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Where to find Rock Phosphate for organic fert.

Posted by pkapeckopickldpepprz z9 a/b FL (My Page) on
Thu, Nov 2, 06 at 9:58

I see a lot of organic Rose Fertilizers that are hommade usinga material called rock phosphate and they mention not to confuse it with triple phosphate or any of the phosphates sold in stores. My question is where does one get this rock phosphate? Can I just substitute the rock phospahte part of the ingredients with bone meal?


Follow-Up Postings:

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RE: Where to find Rock Phosphate for organic fert.

Bone meal and rock phosphate are both mostly calcium phosphate. Bone meal has a more open crytal structure and a higher percent of its phosphorous is available to plants. I see no problem at all with substituting bone meal for rock phosphate but you might want to adjust the recipe for the increased available phosphorous in the bone meal. You can buy either bone meal or rock phosphate from Espoma.

Triple phosphate is essentially rock phosphate which has been acidified. This makes more of the phosphorous available to plants and results in an appreciably more economical fertilizer - but also makes the stuff a synthetic chemical and not approved for organic gardening.

Here is a link that might be useful: Espoma


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RE: Where to find Rock Phosphate for organic fert.

I've read that you can even use Super Triple Phosphate from those on the Rose Forum (not sure if it's still organic) without harming roots, but I have read otherwise that the triple superphospahte is quickly absorbed and seems it would burn.


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RE: Where to find Rock Phosphate for organic fert.

pkapeckopickldpepprz, the general name for all acidified rock phosphates is "superphosphate". Plain superphosphate was made by acidifying with sulfuric acid, a process which also produces gypsum. If, instead, the rock phosphate is acidified with phosphoric acid, a product called triple superphosphate is produced and it's exactly the same stuff except no gypsum by-product is present. Essentially all superphosphates on the market today are triple superphosphates no matter what they are called.

Salt index is the usual measure of a fertilizer's tendency to burn roots. Triple superphosphate has an exceptionally low salt index and is very unlikely to harm roots. I guess my opinion about phosphorous fertilizers in general is that an organic rose gardener should really minimize the use of all forms of phosphorous in an effort to encourage the growth of symbiotic root fungi, the mychorrizae. In any case, I think bone meal and rock phosphate applications are a waste of time and money and, ultimately, a waste of our mineral resources.


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RE: Where to find Rock Phosphate for organic fert.

I'm curious why you mentioned triple superphosphate along with BOne meal as being a waste of time and money? They seem like legitimate ammendments to me, and have been proven for plants. Are you saying for Roses they aren't that important? I made the famous Rosemagazine tonic with alfafa meal cottonseed meal epson salt, bone meal blood meal and I didn't use the rock phospate and didnt know if I could substitute with triple superphospate, so I doubled up on the bone meal. Well any event the roses seemed to like it.


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RE: Where to find Rock Phosphate for organic fert.

My comments were directed at rock phosphate and bone meal, not at superphosphate. Treatment of the mineral resource, rock phosphate, with acid to synthesize superphosphate increases the plant-available phosphorous by a factor of 5 to 15. Spreading rock phosphate or bone meal directly in the soil strikes me as a waste of a mineral resource.

The users of rock phosphate and bone meal are almost exclusively home gardeners. Packaged for the home gardener, these fertilizers usually cost more than the same weight of superphosphate, and provide much less available phosphorous. That's a waste of money.

Many home garden soils contain an excess of phosphorous and this inhibits the michorrizal root fungi on a rose which would otherwise provide the rose with adequate phosphorous from the soil. If you are using an organic fertilizer containing alfalfa and cottonseed meals, these contain adequate phosphorous in themselves and adding bone meal or rock phosphate might be a waste of time, and money, and resources.


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