Nitrogen

Fixing Life

Objectives: Students will be able to . . .

• describe the process of nitrogen fixation.• identify the major components of nitrogen

fixation.• evaluate the positives and negatives of our

dependence on synthetic nitrogen.• explain how the use of native prairie species

can be applied to the problem of nitrogen pollution.

Review

• We have talked about two forms of nitrogen in this class previously (think agriculture), what were they?

• What are they used for and how do they affect

the environment (especially our waterways)?

Why is nitrogen important

• I want you to think about the importance of nitrogen to the maintenance and growth of organisms – specifically to you. Write down what you come up with – you will share with the class.

• Nitrogen is essential for the replication of DNA, the transcription of RNA, and the production of AMINO ACIDS.

Nitrogen

• Earth’s atmosphere is 78% nitrogen gas. • Even though nitrogen is plentiful, organisms

cannot use it unless in the form of ammonium (NH4

+) or nitrate (NO3-) – or some other ion.

• Much of the N cycle takes place underground.

Nitrogen Fixation

• This is one of life’s fundamental processes. Nitrogen fixation takes Nitrogen gas (N2) – which is unusable by plants – and turns it into NH3 (also known as ammonia), which plants and other organisms can use.

• Fixation is carried out by certain species of bacteria. – They are able to convert nitrogen gas into

ammonia.

Nitrogen Fixation

• On land, some of the nitrogen-fixing bacteria live in small outgrowths, called nodules, on the roots of plants such as beans and peas (remember symbiosis).

Nitrogen Fixation

• There are other nitrogen fixing bacteria that live freely in the soil.

• The ammonia that the nitrogen fixing bacteria form is turned into ammonium (NH4

+)• Ammonium, as already stated, is useable by

plants.– It is essential for plants to grow.

Nitrogen Fixation

• Some of the ammonium is taken up by plants but most of it is used by bacteria (in their respiration process) and transformed into Nitrate (NO3

-), which is also taken up by plants. • In the past, nitrogen was a major limiting factor

on food production.• In fact, it was a looming crisis at the beginning

of the 20th century.

Facing a nitrogen poor future

• Nitrogen had built up in soils around the world over centuries and all of a sudden was being depleted at a very rapid rate.– Even from the richest soils were becoming

nitrogen poor. – It was one of those moments in which the world

was at a crossroads. – Then something happened to avert the crisis.

Turd Island and the Guano Conflict

• The nitrogen crisis was so acute that in 1864, Spain tried to take Peru’s bat caves and “turd islands” by force – sparking a “mini-war.”

• At the time, 60% of Peru’s economy was from the sail of bat and bird guano.

• There were just over 1 billion people on Earth and many agricultural experts and politicians were worried about a food crisis.

Guano Mining

• The Peruvians mined the guano.• Guano had accumulated in thick mates inside

bat caves and on islands off of Peru’s coast.• The guano miners took dynamite to the caves

and islands to loosen up the mats for extraction by blowing them up.

• Sadly, they blew up the bat and seabird colonies that had create the guano, too – destroying the source.

Guano Miners

• Other nations like Indonesia also had their guano miners.

• In general, any manure was in great demand.

Nest of Peruvian booby, is made from pure

guano

A guano mine on

the Chincha islands.

Peruvian Booby

The Coming of Synthetic Nitrogen

• Along came Haber . . . to the rescue (sort of). • SciShow on Fritz Haber, the man who invented

the process to make synthetic nitrogen. • This is one of the greatest and most

unheralded inventions due to its impact on feeding the world.

• http://www.youtube.com/watch?v=tdEE5uvFhOM

Bat Guano Still for Sale

• Bat Guano For Sale - Alibaba.com – for sale on the international trading page Alibaba.com.

Nitrogen Cycle

The problem with synthetic nitrogen

• The principle problem is, as Hank in SciShow said (and we had previously discussed in class), we use way too much of it.

• It is cheap and is so effective, more must always be better, or it is better to be safe than sorry.

• This attitude is damaging to the environment, to us, and doesn’t need to be that way.

The problem with synthetic nitrogen

• With farm technology, we can know the nitrogen content of soil of a field in great detail.

• If we wanted, we could apply only what is needed.

• This will happen one-way-or-another – either by voluntary cooperation or regulation by the EPA.

The problem with synthetic nitrogen

• In Iowa State’s rural Iowa poll, two thirds of farmers actually said that nitrogen should be regulated.– The sticking point is, as always, political.

• A plan to reduce nitrogen application and run off is being implemented in Iowa – by the DNR – but is a voluntary program.

Nitrogen Sources

Nitrates: The Dead Zone

Should we in the Midwest be allowed to or allow ourselves to cause such ecological damage other places?

What if the tables were turned?

Stream Buffers and Prairie Strips Reduce Nitrate Pollution

• The Leopold Center at Iowa State has done a good deal of work looking at prairie buffers.– Have found that if 10% of a watershed is planted

to prairie, that erosion and nitrate run off fall by 90%.

– Iowa has lost 1.3 million acres of grassland over the last ten years as erosion prone land is brought into production. This has significantly increased nitrate pollution and raised erosion by over 40% in many counties in Iowa.

Prairie Buffer Strips

Prairie Buffer Strips

Prairie Stream Buffers

Reflection

• How would decreasing the amount of nitrogen we use in agriculture (and on urban lawns) affect the health of Iowa’s ecosystems?

1. What would happen to our water quality?2. What could happen to Iowa’s wildlife habitat

and wild animal populations?3. What about the come back of the prairie?