Harnessing the Power of VRT

  August 2011 - Issue 1
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 New knowledge aims to put more of the variable rate opportunity in farmers’ hands
There’s no doubt it’s an attractive concept. New variable rate technology (VRT) approaches have the potential to optimize nitrogen fertilizer application, seed application and even herbicide application. That means more efficiency, along with the promise of cost savings and environmental benefits

But in practice, VRT is an area where progress with the technology has been far ahead of farmers’ ability to put it to good use.

The equipment, for most part, is there to perform a range of variable rate applications. But often the solid depth of field specific information needed to make prescription maps for it is lacking. At the same time, there’s a knowledge gap where many producers are in the early stages of learning about VRT and haven’t seen a whole lot of data to give them a clear idea of the best approaches and the economics potential those approaches represent. Now new efforts on several fronts in Alberta are aiming to help fill those gaps What they all share is an on-the-ground focus.

“The high tech side of VRT approaches is one thing,” says project engineer Mike Bevans of the Alberta Agriculture and Rural Development (ARD) AgTech Centre in Lethbridge. “But the other part is a thorough understanding of the land where you plan to use it. That means getting down to the soil level and understanding all the factors involved, including responses under different environmental conditions. The more information you can get, the better your opportunity for success.”

The precision approach
More farmers are becoming familiar with the basics of VRT, which is a particular way of applying the core technology of precision farming to manage variability in fields In practice, this is essentially a process of applying different rates of inputs to different areas of a field with a goal to optimize those applications for benefits such as lower costs, better yields, environmental advantages and overall higher returns.

In practical terms, VRT is typically accomplished by developing a prescription map for a particular field transferring the map information to a controller in the cab of the vehicle, and driving the field The controller changes the application rate based on the prescription map, and records how much was applied where. Some more advanced VRT approaches can also be done on-the-fl, using sensors that measure what is needed by the crop and adjust the rate accordingly in real time.

Prescription maps often break fields into to 5 to 10 management zones, based on soil tests, topography, aerial photos, previous yields and other factors, depending on the technology and information available. To help evaluate the effectiveness of VRT approaches and collect data for use in future years, yields are typically measured in each zone and a check strip, using combine yield monitoring and GPS systems.

Managing variability in field
Indications are that precision farming and VRT are growing steadily in adoption for use in seeding and fertilizer application. There is also potential to use VRT for spraying though there are hurdles to overcome for this option to become more viable. For all three options, many see VRT approaches gradually becoming more common.

“There’s anecdotal evidence that VRT is working in the right situations,” says Bevans. “However, it is a difficult area to evaluate because there’s simply not a lot of information out there on the methodologies involved. Most producers who are doing this are working directly with companies and it seems that everyone is approaching it a little differently.”

For example, some producers will base their approach solely off yield maps, while some will go off satellite imagery and some will go off soil sampling. “It may be that there’s lots of different ways to get good results. But we haven’t seen a lot of data to show the best approaches for different situations.”

Records anchor success
More information and data is expected to gradually emerge, including through ongoing field studies by ARD and partners. In the meantime, Bevans advises a cautious, hands-on, eyes-open approach for farmers who are testing the waters.

Like in so many areas of farming today, one of the most critical things is to have good records – the more years and more detail they cover, the better, he says. “When you try a VRT approach, it’s important to have the ability to compare what was done and the results from the period before the practice change to the period after the practice change. Records are the only way to do that. Otherwise, when you see a result such as higher yield, you don’t know if it was due to VRT or some other factor. Good records also help you have a better prescription map that is likely to be more effective.”

The producer needs to keep meticulous records of yields, inputs and a number of related key factors, to really be able to make a good decision, he says. “It’s the only way to answer the question, ‘Is VRT worth it for my field? Don’t simply take someone else’s word for it. Keep the knowledge and the management decisions in your hands.”
For more information about the content of this document, contact Nicole Huggins-Rawlins.
This information published to the web on October 28, 2011.
Last Reviewed/Revised on October 31, 2011.