Gardening Basics – Fertilizer and Soil pH
Compost will take care of most soil’ shortcomings, but it will not guarantee the right degree of acidity or alkalinity, which is measured on a pH scale that runs from 0, for extremely acid to 7, for neutral, to 14, for extremely alkaline.
The correct level of pH in your soil is just as important as your compost. Most vegetables, fruits and herbs thrive in soils with a pH of 6.0 to 7.0, but each has its own “favorite” range. If your soil does not fall within the proper range for the plants you’re growing, you should correct it by adding the proper materials. You can easily determine the pH of your soil with an inexpensive kit sold at garden centers, or by taking or sending a soil sample to your local agricultural extension service for testing.
To raise the pH of an overly acid soil ½ to 1 unit, add 5 pounds of finely ground limestone to each 100 square feet of planting area. To lower the pH of alkaline soils, use either finely ground sulfur, which is slow acting but relatively long-lasting, or iron sulfate or aluminum sulfate, which work quickly but dissipate more rapidly in the soil. One half pound of ground sulfur or 3 pounds of iron or aluminum sulfate per 100 square feet will lower the pH by ½ to 1 unit. For especially heavy soils, increase all these amounts by about 1/3. (more…)
