Soil Test, Don’t Fertilize or Lime Without It

May, 2015
Bridget Stice, UF/IFAS Extension Agent, Polk County

It is that time of year when we need to be thinking about, if we haven’t already, our fertilizer plan for this growing season.  How do you decide what to fertilize with?  Do you ask your neighbor/fellow rancher?  Do you get a recommendation from your fertilizer dealer? Or, do you just do what you have always done?  Hopefully whatever you do involves a soil test.

The purpose of applying fertilizer and lime is to optimize forage production.  Plants require 17 essential nutrients for growth.  If they are lacking in one or more of these nutrients, the plant will only perform to the level of the nutrient that is most lacking.  Fertilizer is intended to supply the nutrients that are lacking.  Liming is mainly intended to increase soil pH to the target pH for that crop.  Soil pH affects the solubility of plant nutrients.  When soils are at the target pH, plant nutrients in the soil are more readily available for the plant to uptake.

UF/IFAS Extension recommends testing your soil in fall/early winter at least once every three years.  If not testing through the UF/IFAS Soils Lab, we recommend having your test completed at a lab that uses either Mehlich 1 or Mehlich 3 extraction methods.  UF/IFAS fertilizer recommendations are based from these methods.  Soil test results from the UF/IFAS Soils Lab include fertilizer recommendations, which make interpretation a little easier.  Fertilizer recommendations will be made based on your forage crop and your soil test results.

If soil pH is too acidic (below the target pH for a specified forage crop), as is common in Florida soils, then a lime application is recommended.  Most liming materials have little immediate effect on soil pH.  Therefore, it is necessary to apply lime 3-6 months prior to the growing season, thus testing in late fall/early winter.  Applying lime without a soil test may result in under or over liming which not only is a waste of your fertilizer dollar, but may negatively affect forage production.

Hopefully by this time of year (March) your soil pH is where it needs to be.  So now we have to figure out what kind of fertilizer you need to apply to supply those essential plant nutrients and optimize forage production.  So deciding how to fertilize should be a little easier with a soil test.  Fertilizing without a soil test may result in under or over fertilizing.  Both of which waste your fertilizer dollar as a result of poor forage production or paying for fertilizer that isn’t needed.

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