Last Updated on September 4, 2026 by Brian Beck
Most people who have heard of soil pH know that 7 is neutral, numbers below 7 are acidic, and numbers above 7 are alkaline.
But that doesn’t really explain why pH matters.
For a lawn, pH is less like a nutrient and more like an access-control system.
You can have calcium, phosphorus, iron, manganese, magnesium and other minerals sitting in the soil, but if the chemistry surrounding those minerals is wrong, the plant may have difficulty accessing them.
That is why one of the first questions we ask when looking at a struggling soil is not simply:
“What fertilizer does this lawn need?”
It is:
“Can the plant effectively use what is already there?”
What Does pH Actually Measure?
Soil pH is a measurement related to hydrogen ion activity in the soil solution.
The scale runs from acidic to alkaline, with 7 being neutral.
What makes the scale interesting is that it is logarithmic. A soil at pH 8 is not just slightly more alkaline than a soil at pH 7. It represents a tenfold difference in hydrogen ion activity.
That chemistry has a tremendous influence on what happens underground.
pH affects:
- Nutrient availability
- Mineral solubility
- Microbial activity
- Root function
- Chemical reactions between minerals
- The effectiveness of fertilizer applications
- The overall biological environment surrounding the root
In other words, pH helps determine whether the underground system can actually function.
Think of pH as the Door to the Grocery Store
Imagine walking into a grocery store filled with food.
There is plenty of inventory on the shelves.
But the doors are locked.
It doesn’t matter how much food is inside if you can’t get to it.
Soil can work the same way.
A laboratory test might show that a mineral exists in the soil, yet the plant may still show symptoms associated with a deficiency.
The mineral isn’t necessarily absent.
Its availability may be restricted.
That is an enormously important distinction.
Because if we mistake unavailable nutrients for missing nutrients, our instinct is usually to add more fertilizer.
Sometimes that simply creates a bigger inventory problem.
What Happens When Soil Becomes Too Alkaline?
This is particularly important in Colorado, where alkaline soils are common.
As pH climbs, several micronutrients can become increasingly difficult for plants to access.
Iron is one of the classic examples.
There can be iron in the soil while the grass still struggles to obtain enough usable iron.
Manganese, zinc and copper can also become less available as alkalinity increases.
Phosphorus becomes complicated as well.
Under alkaline conditions, phosphorus can react with calcium and form compounds that are much less available to the plant.
So we can end up with an interesting situation:
The soil contains phosphorus.
The soil contains calcium.
Yet the plant struggles to obtain the phosphorus it needs.
Adding more phosphorus without understanding why it became unavailable doesn’t necessarily solve the underlying problem.
Low pH Creates Different Problems
Very acidic soil creates another set of chemical challenges.
As pH falls, calcium and magnesium availability can decline, while metals such as aluminum and manganese can become increasingly soluble.
At sufficiently low pH levels, aluminum can become harmful to root development.
Phosphorus availability can also decline because phosphorus may become tied up with iron and aluminum compounds.
So phosphorus is a good example of why balance matters.
At very low pH, it can become unavailable.
At very high pH, it can also become unavailable.
There is a middle range where the chemistry is generally much more favorable.
Minerals Don’t Operate Independently
This is where soil chemistry becomes far more interesting than the traditional idea of simply applying fertilizer.
Minerals interact.
Too much of one can interfere with the availability or uptake of another.
For example:
- Excess potassium can interfere with magnesium uptake.
- High calcium can influence phosphorus availability under alkaline conditions.
- Excessive phosphorus can contribute to micronutrient problems involving zinc and iron.
- High sodium can damage soil structure and interfere with water movement.
- The calcium-to-magnesium relationship can influence physical soil characteristics.
- Excessive nitrogen can drive rapid growth while increasing demand for other minerals.
The soil is not a collection of independent ingredients.
It is a system.
And pH influences many of the reactions taking place inside that system.
Biology Is Part of the Equation
There is another reason we care about pH.
Soil microorganisms participate in nutrient cycling, decomposition, mineralization and the transformation of nutrients into forms plants can use.
Bacteria and fungi live inside the same chemical environment as the roots.
Extreme pH conditions can alter which organisms thrive and how effectively biological processes function.
This is why we don’t view chemistry, biology and soil structure as separate subjects.
They continually affect one another.
A lawn ultimately needs:
Structure.
Life.
Nurture.
If the physical environment is poor, biology suffers.
If biology is weak, nutrient cycling suffers.
If the chemistry is badly imbalanced, both the plant and the microorganisms may struggle.
So What Is the “Perfect” pH?
There isn’t one magical number for every soil and every plant.
For many turfgrass systems, a mildly acidic to near-neutral soil environment—roughly the mid-6 range—is favorable because many essential nutrients have good availability there.
But this is where people can make another mistake.
You should never diagnose a soil from pH alone.
We also want to know things like:
- Calcium
- Magnesium
- Potassium
- Sodium
- Phosphorus
- Sulfur
- Micronutrients
- Organic matter or humus
- Biological activity
- Soil structure
- Water movement
- Gas exchange
A pH number tells us something important.
It does not tell us everything.
How Do You Correct pH?
The first step is surprisingly simple:
Test the soil.
Do not guess.
If soil is genuinely too acidic, agricultural lime is commonly used to raise pH.
Calcitic lime supplies primarily calcium.
Dolomitic lime supplies both calcium and magnesium.
Which one should be used depends on what the soil actually needs.
If soil is too alkaline, the problem is often more complicated.
Elemental sulfur can gradually acidify soil as microorganisms convert sulfur into sulfuric acid, but the amount required depends heavily on the soil’s buffering capacity and calcium carbonate content.
And in highly buffered alkaline soils, dramatically changing the pH of the entire soil profile may be neither practical nor economical.
Sometimes the better strategy is to improve the root-zone environment and nutrient availability rather than chasing an unrealistic pH number.
This is also why gypsum should not automatically be considered a “pH lowering product.”
Gypsum supplies calcium and sulfur and can be extremely useful in certain situations—particularly where sodium and soil structure are involved—but it generally does not dramatically lower the pH of a normal alkaline soil.
The diagnosis determines the treatment.
The Biggest Mistake: Adding More Before Understanding Why
This is the cycle we want homeowners to escape.
The lawn doesn’t look right.
So we add nitrogen.
Then iron.
Then more water.
Then another fertilizer.
Then another treatment.
But nobody asks what the soil is actually telling us.
Sometimes the lawn isn’t starving because the grocery store is empty.
The grocery store can be full and the doors can still be locked.
That’s why soil testing changes the conversation.
Instead of asking:
“What should we put on the lawn?”
We can finally ask the better question:
“What is preventing this lawn from working properly?”
And that is the beginning of building a lawn that doesn’t just look healthy.
It actually functions like a healthy lawn.
We Don’t Guess With Soil. We Test It.
Before spending more money trying to correct color, growth, drought stress or nutrient deficiencies, find out what is happening beneath the surface.
A comprehensive soil test can reveal pH, mineral relationships, nutrient availability and some of the hidden obstacles that ordinary lawn treatments never address.
Knowing what’s in the soil—and understanding whether the plant can actually use it—is where real lawn management begins.
Ready to Stop Guessing What Your Lawn Needs?
If your lawn is struggling with color, drought stress, poor growth, nutrient deficiencies, or inconsistent performance, adding more fertilizer may not be the answer.
The real problem may be hidden in the soil.
pH, mineral balance, soil structure, biology, and nutrient availability all work together. If one part of that system is dysfunctional, the lawn can struggle even when you are spending more money, using more water, and applying more products.
That is exactly why we test.
Our biological lawn program is designed to identify the obstacles beneath the surface and help build a lawn that functions better—not one that simply depends on more treatments.
Stop guessing. Stop chasing symptoms. Find out what your soil is actually telling you.
Start With the Soil
Use the link below to contact us about our Biological Lawn Program and soil testing options:
We don’t guess with soil. We test it.