How to Change the pH of Soil

Soil pH is important for plant growth.

Soil pH falls on a scale of 0 to 14 and indicates how acidic or alkaline the soil is. The pH level of a ground area is critical to the growth and survival of the plants there, since some plants die if planted in an area with improper pH. Before adjusting the pH, local extension agencies will test a soil sample and provide a report explaining the current pH. When needed, soil amendments raise or lower the pH when you mix them into the ground.

Difficulty:

Moderately Easy

Instructions

Things You'll Need

• Hydrated limestone
• Fertilizer spreader
• Tiller
• Granulated sulfur

Raising Soil pH

1. Compare the current pH level of the soil, listed on the soil test report, with the desirable pH for the types of plants you are planting. This tells you how much you need to raise the pH, which makes it more alkaline.

2. Fill the hopper of a fertilizer spreader with hydrated limestone using 4 oz. per square yard in sandy areas, 8 oz. in loamy areas, 12 oz. in clay soils and 25 oz. in peat soils.

3. Push the fertilizer spreader over the soil area until all of the limestone is applied.

4. Work the lime into the top 6 inches of the soil by setting a tiller blade depth to 6 inches and pushing it over the area.

Lowering Soil pH

1. Read your soil test report to determine the current pH level and then research the plants you are planting to determine their optimal soil pH. This lets you know how much you need to lower the pH, which makes the soil more acidic.

2. Fill a fertilizer spreader with granulated sulfur using 0.1 lbs. for every half point decrease in pH. For example, to go from a pH of 6 to 5.5, add 0.1 lbs. of sulfur. To go from a pH of 6 to 4.5, add 0.3 lbs. of sulfur.

3. Push the fertilizer spreader over a 10 square foot area of the soil until no sulfur remains in the spreader.

4. Set the fertilizer spreader out of the way and place a garden tiller at the edge of the soil. Set the blade depth to at least 6 inches and turn the tiller on. Push it over the soil to mix the sulfur into it well.

Tips & Warnings

• Simply stated, grass grows best in "neutral" soil. The reason it grows best in neutral soil is that neutral soil has the most microbial activity. The more soil microbes you have, the more nutrients in the soil that are available to the roots of grass plants. The more nutrients the roots are able to use, the healthier the grass plant will be. The healthier the grass plant, the better your lawn looks!

References

• Iowa State University; How To Change Your Soil's pH; Eldon Everhart; April 1994
• The Garden Helper: How to Test and Adjust the Soil pH in your Garden