[Terrapreta] interesting situation

[MFH]

More info here:  www.fromthesoilup.com.au/soil/ca-mg-ratio

 

M

 

  _____  

From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Jim Joyner
Sent: Saturday, 10 May 2008 12:20 AM
To: Terrapreta at bioenergylists.org
Subject: Re: [Terrapreta] interesting situation

 

Thanks max. 

That statement doesn't appear on A&L's analysis so I've never seen it. I
guess what I don't understand is, how do you figure the amount of calcium or
magnesium you need in the soil from a ratio? You would still need to know
what one figure or the other.

Also, I don't understand what the ratio represents. Why a higher ration in
heavy soils than light soils? (By light, I assume you mean sandy or silty.)

Using percentages of base saturation, I can calculate to the pound how much
of either I need. And, interestingly, the ratio of 60-70% to 10-12% is about
5:1/7:1 at the extremes. Getting it much closer one way or the other is
going to be difficult when you are talking about what is actually in the
soil. I mean, there can be a lot of variation from one foot to the next.
Looking back through my soil tests correlated to response, I can't see any
differences, hence, I am puzzled by what is "critical" and why.

I'm don't mean to chide you on this. There must be something new going in
soil analysis. I'm just trying to ferret out the kosher from BS.

Thanks,

Jim

MFH wrote: 

Jim,
 
My recent soil tests give data like:
 
Calcium (Mehlich III)          389ppm (ideal = 1347)
Magnesium (Mehlich III)               384ppm (ideal = 157)
Ca/Mg ratio                           0.61:1 (ideal = 5.15:1)
 
The explanatory notes include:
 
CA/MG Ratio:  This is the single most important fertility ratio and should
be around 5:1 for light soils and 7:1 in heavier soils. Low Ca/Mg ratios are
usually indicators of serious problems. These include compacted soils,
bacteria that can't proliferate, and weed take over. An appropriate Ca/Mg
ratio will be an obvious consequence of the successful achievement of cation
balance.
 
>From other sources, if the CA/MG ratio is below 2, it is difficult for the
plant to take up potassium.
 
There's lots of web info available, e.g:
www.spectrumanalytic.com/support/library/ff/Ca_Mg_ratio.htm
 
Cheers, Max H
 
 
 
-----Original Message-----
From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Jim Joyner
Sent: Friday, 9 May 2008 10:05 AM
Cc: Terrapreta at bioenergylists.org
Subject: Re: [Terrapreta] interesting situation
 
MFH wrote:
  

Calcium/Magnesium ratio is critical. Should be 5:1 for light soils and 7:1
in heavier soils.
 
Max H
    

Max,
 
I think calcium and magnesium are critical in the soil but I have never 
seen soil tests express it that way. I thought the ideal 
calcium/magnesium would be a a percentage of base saturation (70%/12%). 
Having said that, however, when Richard got his numbers, I believe the 
results showed less calcium as a % than that, but "high". Is there 
something you know that I don't?
 
Thanks,
 
Jim
  

 

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