By Brian Hefty

Some people talk about VRT, Variable Rate Technology.  I like to talk about VRE, Variable Rate Everything.  Here’s what I mean.  Whenever possible, consider using variable rate fertility, variable rate lime, variable rate seeding, and anything else you can variable rate.

The reason why I’m so interested in this is if you have bad areas of fields, why waste your money there on high seeding rates or high fertility?  Just as importantly, if you have a poor yielding area that simply needs an extra dose of a certain nutrient, why not give it what it needs?  Another way to look at this is in a high-yielding area, maybe you already have extremely high levels of a certain nutrient, so why throw more out there?

For example, let’s say you have a sand strip running through a field of good soil.  Your yield goal in the sand may be 130 bushel corn, and your yield goal in the good soil may be 200.  If you overapply nitrogen in the bad area, what happens to the 50 or 75 pounds of extra N you applied?  First, you wasted money.  Second, the nitrogen converts to nitrate and leaches, creating a potential environmental issue.  Third, much of that nitrate will convert to nitric acid, stripping out calcium and lowering your soil pH.  What that may mean is you may have to lime to raise your soil pH back up.  That’s 3 bad things, all of which could be prevented.

Here are the two big concerns with variable rate that most farmers tell me:

  1. I can’t do it because I don’t have the technology.
  2. I can’t make my own variable rate maps.


Chances are you already have a nice monitor with the capability to control a variable rate tool.  Most planters today come equipped to seed at varying rates.  You can buy a dry fertilizer spreader and equip it with variable rate technology for not much money.  If you already have a spreader it will probably only cost you $2000 to $4000 to convert that over for variable rate.  On our farm, we have set up many pieces for variable rate including our planter, our dry fertilizer spreader, our sprayer, our strip-till machine, and our anhydrous applicator.  The payback comes quick when you have areas in fields where you can cut rates significantly.


I don’t care what type of map it is – fertilizer, seeding, or anything else – this is not a complicated process.  On the soils side you can use the website to create variable rate fertilizer maps AND CONTROLLER FILES for free.  We have used SMS software to make our planting maps, but there are many other software systems you can use.  We base our fertility maps on our soil tests.  We base our planting maps typically on previous yield maps, but you could certainly use soil type maps or something else if you want.

In summary, using variable rate applications for a variety of things on the farm makes a lot of sense, and it can save/make you lots of money.  Take a look at it for your farm this spring and in the future.