Rapid, in-stride soil phosphate measurement in archaeological survey: a new method tested in Loudoun County, Virginia

We report the development and field test of a modified method for soil phosphate analysis for survey archaeology. Consideration of relative, rather than absolute, phosphate levels permits the abbreviation of standard extraction techniques, while two-color spectral monitoring provides reliable values without the need for the typical 40–60 min development period. Using this technique, a soil sample may be fully analyzed for phosphate in as little as 6 min. The technique was used in the field simultaneously with a standard woodland shovel-testing survey in an effort to locate a now lost historic farmstead in northwest Loudoun County, Virginia.