Organic Fruit- Controlling Soil pH Organic Fruit- Controlling Soil pH

Controlling you soil’s pH – the balance between alkalinity and acidity – is important for growing your organic fruit. Among other things, it affects the availability of nutrients found in the soil.

Step 1 - What is an Ideal pH for Organic Fruit?

Organic fruit plants should grow in soil that maintains a pH factor around 6.5. They can tolerate a range between 5.5 to 7.2, except for blueberries. Blueberries need to grow in acidic soil between a pH of 4.8 to 5.2. If the soil in your area is not in this range, you need to change it if you want to grow organic fruit. Gardeners and farmers throughout the country often find plants that can thrive in the natural pH of local soil. However, organic gardeners, especially home gardens, often invest in changing the soil pH to gain the optimum growing conditions.

Step 2 - Test the Soil

Before investing in any change in your soil’s pH, test it. Contact your local Agricultural Extension Service for advice on how to collect a soil sample and send it to a laboratory for testing. Sometimes, guidelines are available from the Extension website.

Step 3 - Alkaline Soil

In many parts of the country soil can test as slightly alkaline to highly alkaline, coming in with pH factors ranging from 7.2 to 9.5. This is most likely due to an abundance of limestone in the soil. Furthermore, many homebuilders make a sweeping removal of topsoil when putting in subdivisions of homes and then replace it with additional alkaline soil. Construction materials like limestone gravel, concrete and high pH water used for irrigation contribute to a soil’s high alkalinity. This alkalinity can be lowered through the introduction of several different products, including sphagnum peat, aluminum sulfate, iron sulfate, elemental sulfur, acidifying nitrogen and organic mulch.

Step 4 - Garden Levels

One of the best methods for lowering the pH factor for small garden plots is to introduce sphagnum peat. It generally ranges within a 3 to 4.5 pH factor. It is a great source for organic matter as well. A 1 to 2 inch layer of sphagnum peat can be added to topsoil 8 to 12 inches down before planting any fruit. Sphagnum peat is an expensive additive that would make the use of large plots very cost prohibitive. The cheapest and safest additive is granular sulfur, but it produces the slowest results when trying to lower the pH of the soil. Do not exceed two pounds per 100 square feet to avoid plant harm. Both aluminum and iron sulfate will react more quickly than elemental sulfur, but you will need to apply five to six times more. Do not exceed five pounds per 100 square feet using either aluminum or iron sulfate.

Step 5 - Acidic Soil

Highly acidic pH can be raised by the introduction of limestone into your soil. It will take eight pounds per 100 square feet to raise the pH in sandy soil from 5 to 6.5 in the top six inches of soil.

Note: if your soil has a pH factor greater than 7.5, it is probably impractical to attempt lowering it enough to grow organic fruit.

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