Test garden soil for arsenic

• 1). Map out several areas in your garden to test. The King County (Washington) Health Department suggests avoiding areas that are within 6 feet of a building or that have recently had fresh soil added--these areas will not yield accurate results because of disruptions to the soil. Mark the areas you have selected to test on a sheet of paper; assign a code or label for each test area. Write the labels for each area on separate strips of paper.
  
  
• 2). Clear away any grass, weeds or plants from the spots you selected to test. The King County Health Department recommends clearing a space up to 4 inches in diameter and removing the top 2 inches of soil. Take four to eight ounces of soil (about a cup) for the sample and place it in a zippered plastic bag. Place the sealed bag and its label into a second bag and seal it.
  
  
• 3). Send the sample to a lab for testing. Private testing labs, county extension offices and state university agricultural departments will test soil for arsenic; fees vary depending on the lab, and each lab will have specific instructions for packing and shipping the sample. For example, Soil and Plant Laboratory in southern California has printable forms to complete and pack with the bagged soil sample.