By Darren Hefty

My dad always told us growing up that applying a little extra Phosphorus or Potassium fertilizer was no big deal because it didn’t leach in our soils and we may need it for some future crop.  Both of those things are true.  We have two big cautions about any Phosphorus application, though:

  1. Phosphorus left on the soil surface or lightly tilled in is susceptible to loss through wind or water erosion.  Placing it deep in the soil (8 to 10 inches) is the best practice to protect yourself from Phosphorus loss.
  2. Phosphorus is often tied up and rendered unavailable in your soil within days or weeks of application.  At high pH levels (above 7.3), Calcium combines chemically with Phosphorus, making an insoluble compound that crops cannot access.  In lower pH soils (below 6.3), Iron and Aluminum often tie up Phosphorus and form insoluble compounds.

There are several ways to protect your Phosphorus applications from soil tie-up.  Here are some that we use on our farm.

  1. Banding – by banding fertilizer, you keep it concentrated.  Broadcasting spreads it out allowing tie-up to happen much more quickly.
  2. AVAIL – we’ve been using Avail for years.  On our farm and many others it has been working well to protect Phosphorus from tie up, allowing more of it to enter the crop and help yields.
  3. Pro-Germinator – this is a liquid fertilizer that uses flavonols (organic proteins) to protect Phosphorus from tie-up.  Pro-Germinator is also one of the lowest salt phosphorus fertilizers you’ll find and has shown exceptional safety when applied in-furrow to crops like corn.
  4. QuickRoots – this is a biological seed treatment labeled for most crops.  While the roots of your crop release organic acids into the soil to promote nutrient availability, QuickRoots creates enzymatic activity and expanded root volume so plants can recover more soil Phosphorus.  We’ve seen excellent yield gains with QuickRoots for nearly a decade on thousands of farms.
  5. New products – the makers of QuickRoots have a new compound that is yet to be named.  It contains mycorrhizae fungi that have been proven for decades to naturally bring Phosphorus into plants.  While they are naturally occurring in soils, there are several things researchers have learned to provide higher numbers of them in close proximity to roots and also to provide a signal to trigger the fungi to activate.   We tried this new compound on our farm this summer and saw good gains on soybeans and corn.  This summer, they were calling it Pat 1, but it will have a new name soon and should be available for you to try on your farm by the spring of 2013.

The amount of Phosphorus fertilizer your crop needs varies greatly based on your crop and yield level.  Check out the free Ag PhD Fertilizer Removal App on the iTunes App Store or visit the Resources tab at for a list of nutrient needs by crop.