By Brian Hefty –

How would you react if you learned that you spent $500,000 on fertilizer on your farm this year, yet only $300,000 of it actually got used by your crops this year?

In 2006, we were digging some root pits in July on our farm for a field day we were hosting.  We were digging down about 5 feet in the ground to show things like compaction, root growth, soil type changes and more.  One thing we weren’t planning to find, but did, was dry fertilizer granules (MAP and potash) left from the previous fall when we had strip-tilled.  With strip-till, we place P & K down about 10 inches in the soil.  We like that because our top 6” of soil have lots of fertility already, so it’s a way to build up our subsoil where we often find lots of roots.

If you remember 2006, it was an abnormally dry year, at least up until about August 1.  We simply didn’t get enough moisture down to 10” deep to break down the MAP or potash.  Obviously, we had poor uptake, at least that season, of the P & K we had applied.

Another issue we often see is even with moisture, certain dry fertilizers simply don’t break down very well.  Potash, for example, is basically a rock.  How quickly does rock break down?

A third problem is when other nutrients in the soil can “tie-up” applied fertilizer.  For example, phosphorus can easily bind with excess calcium in the soil to form calcium phosphate.  Calcium phosphate is insoluble in water and won’t get absorbed by plants.

Another common issue is when soil is overloaded with one nutrient and another nutrient can’t get in.  There are lots of different situations when this can happen, but a common one is where a soil has excess phosphorus.  Even if you apply some zinc, that zinc may not get into the plant if zinc and phosphorus aren’t “in balance” in your soil.  The reverse could be true, as well, if your soil had excessive zinc.  That would prevent at least some of your phosphorus from getting into the plant.

On our farm, we’ve done a long-term study on several fields, applying only what we expect our crop to remove (grain only) in strip-till (or a band of any sort) vs. applying 50% more P & K in broadcast.  After doing this for over 10 years, we’ve gained no yield where we have applied 50% more P & K each year.  What that tells me is all the university studies that show better uptake and fertilizer efficiency when fertilizer is banded are correct.  One of the reasons that may be is that roots can only explore a certain percentage of soil.  If your fertilizer is placed where roots will grow, you’ve got a better chance for uptake.

I ran through all those examples so you could see how difficult it may be for your fertilizer to get into your crop.  If you own the ground and have 20 years to extract your fertilizer, this isn’t as big a deal…other than higher short-term fertilizer costs.  If you may only farm a piece of land for a year or two, this is a much bigger concern.  If you want the best fertilizer uptake and efficiency possible, here are my top 7 suggestions:

  1. Band your fertilizer.  This will place it where your crop is more likely to recover it this year, and having a concentrated band reduces tie-up.
  2. Try to get your soil pH in the 6.3 to 7.3 range.  In high or low pH soils, tie-up is increased.
  3. Use at least some liquid fertilizer.  Liquid fertilizer is available more quickly than dry fertilizer.
  4. Try some Avail to help prevent P tie-up.  Try a nitrogen stabilizer to reduce N loss.
  5. Try to keep your soil’s fertility in balance.  Don’t overload your soil with any 1 nutrient.  Get some complete soil testing done and let us know if you need help interpreting the data.
  6. Pray for rain.  Sufficient soil moisture will allow your fertilizer to be in soil solution and have better uptake.
  7. Do everything else needed to raise a great crop.  For example, if you don’t control your seed and seedling diseases, your crop won’t bring in as many nutrients.  If your farm has poor drainage, your crop’s roots will die off and not bring fertilizer in.  If insects are allowed to feed on your crop, it won’t use as much fertilizer, etc.

You are probably investing hundreds of thousands of dollars, if not millions of dollars, each year on fertilizer.  Why not get more of that into your crop this year instead of potentially some year in the future?