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Grittyville, WA

I thought gypsum was relatively benign chemically and too insoluble to worry about any adverse effects.
I hadn't considered any possible adverse affects but this article points out some. I know many growers have used it with success but after reading this (and according to this, not having a soil type that would benefit) I'll probably move on to other better methods of adding calcium. Its written by the local ag. university here, so I assume its good info:

https://s3.wp.wsu.edu/uploads/sites/403/2015/03/gypsum.pdf

[Last edit: 02/25/25 8:11:04 PM]

2/25/2025 8:06:31 PM

Menomonie, WI (mail@gr8pumpkin.net)

Yean. Their website states everything is a myth.

[Last edit: 02/28/25 7:17:14 PM]

2/27/2025 7:08:35 PM

Grittyville, WA

Maybe its only 50% good info. My plants tested ok for calcium the past couple seasons and in my pre season tests it appears that the gypsum I added damaged/inhibited the fine root hairs. This was unexpected, so I had to go looking for some other opinions about it. It may still provide a net benefit but... the alternatives might be better.

I think its fair to categorize it as something that "may or may not" help.

There may be some things like kelp/humic that would be more in the category of "it always helps". But I've read bad things about using excess kelp, too.

Well, if this is purely unhelpful, I apologize.

[Last edit: 02/28/25 1:08:17 AM]

2/28/2025 1:02:06 AM

Bethlehem CT

I have used gypsum primarily for its sulfur and calcium without bringing a pH change in the soil. I am curious as to the data he used to come up with some of those statements. Like this statement "Gypsum will not improve fertility of acid or sandy soils". Why isn't it adding any calcium or sulfur to the soil? Last I knew calcium and sulfur were coonsidered a key part of soil fertility!

[Last edit: 02/28/25 8:07:07 AM]

2/28/2025 8:03:48 AM

Grittyville, WA

Yes, there's a lack of clarity there... a bit of throwing wool at the readers face.

I know its easier to pretend to be smart than to grow a giant pumpkin... So I would still trust a pumpkin grower over this non-pumpkin grower.

I think its true that gypsum will have a better effect in clay soils that lack calcium and good drainage, but its hard to qualify/quantify the other statements.

There are areas of my property where it would still help but other areas where the organics and past amendments may mean that I should not add more.

Growing giant pumpkins is a different ballgame. A lot of gardening/ crop advice, even from a university, would probably only get a person mediocre results. For them a 1,000 lb pumpkin is a good result. But that would be a poor result for a top pumpkin grower. Sometimes its a case of living in two different worlds.

[Last edit: 02/28/25 11:55:11 AM]

2/28/2025 11:54:19 AM