gypsumwhat is it good for?

Gypsum~what is it good for?

Interesting analysis of the pluses and minuses of gypsum here:

http://www.puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/Myths/Gypsum.pdf

I do need a source of calcium which does not contain magnesium as I have a barely adquate level of calcium but way too much magnesium. However one of the the possibile downsides of gypsum--a reduction in mycorrhizal acticity--makes me think calcitic limestone will be a better choice.

Thanks for the link. It was suggested to me on another forum. So I just wanted to get some idea what it was good for.

It is interesting that Linda Chalker-Scott thinks that heavy clay soils only exist in the Southeastern part of the US. We have both heavy clay and high salt in many parts of the west, hence the historical popularity of adobe brick buildings.

Gypsum has been a real blessing to our garden soil. Even after soaking, it took a grub hoe to break up the heavy clay hardpan. We mixed in a lot of compost (~60% compost with 40% native clay soil) and it still took three days to drain. The gypsum gave us a good tilth and the soil lab test showed a healthy population of soil microbes, including mycorrhizae.

Our soil is far to alkaline to use lime.

garden_mermaid....looking around I see that gypsum can address the problem of excess magnesium. The calcium in gypsum (calcium sulfate) is replaced by magnesium forming magnesium sulfate (Epsom Salt). Calcium, which I need more of, stays behind. Magnesium,which I need to get rid of leaches out. This is why Epsom Salt is relatively safe. It doesn't stay in the soil long enough to do much harm.

I will try 40lbs on 1,200 sq ft. this fall. If it works, the spring soil test should show better (higher) levels of calcium and no excess magnesium.



This message was edited Jul 19, 2008 8:45 PM

We had a patch of hard ground that would not let water penetrate and the grass wouldn't grow. A friend sprinkled some 'gypsum' on a small area to prove that within a
week the grass would be greener. It was watered and the water did penetrate this time. We forgot to keep watering it but it was a bit greener! It worked! The soil was made to accept the water, thus feeding the roots and making the grass grow!