Nature seems invincible.  We can cut down trees to make room for farm land.  The trees always grow back.  We can dig holes in the Earth to plant whatever crops we need.  We can always fill it back in with other dirt.  We can catch fish, shoot deer, and have our cows gobble up a grassy field.  Over time they would all come back, but we have to wait for it.  The thing is, it's not just one person who needs to eat each day.  We now have billions of people on Earth that need food.  That's a LOT of farming!  The land needs time to grow back and this means we might need to wait before we plant new plants.  If we do not wait, the dirt cannot recover.  So let's get into the dirt and see what's really happening when we FARM EVERYTHING to grow our food. 


You would think that of all things in nature, dirt would be the strongest.  Dig it!  Stomp it!  Till it for rows of crops!  It's still just dirt, right?  Well, yes, but it will not be able to hold plants as well as it once did.  When we take out trees or plants to make a farm, we take out all the deep roots that have grown for a very long time.  They help to hold the dirt down, but they are gone now.  When we plant new things over and over, we also make it hard for the tiny living things that live in and around plant roots to live.  Bacteria and other very small things that live in the dirt are too small to see, but they hold dirt together and help plants to grow. 


Farms that grow new crops over and over can lead to some problems with dirt.  Erosion is when dirt, sand and rocks move from one place to another with the help of things like wind and water.  If dirt is used too often for farming, it can become dry and easily moveable.  The very small living things that usually hold the soil together and live around roots of plants will die and won't be able to hold the soil down.  The crops we use for food will drink all the water from the dirt and their roots will be torn out every time we plant something new.  Winds will blow dirt away.  Rain and water will push the dirt from where it's needed to grow plants and move it into rivers and streams.  This is bad for things that live in the water and people who need to drink it.  Over time, things may stop growing altogether and we will change the environment by moving all this dirt.  


Over the years, people have become very good at turning plants into what we want them to be.  We have learned how to control how seeds are made so that we can grow the sweetest oranges and the largest ears of corn.  In a field, there used to be many different plants and animals.  Not anymore.  A monoculture is when we grow only one kind of crop in one area.  This has a very bad side-effect.  It is not easy to see at first, but one of the things that makes nature so strong is all the different things that live together in one space.  There are so many things in a forest that help keep it healthy!  The trees hold the soil down.  The deer keep the trees from overgrowing.  The wolves keep the deer in check so they do not eat all the leaves.  The mushrooms recycle all the dead leaves.  All of this gets thrown out when we use a large piece of land to farm only one kind of plant. 


Every year there are more people living on Earth and all these people need food.  Growing food takes a lot of land, but this land was not empty before we started growing food there.  There were hundreds or thousands of different living things there.  For us to plant crops, all these living things have to move.  This isn't always pretty and can mean a lot of living things dying or losing their homes.  Habitat loss is when an environment changes and the living things that used to live there can't live there anymore.  This can happen to land we farm, places we build new homes, and when natural things like fires and volcanoes change the land.  It's sad, but when we farm a place over and over, it ends up hurting the living things who were there before us and the everything that lives around the farm too. 


When we farm land, we use inventions to grow as many crops as we can.  We use pesticides to kill the bugs that eat the plants.  We use tractors to move the dirt and all the crops.  We trap fish in a small part of the sea or river so they can make more fish and we can catch them when we would like.  Pollution is when we put something into the environment that hurts living and non-living things.  Pesticides and extra dirt wash into rivers.  Tractors send smog and dust into the air.  Too many fish in one place will make too much fish waste.  These things hurt the things living nearby, but they can also spread and hurt things living hundreds of miles away by river or ocean. 


It turns out nature is not as invincible as we would like to believe.  By over farming the land, we cause erosion, wearing down the dirt so it no longer sticks together for plant and tree roots.  By growing monocultures, or one kind of plant in one place, we leave the land open to one disease that could wipe it out, leaving nothing behind.  When we farm, we often kill everything there, making habitat loss.  Our actions spread past the land where we farm through pollution, putting new things that hurt living things and can spread far and wide.  We need to not only think about the food we eat, but the land where it came from too. 

References:

Panda.org.  "Environmental impact of farming"  panda.org, 2011.  <http://wwf.panda.org/what_we_do/footprint/agriculture/impacts/>

Pesticide Safety Education Program.  "Modern Agriculture: Its Effects on the Environment"  Cornell.edu, 2010.  <http://psep.cce.cornell.edu/facts-slides-self/facts/mod-ag-grw85.aspx>

Tillman, David.  "Global environmental impacts of agricultural expansion: The need of sustainable and efficient practices"  pnas.org, 1999.  <http://www.pnas.org/content/96/11/5995.full>Resources: