How to Lower the PH Level of High Alkaline Soil. The pH level of soil ranges on a scale from 1 to 14. The middle of the scale is considered neutral, and the higher the number is on the scale, the higher the alkaline content in the soil. Plants require different alkaline levels in the soil, and sometimes the soil needs to be adjusted to suit the plant that will go into a specific area. Here are some helpful tips for lowering the pH level of high alkaline garden soil.
Determine the plants, flowers or vegetables that will be planted into your garden. Some plants prefer a higher alkaline content in soil, and others thrive with a lower pH level making it more acidic.
Take a soil sample in the area where you wish to plant. You may take your sample to a local garden center, or purchase a soil testing kit from the center.
Review the results of your soil sample. Once you've determined the alkaline content of the soil, you can make adjustments.
If you have a sandy soil, you will need to add 1.2 ounces of ground rock sulfur per square yard. This will lower your pH level by 1.0 on the scale.
You will need to add 3.6 ounces of ground rock sulfur per square yard for other types of soil. This too will lower your pH level by 1.0 on the scale.
Add sawdust, compost and peat moss as other options to lower the soil's pH level.