By Jason Clark and Jeffrey Svdin et.al
The soil testing approach is based on identifying a critical value that separates a soil test response into zones that are deficient and sufficient. Recent studies in South Dakota have shown good relationships between relative yield, the percentage of responsive sites, and delta yield with Olsen STP. Further evaluations of what additional soil fertility, soil physical, and soil biological measurements can be included with STP are needed to improve the predictability of corn response to P fertilization. The objective of this research was to determine if the predictability of yield response to P fertilization would be improved by considering additional selected measurements of the soil biology, physical, and chemical properties.
Source : sdstate.edu