5 VRA Tips From VRA Specialist

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Variable Rate Application of Fertilizer

About a month ago we put out an article entitled, “Why Variable Rate Is Still a Tough Sell,” asserting that a combination of a lack of technology understanding and skepticism about the benefits have hampered adoption over the life of the technology.

We asked for comments and feedback, and included a reader poll to get directed response, in particular to the use of VRA nitrogen.

The responses were interesting. In the poll, 7 in 10 indicated that they knew of some farmers in their areas doing variable rate nitrogen, and of those, 4 in 10 said they knew “several” farmers using variable rate fertilizer technology for N.

Then we got some comments telling us some very compelling positive stories about variable rate adoption. So we followed up with one commenter, Larry Schonert at TSM Services (short for Total Soil Management) in Catlin, IL to tell us why he is a VRA believer.

TSM Services, Inc. was established in 1984 to assist fertilizer dealers and growers with all their agronomy needs including the comprehensive soil fertility program called Total Soil Management. The company makes fertility recommendations on more than 90 different crops and crop combinations on all soil types.

“We have seen success using VRA in our own research, and the success has been based upon the yield results we have seen from our Research Farm here in Catlin,” says Schonert. “For 18 years, from 1993 to 2010, we soil tested annually and applied fertilizer annually on individual plots to test different fertility programs available to growers today, including our own fertility program.

“In the past 2 years,” he continues, “we simplified this procedure somewhat by going to 1 acre grids, sampling annually and applying fertilizer annually while concentrating on other kinds of research.”

The results?  Schonert says the increases in yield on the 18 years of research were fairly dramatic on all fertility programs. “We believe variable-rate application is part of that equation, and therefore we have come to some conclusions that we pass on to our customers.”

Schonert shared these five key conclusions with us:

1) Soil test as often as economically possible.   “Don’t miss this important point when it comes to Variable Rate application.  We believe soil tests change too much over a 4 year period to be making accurate applications in the third to fourth year of the test.  We have soil test results over the 18 years to show how much change is possible in a short period of time.”

2) Different fertility programs make large differences.   “We spent 18 years testing different fertility programs, and some programs are better than others.  Frankly, we found that our TSM Soil Fertility program consistently out-yielded other programs by and average of 4-8 bushel over this 18 year period.

“The point is this:  are you helping the grower if you are doing a great job applying a poor fertility program?  Variable-rate application is a great thing, but a grower needs a good fertility program to make it work to the fullest.  In addition, the better the year for growing a crop, the more dramatic the yield differences were between the different fertility programs.”

3) Sample Quality Counts.  The foundation of a good variable rate program is the soil sampling.  If the sample quality is poor, then the recommendation will not be accurate.  Better and more accurate sampling have a higher cost, and there may be resistance here because of higher costs.

4) Determining Grid Size.   What should determine grid size? Is it soil variability or yield variability?  Sometimes these are one in the same, but not always.  We lean toward the yield variability in determining grid size, but obviously grower and dealer preferences play an important role also.

5) Growers Must Be Believers.   “I personally believe the main reason why variable-rate application is a tough sell is because of the mindset of different growers. If the mindset is to keep expenses low, then VRA will be a tough sell for dealers to their customers.

“Another mindset is one of perceived benefit by the growers – if what they have been doing has been profitable for them in the past, why change to something new which costs more?  We believe the research shows the benefits, and as the number of years using VRA accumulate, the benefits increase also.”

We invite you to keep the conversation going and comment here, or send an email to Paul Schrimpf with your point of view.

Schrimpf is the Group Editor for the CropLife Media Group at Meister Media Worldwide, with full editorial responsibility for CropLife, CropLife IRON, Cotton Grower and PrecisionAg Special Reports.
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