Balancing Soil Nutrient Levels in Agriculture
Soil tests provide some great information to producers and consultants. They ususally include such things as pH, buffer pH, and CEC along with nutrient levels like Phosphorus (P) and Potassium (K). Some agronomists and producers look at the pH and then ignore everything else except for the recommendations based on yield. This might not be the best strategy for long term soil health.
There are some people who advocate looking at the relative proportions of the cations (Hydrogen, Calcium, Potassium, Sodium, Magnesium) in the soil and trying to achieve a balanced level of fertility. This would be equivalent to achieving a balanced livestock ration or human diet.
A Virginia website which talks more about cation balancing can be found here: www.vabf.org/soilre1.php . I think the author makes two very important points in the conclusion:
1) A foliar or tissue test will show what the plant is actually using. This may be different than what a soil test indicates.
2) There is no substitute for the knowledge that a farmer has about the land he is managing.