Thursday, May 16, 2013

Variable Rate Fertilizer

Someone asked my opinion of variable rate fertilizing this morning on Crop Talk. 

We basically do not use it here technology wise.  I know the technology is available and some swear by it but the few that use it often swear at it, especially when it doesn't work.

The appeal is great if you have variable soils across your field.  I hear $50 per acre for grid sampling and the equipment or fees to use and apply variable rates.  It sounds great to use less fertilizer, especially nitrate.  The SAP test results at Farm to Plate made me think how we generally over apply nitrate fertilizer to our crops and under apply the other 16 nutrients.  I am more concerned with nutrient balance to produce nutrient dense crops than I am to cut fertilizer rates using variable rate technology.

Years ago I saw how the Soil Doctor saved the Reed Farm in Washington Iowa tons of money by cutting nitrogen rates while increasing crop yields across the field.  The nitrogen application varied from 0-100 lbs of side dressed nitrogen across their fields while the yield monitor stayed much more constant during harvest.  I wish I had a rig with Greenseeker on it right now to touch up my wheat.  I have a few yellow spots.

$50 per acre will buy a lot of lime and fertilizer year to year.  I have had better results focusing on soil biology then cutting rates of fertilizer to save money while trying to produce the same or better yield.  I don't see better yields with less fertilizer, just less cost.

The algorithm can be set up based on nutrient removal, past history and a host of variables.  Which one do you choose?  If we had really good field history records, I believe we could use variable rates as well as any other method.  If the grid or harvest sample is flawed, then the algorithm is faulty.  I see this too often.

The Adapt-N program is very interesting to focus on managing one of the most important yield driving nutrients and that is nitrogen.  Dr. Michael McNeil showed us very interesting results of how the project is helping manage nitrogen usage by careful application of the nutrient when needed in Iowa and New York.

To the original poster, if you want to go this route, set your plan up carefully.  Get the help of experienced minds who have worked with it the last 10 years.  I work with professionals who can help you if need help.   I can't find that at the co-op or any local location.  It's going to take a lot of leg work and brain work but it can be done.

I am focusing more on the trinity of soil physics, chemistry and biology so one leg of the stool is not shorter than the other two.  I am also focusing on the trinity of calcium, sulfur and nitrate as a yield and profit driving leader on my farm and the farms I work with.

How can you use variable rate fertilizer programs to increase profit on your farm?

Ed Winkle


  1. tom schuffeneckerMay 16, 2013 at 9:52 AM

    ed , with my proximity to lake erie and the algae bloom , it is something that is being asked of us to try. just started on some acres this year. will see what happens. more every day in the news on the lake. it is a great natural resource , but so is our soil. some tradeoff has to happen

  2. I could see where the numbers would satsify the government, they need to quanitfy everything. I have seen the numbers but am more interested in the results. I have not seen solid, substantial results unless you are just looking for more even fields and less product used. If it does maximize the farmers profit while meeting their goals, I am all for it.


  3. Nice one, asking all farmers to try this expensive stuff even if it does not apply to your fields. Or is it subsidized by the EDF? What about asking agronomists to come up with a fertilizer that does not leach, or working on the most polluting waterways first, like the Maumee, introducing natural filtering barriers to consume the extra fertilizer before it reaches Lake Erie?

    Lake Erie algae bloom:

  4. I'm going to finally post, Ed. If variable rate is used to even out the soil numbers, you are probably kidding yourself. If you are VR to max production in those areas capable of producing more, then it may be worth it.

    Tonight I am in the process of recommending VR Lime for a field then recommending a constant rate of potash for that same field. The potash levels are a bit on the low side, but not even. Sulfur is VL, and so is Boron. In order to build some Potash levels while getting the boron and sulfur that I want, I'll constant the product. Too many fertilizer plants around here only have the ability to vary one product at a time. Some have the ability to vary up to 4 at a time. That gives one a little more freedom to play with the issue.

    I have no issue with saving money by VRing, but ultimately I want to raise the most possible while being reasonably environmental, and economical.

    Bill Moyer

  5. Thank you for posting Bill! Long time no see! I will never forget when you came down to Waynesville and stayed in the hotel there just to meet me! And, the famous Moyer's Winery in Manchester, that was a good day.

    We are on the same page on this idea. As to your situation, I don't know anyone varying more than one nutrient at a time around here though I may be wrong.

    I have concentrated on the big picture of soil health and nutrient balancing from that picture I don't even think or stay in contact with it much.

    The people I talk to want to see fields that look and perform like healthy fields. There is so much to do before you get to variable rate it's kind of like notill. Buying a John Deere notill drill and starting notilling is one thing but building a farm up from the bottom with a 5, 10, 20 year plan is a whole different thing.

    Thank you, Bill.

    Ed Winkle

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