Steve - In the nursery when we told customer it was hard to overapply gypsum we weren't talking 20lbs/sq foot we were talking a handful/sq foot and so no precise measurement required other than the hand. I'd think a consult with the local ag departtment would be highly advisable before you entomb the plants in gypsum or through the whole soil sytem entirely out of whack.

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johnw coastal Nova Scotia

1 handful per square foot would be sound about right, but to maximize the loosening effect of the soil, I might do more. The supplier also won't give me the discount unless I take an entire pallet of it, do maybe I can spread it around over a larger area as I can forecast that the radius of the groves should be expanding a few inches per year if they happen to be species that are hardy enough to handle my climate.

The only bamboos which I think probably wouldn't benefit from deeper aeration would be the aureosulctas, bissettiis, and rubromarginata or any others that prefer spread/quantity over quality since those species seem to prefer keeping their rhizomes relatively close to the surface, and spreading all over the place. Something like Atrovaginata which tends to stay put, growing taller and thicker would definitely do better even if the root zone gets 5 inches deeper.

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I did get the gypsum in today, and applied it to all my plants. On the bamboos, I spread approximately 3lbs per square foot, up to around 2-3ft away from the culms to as far as I believe rhizomes should run to this year. I used to steel broadfork to work as much in as I could, and avoided using it in the center of the grove since there are too many roots and rhizomes, perhaps forming a solid layer which I hope the gypsum can still penetrate through. Another purpose for the manual aeration is so the gypsum doesn't run off before it gets a chance to seep into the soil. 1 ton of gypsum is not all that much the way I'm using it.

I did look at some rhizome ends, and it still doesn't look like anything is close to starting their rhizome growth yet. Atrovaginata did grow rhizomes before shooting season started, but those have either stalled or aborted, and probably won't start up again until after the 2nd wave of shoots, still rising are nicely leafed out.


My idea now is to give it a few days of rain to allow the gypsum to slip through the cracks, and hopefully wash down deeper into the root zone. I then intend to top dress the groves with some organic matter. I do have lots of weeds growing, but I prefer to let them max out their size before harvesting them, and I usually put a layer of grass clippings on top of that. I will than top that off with some manure to try and trap in the nitrogen into the soil.

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Wow! 30 years worth of gypsum all at once! That'll eliminate any calcium deficiency for a while!
Hopefully in a few years it will also loosen your clay as intended.

Out of curiosity, what type of gypsum did you apply? Mined, synthetic, or recycled drywall?

Pretty scarey to me - kill or cure.

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johnw coastal Nova Scotia

I'm guessing probably recycled drywall since there were a few whole chunks of it in the powder. This is the actual product.
http://www.usagypsum.com/product/3.aspx

We haven't gotten any sunshine or much of a break from this monsoon season yet, but it looks like we may get a couple days of sunshine through the weekend with warmer weather so I expect all the plants to explode in growth as they've been held back by too much rain and cool weather.

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Hopefully that gypsum is low in boron and the bamboo doesn't suffer from boron toxicity.

More gypsum?

Steve you had better google "too much gypsum". I have a sinking feeling that you have already overdone it with this stuff.

Read this on salt acculation due to over-application. http://www.soilduck.com/2010/09/soil-myths-3-clay-breaker-is-not-always.html

Properly applied gypsum takes 1 or 2 years to work, it's not an overnight cure. If you messed up you won't be growing anything for years to come on that soil and we don't want that. I doubt there is a reversal procedure aside from removing all soil and replacing it with fresh.

Stinking hot here for 4 days running now. A friend was here last week from Alabama and he was knocked flat - it's cooler there - but no one has air-conditioning here aside from apt. & office towers.

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johnw coastal Nova Scotia

I'm not too worried about it because the only plants I applied this stuff heavily on was the bamboos and fruit trees because I knew they have the potential to produce deeper roots than anything else.

All my flower beds and vegetables only got a few handfuls vs a few bags for the bamboos.

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I found some scrap drywall the other day.
Shall I join Steve in this bamboo torture, er, experiment?

If you are not under the fragi-pan layer, then it may not even apply to your area, but around here, it does seem like the gypsum is helping in getting rid of the drainage problem.

If it does indeed still encourage deeper roots, the only benefit I could see is a potential increase in hardiness. There's one thing that I've always wondered about leaf hardiness. I've seen a grove of aureosulcata tolerate -8F without leaf burn, but their bamboo was in a decline near a pond.

My neighbor up north of me closer to the lake only applied a layer of leaf mold on his bamboos, letting the leaves be exposed, and none of them leaf burned at all, even dulcis which was nowhere nearly as developed as mine. It may be that keeping the rhizomes unfrozen so that the grove can uptake water is enough to prevent many species from leaf burning. The reason I'm suspecting this is because marginal species such as dulcis, and moso, only got leaf burned on the extremities, and more so on the older culms which are a bit less efficient in their uptake of water.

My current tarps aren't even large enough for me to tarp something as large as my atrovaginata anymore so if I really wanted to ensure they don't get leaf burned, applying a few inches of leaf mold or manure may be the best option eh.

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I always wondered, how can a plant get water through freezing cold culm up to it's leaves that are getting desiccated if roots and rhizomes are not frozen. My guess would be, that no matter what, leaves will get killed if temperature stays below freezing for a longer period of time with some help from wind.

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There's no way that the gypsum has done anything yet Steve. From what I've read it takes months or years to work its magic, unless I misunderstood.

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most soil ammendments take a few weeks to a year to really work. Even doing permaculture it takes 3 - 5 years for the garden to "pop". If I can guess, the gypsum is absorbing excess water atm...

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