Make sure you conduct the test early enough to give yourself time to fix any problems before you find yourself with a bunch of dead plants.
If you have...
- A pH greater than 7: You have alkaline soil. Add sulfur.
- A pH lower than 7: You have acidic soil. Add lime.
- Low nitrogen: Use a nitrogen-rich fertilizer.
- High nitrogen: Probably caused by over-fertilization; stop adding fertilizer.
- Low phosphorus: Add superphosphate, or bone meal, to your garden soil.
- High phosphorous: Probably caused by too much high-phosphate fertilizer. Grow plants to use up the excess.
- Low potassium: Add wood ashes. (Be careful. This could limit the growth of any acid-loving plants.)
- High potassium: Do not use potassium-rich fertilizers, and add nitrogen and phosphorous to help balance the soil.