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  • From: Keith Johnson <keithdj@mindspring.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Phosphorus Theft
  • Date: Tue, 08 Dec 2009 15:50:55 -0500

fdnokes@hotmail.com wrote:
I've never been a fan of fertilizer, and the permaculture movement is largely about supporting nature to create good soil, but it does make sense to acknowledge that the current infrastructure that is responsible for feeding the millions does rely on phosphorous.
It is not merely the "current infrastructure of agriculture" that depends on phosphorus but all life on earth, i.e. the original infrastructure. It is a component of key molecules such as nucleic acids, phospholipids, and AdenosineTriPhosphate, and, consequently, plants cannot grow without a reliable supply of this nutrient. All organisms that eat plants also need phosphorus and we are included in this. It happens to be a nutrient that can be lost from soils and once it is gone it must be replaced. That would normally be done by cycling ANIMAL manures (especially from insect eating birds, and humans) back into the soil. If your soil doesn't have enough you will need to provide it. *Get a soil test.* The continents are "leaking" what they should be conserving and this loss generates vast dead zones in our oceans. Its for this reason that I have supplemented rock phosphates in my own and client's gardens. So far it's still relatively cheap despite substantial price increases.

(snips from http://www.energybulletin.net/49686)

*Mobilizing phosphorus present in the soil *

In many soils phosphorus is naturally present in sufficient amounts, however, it may be chemically locked up and not available for plants. Most of industrial agricultural soils in Western Europe and North America are oversupplied with huge amounts of superphosphate fertilizers, which results in binding phosphorus up with other elements so it ends up unused in the soil. In consequence, the concentration of phosphorus may be as high as 750 ppm, while only 45 ppm is necessary for growing grains . To determine whether you have a sufficient level of phosphorus in your soil, the surest way is to make a soil test. If the amount of phosphorus seems to be okay, but your plants show signs of phosphorus deficiency (purplish leaves, stunted stems), you may need help from a specially skilled team of phosphorus extractors -- fungi. Fungi are decay experts in soils. The enzymes that they secrete allow them to break up lignin, cellulose, chitin shells of insects and bones of animals, which are too difficult to digest for bacteria. A single teaspoon of a healthy soil may contain several meters of fungal hyphae, invisible to the naked eye. The optimum range for phosphorus uptake by plants is pH 6.0 -- 7.5, and on either side of this range phosphorus becomes immobile. A conventional approach would be to adjust pH by adding sulfur in alkaline soils or lime in acidic soils.

There are many soils around the world that are naturally deficient in phosphorus, such as soils in the Amazon Basin, on Java or in Australia. Others have been damaged by inappropriate farming practices -- bare soils were flushed by rains, which washed away phosphorus, they were depleted by overharvesting of crops and their natural soil food webs were destroyed, making it impossible for plants to feed on anything other than artificial fertilizers. *While soil food webs can be restored, wherever there is not enough elemental phosphorus present, for any reason, it must be brought back by the farmer. The other option is to wait until mountain-generating processes raise the bottom of the sea, where phosphate fertilizers end up. When the new mountain ranges are formed, the rain will start to wash phosphorus out of the rocks, making it available for plants again. But this will take some time -- around 10-15 million years....

*Superphosphate fertilizers are made from chemically treated phosphate rocks. They are not recommended for use as they are highly concentrated and reactive. When applied on the field they react with calcium, iron, magnesium and aluminum, creating within seconds compounds that make phosphorus unavailable for plants. They may react also with trace elements, locking them up and causing deficiencies of micronutrients. Superphosphates are water soluble and they can be easily washed away by rains before plants have a chance to assimilate them, which later may cause the eutrophication of lakes and rivers. Not to mention that high concentrations of phosphorus in fertilizers (above 10) are lethal to mycorrhizal fungi.

Another material that is rich in phosphorus is guano -- bird or bat droppings. Bones of fish that are eaten by seabirds contain a lot of phosphates, and as a result seabird guano also contains a high level of phosphorus. Guano has accumulated over centuries on small islands on the Pacific Ocean or on the coast of Chile and Peru, where it was mined in such large quantities that its deposits are now severely depleted. In contrary to phosphate rocks, it is a renewable resource, however, only over a long period. Apart from phosphorus, guano also contains high levels of nitrogen and calcium. It can be fresh, semi-fossilized or fossilized, depending on the source.

Phosphates can also be found in mud from ponds, in freshwater mussels, in fish waste, in algae or in recent volcanic ash. Many plants, such as comfrey, lupine, sweetclovers, nettle or vetches accumulate phosphorus and they can be used as green manure. Note, however, that they don't produce phosphorus in the way that nitrogen is fixed from the air by legumes. Rather, *they just extract phosphorus from one place and you can put it somewhere else, leaving the source with less phosphorus*.

Bill Mollison: "Of all the elements of critical importance to plants, phosphorus is the least commonly found, and sources are rarely available locally. Of all the phosphate fertilizers used, Europe and North America consume 75% (and get least return from this input because of overuse, over-irrigation, and poor soil economy). If we really wanted to reduce world famine, the redirection of these surplus phosphates to the poor soils of Africa and India (or any other food-deficient area), would do it. Forget about miracle plants; we need global ethics for all such essential resources."

It is possible to calculate a fair share of the remaining phosphate rocks for each country, depending on the soil's condition and number of population. And that's exactly what should be done. A global agreement is necessary for sharing the last phosphate rock reserves in a common sense way.

Our current industrial agricultural system and the global economy that supports it are inherently unsustainable. Extracting a limited resource, such as phosphorus, and sending it to landfills or dumping it in the ocean doesn't make much sense. Sooner or later reserves of phosphate rocks will become depleted, then what? There is some back up in the form of deposits on the continental shelves and on seamounts in the Atlantic and Pacific Oceans, but the cost of mining it can be very high and even if industrial farmers were able to buy them, what about farmers from Botswana? What about farmers from Madagascar or India? What will be the cost of food, when the price of fertilizers goes up? Recycling phosphorus is just common sense and it seems inevitable, if we wish to continue living on Earth. It means that the exchange of our entire food supply and waste management systems is inevitable as well.

Why wait till the industrial food supply system collapses from lack of phosphate fertilizers or because they are too expensive to buy? Farming the way nature does provides not only healthy soils and good yields, but also nutritious food, flavorsome food.

If we manage to close the phosphorus cycle in our countries soon enough, we will have plenty of phosphate rocks left. We will be able to use them for restoring degraded lands, for planting trees, and greening our planet once again.

--

Keith Johnson
"Be fruitful and mulch apply."
Permaculture Activist Magazine
PO Box 5516, Bloomington, IN 47407
(812) 335-0383
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