Precision Q&A – for Jan. 26, 2009

Send us your question

Do you have a precision farming question that you’d like the Grainews Precision Q&A team to answer? Please send your question to the editor, Jay Whetter, at [email protected]or call him at 807-468-4006.

Warren Bills, president of GeoFarms Solutions in Calgary, provides the question and the answer this time. He says this question is “definitely” the most common one he gets when talking to farmers at tradeshows and conferences.

The question:

I’ve just purchased some new equipment and I’m told it can variable rate. I want to try some variable-rate application this spring, but I don’t know where to start. What do you think I should do?

The answer:

This question is loaded with answers, but if I had to give two constructive starting points to the people who ask me this, it would be the following:

1. The first place to start in my mind is to double-check again with your equipment dealer that you truly do have ALL the equipment needed for variable rate. If so, make sure it’s up to date. It’s not uncommon to think that when you ordered your equipment, you received all that is necessary to operate variable rate. You leave the dealer thinking that when the shiny new equipment is delivered in spring, we’ll be set to go. However, VRT controls can come as options on equipment, but it will not be ready to work until you’ve bundled it with the correct GPS receivers, mapping monitors, data cards, software and licenses.

If at all possible, create a checklist of what you have for GPS equipment and machinery, and take it to your dealer to make sure you are ready for spring. Last thing you want is to hit the field and find out you need another harness, a difference GPS receiver, or a new monitor program!

2. The next step is to work with your team to gather, assemble, and define your field boundaries. You need a GPS file (commonly in ESRI shapefile format) for the fields on your farm that you want to begin to precision farm with. This step might seem boring, or maybe not necessary, but a good archive of your field boundaries will save you time and headache in the long run.

You have multiple ways to establish field boundaries. One way is to go around the perimeter of your field with a GPS receiver and recording device. Another is to use your equipment data maps, such as spray maps or yield maps, and a common GIS software program to draw the perimeter around the maps you’ve already recorded in a previous year. A third method is to use a service such as Google Earth to draw around your field image, export and convert the file, and make it usable for ag equipment. This method may not be as accurate depending on the date of the image in Google Earth, and the conversion steps take some advanced skills. The last method would be to select the options in your equipment to record your boundary file as you drive your outer headland in your first pass around the field.

Everyday, I use boundaries for clipping yield maps to, finding field locations, ordering aerial and satellite imagery, and writing prescriptions. Without a digital boundary GPS file from the producer, it usually requires some extra steps and maybe a sacrifice in accuracy down the road. Spend your time in the winter establishing a good set of boundaries. It’s usually a one-time thing, and that’s why it’s good to get it done at the start.

After these first two steps, you can continue on confidently into finding out the steps, people, and tools to use that will tell you “what, where, and why” you will be using variable rate.

You can reach Warren Bills, president of GeoFarm Solutions, on his cell at 403.874.3848. Visit the website at



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