Well since none of our scientist that I know of, I would think that a heavy metal would only need a very small amount to be harmful. The plant may not uptake enough of it to be harmful but since there is no studies I'm aware of and it's listed as neurotoxin. A lot of folks here are med users and really should be steered clear away from any unknown practices.... If there are no studies and better and safer known alternatives let's try and promote those.
I wouldn't smoke a plant that was foliar sprayed with STS. So I'd think that the plant on a systemic level could possibly uptake some if this aluminum sulfate.
A quick google search turned this up which also reccomends not using aluminum sulfate. We have a responsibility to all members to try and spread the healthiest information that is out there In regards to our beloved medicine. A two sec google search has turned up safer alternatives to lowering a soils ph.
here is a cut and paste from there and the link
http://www.sustland.umn.edu/implement/soil_ph.html
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.
:Sharing One:
