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Acidic Soil: Understanding pH Soil Acidity

Having acidic soil in your garden isn’t always a bad thing. At the right level or concentration, it can lead to the proper growth of some plants.  This is why testing your soil, and understanding its pH level is important. 

Acidic Soil: Understanding Acidic Soil pH

What Are Acid Soils? 

Any soil sample with a low pH level can be referred to as acidic soil or acid soil. Soil pH can be measured on a scale of 1 to 14. For soil to be acidic, it has to fall between 1 to 7 on that scale. The lower the number, the higher the level of acidity of the soil. 

Most indoor plants or houseplants love a soil pH that is a little acidic (between 6.0 to 7.0). This is because, at that level of acidity, the phosphorus contained in the soil is soluble.  Phosphorus is an important nutrient for plants. It helps them produce fruits and flowers. 

When a soil sample becomes too acidic, it can have negative effects on plants. One of those effects is that it can reduce the amount of proper nutrients in the soil. If the soil pH drops lower than 5.0, the soil is considered “too acidic” for most plants.

What Makes Soil Acidic? 

Acidic soils are often caused by 3 main reasons:

  • Rainfall and leaching 
  • Decay of organic matter
  • Nitrogen-based fertilizers 

Rainfall and Leaching 

In an area with excess rainfall, you’ll find that the soil would be more acidic than usual. This is because the excess rain washes away key nutrients that prevent soil acidity. 

Some of these key nutrients are magnesium, potassium, and calcium. When these nutrients are washed away, you would find that the pH level of the soil would reduce. 

Decay of Organic Matter 

Plant-based organic matter is acidic in nature. This is because they produce hydrogen ions that are responsible for acidity. If the soil gets an excess build up of this organic matter, it would become acidic. 

Nitrogen-based Fertilizer  

The use of nitrogen-based fertilizers does increase the acidity of the soil. Fertilizers like these contain ammonia, which has been known to increase soil aciditcy.  

Is Your Soil Acidic?

Is Your Soil Acidic

Having a proper understanding of your soil’s pH level would help you as a gardener. This can be done by yourself or with the help of a professional in the lab. 

You can test soil samples for acidity using litmus paper. To do this, you would need to mix the soil sample in water and stick a blue litmus paper in it. If the paper turns red, then it is acidic 

For a more accurate result, you can make use of a standard soil testing kit. They are not expensive and can be used with ease. 

You can also be on the lookout for specific weeds. These weeds are known to grow and thrive in highly acidic soil. 

  • Rumex spp (Docks)
  • Ranunculus spp (Buttercup)
  • Urtica dioica (Nettles)
  • Equisetum arvense (Horsetail)
  • Rumex acetosa (sorrel)

How To Fix Acidic Soil 

Not every plant loves acidic soil. Some plants like the Lenten rose love sweet soil or alkaline soil. If you realize that your soil is too acidic, you can consider raising its pH level.

To do this, you would need some garden lime. Garden line is a great substance for sweetening soil, but its effects are gradual. 

On the other hand, if you notice that your soil is too alkaline, you can lower the soil pH using coffee. It contains water-soluble acid. This can be transferred to the soil when used often. 

 Some acid-loving plants you can grow indoors include 

  • Dicentra spectabilis (Bleeding hearts)
  • Narcissus (Daffodils)
  • Tropaeolums (Nasturtiums)
  • Hydrangea spp

Frequently Asked Questions 

What is a Sour Soil?

“Sour soil” is often used as a  definition of acidic soil. While “sweet soil” defines alkaline soil. 

Does clay make soil acidic?

No. Clay is a natural alkaline soil. But it can be prepared to be a little acidic. 

What is the perfect range for acidic soils in gardening?

For perfect acidic soil for your house plant, aim for a range of 6.0 to 6.9.

Which is better acidic or alkaline soil?

This depends on the plant being grown and the range of acidity or Alkalinity. Both can be beneficial and harmful to plants. 

What happens if soil is too alkaline?

Soil with excess alkalinity can stop or hinder plant growth.