Corn+Soybean Digest

Testing soils for ‘everything’ is a waste of money

For Minnesota soils, an analysis for organic matter, pH, phosphorus and potassium is routine for each sample. Most soil testing laboratories have the capability of conducting an analysis for nitrate-nitrogen, sulfur, magnesium, calcium and micronutrients. But you only need an analysis for these nutrients in special situations, Rehm says.

Here are some examples:

  • An analysis for copper is only important if you’re growing small grains on the organic soils of northern Minnesota.
  • Iron deficiency chlorosis is a serious problem with soybeans, but there’s no relationship between chlorosis and soil test values for iron. So there’s no purpose in analyzing soils for iron, Rehm says.
  • A response to applications of manganese has never been measured n Minnesota, Rehm says. This means you don’t need to test for manganese.
  • Except for boron in east central Minnesota, zinc is the only micronutrient of concern. But Rehm says zinc needs to be measured only in western Minnesota soils.
  • Measures of estimated nitrogen release (EMR), strong Bray or Bray-P2 phosphorus, Cation Exchange Capacity (CEC), and exchangeable cations have no value for making fertilizer recommendations in Minnesota, Rehm says. “You’re just wasting money by having an analysis for these properties,” Rehm says.
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