Soil Testing: How to Collect Soil Samples at Home


Hi, I’m Matt Fryer, Soils Instructor for the
University of Arkansas System Division of Agriculture and today I’d like to talk to you about
how to properly take and the importance of taking an accurate soil sample. Regardless of if you’re trying to grow a beautiful yard or tomatoes in the garden, taking an
accurate soil sample is the only way to truly know your soil
nutrient status and pH. To get the most representative results for your
landscape, it is key to correctly take a soil sample. To take a soil sample, the equipment you
need includes a soil probe, a clean plastic bucket, and a clean container. That container can be a soil box that you
get from your County Extension Office or a zip-top bag. If a soil probe is not available, a soil spade
can be used to take the sample, but know that it’s more difficult
to get a representative soil core. The first step is to divide your landscape into sections based on the plants being grown and the visual performance of those plants. So if part
of your yard is growing more poorly than another you would sample those two areas separately. For example, you’ll want to collect separate soil samples from your vegetable garden, lawn, and shrubs because each area will probably have different soil properties, and therefore different lime and fertilizer needs. Next, starting at one end of your sampling area, remove any organic matter or debris like mulch or rocks from the soil surface. If you’re using a soil probe, insert it into the ground at the recommended depth, give it a quarter of a turn, and
remove the core from the ground. As I said earlier, you can use a spade to take a soil sample, but be careful to take a uniform depth and column shape. Soil nutrient concentrations are typically higher at
the soil surface and decrease as you go down the soil profile. So samples collected with a spade may overestimate
soil fertility because the wedge shaped sample tends to over-represent the
surface soil and underrepresent the bottom soil depth. Just like using any tool to take a soil sample, you want to remove the organic matter from the soil surface. Now, when using a spade you want
to take the wedge out of the ground and use a pocket knife to cut a uniform column at the correct depth for your soil sample. Now this is pretty difficult and usually not very pretty, so we always recommend using a soil probe. Deposit your soil core into the bucket and repeat this process ten to fifteen times in a zig-zag pattern across the landscape. Soil nutrients can vary across the landscape, so it’s important to obtain soil cores that are representative of the entire sampling area. The ideal soil core depth will be dependent on what you’re growing in the soil. For lawns and permanent landscaping, the soil sample core should be collected from the top four inches For gardens, soil samples should be
collected for the top six inches of soil. For mature fruit trees, aim for a depth of
about six inches also. Once all soil cores for a sample area
are collected, break them up, mix them together, remove any rocks or organic material by hand, and fill the soil
box or zip-top bag with one pint of soil. Be sure to label each of your samples to
keep track of which area in your landscape they were collected. If the soil is too dry to get a uniform sample
or too wet to break up the soil cores wait until conditions improve to take your soil sample. Samples should be collected every two to three years. Ideally, they should be collected from
late fall to early spring in the dormant season, and samples should be taken at
the same time each year you sample. Finally, always take soil samples before
adding any fertilizer or organic amendments. Thanks to the Arkansas Fertilizer Tonnage Program, the University of Arkansas System Division
of Agriculture offers soil testing services to Arkansas residents for free.
To take advantage of this free service, bring your samples to your local County
Extension Office and they’ll be happy to walk you through the process. Once soil testing is complete, you will receive a soil test report with information about
your soil’s pH and nutrient availability. It also contains specific fertilizer
and/or lime recommendations. With this information you can make informed decisions about your soil and
help your landscape flourish. If you have any questions about
how to collect soil samples, or if you need any help understanding
your soil report, please contact your local County Extension
agent or visit uaex.edu.

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