Does Sulfur Lower Soil pH?

About Soil pH

• Many beginning gardeners don't know about soil pH and its importance in the health of plants. The acidity or alkalinity of soil affects the ability of the root system to take up moisture and nutrients. The pH scale is a way to measure the acidity or alkalinity of various substances, including soil. The scale ranges from 0 to 14, with values lower than 7 being more acidic and numbers higher than 7 being more alkaline. The middle value, 7, is considered neutral. The pH affects the solubility of nutrients in the soil and how easily the plants can utilize it, according to State University of New York specialist Donald Bickelhaupt. You can purchase soil pH testing kits at local garden centers or have your local agricultural extension service conduct testing on a soil sample to determine pH and the amounts of nutrients in your soil.

Adjusting pH

• Soils in different regions have differing pH values naturally. Other environmental factors can also intensify soil pH, such as when rainwater leaches away calcium and magnesium ions or when nitrogen and ammonium fertilizers oxidize, making soil more acidic. To provide the best growing environment for various types of plants, research the preferred pH soil ranges. Plants like azaleas, blueberries and conifer trees prefer acidic soils. Certain vegetables like asparagus prefer an alkaline soil, as do most citrus trees.

Sulfur

• Sulfur is natural compound mined from the earth that is used to lower pH, thus acidifying the soil. Sulfur is spread onto the surface and then worked into the soil to a depth of 10 to 12 inches. Apply the sulfur gradually and re-test to adjust to the correct pH range. Do not apply too much at one time or you will have to re-adjust the pH in the other direction. Never add more than 5 to 10 lbs. of sulfur per 1,000 square feet of area. Too much sulfur can damage the roots of plants, according to University of Florida professors Amy L. Shober and Geoffrey C. Denny.

Lime

• Garden lime is added to soil to raise the pH, making it more alkaline. This compound is added in a similar manner as the sulfur, adding gradually and re-testing for the correct adjustment. When you add too much sulfur to soil and lower the pH value too much, you must add lime to raise it again to the correct range

Precautions

• Always wear gloves and a dust mask when adding these garden compounds to the soil. Granular garden compounds can be irritating to the respiratory system and may cause skin reactions.