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Adjusting Your Soil's PH

By: Jack Claridge - Updated: 26 Sep 2017 | comments*Discuss
Adjusting Soil Ph Acidic Soil Alkaline

pH is the standard measurement of alkalinity and acidity in soil. Most gardeners are familiar with pH and the effects it can have on growing anything in their garden and as such it is well worth taking a closer look at it. The levels of pH in your garden soil can have a very dramatic effect on how well things do or don't grow, especially when it comes to lawns.

Soil pH is an important factor when it comes to creating a lawn, either from turf or from grass seed. The pH affects the availability of nutrients in the soil and many of the nutrients required by grass or turf to grow and sustain a long period of growth are not available in highly acidic or highly alkaline soils.

Generally the soil pH levels are split into three categories:

  • Acid - pH of between 1 and 7, peaty soil for example
  • Neutral - An exact pH reading of 7, clay soils being a prime example
  • Alkaline - Generally with a pH of between 7 and 14, normally chalk-based soils
You can tell without testing the soil what kind of pH level it has by observing plants that are already growing in and around the garden environment; heathers, birch and foxgloves for example blossom in acidic soils whilst Rhododendrons, Ash and Beech flourish in Alkaline soils.

Testing your Soil's pH

If you wish to test the pH level of your soil by slightly more scientific means there are kits that you can purchase at your local garden centre. You do not need to be a garden expert to use these kits and the results are visible in a very short space of time indeed.

These over the counter kits use test tubes into which small amounts of soil are placed along with designated amounts of water. After mixing and leaving to settle the results are shown and can be matched against a simple colour chart, which will show what kind of soil you are dealing with. The general rule of thumb is:

  • Alkaline - Dark Green
  • Acidic - Yellow or Orange
  • Neutral - Bright Green
Most grasses will thrive in soils with a ph of 6.5 to 7.0

Adjusting your Soil's pH

Once you have established what pH your soil actually is there are ways in which you can adjust it to either increase the pH level or decrease it. If your soil's pH level is less than 6.5 then it is classed as being too acidic. Likewise if your soil's pH level is more than 7.5 it is considered to be too alkaline. Once you have established to what degree your pH level is wrong for growing and maintaining a lawn you can attempt to change the level.

The first thing you need to do is obtain a soil chart, which you can get from any garden centre or garden nursery. If, as mentioned before, your soil pH is less than 6.5 and your soil is too acidic, you need to add ground limestone to bring it back into balance again. If the soil is too alkaline, with a pH or 7.5 or higher, you need to add soil sulphur to drop the pH level down.

The way in which this is calculated is usually based on material measured in pounds, which needs to be added to soil per thousand square feet. At this point it is an absolute necessity that you know your lawn's exact size. Measure the length and width of your lawn and multiply the two sizes to get an approximation of square footage.

Once you have accurately measured your lawn and determined how much sulphur or limestone you require, it can be applied to your soil using what is known as a drop spreader. A drop spreader is inexpensive and can also be used for applying fertiliser to your lawn so it is worthwhile in investing in one.

You will need to apply the sulphur or limestone on a regular basis to ensure the soil's pH remains balanced and will allow for constant growth but it should be advised that, when using sulphur, too much will burn your lawn.

For this reason it is best to break up the applications of sulphur and apply it from varying angles of the lawn to ensure a liberal coverage without the chance of burning.

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Share Your Story, Join the Discussion or Seek Advice..
On the ph advice on lawns, you state that rhododendrons flourish in alkaline soil. Really? If so, you need to inform RHS that they are wrong! ?? David
David in Devon - 26-Sep-17 @ 10:29 PM
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