Understanding pH and Garden Lime
Garden lime is a common name for powdered or pelletized limestone, which is used to raise the pH of soils in gardens and lawns. pH is a measure of the acidity or alkalinity of a solution, and the scale ranges from 0 to 14, with 7 being neutral. A pH value of less than 7 is acidic, and a pH value of more than 7 is alkaline. The ideal pH range for most garden plants is between 6.0 and 7.0, which is slightly acidic to neutral.
How Garden Lime Works
Garden lime contains calcium carbonate, which reacts with the acids in the soil to neutralize them. This reaction produces water and carbon dioxide gas, which escape into the atmosphere. As the acids are neutralized, the pH of the soil increases, making it less acidic and more alkaline. The calcium ions in the garden lime also help to improve soil structure and provide essential nutrients for plants.
Lowering pH with Garden Lime
Although garden lime is used to raise the pH of soils, some gardeners believe that it can also be used to lower the pH. This belief is based on the fact that limestone is alkaline, and therefore, adding it in small amounts should neutralize some of the acidity in the soil and lower its pH.
The Reality of Lowering pH with Garden Lime
However, this belief is a misconception. Garden lime cannot lower the pH of soil. In fact, adding garden lime to acidic soil can actually make it more alkaline. This is because the calcium carbonate in garden lime reacts with the water and the acids in the soil to produce calcium bicarbonate, which is alkaline. This reaction increases the alkalinity of the soil, making it less acidic and more alkaline.
Testing and Adjusting Soil pH
The only way to lower the pH of soil is to add an acidifying agent, such as sulfur or aluminum sulfate. These acidifying agents lower the pH of the soil by reacting with the alkaline compounds in the soil to produce acidic compounds. The amount of acidifying agent needed to lower the pH of soil depends on the current pH of the soil, the type of soil, and the plants that are growing in it.
Testing Soil pH
Before adding any amendments to the soil, it is important to test its pH. Soil pH testing kits are available at garden centers and online, and they are easy to use. The pH of the soil can also be tested by sending a sample to a soil testing laboratory, which can provide more detailed information about the soil’s nutrient content and other characteristics.
Adjusting Soil pH
If the soil pH is too high, it can be lowered by adding an acidifying agent, such as sulfur or aluminum sulfate. These agents should be added in small amounts and mixed thoroughly into the soil. The pH of the soil should be retested after a few weeks to ensure that it has been adjusted to the desired level.
Conclusion: Garden Lime and Soil pH
In conclusion, garden lime cannot lower the pH of soil. It is an alkaline substance that is used to raise the pH of acidic soils. If the pH of soil needs to be lowered, an acidifying agent should be used instead. Testing the soil pH is an essential step in maintaining healthy plants, and it is important to follow the recommended guidelines for adding soil amendments to ensure that they are effective and safe for the plants.