Soil pH level in your organic lawn is the measure of it’s acidity. Actually, it’s the levels of hydrogen ions but we won’t go that deep on this page.
Lawn pH is based on a scale from 1 to 14 with 7 being neutral.
A pH of soil below 7 the lawn is considered acidic and above is basic.
Most turf grass, like a pH level at 6.4 to 6.8 which is slightly acidic.
Why is the soil pH so important?
Most nutrient availability to the grass plant is optimum right around neutral, which is 7. So you can see having the correct levels is critical.
Another small tidbit is the more acidic your soil, the more bacterial your it is, alkaline, and it is more fungal dominated.
I’ve talked to many people that would put down the recommended application rates their lawn test results would provide and the next year they would do another soil test and the acidity levels would be the same or even lower.
The pH scale is measured in logarithms, so the difference between 1 and 2 points away from neutral is huge. Raising your soil pH level even one point can take a year and in many cases even longer.
Raising Lawn Soil pH Levels
The two most common additives to raise pH are
calcitic lime and dolmitic lime.
Both work slowly but are effective, dolomite also contains about 28% Magnesium.
- Calcitic lime is a fine white powder
- Dolomite is a brown granular
So this is where we refer back to our percent base saturation level on the lawn test results to determine which one we use.
If just the calcium level is low and the magnesium levels are fine we use calcitic lime. If both are low we use dolomite.
Refer back to our lawn test example:
- We have a soil pH level of 5.5, so obviously it needs to be raised
to achieved the desired 6.8 level
- Look at the Percent base saturation levels
and you’ll see both Ca and mg are very low
- Calcium should be between 60% – 80%
- Magnesium between 5% – 15%
- So in this case dolomite should be applied to raise acidity levels
Remember, do your best to stay true to the 7-1 or 8-1 ratio of calcium to magnesium as we discuss on our Percent Base Saturation page
If both minerals are in proper range and you still need to raise levels, use one or the other and switch back and forth each time to raise pH.
Lime moves very slowly through the soil that’s why you don’t apply more than 50 lbs. per 1000 sq. ft. at a time because the pH in the first two inches of earth could be drastically different than 4 inches deep.
Your first soil pH test should be completed by a lab. Once you achieve your desired levels you re-check and maintain your acidity levels with some of these testing products
Lime goes through sandy earth faster than clay, therefore it works quicker.
If you’re using ground limestone use a drop spreader and a rotary spreader if you use pellitized.
Lower Lawn pH Levels
To lower the soil pH levels use granulated sulfur.
If you need to lower the levels and your magnesium and potassium are low use Sulfate of Potash and Magnesium.
Cottonseed meals are also known to slowly lower basic soils. All these products should be readily available in most agricultural or do – it – yourself chain stores.
Most testing facilities already give you the recommended application rates for adjusting the soil pH with your test results.
Just be aware of calcium to magnesium ratio and the
If your levels are were you want but your calcium levels are low use agricultural Gypsum to raise it.
Gypsum will also loosen up compacted clay soils.
If only the magnesium is low use Epsom salts
Adjusting the Lawn Soil pH does Take a While
I’m not saying don’t move ahead with your project but if your in cool zones and know your going to renovate in late summer, apply the material early spring if not the previous year.
In warm zones. if you renovate in early summer try to make the recommended adjustments the previous fall if not sooner.