Assessing Soil Phosphorus for Crop Production by Soil Testing

Abstract

Soil testing began in the mid-19th century as theories about how plants grow and the science of soil chemistry were developing. Over the ensuing century, soil testing to assess soil phosphorus (P) for crop production slowly evolved as modern agronomy and soil science developed. Soil testing is a process that involves sampling, extraction and analysis, interpretation of the results, and making a fertility recommendation. Proper understanding of soils where a test will be used and the chemistry of P in these soils is critical for developing or selecting an appropriate P soil test extractant for use by a soil testing lab. To make use of the information provided by the amount of P extracted by a given extractant, under a given set of conditions, one must know the relationship between the amount of a nutrient extracted and expected crop response for each crop under the conditions in the field where the test will be used.