A great indicator for diagnosing the overall health of you lawn is your soil’s pH level. Don’t worry if you are unsure exactly what your soil’s pH level means, or what your soil’s pH can tell you about your lawn - we are here to help!
First off - what exactly is “pH”?
The pH level of your yard’s soil indicates whether your soil is primarily acidic or basic (alkaline). The alkalinity or acidity of the soil determines the chemical forms of soil nutrients and how useful they are to your plants. Before a nutrient can be utilized by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble in acidic soils than in neutral (pH 7) or slightly alkaline soils. pH levels range on a scale of 1 to 14, with levels less than 7 indicating acidic soil and levels exceeding 7 indicating basic soil. The pH value of soil is influenced by the kinds of parent materials from which the soil was developed. Soil formed from basic rocks typically have a higher pH value than those formed from acidic rocks. Rainfall also affects soil pH by leaching the soil of basic nutrients such as calcium and magnesium, replacing them with acidic elements such as aluminum and iron, as the water passes through. The optimum pH range for most plants is in the slightly acidic range between 5.5 and 7.0 pH.
Your lawn or plant's soil not testing in this range? No worries, there are ways to improve a lawn that has become too basic or acidic.
Simple DIY pH testing kits are available at your local garden center or many landscaping firms or university/city extension services will come out and test your soil for free. Litmus paper can also be used to determine whether or not your soil is basic or acidic.
Basic soil, also referred to as “alkaline” or “sweet” soil, isn’t exactly sweet. Soil with a primarily basic pH level will filter water poorly, causing plant roots to become waterlogged which may lead to the death of the entire plant or lawn. A solid layer forms underneath the surface of basic soil which is composed of calcium carbonate or lime which the roots of plants have difficulty penetrating.
Increasing acidity in basic soil can be achieved by the addition of iron sulphates, aluminum sulfate, or sulfur.These materials should be worked into the soil after application to increase their effectiveness. Leaf burn may result if these materials remain in contact with plant leaves, so make sure to wash off the leaves immediately after application. You can also decrease the pH of alkaline soil with plant litter, compost, manure, pine needles, pine sawdust, and acid peat.
Slightly acidic or “sour” soil is actually a good thing for your lawn. pH levels between 5.5 and 7.0 pH optimize the availability of the nutrients and minerals in the soil that your plants need to properly grow and flourish. Plants such as blueberries and azaleas prefer even more acidic soil. However, overly acidic soil can cause a change in the chemical form of aluminum in the soil and prevent water and vital nutrients from reaching the plant’s roots. Overly acidic soil can also minimize the availability of nutrients for plant growth including nitrogen, sulfur, phosphorus, and calcium.
Lime is the most common application to increase alkalinity in the soil, but bone meal and wood ash can also be used. When applying lime to your lawn, make sure that your soil is moist. Moisture is essential for the lime-soil reaction to occur, so make sure to water the lime into the soil immediately following application.
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