corn fields, scouts get past the end rows and then walk 35 paces down the main rows before laying out a 30-foot plot on two rows. At the plot, scouts count the number of ears that will make grain on two 30-foot rows, then pull the fifth, eighth and 11th ear from one row (three total ears).
On those sample ears, scouts count (and average) the number of kernel rows around and measure (and average) the length of grain on each ear in inches. The final piece of data for the yield calculation is row spacing.
After that, the calculation is simple: The average number of ears on 30 foot of row, times the average number of kernel rows around, times the average inches of grain per ear, divided by the row spacing. Example: (50 ears X 16.6 kernel rows X 6.3 inches)/30 row spacing
In each soybean field, scouts go to a "representative" area of the field and lay out a 3-foot plot. All the plants are counted in the plot, then three plants are pulled at random. All the pods on the three plants are counted and an average number of pods per plant is calculated. To determine the total number of pods in 3-foot of row, multiply the average number of pods per plant by the total number of plants in 3-foot of row. To make it possible to compare the production potential of a field with 30-inch rows to that of a drilled bean field, multiply the number of pods in 3-foot of row by 36 and divide by the row width. That figures the number of pods in a 3’X3’ square, providing data to compare one field to another.

There is power in numbers —

In four days, the eastern and western legs of the Tour will collect more than 1,000 corn and 1,000 soybean samples and we’ll travel more than 25,000 miles. We do that by traveling in scout teams of three or four with each team following a pre-determined route (but fields are not pre-determined). With a minimum of 10 routes on the eastern leg and at least 7 routes out west, the Tour will average 500 total samples each day.
Here’s an interesting concept. On the Tour, we strive to keep each year’s effort "consistently random." The Tour is consistent by traveling the third week of August every year, by traveling the same routes each year and by using the same sampling procedure each year. 
The "randomness" of the Tour is achieved by not predetermining which fields are sampled and by allowing each team to select the location in the field. But it doesn’t end there... more "consistent randomness" is added by walking 35 paces down the main rows to the sample location. (When scouts start into the field, there’s no way to tell what will be about 35 yards beyond the end rows.) Even the ear selection is "consistently random." By pulling the fifth, eighth and 11th ear from one sample row, scouts might pull the three best, or three worst, ears from the row.

That’s a lot of investigation... but how do you use it?

There is only one way to use the data collected on the Pro Farmer Midwest Crop Tour — compare the results to past Tours. That comparison has proven to be the most reliable analysis of the fresh data.
We’ve studied and analyzed thousands of samples over 16 years of the Crop Tour and we’ve calculated the "historical error" of the Tour data. Simply put, we know the Tour results will be different than USDA’s final yield estimate for each state. Fortunately, we know which states the Tour measures "high" or "low," and we know, on average, by how much. That allows us to "adjust" the Tour results to produce a more "reliable" Pro Farmer yield estimate. (We’ll go over the details of the historical error in next week’s Pro Farmer.)
One last very important point: If scouts accurately estimate the yield in an individual field, it’s completely by coincidence. It means scouts found the average spot in the field. What we’re really trying to do is determine the average yield of one big field across Ohio, Indiana, Illinois, Iowa, Minnesota, South Dakota and Nebraska.
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