A change in soil pH can greatly impact the health of your turf grass. The degree of acidity or alkalinity in the soil is measured by a pH scale that ranges from 0 to 14. A pH value below 7 is considered acidic while above this neutral point is alkaline. Plants can only access important nutrients in the soil if the pH is within a certain range.
Most plants including lawn grasses typically prefer a pH of 6.2 to 7.0. Anything above the range indicates excess alkalinity which has a potential to deter your grass from properly absorbing nutrients and minerals in the soil. In high pH, several soil micronutrients like iron, manganese, zinc, copper and cobalt, become less available to plants.
Low soil pH below 5.5 on the other hand, can also affect plant growth due to the increased availability of some micronutrients such as manganese, aluminium and iron to toxicity levels. Further, at low soil pH, the availability of other essential nutrients, such as phosphorus, potassium, calcium and magnesium decreases which might result in deficiencies.
What affects soil pH?
Soil pH of an area can change due to various reasons whcih include the following:
Weather and climate
Precipitation changes can greatly influence the soil pH. High amount of rainfall for example will wash away essential nutrients out of soil thus making it to become more acidic. Drought on the other hand causes minerals and salts to accumulate in the soil causing it to become more basic.
You risk changing your soil acidity or alkalinity when you add any type of fertilizer to the soil without testing for pH. You may be adding acidic fertilizer to an already acidic soil and this will make the matter worse. Most artificial fertilizer are known to lower pH while organic fertilizer acidify most soils.
Parent soil material
Soil can become acidic or alkaline depending on its parent material. Areas with a lot of shale tend to be more acidic. Shale produces soft soil particles that has higher buffing capacities. Sandy soils and areas rich in limestone are more alkaline.
The type of plants grown in an area are likely to affect the pH of the soil. Soil becomes more acidic when there are plenty of decaying organic matter from the plants around. These include decaying leaves and twigs. Lawns tend to have less of these decaying materials – this makes soils underneath the grass to remain alkaline.
The water you use to irrigate can affect the acidity or alkalinity of the soil. If the water is acidic then expect your lawn or garden to also become acidic. Borehole waters contain high levels of salts and minerals as compared to treated piped water.
Why Test Soil pH?
Understanding the soil pH is very important for the following reasons:
Seed planting – Before seed planting, testing the acidity or alkalinity will help you to know if you need to conduct soil amendments prior to seed planting. Some grasses do well in acidic soil and this will be the best time to make a decision of what you are planting and if any soil amendment has to be done.
Fertilizing – Plants including lawn grasses require a boost in form of fertilizer to fast track their growth. Fertilizers perform based on the type of soil. Testing soil pH will give you an insight on which fertilizer to use on your lawns or gardens. If your soil is alkaline, adding an organic fertilizer can help lower the pH.
Weed control – Alkalinity or acidity of your soil will determines the kind of weeds growing in particular soil. Knowing the pH status of your soil can help you in coming up with a good weed control strategy. For example dandelion thrive in acidic soil while chickweed like alkaline soil.
Soil amendments – Sometimes when plants appear unhealthy, adding fertilizer alone may not be the solution to the problem. A shift in soil pH can be the reasons for your unhealthy lawn grasses. Testing is what will reveal this and now you will be able to carry our appropriate soil amendments that will either raise or lower soil pH.
How to Test Soil PH
There are two prominent ways if testing the pH of a soil. You can do it yourself using basic kitchen supplies – vinegar and baking soda or you can opt to purchase a testing kit that will provide a precise pH measurement. You can also take a sample of your soil to a nearby extension office for testing.
A soil test kits can be purchased online in gardening stores or at any nearest nurseries. They are easy to use and provide accurate readings. You just need a little soil sample to mix with the provided chemical or material in a clean container. Soil pH test kits include an easy color-coded chart that will explain the pH of your soil.
Method 1: Testing without a Test Kit
You will need distilled water, vinegar and baking soda.
Add 1/2 cup of distilled water to the soil sample in a clean plastic container and mix. Then, add 1/2 cup of white vinegar. If you see bubbling or fizzing from the soil, then it has an alkaline pH. Vinegar contain acetic acid that reacts with the alkaline soil. The more pronounced the bubbling happens, the higher the pH.
Place another soil sample into a clean container, add 1/2 cup of distilled water and mix. Then, add 1/2 cup of baking soda. If the soil shows bubbles or fizzes, the soil is acidic. The alkaline baking soda reacts with the acidic soil and you can determine the intensity by vigorousness of the reaction.
Method 2: Using a pH Test Kit
Soil pH testing kits come in varieties of types including; pH test strips (litmus paper), chemical test kits and digital pH meters. Each kit involves a different order of operation
- Using a shovel, scoop 3 to 5 samples from different parts of your lawn. Your samples should be obtained from 4 to 6 inches below the surface.
- Remove any debris from the gathered soil samples including grass, thatch and twigs
- Place your samples in a bucket and thoroughly mix until you end up with correct amount as required in the kit.
- Spread the soil over a clean surface for a day to air dry before you take the dry sample to Extension office.
- If you have to carry out the test at home, follow the instructions listed on your soil test kit.
What to do after testing Soil PH
If your tests show that the soil is alkaline or very acidic, you should add amendments to bring the pH into a range suitable for the plants. Liming your lawn or adding some wood ashes will help raise soil pH to make it less acidic. On the other hand applying a well-decomposed composed will lower the soil pH of your lawn or garden over time.
While it is difficult to determine how much of these amendments are needed without the help of an extension officer, doing small amendments every season as you keep testing will finally reach a fairly neutral pH suitable for most plants.