crushed granite as a soil amendment?

shane1130

Anyone have any opinions on the use of crushed granite, aka poultry grit, as a soil component? *I have been happily using it, ever since I started bonsai. *Recently I read an article saying crushed granite was not good for the roots. *What do they traditionally use in Japan again?

Shane

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TreeBay

Hi Shane,

Do you mean the crushed granite that is used to surface asphalt roads, or the decomposed granite that is found at the base of some of these bluffs and cliffs? Sorry, I know you said poultry grit, I just don't have an inkling of what that is.

Where did you find this article? *I am trying to think which properties of crushed granite would be bad other than its weight. *Seems pretty inert to me, like glass.

At any rate, if what you are doing is working well for you, I would take what you read with a grain of salt.

Regards,

Matt

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ripsgreentree

Shane I think that you will find that there is a difference between poultry grit and decomposed granit. Poultry grit is basicly the quarts componet of granit. Decomposed granet is made up of Quarts Feltspar and mica. When the feltspar and mica decompose it releases componets into the soil that many plants do not like also this decomposing material will clog a soil mix and starve your plant of much needed oxygen. So I would say that chicken grit would be an ok componit for bonsai soil, decomposed granit is not. Also understand that a lot of bonsai experts in sothern california would disagree with me.

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ripsgreentree

It requires an open hand to give and to recieve.

I have not tried it [ still using Turface ] but I've heard that you have to watch out for some of the poultry grit because it's actually crushed oyster shells. It has a lot of calcium and will raise the ph of the soil. Granite sound like it would be harmless.

Tony

bonsaial1

I think the granite issue can be summed up by, where did the decomposed granite come from. I know when I had my pool built, I had a waterfall built into the pool. 15 tons in the fall, and 20 tons on the bond beam. Looked real cool, but I digress, I had about 10 tons of boulders in my front yard and thought I could save some money by useing the stones I allready had. The landscaper sent a guy out that had a rock testing unit. They chisled off a portion of one stone, and put it into a crushing unit. The stones failed. The stones were not dense enough to be used as structural units. What does this have to do with granite in your soil mix, plenty. I feel that decomposed granite is in all states of decomposistion. We have a granite pit here in Sanger that has provided D.G. for about 50 years. It is very hard holds up well under motor traffic in driveways, but I would not use it in my potting mix. Why, well it is still undergoing decomp. The stuff is brittle enough that if used in soil mix it will breck down as Rip says and clog soil. But,,, if you use the granite that the southern Cal. guys do, I'm speaking of folks like John Naka, Harry Hirao, Ernie Kuo, Roy Nagatoshi, Richard Ota, Mel Ikeda, etc., you would see a differance in the granite. The D.G. from the Mojave desert is very old. You could say that the D.G. from this area is done decomposing. It is the consistancy of safety glass that has been shattered. Sort of little polyhedrons of quartz. there are no minerals left. This stuff is very inert. Once it has been sifted for size, I don't think it would breakdown in our lifetimes. The grey stuff that we have here in the valley is very young on the oldness scale and is still very actively decomposing, you can sometimes smash it in your bare hands. I think the bottom line is, Try it one season, I don't think the D.G. would be the reason you might lose a tree. You might find out that it is great, or just the oposite. I don't like uniforms in school and I think everyone should try things and see what works for them. It would be a boring world if we had cookie cutter soil.

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shane1130

Thanks for the info. The stuff I have is pretty hard, not any crumbling. It appears to be what it says it is, crushed granite. Decomposed granit would be found crumbling on it's own and the stuff I am using has definitely been mechanically helped to form small granules. I started using it because it was recommended in John Naka's book. It is quite sharp and works well to split roots that push on it. I am not sure of its exact origin. The bag says Granite City Grit.

denny

i would be interested to know how it works.

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Denny
Still Growing in zone 9
So.Cal.

shane1130

I have been using crushed granite since I started in bonsai 7 years or so ago. It is quite hard, one time I wanted some smaller peices for a shoin and the granite made dents in the hammer and damaged the concrete surface I was pounding on, but didn't really crush into smaller peices.

denny

but it must be working well if your still useing it?

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Denny
Still Growing in zone 9
So.Cal.