All in Soil

November in the Lab: Extractable nutrients, or what color is it?

Phosphorus and nitrogen are essential for plants, but can become pollutants in high concentrations, so I am measuring levels in the soil in my study sites. In this series of analyses, I am using the color of chemical reactions to measure the concentration of nitrogen and phosphorus in soil. In the analysis, I compare the color of my samples to the color of samples of known concentration using a spectrometer. This analysis shows a convoluted and ingenious way that someone came up with to measure these very low concentrations of elements.