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Fertilizer is another thing
that you see in great abundance
on large industrial farms.
Agriculture removes organic matter
and nutrients from the soil.
When you take away the crops and you
take away some of the plant material,
these nutrients in the organic matter
are often replenished with fertilizers.
Fertilizers contain essential
nutrients for plant growth,
primarily nitrogen, phosphorus, and
potassium, often referred to as NPK.
Two main types of fertilizer used in
agriculture are organic and synthetic.
Organic fertilizers are composed of
organic matter from plants and animals,
and animal manure.
Synthetic or inorganic fertilizers
are produced commercially.
Synthetic nitrogen fertilizers
are made by combustion
of natural gas, a fossil fuel
allowing nitrogen from the atmosphere
to be fixed and captured in fertilizer.
Synthetic fertilizers are
more concentrated, better
designed for spreading
over crops, and can
target the specific
nutrient needs of a crop.
Synthetic fertilizers are
especially susceptible to nutrient
runoff that can negatively
affect nearby aquatic ecosystems.
In contrast to organic
fertilizers, synthetic fertilizers
do not add organic matter to the soil.
The Green Revolution was
primarily from 1945 to 1970
in many parts of the world.
It led to significant
increased crop output
through increased inputs of fertilizer
and water, and some plant breeding.
Norman Borlaug received the
Nobel Peace Prize in 1970
for developing many of these
ideas of the Green Revolution.
But the Green Revolution also
led to some adverse consequences
to the environment.
Pesticides, natural or synthetic,
might have been introduced.
These are substances that
kill or control organisms
that people consider pests.
Insecticides target insect pests.
Herbicides target plant species
that compete with crops.
Pesticides have made
agriculture more efficient.
The application of pesticides
is relatively easy.
Pesticides often increase crop yield
by preventing crop damage from pests,
but persistent pesticides remain
in the environment for a long time.
This puts animals at higher trophic
levels at risk for high exposure
to pesticides through bioaccumulation
through the food chain.
There's also another problem with
pesticides, the pesticide treadmill.
Consider a crop that's
infested with pests.
The farmer develops and
applies a new pesticide.
Most of the pests die, allowing the
crop to do better for a period of time.
But some resistant individuals
live on and reproduce.
Over time, the proportion of resistant
individuals in the pest population
grows.
So the farmer applies pesticide
again with little result.
And the farmer looks
for a new pesticide.
And this process starts again, thereby
being called the pesticide treadmill.
Pesticides can kill animals that
are beneficial to farmers, as well
as killing the pests.
As we mentioned, pesticides
can run off agricultural fields
and enter surface water and groundwater.
There's little or no
evidence that pesticides
cause large harm to
large numbers of people.
However, we cannot dismiss the possible
effects of hypersensitive people within
the human population.
We cannot say pesticides are safe.
Pesticides do harm agricultural workers.
Worldwide, an estimated 1 million
to 5 million agricultural workers
experience pesticide poisoning each
year from the application, or coming
in contact, with soil and crops
that has been exposed to pesticides.
Perhaps 20,000 people die of pesticide
exposure each year around the world.
So these are some real
significant things
to consider when you're
weighing the pros
and cons of large commercial
agriculture and smaller scale organic,
or other kinds of
sustainable agriculture.
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