Hello, this is Dr. Gary Hawkins
with the University of Georgia Crop and Soil Sciences
Department and UGA Extension. Today we will be demonstrating
how to use the Enviroscape Watershed model. Funding for this video
has been in part from Georgia’s EPD 319 program. Today we’re going to focus
on a few ways to use the Enviroscape Watershed model. The model will be used
to explain different sources of pollution and practices
to reduce pollution as it relates
to agriculture. What we will show is just
an example of what can be discussed with the model. For more ideas, check your
manual which has some other hints and ways to use the model. As you can see we have our model
set up with roads in place. This is our animal waste lagoon. We’ve got our cows
in the pasture. We’ve got our houses set up
and we’ve got our tractor there in the field. To show how soil moves,
the first thing you’d want to do is to get your cocoa
or some powdered drink mix to represent soil. Sprinkle some of this onto
the field portion of the model to represent the loose
soil that is on the field. The next thing we do is put some
fertilizer on to help grow our food and fiber, this can be a
different colored drink mix. I have found Red, Green
or Purple works best. You can then discuss the
application of fertilizer, pesticide, or herbicide by using
different colored drink mixes. Typically I’ll just use the same
drink mix so we don’t get too many colors mixing into
our lake a little later. As we talk about putting the
soil and putting the fertilizer out, you can also discuss how
the manure in some cases, if available, can actually
be used as well. Some of this liquid could be put
on the field and you can discuss why manure is a very good
organic fertilizer source. The next thing we talk about is
what happens when we receive rainfall. We’ll spray a little
water on the model. When raindrops hit
unprotected soil, the first stage
of erosion begins. This is called splash erosion. As you can see in this picture,
the force of the raindrop causes soil to be dislodged where it
then is able to move more easily. As more rain falls,
the water starts puddling. That puddling allows the applied
fertilizer to dissolve. This puddling doesn’t move any
soil around and it also allows that water, fertilizer,
and pesticide to actually infiltrate the soil
and help crops grow. By adding more water,
you can mimic a large storm. At this point you can start to
see the fertilizer, soil, and pesticides start to run
into our lake and our rivers. This is typically what would be
seen from a “clean tilled” or conventionally tilled field. As the water starts
to move downhill, we enter the next
phases of erosion. These are sheet, rill
and gully erosion. Sheet erosion typically
occurs in short distances at the beginning
of water movement. Sheet erosion moves the
soil that was dislodged by splash erosion. The next stage of erosion
is Rill erosion. Rill erosion is the formation
of small eroded channels having a depth easily fixed
with tillage and they don’t have
any specific length. The last phase of erosion
is Gully erosion. Gullies are defined
as any eroded trench with a depth unable to
be fixed with tillage. As can be seen here gullies
can be quite deep. As we continue to add rain
to the model, you can see how the water starts moving
downhill into our lake, rivers, or streams. This movement of water also
can carry with it the soil, fertilizer, pesticides
and manure. As this water enters the
lake here on the model, you can see the movement
of the soil, fertilizer, and pesticides throughout
the lake. As the water slows down in the
lake, the soil settles out. This is the process of
deposition and can cause the depth of the lake
to drastically be lowered over time. The movement of soil and then
the deposition as sediment is one of the largest forms of
pollution from agriculture. As the soil settles it has
the potential to cover lake, river and stream bottoms causing
the plant and animal life to die. The fertilizers and pesticides
that run off the land into the water are also pollutants
that can cause excessive plant growth and potentially
plant or animal kills. Another potential source of
pollution from farms is animals. If you notice on the model
there are no fences around these animals. With no fences, the animals
have access to the creek at pretty much any location. This allows them to get in
and out of the creek wherever they would like. If we had trees on the creek
bank such as a riparian area, they would tend to stay in the
shaded areas longer and have a higher potential of
polluting the creek. By allowing the animals
easy access to the creek, they can cause increased
erosion on the banks as a result of
vegetation removal. In addition to sediment,
if the animals are allowed to spend long periods of time in
the creek, they will urinate or defecate in the creek causing
more water pollution problems. To show this on the model,
some of the cocoa or colored drink mix can be sprinkled
on the banks adjacent to the pasture area and then water
sprayed on to simulate rainfall. The sediment, urine, and
feces then can move further downstream into
the pond or lake. These are some of the sources
of pollution from our agricultural fields and animal
areas adjacent to creeks. Now that the sources of
pollution have been discussed for both the fields and animal
areas we’ll leave the model set up and talk about some of the
best management practices or sometimes called BMP’s that can
be used on the land to hopefully reduce and stop the movement
of pollutants offsite. For more information about BMP’s
you can see your local county Extension agent, your local NRCS
professional, or your Local Soil and Water Conservation District
personnel here in Georgia. To show some of the BMPs
that could be used, and this is not a complete list,
we’ll start with our cropland. As you can see with the water
is just puddled from when we eroded the field earlier. One of the ways, and this is
just one of the many different ways you can put BMPs
on the site, is by using some of the clay
in your model kit. Model a little bit of clay
which you can then put around the end of the field here. What this will do is actually
make a small dam. This small dam on a working
farm would cause a formation of a small wetland just upstream
of your pond, right on the end of your field. As it rains, the dam will catch
the water to form a small wetland. As you can see here, some of the
water is getting past the dam, but as you set-up your model,
you can better form the clay to stop water flow
under the dam. This small wetland will allow
you to initially catch any water draining from the field and
allow you to discuss how wetlands are used as a means
to provide some treatment of the water prior to
release into the pond. This treatment could consist
of sedimentation of soil and removal of nutrients
through plant uptake or denitrification process. Another way to reduce sediment
and nutrient movement off-site is through the use of vegetation
in areas where water flows. In your kit there’s some
small felt strips. You can take the back off of the
strips and use them as filter strips which would be placed
here at the end of the field. These strips are called
vegetative filters. This should work the same
way as the wetland dam. It would stop the liquid from
flowing into the pond or at least slow it down to the point
where the soil settles out and then you can further discuss
how vegetated filters work. The grasses and the roots of
the trees and the grass in that filter strip take up the
nitrogen, slow the water down enough so that deposition
can occur, and reduce the amount of pollution
moving to the pond. Another thing you can talk
about as you’re looking at the cropland itself is residue
management as one of the NRCS practices, or
conservation tillage. Conservation tillage allows the
farmer to grow rye, or wheat, or another cover crop during
winter time on the bare land. Then in the spring, a few
weeks prior to planting, farmers will kill
the winter cover. Killing the winter cover
allows the soil to store some water for planting the
summer crop, but also provides a mat of residue
or a residue cover. This mulch is not exactly like,
but is similar to, the pine straw or mulch we put
in our flower beds. The purpose of this residue or
mulch on the ground is to help increase water retention, help
water infiltration, decrease water runoff, build organic
matter in the soil, build the living community in that soil,
and a multitude of other benefits. If you want to know more about
conservation tillage or other Best Management Practices for
the cropland itself, see your local Extension agents,
your local NRCS personnel, or your local Soil and Water Conservation District personnel. Those are some of your cropland
type BMPs we can use. Like I said earlier, there are
many more that can be discussed using the items in the kit. For the animal BMPs, again
you can see here we just have animals
roaming free. Typically there would
be a fence here. We left the fence off in
this case just for clarity, but of course to keep the
animals confined to the pasture and out of the creek we would
have a fence in place. A controlled stream crossing
practice can provide the animals with a specific place to
either cross the creek or have access for drinking water. Such a stream crossing allows
the animals to get into the creek for water, but does not
provide room for lounging. You also notice, in the picture
and on the model, that the crossing is located
in a sunny area. This placement allows the
animals to have access to water, but further encourages
them to get back away from the water to find shade. The movement away from the water
reduces the potential of the animals urinating or
defecating in the water. We could even have them totally
fenced out of the creek and in some instances use a solar-
powered pump to pump water up to them out of the creek. That would allow them
to have water, shade, and not need access to the
pond or the creek itself. You would then have
them corralled in a whole corral
as you see here. That concludes our look at
the agricultural section of the Enviroscape:
Watershed model. If you have questions on the
BMPs shown, or questions about water quality, please contact
your local Extension agents, NRCS or the Soil and Water
Conservation District. Thank you. © 2017 University of Georgia College of Agricultural and
Environmental Sciences Department of Crop
and Soil Sciences UGA Extension