Lloyd Murdock, Extension Soil Scientist, University of Kentucky
There are two concepts for making fertilizer recommendations. Both take the same soil test but they usually result in two very different fertilizer recommendations. One is the Sufficiency concept and the other is the Cation Saturation Ratio (CSR).
The Sufficiency concept is based on local or regional research on similar soil types that find a level of each plant nutrient resulting in maximum yield. When a soil test is below this Sufficiency level, crops respond to the addition of the nutrients.
The CSR was developed in the 1940’s to create an ideal balance of calcium (Ca), magnesium (Mg) and potassium (K) that would result in maximum crop yields.
There are two concepts for making fertilizer recommendations. Both take the same soil test but they usually result in two very different fertilizer recommendations. One is the Sufficiency concept and the other is the Cation Saturation Ratio (CSR).
The Sufficiency concept is based on local or regional research on similar soil types that find a level of each plant nutrient resulting in maximum yield. When a soil test is below this Sufficiency level, crops respond to the addition of the nutrients.
The CSR was developed in the 1940’s to create an ideal balance of calcium (Ca), magnesium (Mg) and potassium (K) that would result in maximum crop yields.
