Soil Sampling Basics

   Spring has sprung, and folks I visit with are getting tired of cold windy weather and feeding hay. They are longing for warm days and green grass. But in order to have that green grass, it has to be fed by your soil. I thought it would be good to review the basics and remind folks how easy (and cheap!) it is to get a soil test.
   It is very unwise to fertilize or lime pastures without a soil sample. There is absolutely no way to know the pH or nutrient levels in a soil without an analysis. There are some indicators of problems, such as the presence of certain weeds or poor crop performance, but these weeds and symptoms can have a variety of causes, and liming or fertilizing without a soil test can make the problem worse. Also, if you fertilize without a soil sample, you could be applying nutrients that your pasture does not need, which is a waste of money and even a potential natural resource concern.
   First of all, soil sample boxes and forms can usually be found at your Extension office. Visit ces.ncsu.edu and click on "Locate Your County Center" to find your local office. While you're there getting sample boxes, check and see if the office can ship your samples to the lab in Raleigh; most Extension offices are able to do this. Sample boxes are free, and routine soil samples are also free for NC residents.
   Then, collect your tools for sampling. You will need a plastic bucket, and some sort of tool to collect the soil. A soil probe is quick and easy, but not completely necessary. You can use a trowel or small shovel.
   Select areas to sample that have similar soil characteristics. If the soil profile changes across a field, or if there is a slope and a flat bottom area in the same pasture, you may want to sample them separately. A good rule of thumb is that if an area is significantly different for some reason, and it's big enough to manage separately, then you should sample it separately. Also, keep in mind that you have to assign a crop code to each sample, such as bermudagrass, fescue or pearl millet, and the recommendations you get back from the lab will be for that specific crop. So always sample separately for different crops.
   In each sample area, collect 15-20 cores or small subsamples from random spots throughout the sample area. Place all of these small subsamples into your bucket. Avoid areas that would have a significantly different nutrient profile, like an old burn pile, or the spot where the round bale feeder sat all winter, etc. This could skew your results. In an established pasture, you want to sample down to just about four inches. When you are done, thoroughly mix the soil in the bucket, write your information on the sample box (TIP-it's very difficult to write on the box once you assemble it!) and fill the box.
    The NC Department of Agriculture & Consumer Services analyzes soils at their Agronomic Lab in Raleigh. Sample turnaround time can be quite long in late fall and through winter, up to nine weeks in some instances. By March, this turnaround time is decreasing to 2-4 weeks.
   Here are some NCDA&CS links of interest regarding soil sampling.

The first is Soil Sampling Basics

Also, check out Fertilization of Forage and Pasture Crops

And the Soil Test FAQ's