Much of a Good Thing
Chemical fertilizers contain mostly nitrogen, phosphorous, and potassium. They are used on crops because they make crops grow better. Indeed, new genetic strains of crops were developed because they could grow better if given extra fertilizer that is not normally present in most soils. The "Green Revolution" has saved millions of people from starvation because fertilization of genetically improved plants has allowed us to increase food production in order to keep up with the demands of the rapid growth in human population to 6 billion people. The argument has been made that we should do even more fertilization, so that we can grow more food on the same amount of land and thus stop clearing of forests and farming on land that is subject to washing away when it rains.
water lilies, and sea "weeds" can grow so fast that they
cannot rot as fast as they die. The decay of this massive growth robs the water of oxygen, so
fish cannot live. Ponds and lakes can become really stinky. The
overgrowth robs other living things in the water of light and
nutrients. It changes the niches and breeding grounds for other species
and typically drives them out. Click
here to see examples of these problems.
We should also mention that fossil fuels are used to make fertilizers, and we are already running out of fossil fuels. Extra growth of plants also makes demands for more water. This is a real problem when farmland has to be irrigated. There may not be enough water to go around.
What would happen if you took the same antibiotic all the time, that is, every time you got a cold or felt bad. A few bacteria would survive, and at some point, they might even start to thrive in the presence of the antibiotic. The constant exposure to the same antibiotic would become a natural selection force that could select the creation of a new species or strain of bacteria that is resistant to that antibiotic. Now when you get sick again with these resistant bacteria, your antibiotic will no longer work.
exactly what has happened with penicillin. Penicillin, the first
antibiotic, was discovered in the 1940s and was very effective against
many kinds of bacteria. Now,
because of overuse of antibiotics, many of these bacterial strains are
no longer affected by penicillin.
problem has developed with several other antibiotics. The more popular
and widely used an antibiotic is, the more likely it will lead to
resistant strains of bacteria. Eventually, we may run out of effective
antibiotics. Then what?