Soil sampling is not that difficult or confusing but it is more than just getting some dirt out of your "field" be that a garden, yard, or pasture. It is the first step in determining the soil fertility (Phosphorous, Potassium, Calcium & Magnesium), soil pH and organic matter content.
A soil sample should be pulled whenever you are growing a crop on a new peice of land; like if you just bought a home and want to start a garden in the backyard. It's also the first thing to check if your plants are not growing quite right. Like if the yard doesn't seem as thick or healthy as it once was.
Soil sampling is also just smart. It's smart for at least two reasons. First, it saves money. Why spend money putting fertilizer or lime on your ground when that may not be what it needs? It is better to give the plants what they want without going overboard. Second, it protects the environment. Putting more nutrients on the soil than the plants can use (especially nitrogen) leads to the loss of nutrients through runoff and leaching which ends up polluting water and streams.
You are going to need a few supplies to pull a soil sample.
- A trowel or soil probe
- Zip-lock bag, brown paper lunch bag or bag provided by soil testing lab
- Marker or Pen
To start, label your bags with your name and contact information like phone number or address. Next, decide how many samples you want to pull. If it's a yard, you may want to pull two samples, one from the front yard and one from the back. A small garden could be one sample while a large garden or pasture may be two or more samples. (Word of advice: If there is a "good" spot and "bad" spot and you are trying to figure out whats going on you'll want to split those into two samples). If you have more than one sample, label the bags for each sample. Finally label the "crop" that it was and the "crop" it will be like "vegetables" to "vegetables" in a garden or "lawn" for a yard.
Now finally pulling the sample. Using a trowel or probe, dig a small hole to about 6 inches for vegetables or 4 inches in grass and collect that sample of dirt. Take 5 to 10 samplings of dirt depending on the size of your "field." You want a total of one cup's worth of dirt for each sample in your bag.
Finally, send or drop off your samples of dirt to a soil testing lab. Most land grant universities have soil testing labs and soil sample bags available. There are also many independent labs that can test soil.
Once the soil test results are returned you'll have a much clearer idea of what your soil needs to grow the desired plant. If you are unsure of what the results mean, take them to your extention office or home & garden center. They can give you advice about any fertilizer or lime your field may need based on your soil test. With a soil test you can be confident you are giving the plants what they need without putting excessive nutrients into the environment.