Soil pH

Soil pH is referred to as the acidity of the soil and is measured by the number of Hydrogen ions present in the soil .

When the soil pH is too acidic (low pH) or alkaline (high pH), nutrients present in the soil become locked-up or unavailable. Correcting the pH has the same effect as applying fertilizer as it unlocks plant nutrients already present, and it is more cost effective as well.

Some garden plants thrive in acidic soils while others prefer an alkaline soil. The acidity or alkalinity of soil is measured by pH (potential Hydrogen ions). pH is a measure of the amount of lime (calcium) contained in your soil, and the type of soil that you have.

A soil with a pH lower than 7.0 is an acidic soil and one with a pH higher than 7.0 is alkaline.

Adjusting Soil pH

To raise or lower the pH level in the soil either Limestone or Sulfur is utilized. There are other materials that will do the job also, but the aforementioned are the most widely used.

Limestone is added to soil raise the pH level because limestone is essentially calcium and calcium reacts with water in the soil to yield hydroxyl ions .. a process known as, hydrolysis... thus the pH level in the soil is raised. 

Sulfur reacts with bacteria in the soil and produces sulfuric acid, which releases hydrogen ions thus causing the soil to become more acidic..... the pH level is lowered. 

Application Of Lime (To Raise Soil pH)

To increase your pH by 1.0 point and make your soil more alkaline.

Add 4 ounces of hydrated lime per square yard in sandy soils

Add 8 ounces of hydrated lime per square yard in loamy soils

Add 12 ounces of hydrated lime per square yard in clay soils

Add 25 ounces of hydrated lime per square yard in peaty soils

The addition of ash, bone meal, or crushed oyster shells will also help to raise soil pH levels.

Application of Sulfur (To Lower Soil pH)

If your soil needs to be more acidic, sulfur may be used to lower the pH if it is available.

To reduce the soil pH by 1.0 point

Mix in 1.2 oz of Garden Sulfur per square yard if the soil is sandy

Mix in 3.6 oz per square yard for all other soils.

Composted leaves, wood chips, sawdust, leaf mold and peat moss, will also help to lower the soil pH.