One example given was a 20% reduction of all fertility products they normally purchase. Here is why you most likely don’t want to make your cuts in that particular fashion.

Think about the very best, highest-yielding 10% of your farm. You likely have spots in some of your fields where the yields are off the charts. Unfortunately, when you remove lots of bushels from those areas, you also deplete the soil’s fertility far faster than anywhere else on your farm.

IF YOU WERE TO RUN A PROFIT AND LOSS STATEMENT ON EACH INDIVIDUAL ACRE OF YOUR OPERATION, I’LL BET THOSE HIGH-YIELDING AREAS ARE MAKING YOU REALLY GOOD MONEY.

Now I ask you, is it wise to cut the fertilizer application in the zones where you’ve got lots of profit AND where you just removed a crazy amount of fertilizer? If you do, your yields will likely go down in those places, and your profits will be reduced, as well.

ON THE OTHER HAND, IF YOU ALREADY HAVE ENOUGH N, P, OR K TO MEET YOUR YIELD GOAL IN CERTAIN SPOTS IN YOUR FIELDS, WHY SHOULD YOU ADD MORE?

Where I’m going with all this is we believe the most efficient way to make cuts is to vary your fertilizer rates through each field. That is not only a wise agronomic and economic move, but it is the most environmentally responsible way to apply crop nutrients.

ALL THIS SOUNDS GREAT, BUT WHAT TARGETS SHOULD YOU BE SHOOTING FOR?

BELOW ARE 3 DIFFERENT OPTIONS FOR YOU TO CONSIDER, AND I’LL SHARE HOW WE DO THINGS ON OUR FARM.

We use an inexpensive software program called VRAFY to replace fertility we’ve removed last year or the last two years, depending on how often we spread fertilizer. VRAFY takes your yield map from last year (or the last two years) and simply runs calculations on nutrient removal based on yield. Then, it creates a variable-rate prescription map that easily imports into pretty much any brand of equipment. It’s simple, and this program allows you to maintain fertility levels over a period of years. More fertilizer is applied where yields have been higher, and less fertilizer is spread where yields have been lower.

USING MEHLICH 3 ANALYSIS, WE ARE SHOOTING FOR THESE LEVELS IN MANY FIELDS: 100 PPM P, 4% BASE SATURATION K, 8:1 P:ZN, 30:1 P:CU, AND 1000:1 CA:B. We use the VRAFY software to create variable rate maps to get every area up to these levels in the fields where we use this method. We then run the scripts in our floater, planter, or sprayer, depending on if we are applying dry or liquid fertilizer.

While this is the most complicated method, it’s also probably the best. First, we create a “Potential Yield Map” in the spring. This is based on past history, but we can tweak it if necessary. In VRAFY, it takes just a few seconds to create, and we have been impressed with the accuracy. To that, we add in our soil test data with carryover nitrogen and organic matter, since more nitrogen is released in soil where there is more organic matter. You can add more N to the formula if you are in high carbon residue (think corn on corn) or if you are worried about loss. In our very heavy soils, we can apply quite a bit of nitrogen safely, so loss is usually minimal. At the bottom of this page is an example of a map and a script we created for one field last spring. Note how we varied the applied urea rate from 196 pounds all the way up to 562 pounds!! Think of the savings in the poor areas and where organic matter was high.

Varying micronutrients is just as easy as varying rates of macronutrients. With the floater we use on our farm, we have a “micro” bin. Last spring, for example, we had zinc sulfate in there, so we were applying phosphorus and urea from the big bins and zinc sulfate from the small bin, all at varying rates as we crossed the field. Best of all, the machine does all the work. The operator just drives.

IF YOU’VE NEVER DONE ANY OF THE THINGS I LISTED HERE, I’M GUESSING YOU MAY BE A LITTLE NERVOUS TO JUMP INTO SOMETHING DIFFERENT…

On our farm, we had never done any of these things a few years ago, but we stepped into them slowly, and now we’re 100% comfortable with everything I listed.

Applying different rates of fertilizer as you cross the field has enormous benefits, and especially in a year like this one where everyone is trying to spend their money as wisely as possible, I can’t say enough good things about the VRAFY software we’re using and the variable rate technology in today’s equipment. It’s awesome!

*Organic matter, residual nitrate, and yield potential are all figured into these types of applications.

For more information about how to get started on your farm, go to VRAFY.com or visit with your Hefty Agronomist.