How to Collect a Soil Sample

on January 14, 2012

Soil samples are very useful when trying to determine the quantity and quality of nutrients in your soil. The University of Connecticut Soil Nutrient Analysis Laboratory tests soil for plant nutrients, lead, pH and soil nitrate. When you know what nutrients your soil is lacking or has an abundance of, you can better care for the plants you are growing. It is also value conscious, as you can target soil additives without wasting a penny on unnecessary nutrients.

What you’ll need. The materials and tools for soil sampling are straightforward and easy to find.

  • Professionals will probably use a special soil auger, but a spade will do just fine.
  • A bucket for mixing the soil samples together. Plastic is lightweight and non-contaminating.
  • A large zip-top plastic bag for containing and transferring the final soil sample. Some places like the Soil, Water and Forage Testing Laboratory at Texas A&M will provide you with a soil sample bag.

Soil sampling technique. Follow these steps to collect your soil sample.

  • Since the soil sample results are only as good as the samples you take, it’s best to err on the side of more samples rather than less. Most homeowners will need about five soil samples. Large areas and farms will use about 10 samples per 100 square meters of growing area.
  • Select samples from a variety of zones in order to fully represent the areas that you cultivate. Turf, vegetable gardens and shrubbery will all have a unique soil content.
  • Dig a hole about 6 inches deep and slice about 2 inches thick into the soil. You may need to remove plant material and rocks. Remember, you are trying to measure the nutrients that the plant will be growing in.
  • Set the soil sample aside.
  • Repeat the process, as you will need soil from a number of areas.
  • Once you have all the samples, mix them together in a bucket.
  • When the soil is thoroughly combined, remove 2 cups and place in a zip-top plastic bag.
  • Take the soil (or mail the soil) to a soil testing lab, such as your local agricultural university or garden center, for analysis. You may be requested to fill out a soil sample form.

Soil sampling tips. Be sure to use clean equipment. Soil sample tools that have fertilizer, salt or other compounds will render your results inaccurate and you’ll waste your time and money. Use the correct material tools. Avoid galvanized steel since the zinc coating will throw off the results. While it may not be necessary, Clemson University Ag Service Lab recommends air drying the soil on a newspaper and crumbling it before filling the soil bag.

Found in: Gardening