by Rick Blanke, CPSSc
Certified Professional Soil Scientist
Resource Specialist, King Conservation District

It is highly recommended that land owners sample and test their soils regularly. Regardless if you are growing forage for livestock, gardening, have an orchard, or are growing trees for wood production, proper soil sampling will save you valuable time, money, and resources by:

• having you apply only the amount of fertilizers actually needed by the plants you are growing.
• protecting surface and ground waters from contamination by runoff and leaching of excess fertilizers.
• ensuring that soil nutrients and other conditions (such as soil acidity) affecting plant growth are present in the right amounts. This results in increased plant growth and higher quality plants being grown. This may result in you having to purchase less feed or in having higher fruit, vegetable, or tree yields.
• helping you use manure on your pastures, lawns, and gardens, decreasing or eliminating the amount of fertilizer you need to purchase, and decreasing problems with manure storage and disposal.

Your samples have to be representative of your fields to get good results which you can use. Avoid sampling when soils are very wet such as Winter and early Spring as this makes taking a good sample difficult. Don’t sample within a few weeks after applying lime, fertilizer, and compost (or aged manure).

You should separately sample areas with differences in soil textures (i.e. clay, sand, silt, gravel, muck), topography, drainage, color, productivity, and past management practices or where plant growth is poor. To make sure that your samples are representative, take a number of small samples (called subsamples) from each field which you want to test. You can use the following guidelines for the number of subsamples to take:

TYPE OF CROP	NO. OF SUBSAMPLES	SAMPLING DEPTH
Established Lawns and Pastures	10 or More	Top 3 to 4 Inches
New Lawns and Pastures	10 or More	Top 6 Inches
Gardens	10 or More	Top 6 to 8 Inches
Trees and Shrubs	6 or More	Top 8 to 10 Inches
Commercial Crops	12 or More	Top 8 Inches

You will need a spade or spoon (stainless steel or wood), a clean plastic container, and a sampling bag and order form from a soil testing lab. Take thin slices of soils to the right depths areas as indicated in the table above and put them in the container. Thoroughly mix the subsamples and put two cups of soil into the sampling bag.

Label the sampling bag, fill out the form with the information requested, and mail the sample to the lab. The lab will send back the results and will usually furnish recommendations for the amounts of fertilizers and lime to add for you to reach your production goals.

It is recommended that you test your soils for nitrogen (sometimes called nitrate-nitrogen), phosphorus, and potassium every 1 to 2 years. Test for lime ( sometimes called pH or soil acidity) every 2 to 3 years and for micronutrients every 5 years.