Soil pH: A matter of balance

Do you know the pH of your soil? There is a good chance it is either too high or too low. Soil pH problems are common in our area, often causing poor plant growth, pale or discolored leaves, and wasted fertilizer applications. Adjusting soil pH can dramatically improve plant performance, but first you need to know which direction it needs to be adjusted. Lime and sulfur, both natural products, are used to adjust soil pH.

Finding out your soil ph

Soil pH is a measure of how acidic or basic a soil is and can range anywhere from 4.0 (very acidic) to over 8.0 (moderately basic) in our region. Most plants grow best when the pH is between 5.8 and 6.5. At levels higher or lower than this, several important nutrients become unavailable to plants, even if they are present in the soil. If your soil pH is too extreme, plants will not grow well, no matter how much fertilizer you add.

Soil test kits can be purchased at garden centers or online, but they do not provide accurate results or tell you how to change your soil’s pH. Fortunately in Arkansas, there is an easy and free way to determine your soil pH and get recommendations for how to adjust it, through our state’s soil testing lab and the Cooperative Extension Service.

To send samples to the soil testing lab, bring them to your local Cooperative Extension office. For each area you would like to sample, you will need at least a pint of soil. Potting soil and mulch will not be tested. Samples can be submitted any time of the year and results are mailed, usually within three weeks.

Adjusting soil pH

The ideal pH range for your soil will depend on what you are trying to grow. Most trees, shrubs, vegetables and flowers are happiest when the pH is slightly acidic, ranging between 5.5 and 6.5, but there are exceptions. Acid loving plants prefer the pH to fall from 5.0 to 5.5. Common acid lovers include azaleas, gardenias, dogwoods, camellias, centipedegrass, loropetalum and blueberries. When the pH is too high, the new leaves of these plants appear pale or yellow and they grow poorly.

If soil test results show that your soil has a high pH, you can temporarily lower it by adding elemental sulfur, but this must be done very carefully to avoid damaging plants. To lower soil pH from 8.0 to 6.5, till 2-3 pounds of elemental sulfur into the soil for every 100 square feet of area before planting. It will take a couple of months of warm, wet weather for the sulfur to change the soil pH, and the effects will only last a couple of years.

In very acidic soils, where the pH is below

5.0, plants will be stunted and more prone to root diseases. Nutrient disorders like blossom end rot, a common problem in tomatoes, squash, peppers and watermelons are also more prevalent in acidic soils. Lime is used to raise soil pH, but should only be applied if your soil test report indicates it is needed. Many factors affect the amount of lime needed to change soil pH. The only accurate way to know how much you should apply is by soil testing. Like sulfur, lime needs to be tilled into the soil to work and takes several months to change soil pH.

If you have a question about any of the services the Cooperative Extension Service offers, visit website http://www.uaex.edu and follow the links. You may reach Jimmy Driggers, county extension agent – staff chair, at 623-6841.

Master Gardeners

If interested in gardening, the Garland County Master Gardeners hold their meetings at 1 p.m. the third Thursday of each month at Lake Valley Community Church. It is open to the public. For information call the Extension Office at 623-6841 or email Allen Bates at abates@uaex.edu.

EHC

Interested in joining an existing Extension Homemaker’s Club or would you and a group of your friends like to organize a club in your community? For information, call 623-6841.

4-H

If between the ages of 5 and 19, we have a club for you, or you and a group of friends can organize a club of your own. For information, call Linda Bates at 623-6841 or email lbates@uaex.edu.