This course will cover the agricultural and urban water quality issues in Florida, their bases, land and nutrient management strategies, and the science and policy behind the best management practices (BMPs). Students will learn to evaluate BMP research and analyze its role in determining practices and policies that protect water quality.
Soil Management, Part 1
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From the course by University of Florida
Sustainable Agricultural Land Management
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From the lesson
Soil Management
For week 5, we will look at soil management in detail and begin to discuss soil testing.
Meet the Instructors
George J. Hochmuth, Ph.D.Professor
Urban and Agricultural Environmental Sciences
Hello again, everyone. I want to move on now to a discussion of
more about best management practices. We've taken a look at soils we've taken a
look at nutrient phase and flows in our farming system and so now, we should have
a, an idea about nutrients, where they come from what they do in the farm and
where they might go. And so now, it's logical to step back and
take a look at some of the management practices that we might instill on this
farms to gain some degree of control over these nutrients and make sure that they
are where we want them to be. So, today, I want to talk about a little
bit about some of the best management practices and we'll probably focus on
these over the next few lectures of the course.
I want to start sort of at the big picture looking at our soil on our farms and how
do we keep the soil on the farms. Keep it in mind, that soil is very, very
important to farmers. In fact, it's their major asset.
In my classes on campus, I sort of take the students through a little bit of a
timeline because this is sort of my approach and lead up to soil management on
farms. If you look at tillage over the many, many
years that farmers of all ages have been preparing soil and planting seeds and
growing crops there is a rich history of development of tillage techniques.
I just put Jethro Tull up here because his name comes up many, many times.
He was an English agriculturist who had a, a penchant for developing farm equipment
technologies he developed drills for planting seeds and he's also been
associated with the development and the refinement of the plow over the years.
And here are some drawings of some early versions refinements made of the tillage
implement that we know as the plow. The Moldboard plow more appropriately has
gone through a lot of development over the years.
For example, when I grew up on the farm we had small plows.
They might be a 2 or 4 bottom plow and you can see that as farmers developed, as
technology has developed over the years and our tractors and our power systems got
bigger and bigger, so did our implements. And so, I've given a few pictures here of
just how the Moldboard plow have developed over time and you can just you know, just
notice the, the size of this equipment and the massive amounts of soil that can be
tilled with one pass over the, the field. So, tillage has a lot of advantages and
these have been known for, for a long, long time turning under and incorporating
the soil and the organic matter to get it to, to decompose.
For example, our old crop refuse weeds. If we till them into the soil, that
organic matter will decompose and release nutrients for the next crop.
We can use tillage to control weeds we can turn under disease organisms and insects
to kill them or destroy them in between crops.
Tillage helps dry out the soil particularly early in the season.
And this is very important coming out of the winter when the soils tend to be wet.
And so, if we till those soils as soon as possible, then we can help them dry out
and we can plant crops and get crops established earlier.
So, this all comes with preparing seed beds.
Here's a 4 bottom, so-called 4 bottom plow that we use on our research center here in
Florida. Research centers tend to use smaller
equipment than, say , some very large commercial operations, but you can just
get a picture of the type and size of this equipment.
They're very heavy, and it takes a considerable amount of horsepower to pull
them through the field. Soil tillage I point out to students that
soil tillage, these advantages can also be disadvantages.
When we loosen the soil it does dry out. That's good on the one hand.
But it also can dry out to a certain extent that it can actually blow if we
have windy periods, especially during the early spring.
I remember growing up on our family vegetable farm and in the spring, even
though we use cover crops and windbreaks to reduce the amount of blowing sand, some
neighbors did not and in the spring, in March, for example, when we had wind
storms, there was a considerable amount of, of soil blowing around in the area.
Tillage also exposes the organic matter to decomposition, which on the one hand,
because, you know, we may want to decompose the rough organic matter.
But on the other hand, on sandy soils that are well-aerated, this organic matter can
decompose and, in fact, disappear from our soils.
Our sandy soils in Florida are like this. It's very difficult to build up organic
matter in these soils because of our tillage and because they are so highly
aerated. Tillage also can lead to problems such as
that depicted in, in this photograph, particularly when we leave our soil tilled
say, for example, in the fall after a summer or fall crop and then in the spring
when the snow melts. Or if it rains we can have runoff from
those fields, and that runoff can carry some of the soil and any associated
nutrients particularly phosphorus with it. Now, I don't want to give everyone the,
the idea that I'm negative on soil tillage across the board.
I'm, I'm not. I's really the knowledge and understanding
we have about soil tillage and what it does and what it does not do.
And we're going to talk a little bit about how to use soil tillage effectively in
crop production systems. In many crop production systems, tillage
is very important. For example, I'll show you some
photographs of vegetable production on plastic mulch.
In that particular production system, tillage is very, very important.
But over the years, we've learned a lot about soil tillage and the challenges that
it presents in our, on our farms. And so, we've learned to do some things to
implement some practices, we call them best management practices, so that we can
use soil tillage to its proper effectiveness but also be able to manage
and reduce the amounts of soil that are lost due to our tillage.
I also take the students back a little bit in history to what is known as the
American Dust Bowl period. If you look back in the 1860s settlers
were encouraged to, to move west and to homestead pieces of property for a certain
period of time after which they would become the owner.
Time and technology moving forward has developed agriculture and our agricultural
systems, particularly our mechanization to a level that in the 20s and 30s we ran in
to some particular problems, some of which were related to the way we farm the soil
but some of which were natural in, in the way that the weather changed and we had a
drought period. So, the disadvantages of the widespread
tillage plowing of the prairie soils and the many, many acres that were put into
production, notably wheat production during this time and the change in weather
to a drier period all sort of conspired, as it were, in a perfect storm.
And these dry periods and the windstorms that accompanied them led to terrific dust
storms for a, a decade or more. The Dust Bowl period is what, what it was
known aptly named by a as I understand, a newspaper writer at that time.
The Dust Bowl was particularly troublesome and, and severe in what we call the great
plains area, Kansas, Oklahoma, Texas in that part of the, the United States.
As I said, when the farmers moved out to homestead they were met by the prairie
soils and as a result needed to till these soils.
And so, by this time, we had draft animals and, and plows that we could effectively
till the soil and prepare it for, for wheat production.
In the beginning, small acres were tilled, but as technology developed and farms grew
and grew, large expanses of, of this area of the country were tilled and, and
planted to crops. And then, when the weather changed into a
more dry period and these dust storms became very prevalent, sometimes several
dozen of these storms in a season. You can see the, the lasting impacts on
the agricultural land. Lot of the topsoil was blown off and
removed. In fact blown considerable miles East of
the, of the Great Plains area. So, I, you know, I bring that up because
here's a, a timeline that shows how agriculture, and the way we the way we
farm and the way we till soils, and the added impact of changes in the weather
conspired to create a real serious soil conservation situation, especially during
the 1930s. It was so bad back then that the President
FDR Roosevelt did some u, science and legislation and formed what was then
called the Soil Conservation Service in 1935.
We call it the Natural Resources Conservation Service today, it's the same
agency. Back then, the main goal was to try to
teach farmers soil conservation practices on these farms so that more of the soil
would stay on, on the farm and would, would not be subject to blowing away.
The first head was head was a person named Hugh Bennett.
Now, Hugh Bennett was an interesting individual because he was a trained
surveyor. And so, Mr Bennett saw a lot in his
practices and practicing of survey and he saw what he saw the problems with soil
erosion on this farms and he wrote about it a lot um,during the decibel years.
And he was so outspoken about soil erosion and the negative impacts it has on
agriculture and the need for conservation practices that he was appointed the first
head of the new soil conservation service. And as I said we now call this the NRCS.
I think we've mentioned NRCS a couple of times already in the course and we will
refer to it as we go, go forward as well. A, a side or just sort of along the same
at this same time period the country was going through the Great Depression and so
these folks that were trying to farm under these conditions and also having to try to
market crops during this time in this country, made it very, very difficult for
agriculture. At the same time it's kind of interesting
to see how these two things these, these came together, the, the Dust Bowl and the
need for conservation practices and the, the Great Depression there were many
programs developed, one of which here, the Civilian Conservation Corps, lead to the
planting of many, many, many miles of shelterbelts and windbreaks, some of which
you can still see today in, in some of the states.
This was a work program for young people who could not get jobs during the, during
the Great Depression years. And also some of our national parks in
this country were developed at that time. It put a lot of young men to work.
One of the first programs that Hugh Bennett encouraged farmers to adopt was
called terracing. Terracing supposedly at that, you know, as
the way he was proposing it to be implemented, would help conserve the soil,
would help conserve soil moisture from the winter, from melting snows and rains and
farmers were encouraged to break up their land by terracing.
Terracing is a very old practice so in effect Hugh was asking farmers to adopt
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