Agriculture's Phosphorus Crunch

by Natasha Chart

categories: Farm Economics, Pollution

Published August 04, 2009 @ 08:16AM PT

From Parke Wilde at the U.S. Food Policy blog, industrial agriculture's much-needed phosphate fertilizer supply is running into trouble as growing demand meets environmental and space constraints on phosphate mining (pictured here.)

Fertilizer-hungry industrial crops need vast amounts of phosphorus, and it has increasingly come from mineral phosphates that need to be mined at great financial and environmental cost. It used to come from well-managed animal manure, but even this is applied in excess in certain areas. All around, phosphates applied to fields are further ruining the planet's water supply:

Even more highly concentrated in farm runoff than pesticide residues are plant nutrients, such as nitrogen and phosphorus.

... In the [federal government's 1998 National Water Quality Assessment], phosphorus levels exceeded suggested EPA standards in 80 percent of stream samples. High phosphorus levels promote the growth of nuisanceplants and algae, which can kill fish and other aquatic life by reducing levels of dissolved oxygen in streams. These algal blooms can also damage municipal water systems. ...

- The Fatal Harvest Reader: The Tragedy of Industrial Agriculture, edited by Andrew Kimbrell, in the Water section, by Mark Briscoe

And as we're mining phosphorus that's then often ending up in rivers because the stripped-down agricultural ecosystems created by industrial farming can't take it up, we're wasting much of the phosphorus in existing manure sources. Animals eat plants, plants eat us and our waste; it worked for a good long time. Then, as Michael Pollan says, we turned a perfectly good solution into a set of problems:

... I asked the feedlot manager why they didn't just spray the liquefied manure on neighboring farms. The farmers don't want it, he explained. The nitrogen and phosphorus levels are so high that spraying the crops would kill them. He didn't say that feedlot wastes also contain heavy metals and hormone residues, persistent chemicals that end up in waterways downstream, where scientists have found fish and amphibians exhibiting abnormal sex characteristics. CAFOs like Poky transform what at the proper scale would be a precious source of fertility - cow manure - into toxic waste. ...

- The Omnivore's Dilemma, by Michael Pollan

In fact, there are indications that the application of properly composted manure feeds a soil ecosystem that retains more phosphorus and produces less nutrient-contaminated runoff. That's not only good for what grows in a given patch of soil, but a sensible way to retain valuable and finite nutrients.

It could well be that the world is already past peak phosphorus, but "[f]ortunately, phosphorus - unlike oil - can be recycled. Responses to a phosphorus peak include re-creating a cycle of nutrients, for example, returning animal (including human) manure to cultivated soil as Asian people have done in the not-so-distant past [4]." Collected food waste can also be composted to return its store of phosphorus to the soil and prevent dispersion away from agricultural ecosystems.

Even if phosphorus doesn't peak until 2030, as David A. Vaccari pointed out in Scientific American, we're now dispersing this critical nutrient much faster than natural land ecosystems would:

... Land ecosystems use and reuse phosphorus in local cycles an average of 46 times. The mineral then, through weathering and runoff, makes its way into the ocean, where marine organisms may recycle it some 800 times before it passes into sediments. Over tens of millions of years tectonic uplift may return it to dry land.

Harvesting breaks up the cycle because it removes phosphorus from the land. In prescientific agriculture, when human and animal waste served as fertilizers, nutrients went back into the soil at roughly the rate they had been withdrawn. But our modern society separates food production and consumption, which limits our ability to return nutrients to the land. Instead we use them once and then flush them away. ...

Industrial agriculture's lack of responsiveness to this critical problem is basically nothing and to no great shock.

An agriculture that recycled nutrients wouldn't need as much, if any, of their synthetic or mined fertilizers. An agriculture that was adapted to local conditions wouldn't want their needy, greedy crop varieties, nor would it raise huge monocrop deserts to feed the industrial food processing beast. A sustainable agriculture would not be pouring into our rivers and oceans one of life's critical limiting nutrients at a rate far faster than it can be recovered to the land.

That sustainable agriculture, it wouldn't be run by the same people who profit from industrial agriculture today. So even if it kills us, the world's agribusiness companies and agribusiness-friendly governments are going to hold onto the current stupidity as long as they can get away with it. Because they just don't give a damn about anything besides concentrating profits, and power, in the hands of the few.