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.