Soil tests are laboratory procedures that measure the presence and availability of vital plant nutrients in soil—phosphorus, nitrogen and potassium as well as other secondary and micronutrients among them. The tests also often measure other components or characteristics of soil, such as acidity (pH) and organic matter content.
By knowing your soil’s makeup, you can determine which (if any) fertilizers you need to apply and the proper amounts of those fertilizers to use. Knowing that will save you money—after all, there’s no need to buy unnecessary types or amounts of fertilizer—and protect the environment by avoiding runoff of excess fertilizer into water supplies. Yes, there may be some fee for the soil test (though some states provide these free of charge), but that expense is nominal, especially compared to the cost of poor soil nutrition or improper use of fertilizers.
When is the best time to test?
Soil testing can be done almost anytime of the year, though fall and early winter (before the ground freezes) can be a great time to do this so that your samples are submitted before laboratories get busy with spring gardeners. Incorporating some nutrients and amendments, such as lime and organic matter, in the fall and winter also gives those amendments plenty of time to improve the soil before spring planting begins.
How often should I test my soil?
A good strategy is to get soil analyzed every one to three years in established landscape areas, such as lawns and perennial beds, and once a year for vegetable gardens. If you plan to break ground on a new bed or landscape area, get a soil test on that land several months ahead of planting so any amendments you add will have plenty of time to improve your soil before you install the plants.
How to get the best results:
Soil sampling kits are available from Cooperative Extension offices, many land-grant or agricultural colleges and universities and some state agriculture agencies and local agribusinesses. Many testing facilities also provide further diagnostic services to identify harmful soil-borne organisms such as nematodes or pathogens.
Directions for taking and shipping soil samples are included in these kits, so follow them closely because the results are only as good as the sample.
The goal is to create a representative sample of each garden or landscape area’s soil.
To do this, use a clean trowel, spade, shovel or coring device to collect six to eight scoops of soil from different spots throughout the area. Blend these together in a clean bucket or pan to create a composite profile of the entire area.
Make sure to fill out the entire test form, including information about the types of plants you intend to grow or already are growing in that area so the recommendations can be tailored specifically for those plants’ needs
How to use your soil test results:
Depending on how busy the lab is, you should receive results and recommendations within a few weeks. Use the results to add fertilizer and other amendments to your soil and, as they are working their magic, you can feel good about the goodness of your soil.