Soil Chromatography and Nitrate Leaching.

As water passes through the soil some compounds are held in the soil surface and others separate and may move quickly through the soil, leaching into the ground water. A black line drawn on filter paper and placed in water illustrates this principle. This illustration also works to explain capillary rise. For young students this is a simple demonstration of the primary colors as seen in a rainbow.

Nitrogen is a key nutrient in plant growth but all nitrogen compounds are not alike, one form is adsorbed while another leaches.  Using a simple test strip procedure, students will see if Nitrate, NO^-3, has leached through the soil and if it is found in various ground water samples.