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91 comments on How Might We Be Fed? Part One

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Peter Salonius on March 12, 2009 - 8:21am Permalink | Subthread | Parent | Comments top

Further to my reply to Chrisvarik yesterday -

- as I have read many of the posts replying to this article concerning NITROGEN in agricultural systems, It ocurrs to me that there is not much appreciation for the ferilizer element that is NOW closest to global exhaustion - PHOSPHORUS.

I copy below part of an email exchange re: PHOSPHORUS that was initiated by my mailing the same OILDRUM essay that I rerred to yesterday's posting:
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From: Laird, David [mailto:David.Laird@ARS.USDA.GOV]

Sent: Thursday, January 01, 2009 14:59

To: Salonius, Peter

Subject: RE: Maybe there is hope for SOME cultivation agriculture

Peter,

I just read your internet article:

http://www.theoildrum.com/node/4628

Overall I agree with most of your analysis. Biochar is part of the answer and will make food production more sustainable. Mostly, I think it can buy time. For example, if we had global use of biochar on ag soils, perhaps we could make our PHOSPHORUS reserves last 300 to 500 years rather than 60.

David

======================================================================

From: Salonius, Peter

Sent: Wed 12/31/2008 10:42 AM

To: Laird, David

Subject: Maybe there is hope for SOME cultivation agriculture

Hello David A. Laird

Just read 'THE CHARCOAL VISION: A Win-Win ...... and Water Quality' Agron. Journal. 100(1): 178-181, 2008.

I have been suspicious about the role of charcoal in Chernozemic soils but your "guess" of 5 to 15% of the C in Midwestern prairie soils as a legacy of 10,000 years of prairie fires - is the first I have seen in print. So maybe there is a 'terra preta' aspect to the fertility of these soils. I went to agricultural college with a fellow who said that on their farm on the Canadian prairies (Vermillion) they had not needed to use fertilizer YET (early 1960s).

I have been tempted to get into the nuts and bolts of the "terra preta de indio" soils phenomenon for a couple of years -- especially after reading David Montgomery's recent book 'DIRT' which I am now reviewing for a forestry journal.

Peter Salonius

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Engineer-Poet on March 15, 2009 - 6:56am Permalink | Subthread | Parent | Comments top

Just as a reality check, phosphorus is potentially renewable.  Not only is phosphate rock being actively laid down in a few places around the world, anadromous fish such as salmon take up phosphorus from oceanic sources as they grow and bring it upstream when they return to their home streams to breed.

This is one more reason we should remove water diversions and other threats to salmon runs.  They are far more important than this year's crops.

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Luke H on March 15, 2009 - 5:07pm Permalink | Subthread | Parent | Comments top

Like many I like the idea of giving wild salmon better odds every chance we get (I've netted a 'few' reds leaving the Bering Sea over the years myself). Just curious though, what percentage of the phosphorus salmon gather could be actually mined without tearing up the salmon habitat? A related second question, how much phosphorus would be the maximum anadromous fish could put into our system a year and how does that compare to what we take out? I wouldn't be surprised if most of those numbers are tough to find.

I'm guessing catching the fish and eating them doesn't help the phosphorus to build up either. The big runs are spectacular, but we are not going to just leave the fish alone even if by some miracle we start to manage a whole lot more of the world's waterways in ways which allow full wild runs to return. I have a feeling we will never manage fish for maximum phosphorus production, but I could be wrong.

I'm guessing phosphate rock isn't being laid down near as fast as we are tearing it up, but I could be wrong there too. Just a reality check.

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Engineer-Poet on March 16, 2009 - 12:45am Permalink | Subthread | Parent | Comments top

A lot of the salmon already go to feed mammals and birds (both before and after spawning).  Bears and such remove the nutrients from the streams and deposit them on land; they eventually wash back out again, but that's part of a loop, not a one-way traffic.

If we caught the fish, ate them and cycled the nutrients back to fields, we could build phosphorus stores on land.  Our biggest problem at this time may be keeping the oceans productive enough to have the salmon return.

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Luke H on March 16, 2009 - 5:48am Permalink | Subthread | Parent | Comments top

The health of the oceans is a huge concern, right now it looks pretty grim, but not hopeless. I'm all for the return loops you mention, the more the better that is for sure. What I was pointing up was that it is very unlikely we could use the sources you indicated to replace the accessible phosphorus stores at near the rate we are now depleting them.

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91 comments on How Might We Be Fed? Part One

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