To make your lawn as healthy as possible, you always look for ways to improve it. In your research, one thing that keeps popping up is your “soil pH”. What is pH, and how do you lower it if it is too high? The type of grass in your lawn will determine how much sulfur you should apply, and how often to check your soil’s pH. But you should generally apply up to 5 pounds of sulfur per 1,000 sq. feet of lawn.
What is pH for a Lawn?
Potential hydrogen (pH) refers to the hydrogen ion concentration in a particular substance, in this case, your soil. The capitalized “H” is used to properly identify the element. pH is measured on a scale of 1 to 14. The more alkaline your soil is, the higher on the scale it will fall. Alkaline levels are also referred to as “basic”. The higher the acidity levels, the lower your soil’s pH value.
The neutral pH level is 7, and most plants can thrive with a neutral pH. But when your pH needs to be adjusted there are two commonly recommended additives. Lime is used when your soil is too acidic, and you need to raise the pH. Sulfur, the topic of this article, is what is most often called on to lower the pH of your lawn.
How Does Sulfur Amend pH?
The addition or removal of hydrogen ions is what causes a soil’s pH level to fluctuate. The higher the hydrogen ion concentration is in a soil sample, the lower on the pH scale it will fall. When sulfur is added to soil, it introduces more hydrogen ions. The hydrogen ions that are introduced, and subsequently released, cause the pH level to decrease.
Therefore, lime has the opposite effect. Lime will remove hydrogen ions from the soil causing their concentration to decrease.
How Does pH Affect Turf and Plants?
Most common turfgrasses prefer a neutral pH somewhere between 5.8 – 7.2. When any plant is placed in an environment outside of its ideal range it is difficult for them to take in the nutrients they need to survive. Not even frequent fertilizing can make up for a poor pH level.
When pH levels are too high, the nutrients that plants need are not soluble enough to be taken up into the roots. Soluble means how easily nutrients are broken down by water. If they can’t be broken down, they can’t be taken up into the roots. Lowering soil pH to a level where nutrients are more soluble is where sulfur comes in.
Ideal pH for Specific Grasses
Each type of grass may be slightly different as far as what it prefers for a specific pH. Bermudagrass and Zoysia’s ideal ranges are 6.0 – 6.5, according to Clemson University’s College of Agriculture. An Oregon State University study tells us that tall fescue’s best growth occurs between 5.5 – 7.5. Perennial ryegrass also falls in the 5.5 – 7.5 range.
But, knowing where a plant wants its pH to fall does not do us any good unless we take a soil sample.
How Do You Take Soil Samples? How Often?
The easiest and most common way to test your lawn’s pH is through a soil sample. This can be accomplished by using specific soil sampling tools or a simple shovel. Whichever way you choose, try to dig in multiple places across your yard.
Aim for pulling dirt from 6 – 8 inches below the surface. Remove the top two inches and bottom two inches, so that all you have left to test is the center portion of each sample.
This ensures that the soil you are sending to be tested is the portion which most of your grass root system is pulling nutrients from. Combine your samples, let them dry at room temperature, and bag them up. University agriculture extensions, private companies, farmer co-ops, and many other sources will test your sample for a small fee and send back a wealth of information about your soil health.
If you are in the process of adjusting your lawn’s pH, test it twice a year – once in the spring and once in the fall. The gap between the tests should give plenty of time for your lawn to adjust to chemicals applied in the spring. Once your pH is at the level you want, you can test it every other year.
The exception to this is if your grass starts to prefer poorly, or if large portions of it become discolored. Stunted growth, excessive growth, discoloration, and bare soil are the most common signs of a yard with a pH level that needs to be amended.
How to Apply Sulfur
The weather must be right when you apply sulfur. Make sure that the air temperature is below 75 degrees. In established yards, sulfur can be applied at a rate of up to 5 pounds per 1,000 square feet. Every three to four weeks, you can apply additional applications (of up to five pounds each) until the pH level is brought down to the desired level.
In a bare yard where you are preparing to seed, sod, or sprig, you can be much heavier with your application amount. Up to 25 pounds per 1,000 square feet can be applied and should be done before any seed or sod is put down.
For exceptionally large lawns or fields, a fertilizer spreader attachment on a tractor may be what’s best suited for you. For one acre, approximately 200 pounds of pelletized sulfur is where you would want to start for each application.
The most common forms you will find sulfur in are powder and pelletized. Powder sulfur can be dusted over your lawn and pellets can be spread by hand or with a walk-behind broadcast spreader. For large areas, it is much easier to ensure the even distribution of pelletized sulfur.
Who knew that some of those high school chemistry classes would come in handy when managing our lawns? It can seem intimidating to try and understand all the nuances of playing with pH levels, but a few key steps can simplify the process for us. Take your soil samples, identify the ideal zone for your grass, and apply the correct additive to help your lawn get there.
If big changes need to be made, start with 5 pounds for every 1,000 square feet, and watch as your lawn starts to recover and grow healthier than it ever has before.