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I found out that the soil in my neighborhood is heavily compacted when the houses were built. Therefore, the roots of my plants have had a hard time penetrating it. I was advised to spread gypsum all over the yard and water it down, do this once a year. Any harm to the existing trees? Is now, in the heat of summer, OK to do this? I have a layer of wood chips on top too, so it'll be a big job brushing them aside, spread the gypsum, and replacing the wood chips afterwards.

Thanks,

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Richard

Get a cheap soil test kit to check the calcium already in your soil. Adding more won't necessarily help. Many of the reported benefits in California soils have actually been due to the heavy soaking of the soil rather than the gypsum itself. If your soil is low on calcium, consider using "Liquid Gypsum" instead of dry -- it is more cost effective and easier to apply.

The mulch is a very good thing. You could put down a 1/4 inch layer of worm castings under the mulch, or to save money use humic or fulvic acid.

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sbl

I used it on my garden and it has completely prevented blossom end rot that used to be a major problem. Over application can cause problems with uptake of other minerals such as iron and magnesium.

damaclese

my soils are naturally full of Gypsum 80% to exact and i can tell you this getting my plants to take in Iron is a pain i have to add it quite often

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Want Them All

Where can I find a "cheap soil test kit", Home Depot or Lowes? BTW, I'll be in San Diegoo for the Labor Day weekend, is it OK if I pick up some fertilizers from you?

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Nicolas Naranja

The calcium in the gypsum makes the soil clay particles clump together so that it makes the soil behave as if it were made of large sized particles. It can do wonders for drainage and workability. Another option would be to use large quantities of organic matter and work it into the soil. Your goal is to get a crumb structure in your garden soil.

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Richard

Here in the west, our clay soils often already have a lot of calcium in them so that more calcium is not necessarily a good answer. Our water supply tends to be alkaline as well. A long term plan to keep the soil pH in the 6 to 6.5 range helps a lot. Carbon is sometimes scarce in these soils, so adding more via plant matter, humic acid, etc. can be very beneficial.

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Want Them All

2 months ago, I applied a "soil acidifier" product around some fruit trees. Lightly sprinkled the powder away from the trunk, worked it into the soil, watered. Many of those trees lost their leaves, or failed to show as much growth or did not appeared as lush as before the application. The fig was hit the hardest, all leaves browned, curled up, fell. Now it's showing lots of new growth at the tips of branches. The avocado, which had nice green, large leaves, dropped all of them. The numerous new growth now only have very small leaves, and about half of those small leaves curled up, dried out, fell down. Even a citrus was hit, all leaves yellowed, feel very dry and hard to the touch. It's been very frustrating not knowing what the right thing to do is. The soil is very alkaline, as expected, I just wanted to reduce the pH as much as feasible, that was why I bought the "soil acidifier", came in a small bag at Home Depot.

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Richard

Fruit trees and most plants have feeder roots near or at the surface. Some of these are as fine as human hair and you will only see them upon very close inspection. "Working into the soil" cuts these roots. If you have a thick layer of mulch (1-inch diameter), then you can rake the larger pieces away, apply your amendment, and recover. I never bother -- just apply directly on top of the mulch and then water in. Subsequent irrigation cycles will take it farther on down.

As for "what and how much" to apply, that depends on the pH of your soil and the pH of your irrigation water. It is best to take a long term approach with something that adjusts the pH of your irrigation water. This way, the pH of the soil is slowly changed to the water pH and stays that way. There are multiple ways to do this: a plant material or granular fertilizer that the irrigation water hits everytime it comes on, or a water-soluble fertilizer that is injected at a very dilute rate into your irrigation water.

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Ohio'sBest

Add nails..........works great for me.

Nicolas Naranja

I'm willing to be that there is quite a bit of sodium in the soil as well though and the goal of gypsum is not so much to add calcium for the plants but to add calcium to the soil to change the way the individual soil particles(clay colloids) act. If a clay colloid has a sodium or potassium ion attached to it it tends to stay as a single colloid, however if it has calcium or magnesium attached to it, it can attach to another soil particle and create a larger particle. I think it's pretty hard to overdo calcium especially in the form of gypsum since you aren't altering the pH. From what I recall from my soil classes it is just about impossible to give plants too much calcium. The key is to not add calcium in a form that will raise the pH such as calcium carbonate, but in that case it's not necessarily the calcium but rather the pH change. If you could get your soil to about 6 or 7% organic matter you'd probably have great soil structure for a long time of course that would likely require about 1.5 tons of compost per 1000sqf

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Nicolas Naranja

I'm willing to bet that that product had aluminum sulfate in it and you have to be extremely careful with it. In agricultural areas around here with Iron or manganese issues we will apply the product in a chelated foliar form, which works pretty well.

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Richard

Or 6 applications of 1/2 cup of fulvic acid.

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Nicolas Naranja

Now I know that it doesn't rain much in southern california, but 6 applications of a 1/2 cup of fulvic acid to 1000sqf of soil would do as much good as urinating on it. I know a lot of "organic" manufacturers try to market miracle foods to people but such a statement ignores basic soil chemistry. Soil pH and structure are games involving thousands of lbs of product per acre.

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Richard

The purpose is to add carbon, not change the pH. I'm very comfortable with the recommendations from UC Davis for our soil.

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Nicolas Naranja

3 cups of fulvic acid isn't going to do much at all to the organic matter content just because of the simple math involved. Lets just say that it weighs 10 lbs per gallon so you are spreading 3.75 lbs of chemical on 45913 lbs of soil so you have increase the organic matter content of your soil 0.008%. There may be other benefits to it such as chelation, but it's just not going to do the same job as spreading 1.5 tons of compost on your garden.

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