“To every thing there is a season.” And fall is the season to soil test. Soils tests provide information on the soil’s actual nutrient status. Fall is a preferred time to take soil tests if one suspects a soil pH problem and wants to avoid the spring rush. Fall soil testing will allow you ample time to apply lime to raise the soil pH. Lime reacts slowly and, if possible, it should be mixed with the soil two to three months before planting.
Most soils in Georgia lean towards being more acidic than what is ideal for a majority of plants. They are also usually deficient in one of the three primary plant nutrients (nitrogen, phosphorus, or potassium). For soils in the Piedmont, the soil likely has a pH hovering in the 5.0-5.5 range, well below the 6.0-6.5 range recommended. Most Piedmont soils are not deficient in phosphorus, but potassium deficiencies have been common and can have great impact on plant growth. Having a soil sample tested will allow you to accurately apply the correct amounts fertilizer or lime to meet plant needs.
The most important steps in collecting a soil sample are identifying the sampling location, collecting at the right depth, and collecting enough soil. The equipment used to sample is relatively standard. A shovel or garden trowel can be used to collect soil for a sample. Or you can use a soil probe which will take a small-diameter core, but the cost of purchasing one of these probes could be prohibitive. We have probes for check-out at the Extension office free of charge.
Identify and map out the area where the pants are growing or are to be grown. Collect 8-10 sub-samples from each location using a zigzag pattern. Combine all sub-samples together in a plastic bucket (not metal), mixing well. It is also important to obtain a representative sample, meaning
that you should make sure that the sample represents a similar area in the landscape or area of similar productivity. For lawns, sample to a depth of 4 inches. For gardens, ornamentals, and fruit trees, sample to depth of 6 inches.
You can come by the Extension office to pick up soil sample bags, or you can bring in your sample in a sandwich bag. Make sure that you bring in a large enough sample: 2-3 cups are needed. Make sure to label multiple samples so you know where they came from. The plant or crop being grown is also needed.
A routine soil test, which provides results on soil pH, major plant nutrients, and recommendations for fertilization, will cost $8 per sample. Lawn and ornamental areas need to be sampled every two to three years. Vegetable gardens should be sampled every 1 to 2 years. The cost and effort of proper soil sampling will pay greater dividends in plant health and efficient use of fertilizer over the long term.
If you have questions about soil sampling, please contact me at clh@uga.edu or 706-795-2281.
