PH Adjustments

Proper PH for Growin Grass
Why is PH so Important?
Soil pH affects the availability of nutrients to plants and the activity of soil microorganisms. Soil pH is a measure of the acidity or alkalinity of the soil with a scale of 0 to 14. The neutral point or balance for soil pH would be 7. As the number of the soil pH increases this indicates an increase in soil alkalinity. As the soil pH number decreases this indicates an increase in soil acidity. The ideal pH for most grass types is 6.5 to 7.0. This would be an optimum pH but different grass types can tolerate a range of pH levels — see our grass species pH chart below. Note that some grass species such as centipede prefer a more acidic soil with pH levels around 5.0 – 5.5 considered optimum.
If your soil tests indicate too much acidity, then we would need to add lime to increase the alkalinity to reach your target pH. If your soil test indicates too much alkalinity, then we would add sulfur to increase soil acidity to reach your target pH. Please note that lime and sulfur can take up to 2 – 3 months (or longer) to react with soil. The soil pH will be tested again at this point and may require that the soil be treated again. For the best and quickest results we recommend PH adjustments are made immediately following aeration.

Soil pH for Grass Types
Listed in the chart below are grass types with the lowest and highest pH level tolerated.

BERMUDA HYBRIDS & COMMON
Low = 5.6
High = 7.0

CENTIPEDE
Low = 4.3
High = 5.8

St. Augustine
Low = 6.3
High = 7.8

ZOYSIA
Low = 5.5
High = 7.0

Raising Soil pH
Lime is considered a natural soil amendment rather than a fertilizer and furnishes important plant nutrients such as calcium and magnesium. Lime also reduces soil toxicity while promoting the regulation of nutrients such as zinc, copper, and especially phosphorous.

Lowering Soil pH
The lowering (acidifying) of soil pH is much more difficult and expensive than raising (alkalinity) soil pH. The sulfur used to lower soil pH is different from the plant nutrient sulfur. Elemental sulfur can be added to soils that are too alkaline for plants that prefer a more acidic pH. This is a yellow powder sometimes referred to as “flowers of sulfur” and is not nutritionally available to plants until it is oxidized by soil bacteria into the sulfate form.

In other companies fertilization programs their fertilizers can act as acidifying materials. Sulfate is also present in conventional fertilizer and can acidify soil. However, the ammonium in fertilizers, not sulfate, is responsible for the soil acidification. Ammonium containing fertilizers can acidify soil. This process is slow compared to acidification by the natural elemental Sulfur.