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How To Change Soil pH: What to use and Monitor Explained

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Just like soil is the foundation of any garden, knowing its pH is also an essential part of gardening. It affects the soil’s ability to retain nutrients and water and plant growth. 

Soil pH can be changed by adding lime or sulfur to the soil. While lime will raise the pH value of the soil, sulfur, on the other hand, will lower the pH. Proper testing will indicate the current pH and whether or not to increase or decrease the pH of the soil.

Maintaining a proper soil pH will not only ensure that present crops are growing healthy but also future plants as well.

This article will explain how soil pH affects plants and what you can use to test, increase and also decrease the soil pH where necessary.

Why Is Soil pH Important?

Testing Soil pH

Soil pH is important because it directly affects plants by influencing the soil’s resistance to diseases, such as root rot and powdery mildew, as well as the availability of nutrients for the plant.

Soil pH is a measure of the acidity or alkalinity of the soil, and it can significantly affect the growth of plants. Soil pH is important because it affects the soil’s nutrient availability for plants.

It can be measured on a scale of 1-14, with 7 being neutral. Anything below 7 is considered acidic, and anything above 7 is considered alkaline—the more acidic the soil, the lower its pH. 

The higher the alkalinity, the higher its pH.

The level of acidity or alkalinity in the soil can affect the availability of nutrients to plants. 

pH range for plants

The ideal range for most plants is between 5 and 7 on the pH scale. Some plants prefer a more acidic or alkaline environment, but most thrive in this range.

Soil pH is important because it affects how plants absorb nutrients and water from the soil. If a plant has too high or too low a pH, it will not be able to grow correctly.

Some plants are more sensitive to changes in soil pH than others. For example, trees and shrubs are less susceptible than vegetables which need more specific conditions for growth.

Factors Affecting Soil pH

The pH levels are measured on a logarithmic scale, meaning that each whole number represents a 10-fold change in acidity or alkalinity. 

For example, soils with a pH level of 1 are 10 times more acidic than soils with a pH level of 2 and 100 times more acidic than soils with a pH level of 7.

Various factors can affect soil pH, including organic matter content, type and number of plants in the garden, type of fertilizer used, and rainfall patterns.

The following factors affect the soil’s pH:

  • Organic matter content
  • The type of soil (sandy, clayey, etc.)
  • The amount of organic matter present in the soil
  • The amount of rainfall and irrigation
  • The type of plant life growing in the area
  • The kind of rock that makes up the parent material for the soil;
  • The variety of vegetation (e.g., trees) growing on top of it;
  • How much water drains through it;
  • It has been treated with lime, sulfur, or aluminum sulfate to raise its pH level.

So, take care of the above-stated factors because these can significantly impact the soil’s pH.

Why Does Soil pH Change?

Soil ph change

There are various reasons the soil pH changes. Following are the reasons the ph of the soil varies:

1) Wet and dry cycles

2) The type of mineral present in the soil

3) The type of plant that is growing in the soil

4) The amount of organic matter in the soil

5) The amount of rainwater that falls on the ground

6) Natural disasters such as earthquakes, hurricanes, and tsunamis.

7) Acid rain from factories and power plants creates a more acidic environment for plants to grow. This can cause an increase in soil acidity.

These were some of the primary reasons the pH of the soil changes.

How Soil Type Affects pH

Types of Soil

The soil’s pH measures how acidic or basic it is. It ranges from 0 to 14, with 7 being neutral. The higher the number, the more alkaline the soil is.

Different soils have different pH levels. This is because they contain different amounts of minerals and organic matter, which affect their pH levels.

The type of soil affects how plants grow in it and what kind can grow there. For example, some plants need a lot of lime to grow correctly, and others require little or none for healthy growth.

For example, clay soils are more acidic than sandy soils because they contain more aluminum and iron ions, which react with water to produce hydrogen ions that lower the pH level. 

The second instance is limestone is more alkaline than granite.

How to Change Soil pH

The most important consideration when adjusting soil pH is to know what your desired result should be. 

Some plants prefer more acidic or alkaline soils, so it’s essential to consult with your plant’s care guide before making any changes.

There are two main ways to change the soil pH: 

  1. Lime
  2. Sulfur 


Lime - Calcium Carbonate

Lime raises the soil’s pH by adding calcium carbonate, which contains calcium and carbonate ions that react with hydrogen ions in the soil to form calcium hydroxide and release carbon dioxide gas. 



Sulfur lowers the soil’s pH by adding sulphuric acid, which reacts with hydrogen ions in the soil to form sulfates that rainwater can wash away.

The other ways to adjust the soil pH are by adding organic matter or applying an amendment containing lime, sulfur, wood ash, or iron sulfate.

It is no doubt that changing soil pH is not an easy task. It requires a lot of time, effort, and money. But once you have poured your efforts into it, you are going to get unlimited benefits of healthy growth of the growing plants.

How to Raise Soil pH

There are many ways to raise the pH of soil. The following are some ways to increase the pH level of your soil:

– Add lime or limestone to the soil.

– Add organic materials such as peat moss, compost, and manure to the soil.

– Add ash from hardwood trees (not pine) to your garden bed.

– Use a fertilizer that includes limestone in it.

Gardeners also often use inorganic materials like crushed oyster shells, dolomite, or limestone to raise the pH of their soil. 

These materials contain calcium carbonate, which reacts with the acid in the soil and creates a more alkaline environment.

How to Lower Soil pH

To lower soil pH, adding sulfur to the soil is necessary. Sulfur lowers the pH level by adding sulfuric acid, which is acidic.

Two common materials used for lowering the pH of the soil are 

  1. Aluminum Sulfate 
  2. Sulfur

They are used to changing the balance in soils that are too alkaline. In addition, they can make soils more fertile.

Aluminum Sulfate 

Aluminum sulfate instantly changes the pH of the soil because as soon as the aluminum sulfate dissolves in the soil, it produces acidity.

Compared to aluminum sulfate, Sulfur requires some time to convert into sulfuric acid with the assistance of soil bacteria. 

Various factors play a deciding role in how quickly the sulfur will convert into sulfuric acid. These factors are:

  • Fitness of the sulfur
  • Amount of soil moisture
  • Soil temperature
  • Presence of bacteria

But these are the two materials that help lower the soil’s pH. However, use them wisely. 

Overapplying the amounts of sulfur and aluminum sulfate to the soil can have detrimental consequences on soil fertility and plant growth.

How to Test Soil pH

The following steps are needed to test soil pH:

1) Collect a soil sample and put it in a container.

2) Add water to the sample and stir until it is dissolved.

3) Fill a small vial with some mixture and add one drop of universal indicator solution (available at your local garden center).

4) Observe the color change in the vial after adding the solution.

5) Record color change on a chart provided by your local garden center.

The other simple way to test the pH level in your garden is by using litmus paper strips or an electronic tester. 

If you are using litmus paper strips, dip them into your garden’s water and wait for the color change in the strip before you compare it to the color chart on the side of the container.

To test the moisture and pH of the soil you can also use the cost-effective Trazon Soil 3-in-1 Meter. It tests for not only pH but also moisture content and light intensity. You can find it by clicking here!

Trazon Soil pH Meter 3-in-1 Soil Tester Moisture

The Takeaway

Before you add lime or sulfur to your garden to change the soil pH, check the soil’s pH level and monitor it regularly.

To test the soil pH, buy a kit at a garden center or online or use your litmus paper (which you’ll need to buy). After that looking at the results, decide whether you need to change the pH level of your soil or not.

Adding lime or sulfur to your soil will change its pH. While lime will raise the Ph of your soil, sulfur will lower the pH value of the soil. 

Therefore, when adding lime and sulfur to the soil, it is crucial to do so sparingly. Otherwise, it will make it difficult for plants to grow.

A good tip before amending soil to change its pH is always to check it firsthand. Litmus paper can quickly do this. 

Litmus paper can test the soil pH and make amendments to the soil as needed for growing plants at the correct pH.

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