Hi. It’s Mr. Andersen and this is environmental
science video 16. It is on agriculture. This is a picture of wheat. We grind it to make
flour and then make things like bread. And we have been doing so for thousands of years.
This sickle is over 5000 years old and was used to harvest wheat. We still harvest wheat
today in a similar fashion but now on an industrial scale. What is the function of agriculture?
It is to provide for our human nutritional requirements. If you do not get enough calories
in your diet we call that undernourishment. And it is less of a problem. We generally
can make enough food but it is not always in the right place at the right time. And
things like war can disrupt that flow. A bigger problem is malnutrition. It is when you are
not getting the proper nutrients. You are not getting the right proteins, vitamins,
minerals in your diet. A growing problem is actually over nutrition where we eat too much
and can lead to things like obesity. Agriculture provides for these needs and it has been doing
so for thousands of years. Now what happened with industrialization is as we had exponential
growth in the population we had to feed that population. And therefore we had the green
revolution where we have industrial agriculture today. There are five characteristics of that.
The first one is mono cropping, when you plant just one crop type. We also have irrigation,
the use of pesticides that target different things. The major ones are herbicides and
insecticides. We use fertilizers. Some of those are going to be organic, like manure.
But a lot of those are going to be synthetic. And now we have the arrival of genetically
modified organisms. All of these together have allowed us to create more food than we
ever have. But each of them have draw backs. Mono cropping for example, when you harvest
all of those plants, it can lead to soil erosion and a lack of biodiversity. How could we prevent
soil erosion? Things like contour plowing. Irrigation depletes aquifers and can lead
to salinization. So we could maybe have the arrival of new salt tolerant crops. Pesticides
have a double problem. Pests are going to become resistant to the pesticides and also
those chemicals are going to bioaccumulate within the food web. What can we do? We can
use processes like integrated pest management to try to mediate those problems. Fertilizers
require a lot of energy. They require fossil fuels to make and also they will run off the
fields and enter into the food web causing things like eutrophication. So what can we
do? We can use other crops as fertilizers using something called intercropping. Genetically
modified organisms, most of the studies are saying are not harmful to humans to eat, but
they can lead to a decrease in biodiversity. And so there is a big push away from industrial
agriculture towards alternative (or sustainable) agriculture. We still have to feed the humans
on our planet, but we can do it in a smarter way. And so if we look at the history of farming,
most of it has been subsistence. So this is over 3000 years old in a burial tomb. And
so this is an early farmer plowing his field. And so what has happened is as the population
has grown exponentially, we have only been able to create food in a linearly increasing
fashion. And so eventually what you have is this catastrophe where you cannot make enough
food to feed everyone. And this happened in the last century. So we could see that the
food growth was quickly going to be outpaced by the exponential growth of the population.
And so biologists like Norman Borlaug, farmers brought forth these industrial ways, called
the green revolution, of providing more food. You could see this in wheat yields. So this
is in developing countries. Back in the last century it was increasing in a linear fashion
and then we had this green revolution. Places like India and Mexico. So what are the characteristics
of industrial agriculture? One big one is mono cropping. It is when you plant just one
crop. So this is corn for example. What is great about that? You become really good at
planting corn and taking care of corn. It is easier to plant this way. It is easier
to harvest it as well. What are some of the problems? Well we have a decrease in biodiversity
and it can lead to things like soil erosion. You have to harvest all of that food at the
same time. Rain can wash that really valuable soil away. So what could we do to prevent
that? Things like contour plowing where you are plowing with the contour of the field.
It keeps it flat, the surface is flat so we have less of that runoff. Irrigation has allowed
us to farm in areas where we never could of in the past. So this is in Kansas for example.
What are some problems with irrigation? Well you are going to deplete, this is the Ogallala
Aquifer that this sits on, so eventually that will run out. You also have the problem of
salinization. So rain water will generally wash the natural salts away. But if you start
pumping water out of the ground, that is ground water. And it is going to contain salt. Those
drops of water have salt in it and so we are going to have an increase in salt. Salinization
over time. How do we solve this? Well we could try varying the crops that we have. We could
limit irrigation. Or we could start to evolve, through artificial selection, salt tolerant
crops. Another major part of industrial agriculture is the use of pesticides. The major ones are
going to be herbicides that kill other plants or weeds. We have insecticides, fungicides
and other biocides. Now why are farmers using them? It is because they can get return on
their investment. For every dollar they spend on pesticides they get four dollars in higher
crop yield. So an example. If we look at one of the most popular herbicides in America,
Atrazine, it is a broad leaf plant killer. So it is going to kill the weeds in crops
like corn. And so you can see it is going to be aggregated where we are growing a lot
of corn. And the reason why is that they can get more corn back. Now what are the problems
with this? One is bioaccumulation. Those chemicals do not just go away. They are going to build
up in the food pyramid. And so pests are killed but they are eaten by other consumers and
other consumers. Like the example that we are familiar with is DDT aggregating inside
and eventually killing things like bald eagles. Another problem is resistance. If you spray
pesticides, what pests are you killing? The ones that are least resistant. So if you spray
it the first time you will kill a lot of those insects. But the ones that survive are resistant.
And over time through natural selection those pesticides do not work anymore. So how do
we solve this problem? Well if we look at the population of the pest itself, so one
individual pest, it is going to undergo exponential and then logistic growth. So right down here
in this area it does not make sense, financial sense, to spray pesticides. The numbers are
not large enough. We have not gone over what is called the economic injury level. And so
farmers are constantly monitoring the fields, figuring out what pests do I have? What is
the level of them? They can use other things beside pesticides. We can mechanically remove
those pests. We could use things like traps. We could use other life. We could use things
like this lace wing larva to kill other aphids. And then we could monitor it to the point
where maybe it is going to a level where it is going to hurt us. So then we could use
pesticides but we could use pesticides wisely. Another characteristic of industrial agriculture
is the use of fertilizers. It puts those important nutrients that plants need, like nitrogen,
potassium, phosphorus, into the soil. And so this right here is spraying anhydrous ammonia
into the soil. That is a process that humans have invented to take nitrogen out of the
air using the Haber process and making ammonia out of it. You can spray it on the fields
and the plants are going to grow more quickly with a higher yield. What is the problem?
As we have rain that runoff is going to push those fertilizers into the water supply and
it can lead to problems like eutrophication. How could solve this problem? Well we could
start using other crops. And so this is intercropping where we are having beans mixed in with corn.
And so the beans are providing manure, essentially green manure for that corn to grow. A growing
characteristic of industrial agriculture is the use of genetically modified organisms.
Now we have always been breeding plants, but recently we are taking genes from one organism
and inserting them in another. An example could be golden rice. And so you are inserting
genes into rice so they produce vitamin A. Why is this a big deal? Over a 500,000 children
under the age of 5 die each year due to vitamin A deficiency. So we could insert those genes,
they can eat the rice and that is not going to be a problem. Another example could be
Bt corn. We are taking genes from a bacteria and inserting it into corn and it produces
a natural pesticide so things like a corn bore cannot eat it. Now most of the studies
are saying that this food is generally safe for humans to eat. But depending on where
you are, in the US we use lots of GMOs but in Europe not so much. And so there is controversy
over the effects to the environment through the use of genetically modified organisms.
And so the current push is towards sustainable agriculture. We do not want to have such an
impact on our planet. And what is interesting is a lot of these practices will return us
towards our subsistence farming roots. And so did you learn the following? Could you
pause the video at this point and fill in all of the blanks? Well let me do it form
you. So malnutrition is a lack of calories. The green revolution led to industrial agriculture.
Some of the characteristics are mono cropping, irrigation, pesticides, fertilizers and GMOs.
Herbicides are the most popular type of pesticides. Our fertilizers can be either organic or synthetic.
And what are we moving towards? Alternative agriculture, where we do not have so much
of an impact on our planet. And I hope that And I hope was helpful.