Gypsum in your organic soil mix!

[moses wellfleet]

If you have used gypsum or have any thoughts on this soil amendment please post here?

I have seen it mentioned as a source of calcium that will not alter PH. I believe it is mined from natural deposits of calcium sulfate?... Some folks seem to be throwing out the lime and preaching gypsum... Lets learn more?

 

[VerdantGreen]

i recently halved my dolomite lime addition and added gypsum to make up the difference.

plants seemed to like it and i added a bit more this recycle.

VG

 

[dank.frank]

1/3c dolo
1/3c gypsum
2/3c oyster shell

I use that mix per 1.5 cu ft of medium.

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The idea behind having more Ca in the medium is to increase the number of cation exchange sites, which is based on the "basic cation saturation ratio" (BCSR) theory. You can read about this at many different university agricultural extensions...

Keep in mind things like bone meal also have large amounts of calcium; in general Ca is not really that hard of a thing to supplement in soils.

The bigger picture focuses on having Ca:Mg:K:Na all in a particular balance.

This leads down the path of Albrecht ratios: "H, 10%; Ca, 60 to 75%; Mg, 10 to 20%; K, 2 to 5%; Na, 0.5 to 5.0%; and other cations, 5%"

Another name worth mentioning in this topic of conversation is Charles Walters, who Albrecht left all his work to and later started Acres magazine. Should also mention Neal Kinsey, who wrote a book called Hands on Agronomy that heavily discuss this general topic as well...

There are plenty of studies that support such ratios - but also plenty of studies that indicate it to have no general impact and to be much more costly...

Either way - the topic makes for some good reading. This is a bunch of the stuff I was reading back in 2008-2009...



dank.Frank

 

[Coba]

I like it because it has sulfur.

 

[VerdantGreen]

the other benefit of gypsum is that it improves soil structure.

it flocculates small soil particles (makes them stick together) and improves tilth (crumb structure)

traditionally in horticulture it is used to break down heavy clay soils into a more workable loam.

am i right in thinking that gypsum is somewhere between fast and slow in it's breakdown rates? probably 3-6 months, so re-amending at least some every grow or two might be good practice.

VG

 

[bigshrimp]

Its not Calcium Carbonate - that's always good for hardwater growers.

 

[dank.frank]

http://www.spectrumanalytic.com/support/library/rf/Gypsum.htm



dank.Frank

 

[moses wellfleet]

Ha great start to the thread, thanx guys, was hoping for VG and DF, and managed to get both already

Dank Frank are you recycling your soil?

 

[Scrappy4]

http://agnr.osu.edu/fall-gypsum-applications-improve-soil-increase-sulfur-and-calcium-next-crop

 

[moses wellfleet]

am i right in thinking that gypsum is somewhere between fast and slow in it's breakdown rates? probably 3-6 months, so re-amending at least some every grow or two might be good practice.

VG

In the link posted by DF it says that gypsum is 'highly soluble'. So I imagine it would leach out of the soil quite quickly?

 

[epicorchard]

I use a lot of native dirt heavy in clay. I use gypsum to soften and condition the soil. I'm not sure if it really has a place in indoor gardening unless you re-use your medium.

 

[epicorchard]

Heres a cool article on gypsum...

http://puyallup.wsu.edu/~linda chalker-scott/Horticultural Myths_files/Myths/Gypsum.pdf

 

[VerdantGreen]

In the link posted by DF it says that gypsum is 'highly soluble'. So I imagine it would leach out of the soil quite quickly?

it would be better described as 'moderately soluble' which is how wiki puts it.
it is a lot more soluble than calcium carbonate thats for sure.

if you are treating fields with it then it is usually added once or twice a year.

VG

 

[moses wellfleet]

I use a lot of native dirt heavy in clay. I use gypsum to soften and condition the soil. I'm not sure if it really has a place in indoor gardening unless you re-use your medium.

Yes many of us are seeing the benefits of re-using soil, but it comes with a hefty learning curve price tag!

 

[Gubar1]

I use it on my outdoors because Ive always been under the impression it breaks down slower then dolomite. Ill usually go half and half with dolo and gypsum then throw in some azomite.

 

[Granger2]

I've been reading up on Gypsum lately, and considering how it relates to high brix, and sulfates needed for aromatics.

There is micronized gypsum available, but so far I haven't found it locally. Online only in 50 lb bags. Shipping costs are prohibitive.

I have regular gypsum in a 50 lb., and I'm incorporating it into my coco at 2 Tbl/gal. I would like some micronized, with its quicker solubility, to use as a top dressing about the last 4 weeks of bloom.

Does anyone have ideas about this strategy and do you know of sources for micronized gypsum in smaller bags than 50 lb? Thanks. -granger

 

[dank.frank]

@Moses - yes, I recycle my mediums.

@Granger - I don't know that it's micronized, but the Espoma 4# bags of gypsum is a fine powder as opposed to being pelleted.



dank.Frank

 

[Scrappy4]

I've been reading up on Gypsum lately, and considering how it relates to high brix, and sulfates needed for aromatics.

There is micronized gypsum available, but so far I haven't found it locally. Online only in 50 lb bags. Shipping costs are prohibitive.

I have regular gypsum in a 50 lb., and I'm incorporating it into my coco at 2 Tbl/gal. I would like some micronized, with its quicker solubility, to use as a top dressing about the last 4 weeks of bloom.

Does anyone have ideas about this strategy and do you know of sources for micronized gypsum in smaller bags than 50 lb? Thanks. -granger

A garage sale coffee grinder comes in handy on small amounts. There also nice for busting up buds, better get two, or steal your significant others.

 

[Scrappy4]

I use it on my outdoors because Ive always been under the impression it breaks down slower then dolomite. Ill usually go half and half with dolo and gypsum then throw in some azomite.

It's just the opposite gypsum breaks down much faster than lime.

 

[Speed Racer]

Nice thread. I have done some reading on gypsum before and still thinking to add to my mix as I found out too much dolomite lime will raise ph over 7. I use Oyster shell flour too and seems good stuff. I think maybe a tsp-tbsp gypsum for promix and maybe 2 tbsp for coco as mentioned. I am trying to diversify all my nute sources so to hopefully get a better rounded mix using more than one source for each specific nute. I use maybe a tsp only dolomite lime now and same or more of oyster shell flour and azomite. I use ro water too and still thinking to add some gypsum. Maybe only a tsp gallon with all my other cal/mag sources already added. Interesting stuff. I also read it can bind with salts and helps remove in the runoff, not sure, but very interesting. I went in a tunnel recently and saw some natural gypsum on the walls in spots, very cool. May have to give it a go. People say used in drywall, but many uses for many things and if it works it works. Any more info anyone? pros and cons? Thanks for the thread. peace... SR