GOOD TO KNOW
Before you decide to fertilize, test your soil to see what, if any, nutrients your lawn is lacking. If you apply more nitrogen and phosphorus than your lawn can absorb, it will run off the yard and end up in our waterways. Once in the waterways, the excess nutrients cause “dead zones,” or areas with low amounts of oxygen. With little or no oxygen, fish, crabs, oysters, and other aquatic animals literally suffocate. An excess of these nutrients also fuels the growth of dense algae blooms that block sunlight that underwater grasses need to grow in order to continue providing food for waterfowl and shelter for blue crabs and juvenile fish.These blooms also cause our waterways to become discolored, smelly and undesirable for swimming and boating.
GOOD TO DO
Soil test kits can be picked up at a garden store or a local Virginia Cooperative Extension office. The Elizabeth River Project and Lynnhaven River NOW both recommend A&L Eastern Laboratories for testing.
- Soil test kit
- Stainless steel or chrome-plated soil probe, hand garden trowel, shovel or spade (Do not use brass, bronze or galvanized tools because they will contaminate samples with copper and/or zinc.)
- Clean plastic bucket or container
- Take a soil sample a few months before initiating any new landscaping. Sample well in advance of planting. Sampling in the fall allows time for corrective pH and nutrient management before new growth starts in the spring. Fall sampling also avoids a sometimes busy spring period at the Soil Testing Laboratory, thus avoiding delays in getting your soil test results.
- If an established area exhibits abnormal growth or plant discoloration, take a soil sample right away. For areas recently limed or fertilized, delay sampling at least six to eight weeks.
- In Hampton Roads, it’s is best to test every two to three years.
- To obtain an accurate soil sample, divide your landscape into areas of unique use (ex. vegetable garden, lawn, perennial flower bed, etc.) and sample those areas individually. It is best to use the same sampling depth from year to year so soil test values can be more accurately compared.
- Step 1: Open a hole with a shovel, spade or trowel from the surface to the proper depth for your landscape area. Set that soil aside. (If you are using a soil probe, insert it into the soil to the proper depth and remove the plug from the ground).
- Recommended sampling depth: Established lawns: 2-4 inches Vegetable and flower gardens: 6-8 inches (tillage depth) Trees and shrubs: 6 inches
- Step 2: With your shovel or trowel remove a 1-inch thick slice from the smooth side of the open hole.
- Step 3: With the slice of soil on the blade of the shovel, remove the sides of the slice with a trowel, knife or your hands to create a ribbon of soil 2-inches wide and 1-inch thick of the proper depth.
- Step 4: Remove any surface mat of grass, litter and any rocks. Place the soil in a clean plastic container or bucket. If the bucket has been used to hold fertilizer or other chemicals, wash and rinse it thoroughly before using it for soil samples. Even a small amount of lime or fertilizer transferred from the sampling tools to the soil can seriously contaminate the sample and produce inaccurate results.
- Step 5: Take 10 additional soil sub-samples from different locations within each uniform landscape area to make a composite sample. Take the sub-samples in a random manner, such as with a zigzag pattern to minimize the variability that may be present in your sampling area. The larger the area, the more sub-samples you should take.
- By mixing these sub-samples together, you create the composite sample that will be sent to the soil testing laboratory.
- Step 6: Thoroughly mix the sub-sample slices or cores. Break up clumps and remove all foreign matter such as roots, stalks, rocks, etc.
- Step 7: Fill the container from the soil test kit with your sub-sample. Use a different soil kit container for each sub-sample. Make sure to label with the name of the sub-sample it represents (ex. FYARD, BYARD, ROSE, GARDN).
- The soil test lab will provide you with information on the availability of nutrients in your soil. The routine soil test costs around $10. The test measures and makes recommendations for the following major nutrients: P (phosphorus); K (potassium); Ca (Calcium); Mg (Magnesium) and five micronutrients.
- A soil test is not usually performed for the presence of N (nitrogen). Soil Testing Laboratories still provide nitrogen fertilizer recommendations. You can often use much less than is recommended to get successful results and may not need to use any if you are mulching your grass clippings back onto your lawn. In Hampton Roads, our soil is naturally rich in phosphorus so, with the exception of new plantings, adding phosphorus is often not necessary.
Sources: Virginia Cooperative Extension, Lynnhaven River NOW
Visit askHRgreen.org/fertilizing-in-hampton-roads for more fertilizing information.