When PH levels in soil are too low, it’s referred to as soil acidity, which can ruin crops and prevent certain plants from properly growing.
In order to avoid these issues, soil needs to be monitored and kept at just the right levels.
So, what’s the ideal level of soil acidity?
Well, it is true that a majority of plants are most at home in soil with neutral pH levels, but that won’t mean much if you don’t understand the concept as a whole.
So, this article is going to be your guide that breaks down everything you need to know about pH levels in soil.
We won’t leave a single stone unturned and will make sure you are an expert on all things soil acidity, from what it is, what causes it, and what plants favor more acidic or alkaline soil.
So, get your gardening gloves on, and let’s talk about some soil!
1. What is Soil Acidity?
Soil acidity refers to the condition when the pH or soil is lower than neutral levels.
When the pH level is low, it means that there is a high concentration of hydrogen ions, indicating acidity.
Neutral levels of soil pH are around the pH 7 mark.
Anything above pH 7 is considered soil alkalinity and anything below pH 7 is considered soil acidity.
Here’s a quick breakdown of pH levels in soil:
pH 3 and under: Very strong acidity
pH 4 to 5: Strong acidity
pH 5 to 6: Moderate acidity
pH 6 to 7: Slight to neutral acidity
pH 7 to 8: Neutral to slight alkalinity
pH 8 to 9: Moderate alkalinity
pH 9 to 10: Strong alkalinity
pH 10 or above: Very strong alkalinity
When soil has strong levels of acidity, fewer nutrients are available for plants, and certain elements of the soil, such as manganese, aluminum, and iron, can become toxic and poison the plants.
Acidic soils have been responsible for ruining the performance of crops and have to be carefully managed to ensure the vegetation is able to survive.
With that being said, there are some plants that favor more acidic soil, which we’ll cover later in the article.
For now, let’s look at where soil tends to be more acidic and what causes soil acidity.
2. Where is Soil Most Acidic?
As a rule of thumb, soil in wet climates tends to be more acidic than soil in arid climates.
The regions in the United States with the most soil acidity are the East, Southeast, and Pacific Northwest.
During heavy, consistent rainfall, the water washes away alkaline elements, leaving behind acidic soil.
Another reason these regions have high levels of soil acidity is due to more tree coverage.
Trees mean leaves, and when leaves fall to the ground, decay, and release carbon dioxide into the environment, it increases the acidity in the soil.
Where is Soil Most Alkaline?
The western half of the United States, with the exception of the Pacific Northwest, tends to be where most of the alkaline soil is found.
These regions experience less rain and have less tree coverage and acidic rocks.
Instead of granite, which has high acidity levels and contributes to lowering pH levels in soil, the western part of the United States has a lot of shale and limestone, which are alkaline.
Where is Soil Most Neutral?
Neutral soil in the United States is typically found in the Midwest.
The ground in these areas is mostly grasslands that experience some rain; however, the water quickly evaporates due to high sun exposure.
The Midwest also has much less tree coverage than the East and Pacific Northwest.
Most of the acidity found in the soil of these parts was caused by generations of intensive farming.
3. What Causes Excess Soil Acidity?
Soil acidity occurs naturally, but sometimes it can be exaggerated by human activity.
So, let’s take a look at the most common causes of soil acidity.
Fertilizers
Certain fertilizers, especially fertilizers with high levels of nitrogen, have been linked to unnatural soil acidity.
When these products are used, the materials containing ammonium become nitrates due to bacteria in the ground, which then lowers the pH levels and increases soil acidity.
Sometimes, nitrates move away from the root zone, which means they can’t be used by the plants, and consequently stay in the soil.
Organic Waste
When organic waste decays, it produces carbon dioxide (CO2).
If carbon dioxide comes into contact with water in the ground, it creates carbonic acid, which contains hydrogen and causes acidity.
However, carbonic acid is considered a weak acid, and it takes a long time for decaying organic waste to impact soil acidity.
Rainfall (Leaching)
During severe rainfalls, the water leaches alkaline elements, such as potassium and magnesium, and leaves behind acidic elements, such as manganese and aluminum.
Additionally, due to carbon dioxide in the atmosphere, rainwater tends to have lower pH levels, which also contributes to soil acidity.
High-Yielding Crops
When land is used over and over to grow and harvest crops, naturally occurring nutrients that combat soil acidity are taken from the ground.
Over time, lands that once had moderate or neutral pH levels suddenly experience dramatic changes.
High-yielding crops are one of the biggest causes of soil acidity.
Acidic Parent Material
The geological material that soil is formed from is called parent material.
When those objects have low pH levels, it’s a strong indicator that the area’s soil will also have low pH levels.
Granite parent material is more acidic than shale and limestone.
4. What Happens if you struggle with soil acidity?
Soil acidity can cause several issues for an environment that is typically neutral or alkaline.
Low pH levels can make it more difficult for plants to access vital nutrients, and it can also cause certain elements to become toxic–this typically happens with manganese and aluminum.
High acidity is also known to cause nutrients to leach below the root zone, meaning they go beyond the plants’ reach.
When plants don’t have enough nutrients, growth is stunted, or the flora dies off.
Additionally, soil acidity can create an environment that is not well suited for ground organisms, bacteria, and earthworms, which play an important role in the health of ecosystems.
When the land becomes more acidic after excessive crop farming, yields can become smaller and smaller, negatively impacting yearly profits.
So, in most cases, when acidity levels go beyond moderate levels, it creates serious issues that need to be solved.
But how exactly would you go about fixing acidic soil?
5. How Do You Fix Soil Acidity?
Fixing soil that has become overly acidic is, fortunately, a simple process.
You should first begin by testing the soil to get a read of the pH levels (see section eight on how to test your soil).
Once you know the levels of your land, you can begin adding materials with alkaline elements.
Here are four materials you can add to reestablish high pH levels:
Limestone
Pulverized limestone (and dolomite) is considered one of the best materials to add to soil that has high pH levels.
Limestone is rich in magnesium, which is an alkaline element that helps fight against acidity.
You want to make sure you use limestone that is specifically produced for yards and gardens.
Avoid quicklime and hydrated lime; these will not have the same beneficial effect.
Wood Ash
Wood ash can be used to increase pH levels in soil, as long as the wood isn’t treated, which could be harmful to the plants.
The ash has adequate levels of calcium and other alkaline chemicals to have a fairly quick impact.
Keep in mind that most wood ashes can cause an accumulation of salt, leading to damaged plants.
Bone Meal
Bone meal is an excellent way to introduce calcium to acidic soil.
The only downside to bone meal is that it takes longer than other solutions.
So, the other materials may be a better option for anyone with yards that have severe levels of acidity–bone meal works great for slightly acidic soils.
Compost
As the pH levels return to more neutral levels, adding compost will ensure that plants are receiving adequate nutrients.
Compost, due to its own neutral pH levels, will also slowly fight against soil acidity.
Make sure to be careful when applying compost–too much can cause excessive moisture and prevent plants from getting enough oxygen.
6. What Plants Like Acidic Soil?
Remember, not all plants prefer the same soil.
As problematic as soil acidity can be, some plants actually favor soil with low pH levels.
So, if you live in an area with naturally acidic soil and you don’t want to take the steps to continuously neutralize it, don’t worry!
There is a great selection of plants (including trees) you can put in your garden that will look great and thrive.
Here’s a list of some plants that thrive in acidic soil:
Camellia
Ferns
Magnolia
Hydrangeas
Rhododendrons
Azaleas
Heathers
Beech trees
Japanese maples
False cypress
The list of potential plants goes on and on.
So, no matter what aesthetic you want to create, you should have no problem getting your desired look with acidity-loving plants.
7. What Plants Dislike Acidic Soil?
Despite the long list of plants that favor acidity, there are even more that dislike acidity.
A majority of all the plants in the world prefer a neutral pH; however, there are many plants that favor alkaline soil.
So, let’s take a look at the options people who live around alkaline soil have for their yards and gardens.
Here’s a list of some plants that thrive in alkaline soil:
Lavender
Buddleia
Lilly of the valley
Honeysuckle
Spindle
Lilac
Strawberry trees
Field maple
So, alkaline soil doesn’t mean that your flora options are limited.
On the contrary, there is a wide selection of plants to choose from to bring life and color to your property.
You could even grow a number of edible plants, such as broccoli, peas, rosemary, kale, and so much more!
8. How Do I know if My Soil is Acidic?
The best way to tell if your soil is acidic is by testing it.
Yes, there are deficiency symptoms to look out for, such as plants that are stunted or struggling, but that could also be an indicator of a laundry list of other issues.
It would be a good idea to test your soil every three to five years to ensure the pH levels are where you want them.
If you see unusual levels, you can take steps to bring them back to where you want them.
But how do you test for soil acidity?
Well, gardening stores (or shops online) sell DIY soil testing kits.
All you have to do is take samples, ideally from various parts of your yard, by digging a hole around six inches deep.
Once you have the soil, your test kit will likely encourage you to mix in a dye (or other solution), which will cause the soil to change color.
You will then compare the color of the soil with the chart of various pH levels.
If you don’t want to buy a test kit, there is another option.
Take samples from a six-inch deep hole.
Put two tablespoons of soil in a bowl and add half a cup of vinegar.
If it begins to fizz, that means the soil is alkaline.
(Another option is to wet the soil with distilled water and add half a cup of baking soda. If it fizzes, you have acidic soil.)
9. Is Most Potting Soil Acidic?
Potting soil tends to be neutral and slightly acidic.
But don’t worry.
The pH levels of potting soil won’t be low enough to cause harm to your plants.
There is, of course, potting soil designed for specific types of plants that favor acidity and alkalinity.
Before you purchase a bag of soil, research what kind of soil your plants prefer and check the ingredients of the bag.
You can make your potting soil more acidic by adding things like coffee grounds and aluminum sulfates.
You can make your potting soil more alkaline by adding pulverized limestone, wood ash, bone meal, and ground eggshells.
Just be careful not to make the soil too acidic or alkaline, which could harm the plants.
Final Thoughts
Soil doesn’t seem like it has a lot going on, but it does!
Whether you are growing crops or just landscaping your backyard, it’s very important to know the pH levels of the soil.
Soil acidity can be a real issue for farmers, resulting in a decrease in crop yield, and also for individuals who are unsure why their plants are no longer thriving on their property.
The good news is that testing pH levels at home is quick, easy, and cheap.
Remember that you should test your soil every three to five years to ensure that the pH levels are exactly where you want them to be.
So, I hope this answered all your questions about soil acidity and that you feel confident in knowing how to raise or lower pH levels using the right materials.
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Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.
Prior to starting Gokce Capital, Erika received a Bachelor of Architecture from the University of Southern California and a graduate degree in Urban Policy from Columbia University. She worked as both an architectural designer and engineer in New York before joining the New York City Department of Housing Preservation and Development.
Erika currently lives in the New York Metropolitan area with her spouse, daughter and cat. She is originally from Chicago and still considers herself a midwesterner at heart.
Erika also loves to read, write and travel (fun fact, she has visited all 50 states and more than 30 countries!). Her new book, Land Investing Mistakes: 11 True Stories You Need To Know Before Buying Land, is now available on Amazon.