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Thursday, January 19, 2006
 

There's a lot of confusion about fertilizer.

Then, in 1909, German physical chemist Fritz Haber developed a high-temperature, high-pressure process to fix atmospheric nitrogen in his lab. Another German chemist, Carl Bosch, soon expanded Haber's process to a factory scale. Known as the Haber-Bosch process, industrial fixation of nitrogen combines atmospheric nitrogen and hydrogen into ammonia, the basis for all synthetic nitrogen fertilizers. Natural gas is most often the source of the hydrogen.

Imagine the power now vested in humankind. With the ability to fix our own nitrogen we could free ourselves from dependence upon lightning and microbial masses and ramp up agricultural productivity to feed a hungry world. Perhaps the human species could yet outwit the Malthusian math that predicted that population growth would always outstrip our ability to increase food production. Indeed, so marvelous was this alchemy that both Haber and Bosch were awarded the Nobel Prize for chemistry.

Human kind had already outwitted Malthusian math before Malthus did his work, but Malthus was unaware of it. Huge deposits of sea bird and bat dung were mined and shipped around the world, and huge deposits of Chilean nitrate, a.k.a saltpeter, were used for everything from fertilizer to gunpowder.

It may help to remember that natural gas is methane, plus a few contaminants, and that methane is not just a fossil fuel, it is continuously produced.

Imagine now, just a little less than 100 years later and as world hunger continues to rise, asking farmers to stop using industrially fixed nitrogen. It's a wonder that the organic movement ever got off the ground.

The National Organics Program, which regulates the use of the organic label in the United States, prohibits the use of synthetic substances unless their use is specifically allowed via exemption, an exemption not granted for synthetic nitrogen fertilizer.

The reasons why are of such import that they alone should set off a stampede to the nearest organic farmer's market.

Reason No. 1 is that synthetic nitrogen fertilizers are not sustainable. Building an agricultural system based upon industrially fixed nitrogen makes our ability to feed ourselves dependent upon a non-renewable fossil fuel and upon the wisdom, benevolence and cooperation of heads of state and multinational petroleum companies.

No, it doesn't. Every farmer can make his own methane and could have home made nitrogen fertilizer if he also had a solar powered Haber-Bosch type system. That fertilizer is currently made from fossil methane as a centralized industrial practice is due to economics and habit. Both can change.
Synthetic nitrogen fertilizers also fail to pass muster because of the environmental damage done when we pump enormous quantities of nitrates into the natural atmospheric and biological cycling of nitrogen. Overuse of nitrogen fertilizers are a primary cause of "dead zones" in coastal waters because nitrates are highly soluble; any nitrates not taken up by plant roots move quickly down through the root zone and enter ground water. When nitrate-laden rivers enter bays and estuaries, the excess nitrogen can cause larger than normal algae blooms.
This is a symptom of agronomic practice, one that is rapidly being resolved. Nitrogen is expensive and farmers can't afford to waste it. Applying nitrogen fertilizer to fields is expensive too. It usually takes labor and machinery though there are "fertigation" systems that mix fertilizer with irrigation water. The trade off is nitrogen loss before uptake by plants vs. extra costs to apply it in small quantities as plants need it. When many small applications are made there is no leeching from the field.
Nitrates may create a dead zone of sorts on the land as well.
Well, so does water when there is too much for too long. This is a nonsense claim made for instrumental reasons. When nitrogen is applied properly there are no dead zones, it's the exact opposite, everything flourishes.
Finally, nitrogen oxides also contribute to acid rain, reacting with water in the atmosphere to form acidic compounds. When the compounds rain on or wash into lakes and rivers, they jeopardize fish, plant and bacteria populations that are sensitive to changes in water pH. As it percolates through the soil, acid rain leaches nutrients such as calcium, magnesium and potassium out of the root zone and mobilizes aluminum, which inhibits root growth.
Most things you do to soil make acids. Plants themselves make acid as they take up cations such as calcium through their roots and exude anions (acidic) to maintain internal electroneutrality. Sometimes all of this is wonderful, such as on farms with calcareous soils that need acids to become more neutral, and sometimes the soil is neutral or acidic naturally, such as with granitic soils weathered from rock, so farmers add lime, calcium carbonate from limestone, to both lower acidity and provide calcium to plants.

Organic agriculture is based on ignorance, and that's a shame because an informed agriculture that avoids truly dangerous chemicals and cultivation techniques that degrade land is not that difficult or expensive. With population expected to reach half again as many people as there are today we don't have enough land to humor quasi-religious superstitions about agriculture. If some of the energies and resources being squandered on organic systems were spent instead to develop solar powered farm scale fertilizer production systems then something closer to a closed system could be used. Crops wastes and dung could be turned into methane and compost in bioreactors by anaerobic bacteria, and the methane could be turned into nitrogen fertilizer by the heat of the sun in solar furnaces that can produce the heat and pressure needed for the Haber process.

Still, it may be cheaper to have centralized facilities with larger solar furnaces so long as the methane is available. The problem is transporting the feedstocks, the organic materials, to a central site. Feedlots, mills and urban waste disposal sites are natural candidates since they already have lots of organics available to decompose into methane. Farm scale systems might be limited to just making methane to power machinery, and generate heat and electricity. And compost, of course.

posted by back40 | 1/19/2006 09:01:00 PM

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