Re: CULT: fertilizer chemicals (good? bad? for whom?)
- Subject: Re: [iris-talk] CULT: fertilizer chemicals (good? bad? for whom?)
- From: o*@aol.com
- Date: Wed, 21 Aug 2002 11:05:12 EDT
In a message dated 8/20/2002 6:12:30 PM Central Daylight Time,
unionzone@yahoo.com writes:
> I bought a superphosphate labeled 0-42-0 (or something).
>
>
> I know nothing of the true chemistry of it all. Does this
> bag of fertilizer have in it any "inorganic compounds"
> or chemicals that are not naturally occuring?
>
> I thought I had read that phosphates are adding to run-off
> problems and algae blooms in the Midwest. My beds (eventually)
> drain into the Mississippi.
>
> I don't want to throw things out of whack just for
> a couple of extra blooms.
>
> Can anyone give me scholarship or resources on the matter?
>
Super phosphate is produced by treating phosphate rock with phosphoric acid
to convert the phosphorus to a form that it may be used by plants. And
contains 42 to 50% P2O5. In your purchase 42% P2O5.
Normal phosphate is produced by treating the phosphate rock with sulfuric
acid for the same purpose and contains 18 to 20% P2O5.
Phosphate rock is a naturally occurring mineral that has been mined in
Florida, Tennessee, Utah, Idaho, Montana and Wyoming. While P2O5 is present
in the rock itself it is not typically or readily available to plants in most
soils hence the manufacturing process.
It is of little consequence whether one chooses to use a 20% or a 40%
concentration product. The key to successful use is to apply the proper
amount for the concentration you are using. Necessarily, you must start with
a soil test if you wish to apply the proper amount. Application of excess
amounts contribute to run off. Poor incorporation into the soil contribute to
run off. Removal of weeds, grass and under story plants contribute to run
off.
Generally speaking, properly incorporated into the soil in appropriate
amounts P2O5 remains in the soil until it is used by the plant as does K2O
(potassium component in fertilizer). Excess on the other hand can to a degree
be leeched to the soil surface as salts and contribute to chemical
contamination (run off). Excesses at extreme levels can also poison your
plants. Again soil tests are highly desirable and should be considered a
routine component of responsible use.
The vast majority (all for practical purposes) of the elements represented in
the periodic table are naturally occurring as are many of the rudimentary
compounds found in common use by gardeners. It is not use but irresponsible
use that create contamination problems.
Yes, your fertilizer is inorganic. The P2O5 in a 50# bag is the same that
might be found in 525 # of ashes (arguably no longer organic since the
organic source has undergone chemical conversion through burning). Or, you
could add 1,400 pounds of cattle manure. Or you could add 1500 pounds of
digested sewage sludge. Each contains the desirable phosphorus as a plant
nutrient in a usable form. Each comes with its own set of benefits and
deficiencies. Each is capable of producing run off problems with
irresponsible use.
Hopefully this aids your effort to put phosphates in perspective,
Bill Burleson 7a/b
Old South Iris Society
Obstacles are those frightful things you see when you take your eyes off the
goal.- Henry Ford
[Non-text portions of this message have been removed]
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