Jul 9, 2009
Great Work, Fritz!

Great work, Fritz!

Officially, the birthdate is given as July 3, 1909. Actually, somewhere in the span between 1890 and 1909, a German scientist named Fritz Haber worked out the process to make ammonia by combining methane with nitrogen in the air. The process (commercialized with the help of Carl Bosch) is still used today.

Some say there would not be enough food for 3 billion of the world’s 6.7 billion people alive today were it not for his work. Others, of course, spurn this industrial process.

Some 80 percent of all the ammonia manufactured is used to make nitrogen fertilizer, about 100 million tons of it a year.

Half of all the nitrogen fixed each year is fixed using Haber’s process. The other half is fixed by natural processes, most involving bacteria that live symbiotically with legume plants and in the stomachs of ruminant animals. A minor amount of nitrogen is fixed by lightning.

Without a way to “fix” nitrogen, we swim in an atmosphere composed of 80 percent nitrogen that is inert to us. Nitrogen is the essential building block of plant and animal protein.

Nitrogen is a severely limiting factor in crop production. Farmers a century ago were just learning how to use rotations to transfer nitrogen from legume crops like alfalfa, clover, beans and soybeans to grassy crops like grains or to fruits and vegetables. Recovering nitrogen from animal wastes and using it on crops was long known to be important, even before farmers knew why. The only “commercial” source of nitrogen back then was nitrate deposits, many from Chile, where they were mined from deposits of bat and bird manure.

What Haber learned was that natural gas – methane, CH4 – could, with heat and pressure, be forced to give up its carbon atom and replace it with an atom of nitrogen from the air, changing it to NH3, or ammonia.

Haber was a controversial man. His work with ammonia was very important to the development of the German explosives and munitions industry, so he played a role in making the world wars of the 20th century more deadly.

So, did Haber help kill millions in the wars? Or did he help save billions who might otherwise have starved? That was a controversial question, even at the time. But in 1918, he was given the Nobel Prize in chemistry for his work in the development of the process for manufacturing ammonia.

No doubt about it, if farmers did not have commercially made nitrogen fertilizer, farming would be very different today, and how many people agriculture could sustain could be debated.

Recycling animal manure, careful use of cover crops and rotations using legumes are good farming practices, but not adequate ones.

Specialized crop farming would be hard to do without commercial fertilizer. Organic fruit and vegetable farmers attempt to get additional nitrogen by using compost, manure and mulches, but it takes more farmland to produce both food crops and fertilizer crops.

Over the years, there have been debates over nitrogen sources, but there’s no evidence that a plant knows the difference between nitrogen atoms provided by the Haber-Bosch fertilizer manufacturing process, by the decay of organic matter or by nitrogen fixed by bacteria living on the roots of hospitable plants. It’s all nitrate to them.

We now depend heavily on a technology invented a century ago to feed half the humans on the planet. Being so dependent never makes one comfortable, especially when natural gas -– a fossil fuel and a potent greenhouse gas – is the key element in the process. In another hundred years, our great-grandchildren will see how Fritz Haber’s legacy is holding up or whether we have found something better.


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