do you think that much would kill the plant
I've never had to lower my PH but I'm sure that's too much.
Alkaline Soils:
Alkaline (basic) soils have a pH of more than 7.0. Basic soils are generally found in areas with lower rainfall levels, in urban areas (due to large amount of cement), and in areas where there is a high concentration of clay in the soil (Midwest, Southwest).
There are several materials that can be used to lower the pH of alkaline soil.
Liquid soil acidifiers, such as Stern's Miracid, temporarily lower soil acidity. Miracid lowers the soil pH resulting in increased availability of micronutrients in high pH soils. Miracid can be applied to soil or on leaves for a fast foliar feeding. Because of the temporary nature of this product, it must be applied every two weeks. Liquid soil acidifiers, such as Miracid, are time consuming to apply and are therefore best used in small areas.
Application Rate: One tablespoon of Miracid to one gallon of water (one gallon of solution covers approximately 10 square feet).
Iron sulfate is a fast acting soil-acidifying amendment. Changes in pH level usually occur with 3 to 4 weeks. Table 2 shows the application rate of iron sulfate. If more than 7 pounds per 100 square feet is to be applied, split the applications in 1 to 2 month intervals and water frequently to avoid excessive levels of soluble salts. Table 2.
Pounds of Iron Sulfate Needed to
Lower Soil pH by One Unit (lbs. Per 100 square feet)
Soil Type Sand, Loamy Sand, Sandy Loam Loam, Silt Loam 4.8 lbs. 19.2 lbs.
Adapted from University of MN Extension Service publication "Soil Acidification."
Aluminum sulfate can be used to lower pH. However, it is not recommended as a soil-acidifying agent because it can produce aluminum toxicity in plant roots.
Elemental sulfur reacts slowly with the soil. It should be applied and worked into the soil to a depth of 6 inches. Because elemental sulfur is a slow reactor, it should be applied the year before planting for best results. Table 3 shows the application rate of elemental sulfur used to lower soil pH by one unit. Table 4 provides the application rate of elemental sulfur used to lower soil pH to 4.5.
Table 3.
Pounds of Elemental Sulfur Needed to
Lower Soil pH by One Unit (lbs. Per 100 square feet)
Soil Type Sand, Loamy Sand, Sandy Loam Loam, Silt Loam 0.8 lbs. 2.4 lbs.
Adapted from University of MN Extension Service publication "Soil Acidification."
Table 4.
Pounds of Elemental Sulfur Needed to
Lower Soil pH to 4.5 (lbs. Per 100 square feet)
Soil Type Soil pH Sand, Loamy Sand, Sandy Loam Loam, Silt Loam 7.0 1.9 lbs. 5.8 lbs. 6.5 1.5 lbs. 4.6 lbs. 6.0 1.2 lbs. 3.5 lbs. 5.5 0.8 lbs. 2.4 lbs. 5.0 0.4 lbs. 1.2 lbs.
Adapted from University of MN Extension Service publication "Soil Acidification."
Organic compounds such as sphagnum peat moss, compost, and manure can be used to lower soil pH. Table 5 provides the approximate application rate used to lower soil pH by one unit.
Table 5.
Pounds of Organic Compound Needed to
Lower Soil pH by One Unit (lbs. Per 1 square yard)
Compound Type Peat Moss Compost Manure 2.5 lbs. 14 lbs. 5 lbs.
Adapted from Smartgardening.com "Soil pH."
Tools and Equipment:
Materials necessary for amending the soil:
- Shovel
- Wheelbarrow or Tarp
- Rototiller
- Spreader
- Amendment material
- Paint to mark off area
Site Considerations: Make sure that the area you will be amending has adequate drainage, and that the soil doesn't have an extreme pH problem. A soil with an extreme problem would be one that needs to have a drastic change in pH in order for a plant to grow (eg. changing a soil ph from 8.5 to 4.5). Keep in mind that landscaping materials can affect pH. Materials such as cement or limestone walks and patios will raise the pH of soil.
Process for Application:
For both acidic and basic soils, it is best to incorporate the amendments at least six inches into the soil. For alkaline soils this should be done a year before planting time. In acidic soils this can be done anytime prior to planting. The easiest method for incorporating amendments is:
- Mark off the area to be amended.
- Till the top one foot of soil with the rototiller.
- Apply amendment at the recommended rate (from the above charts).
- Till the amendment into the soil.
An alternate method for incorporating the amendments into the soil is double digging.
- Measure off the area to be amended. Dig a trench 1 foot wide by 1 foot deep. Place soil alongside trench on a tarp or into a wheelbarrow (Fig. 1). Break up the subsoil on the bottom of the trench (Fig. 2).
- Dig another trench of the same size next to the first one. Place soil from this trench into the first trench (Fig 3.). Break up the subsoil on the bottom of this trench.
- Repeat these steps until the whole area has been double dug. Fill the last trench with the soil from the tarp or wheelbarrow (Fig 4).
- Spread the recommended amount of amendment (from charts above) over this area. Dig it into the top foot of soil.
Adapted from Stefren Buczacki Conran's Basic Book of Home Gardening.
A third method of application is to topdress.
- Apply the recommended amount of amendment over the area to be amended.
- Distribute amendment evenly over soil using the spreader.
The disadvantage of this method is that only the upper 1-2 inches of the soil will be affected by the amendment.
