Time to get back on the horse after a week of midterms.

Nitrogen was the primary limiting nutrient in terrestrial ecosystems.  Nitrogen levels could be increased by using composted organic material, but that took a long period of time and was hard work.  Keep that in mind.  World War II is raging and ammonia is needed to create munitions.  Cue Fritz Haber and Carl Bosch.  They came up with the aptly named Haber-Bosch Process which synthetically fixes nitrogen by reacting nitrogen gas and hydrogen gas over an enriched iron catalyst to produce ammonia.  Before this, ammonia was difficult to produce on an industrial scale because atmospheric nitrogen, N2, contains resilient triple bonds. During the process, N2 gas is combined with H2 gas at high pressures and high temperatures.  This reaction takes place in the presence of a catalyst, usually some sort of iron, which lowers the activation energy required to break chemical bonds, allowing the reaction to happen more efficiently.   After all is said and done, we have gaseous ammonia which can be condensed into liquid ammonia.  This, in turn, can be used in munitions.

 

Haber Bosch Process

Soldiers were coming home after the end of the second World War.  Everybody wants to forget about the staggering losses of life that took place during the War.  But, the chemical companies which supplied chemicals needed for weapons during wartime have a problem.  No war means no sales.  They had to adapt to a new market quickly.  So, they came up with a brilliant idea: they would work to create chemical fertilizers and pesticides.  I bet you didn’t know that chemicals used in wartime could be so easily converted to fertilizers and pesticides (take Agent Orange and DDT, for example).  These chemicals greatly improved our agricultural output.  In fact, the increases in crop yields were so drastic that it is still called the Green Revolution.  Crops were specifically chosen and bred so that they could tolerate high nutrient levels that are not normally present in nature.  The problem is that the Green Revolution was not very green.

One cannot be led to believe that pumping inordinate amounts of  nitrogen fertilizer into the soil is natural.  And since the soil cannot possibly hold all of it, much is lost when irrigation (more on that next time) percolates through the soil, flushing many of the nitrates into streams, rivers, and groundwater.  Oops.  As I mentioned before.  Nitrates from fertilizers often flow into rivers which dump the excess nutrients into bodies of water, creating algal blooms.  The algal blooms don’t have all that much oxygen in the rather warm waters (warm liquids don’t hold gases as well as cold ones (why pop is better cold)), so they die relatively quickly, but not before using up all of the oxygen in the water, creating a dead zone.

The nitrates can also seep into ground water which is then used for drinking, bathing, washing dishes, etc.  Not surprisingly, this is not great for your health.  In fact, excess nitrates have been linked to many diseases, particularly in children, whose small bodies cannot tolerate as many chemicals.  Probably the most horrifying disease is Blue Baby Syndrome, or Methemoglobinemia, which results in decreased oxygen carrying capacity of hemoglobin in babies leading to death or other birth/developmental disorders (similar diseases can be caused by excess nitrates from cesspools of fecal matter from factory farms as described previously).

Pesticides are used extensively.  Most of us use them without a second thought.  But perhaps, we are doing more harm than good.  Imagine you are spraying some pesticides to kill off some Japanese beetles (the little iridescent buggers which eat all of your flower leaves).  You kill off most of them, but some survive.  They have a resistance to the chemical.  Now, these beetles reproduce and pass on their resistance to some of their offspring, so we spray more and more, to kill fewer and fewer beetles.  That is the story since the beginning of time: a process of coevolution between pests and pesticides.  Our response is to either increase the dosage of pesticides, or increase the toxicity of the chemicals, neither of which is good in the long run.  Because of genetic resistance, farmers can pay more and more for pest control programs that become less and less effective.

Another big problem with these pesticides is that they are nonspecific: they will kill most of the pests, but many of the pest’s natural predators as well!  Not to mention, when the pesticides are sprayed, some of the chemicals will end up in nearby natural areas like forests and streams, which will kill many species in the nearby area, limiting biodiversity.It turns out that pesticide use has not reduced US crop losses to pests, mostly because of genetic resistance and reduction of natural predators.  I am sure we all remember the effects of DDT as presented by Rachel Carson in Silent Spring.

The Cosmic Perspective

Today, 50% of the world’s population is alive thanks to synthetic fertilizers and pesticides.  Don’t forget to couple that with the 40% alive thanks to antibiotics.  If the fact that fertilizers and pesticides are destroying the earth didn’t convince you that there is a problem, perhaps you wonder who is spraying these toxic chemicals.  More often than not it is migrant workers who are given little to no protection, causing serious medical conditions.  So what can we do to limit our and the earth’s exposure to pesticides?  Grow some of your own food using organic methods.  Wash and scrub fresh fruits and vegetables.  Eat less meat.  And, if you think that you cannot get around using some sort of pesticides, here are some tips.  Rotate the types of crops and adjust planting times to fool the pests.  Provide homes for pest enemies.  Inplant genetic resistance.  Use pheromones to lure pests into traps or attract natural predators into crop fields.  By changing our habits, if only a little bit, we can make a big difference.