  Runoff and Fertilizer Use *  Time Required Average (6-10 days)
Many people routinely use fertilizer for crops, gardens, and
lawns. What people don't know is that each time they apply
fertilizer, the fertilizer seeps through the soil into the water
table. This can eventually lead to the contamination of a local
water source, like a stream, pond, lake, bay, or ocean. This is
an especially big problem for agricultural practices that
frequently use large amounts of fertilizer on fields that are
connected by irrigation channels. The run-off of fertilizer
seeps into the irrigation channels and eventually joins with a
river or other body of water. You can do an experiment with sod
in a tray to measure the amount of fertilizer run-off. Apply
different concentrations of fertilizer in water to sod in a
plastic tray. After allowing the sod to soak in the solution,
tip the try over a bucket to collect the run-off. You can test
for the concentration of nitrogen in the run-off as a test for
how much fertilizer collecte