How to Test Soil pH for Grass: DIY Guide

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 the potential to deter your grass from 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, aluminum, 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?

The soil pH of an area can change due to various reasons which include the following:

1. Weather and climate

Precipitation changes can greatly influence soil pH. The high amount of rainfall, for example, will wash away essential nutrients from the 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.

2. Fertilizers

You risk shifting 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 which makes the situation even worse.

Most artificial fertilizers are known to lower pH while organic fertilizers acidify most soils.

3. Parent soil material

Soil can become acidic or alkaline depending on its parent material. Areas with a lot of shales tend to be more acidic. Shale produces soft soil particles that have higher buffing capacities. Sandy soils and areas rich in limestone are more alkaline.

4. Native Plants

The type of plants grown in an area is likely to affect the pH of the soil. Soil becomes more acidic when there is 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 remain alkaline.

5. Irrigation water

The water you use to water your plants 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 starting a new lawn, 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 about what you are planting.

Fertilizing – Plants including lawn grasses require a boost in form of fertilizer to enhance their growth. Fertilizers perform based on the type of soil. Testing soil pH will give you an insight into 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 – The alkalinity or acidity of your soil will determine the kind of weeds growing in a particular soil. Knowing the pH status of your soil can help you in coming up with a good weed control strategy. For example, dandelions 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 reason for your unhealthy lawn grasses. Testing is what will reveal this and now you will be able to carry out appropriate soil amendments that will either raise or lower soil pH.

How to Test Soil PH for Grass

There are several ways of testing the pH of 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.

Soil test kits can be purchased 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.

Method 1: Testing soil pH 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 in the soil, then it has an alkaline pH.

Vinegar contains 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 acidic intensity of the soil by the 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

  1. 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.
  2. Remove any debris from the gathered soil samples including grass, thatch, and twigs
  3. Place your samples in a bucket and thoroughly mix until you end up with the correct amount as required in the kit.
  4. Spread the soil over a clean surface for a day to air dry before you take the dry sample to the Extension office.
  5. 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 compost will lower the soil pH of your lawn or garden over time.

While it is difficult to determine how many 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.


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