<DrumBeat: August 17, 2007 The Oil Drum Peak Oil Booklet - Chapter 4: What Should We Do Now?>

105 comments on Peak Phosphorus

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Jason Bradford on August 17, 2007 - 12:37pm Permalink | Subthread | Parent | Comments top

I think you are correct that farmers are becoming better at managing fertilizer application. Have world sales of phosphate decreased because of greater use efficiency, or are sales still rising with previously mined phosphates stores being depleted to compensate for lower extraction rates?

Another reason for run off problems, in addition to over application, could be the type of phosphate applied. I believe those superphosphate products have been manipulated to increase solubility and rapid availability to plants, but since the soils are mostly dead and organic matter levels are so low, any excess phosphate runs off fast.

Organic farmers use products that are less immediately available, have slow release properties, and therefore don't have these run off problems.

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Foger Rox on August 17, 2007 - 2:10pm Permalink | Subthread | Parent | Comments top

In areas with low soil PH, runoff is more unlikely. In soil conditions with a PH of say... under 5.3, P tends to bond with soil particles, more so in fine/clay soils which have more surface area per gram.

Liquid calcium or Lime will raise the PH and make the "P" water soluble again.

N,P, K & Fe are not water soluble at low PH. So the mechanism of runoff should be of low concern in soils with PH below 5.3 or so.

See: cation exchange capacity

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semaley on August 17, 2007 - 3:33pm Permalink | Subthread | Parent | Comments top

Conveniently, Fertilizers lower the pH. If the pH goes below 4.5, then the plants suck up potential heavy metals (and I don't mean Black Sabbath). Below 3.5 pH, Aluminum becomes soluble and everything dies.

Expanding further, the fungus and bacteria association with the plant diminishes with these fertilizers (and much soil life is killed). The plants become bloated with water, which the herbivore insects take note and feast. Then the insecticides kill these "pests", but also the insect life in the soil. Without the insects to burrow into the soil, bringing down fungi, bacteria, and protozoa to the roots, the soil goes anaerobic.

Anaerobic soil means low pH, so even applications of Lime or whatnot don't work for long, as the nutrient plugs are already gone, the bacteria fight to keep a low pH, and nutrients wash out. Even worst are the blights that can now infiltrate an unprotected ecosystem (note fungi above).

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Foger Rox on August 17, 2007 - 5:11pm Permalink | Subthread | Parent | Comments top

Below 3.5 pH, Aluminum becomes soluble and everything dies.

http://soils.tfrec.wsu.edu/mg/chemical.htm

Aluminum starts becoming water soluble at 6.0 and lower.

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PH of 4.5 is a bit too late, the nitrogen ammonia cycle is basically stopped at 4.5. At a PH of 5.6 nitrogen fixation by plants starts to be problematic.

Anaerobic soil means low pH,

Water logged soil is anaerobic, re: lack of oxygen.

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robert2734 on August 17, 2007 - 9:36pm Permalink | Subthread | Parent | Comments top

Off topic but still an energy post. Both heavy duty and alkaline batteries use carbon and zinc electrodes but heavy duty batteries use an acid electrolyte and alkaline batteries use (you guessed it) potassium hydroxide. Alkaline batteries are mucho superior in every respect except initial cost and I never knew why until I saw your post. You do NOT want your electrode, in this case zinc, dissolving in your electrolyte.

Nickel Iron batteries, touted by one of us, last essentially forever because the electrodes are essentially insoluble in potassium hydroxide. They have other issues, but they last forever.

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semaley on August 18, 2007 - 7:37am Permalink | Subthread | Parent | Comments top

I shoulda known quoting from my Permaculture class. However, the pH and Aluminum problem is still around 3.5 pH when no plant can survive. The issue relates to the interaction between Phosphorus and Aluminum across a spectrum of pH.

http://www.plantphysiol.org/cgi/reprint/18/4/708.pdf

I'm sure there are other references out there.

Yes, water logged soil is indeed anaerobic. I'm trying not to write a book inside a comment, so have compressed the whole process of tilling, fertilizing, biocides, etc that comprise our conception of food "production" as fundamentally flawed and always ends in depleted soil and desertification.

PH of 4.5 is a bit too late

http://www.tropicalforages.info/key/Forages/Media/Html/Desmodium_heterocarpon_subsp._ovalifolium.htm
Extremely well adapted to low fertility, acid soils (pH 4-7), with high Al and Mn, and low P.

Let's not split hairs to fill in the 0.5 pH to go. It's out there, if you want to find a plant that "survives" it. However, below 3.5 is certainly a dead zone.

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robert2734 on August 18, 2007 - 2:04pm Permalink | Subthread | Parent | Comments top

Stream of consciousness. Nobody thinks without phospourus. Aluminum causes phospourus to precipitate. Aluminum is implicated in Alzheimers.

Blood is a mild base. Unless you suffer from acidosis. CO2 makes carbonic acid. Therefore exercise is bad for you. Couch potatoes have the best brains on the planet.

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105 comments on Peak Phosphorus

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