Next to fertilizer, the second, most commonly-used lawn treatment is liming. Essentially a soil supplement, lime is a solution made from ground limestone that is often touted as a beneficial way to balance your soil’s pH. However, soil pH shouldn’t be viewed as the ultimate indicator for soil health, and if applied incorrectly, liming your lawn may actually do more harm than good.
What Is a Soil’s pH?
You might remember from chemistry class that pH stands for the measurement of how acidic, or alkaline, a solution is—based on how much hydrogen is present.
A pH balance of 6.0-6.5, for example, is more desirable for soil. If too acidic, its levels of calcium, magnesium, potassium, and sodium might be off balanced, meaning your soil won’t be able to absorb the added NPK nutrients from fertilizer.
When this occurs, you may consider liming your lawn. Please note that the typical pH of Minnesota home lawns is between 6.8-7.3. Anything above 7 will not improve with liming. In fact, it could raise the pH above grass-growing levels. Therefore, it’s essential that you first conduct a soil test.
What Does Liming Do?
The two main compounds in lime consist of calcium carbonate and magnesium carbonate, which help neutralize acidity.
- Calcium helps plants build cell walls, extend primary roots, and transport nutrients
- Magnesium is an essential part of chlorophyll, thus helping plants generate photosynthesis and retain their vibrant green color.
Combined with fertilizer, liming should essentially work magic on your lawn, right? Unfortunately, finding the perfect balance can be a bit tricky.
What If There is Too Much Lime in Soil?
As organic gardening author Phil Nauta phrases it, “pH is the result of the elements in our soil, not the cause.” A pH test will only reveal a potential imbalance, rather than which specific mineral deficiencies your soil is suffering from.
Adding too much lime to soil can tip the pH scale even further, exacerbating the problem. Excess calcium can block the soil’s absorption of magnesium, or cause iron deficiency, leaving grass looking yellow and bleach-spotted. Excess magnesium can cause compaction.
Although soil pH levels vary across Minnesota, our drier climate means there isn’t much fluctuation throughout the year. We don’t get heavy rainfall, which can wash nutrients away, and half the year the ground is frozen.
Liming simply isn’t necessary in this part of the country.
Remedies for too much lime in soil include sulfur solutions or fertilizers with ammonia or urea to neutralize the alkalinity, but these short-term fixes only add chemicals to your lawn. And this can bring you right back to your initial dilemma. We always recommend an organic approach like compost, mulch, or sphagnum peat moss to counteract any liming gone awry.
Need an Organic Lawn Care?
The best first step to addressing your lawn’s needs is to get a soil test. You can purchase a soil test kit from a gardening center or send a sample to the U of MN Soil testing lab. Be sure to check out their website on how to effectively obtain an adequate sample for accurate results—as this will tell you the soil’s pH, but more importantly, which minerals it’s lacking.