The Discover Best Practice Farming for a Sustainable 2050 Course is based on a clear vision: imagine best practice farming for 2050, start to implement these strategies now, all the while making sure it will still be profitable. At UWA we're doing just that with the Future Farm 2050 Project, set on a mixed-enterprise farm in Western Australia and we want you to learn how it can be done in your part of the world. Although this course is based on agriculture, it's not only about farming. It is a multi-disciplinary course that addresses a wide range of issues confronting the industry, including rural communities, rural infrastructure and conservation of biodiversity in agriculture. By completing this course you will understand that feeding and clothing the planet requires a multi-disciplinary approach and upon completion you will be able to explain best practices of sustainable farming and apply them in new contexts.
Professor Stephen Powles: Cropping and Weed Management
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來自 University of Western Australia 的課程
Discover Best Practice Farming for a Sustainable 2050
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從本節課中
Ecological Cropping
Welcome to Week 3 of "Discover Best Practice Farming for a Sustainable 2050". This week you'll be introduced to Ecological Cropping, and more specifically weed management and plant breeding. Effective weed management strategies, in a changing environment with increasing resistance to herbicides, has become increasingly important for crop management. In addition to these management strategies, successful cropping also depends on high yielding varieties, tolerant to a changing environment.
與講師見面
Graeme MartinProfessor
School of Agriculture and Environment
My name is Stephen Powles.
I'm a professor in
the School of Agriculture and Environment at the University of Western Australia.
I'm also the director of
the Australian Herbicide Resistance Initiative which
I'll tell you in a little bit about in a few minutes time.
But firstly, let me say something about the production of crops in Australia.
Australia is a very large country and much of the area is not suited to crops.
But because it's a very large country,
there's also a very large area which is very
well suited to the production of field crops.
What is important to realize about Australia is that farms are very very
large and are overwhelmingly dependent upon natural rainfall.
So the amount of irrigated crop is very
small whereas the amount of rain fed crop is very large.
And cropping occurs on very large farms that produce the field crops particularly wheat.
Wheat is by far the most dominant crop in Australia
with at least 15 million hectares being grown of wheat every year.
The other major crops are barley and canola.
Barley is an important crop and canola an increasingly important oilseed crop.
This is then followed by a range of pulse crops which are grain legumes that both fix
nitrogen for subsequent crops and produce high protein human grains such as field peas,
fava beans, lentils, lupins,
and some other pulse crops in the north like chickpeas.
So in total, in any one year,
there's 20 to 25 million hectares of crops that are grown each year.
Now most of these crops are grown in the southern part of the continent,
although it extends into warmer regions as well.
But in southern Australia we grow crops during,
important to realize, during the winter months.
In other parts of the world,
crops are grown during the summer months.
But in southern Australia the rainfall which occurs,
occurs in the cooler winter months.
So in Australia our big crops,
particularly wheat but the other ones barley,
oats, canola and the pulses,
are grown during the cooler months.
Normally what happens is in early May,
we get the start of our rainfall events.
And this is the southern hemisphere,
so the winter months are June, July, and August.
So the crops are planted in May and they
grow during the winter months of June, July, and August.
They then grow rapidly in the early spring months until
the rainfall events taper off and the crops mature and are harvested,
depending on the region,
in October through December.
The other thing to understand about agriculture in Australia is that livestock,
particularly sheep and beef cattle,
are also a very important part of the farming systems.
Since the commencement of European farming in Australia,
there has been a great increase in the number of livestock on farms,
particularly sheep in southern Australia,
but also in many areas beef cattle.
And the farming system for many farmers has been a rotation between the crops,
the annual crops particularly wheat, and annual pastures.
So if we take an average field,
a field in Australian agriculture will be very large,
say, 200 hectares or greater.
And that field, for the last hundred years,
has been a rotation of the crops with pastures and livestock.
So for example, this year,
the field could be in wheat as the annual crop and,
next year, it would be in pasture in which volunteer species
would germinate from the seed bank and form the pasture on which livestock,
principally sheep, are grazed.
And that is the way European type agriculture has operated in Australia since
the first European settlers started to farm land in Australia from about 1800s onwards,
a combination of sheep, livestock, cattle,
and annual cropping in a rain fed system in which
the rainfall in southern Australia occurs during the winter months.
And what I've described for Australia is generally true for Western Australia which is
a very large state with a very large rain
fed agriculture in which the primary crops wheat,
barley, canola, oats.
And smaller areas of the pulse crops in
Western Australia particularly the pulse called lupins.
Sheep and livestock in general are still quite
important but not as important as they were 20 or 30 years ago.
Over the last 20-30 years there has been
a substantial increase in the importance of the annual crops, particularly wheat.
Farms in Western Australia are very large,
with the average grain cropping farm now being around 4000 hectares.
These are family farms in which a farm of
4000 hectares is operated by two families in many cases.
So agriculture is big,
agriculture involves very large machinery,
agriculture involves very skilled farmers able to
operate very large farms with minimal labor input,
with machinery being very very important.
Now, of course, what I've described for
Western Australian agriculture is also true for the University of Western Australia,
UWA, the University of Western Australia farm which reflects
agriculture both in Western Australia and Australia in involving the production of crops.
And your crops wheat,
canola on the UWA farm and rotated with the production of
pastures on which grazing animals, principally sheep.
So the UWA farm is representative of the broad anchor agriculture
that's practiced in Western Australia and throughout Southern Australia.
Of course, as for agriculture anywhere in the world,
there are substantial challenges that have to be overcome to produce
crops and livestock in the big farms of Australia.
One of the distinguishing features, and great successes,
of Australian cropping has been the replacement of
destructive soil cultivation with no-till farming systems.
When agriculture was commenced by European settlers in Australia
the practices were very similar to that which occurred in the homelands of Europe,
particularly Britain from which our first farmers came.
European agriculture is marked by soil cultivation,
the use of moldboard ploughs and other deep tillage instruments,
which can disturb the soil and produce a seed bed for the planting of crops or pastures.
But over time what was realized is that soil cultivation,
soil tillage, is a very destructive practice,
particularly in the lighter,
fragile soils of Australia in which rainfall is a limiting factor.
When we had extensive soil cultivation,
we were losing precious soil moisture,
we were suffering soil erosion,
and we were losing soil structure.
The homegrown answer was to replace
destructive soil cultivation with no tillage farming and cropping.
This was a major advance,
this was driven by farmers together with researchers who could see that
the soil cultivation which was occurring in Australia was
leading to loss of soils and loss of productivity.
And from about 1980 onwards
there has been the development of no-till cropping systems
in which the soil is not disturbed anywhere near
the extent that it was done in European type agriculture.
You will see an accompanying video shots
that special equipment has had to be developed to
enable crop seeds to be placed into the soil
without the preparation through tillage of a seed bed.
And this involved a whole range of
technologies which had been developed to enable no-till cropping.
The principal advantages of no-till cropping is that they protect our soils
from the destructive effects of cultivation and preserves soil moisture in the soil.
And this has enabled earlier crop seeding for an earlier date of seeding of the crop
which has meant a longer growing season and therefore
potentially higher yields through early planting,
a lengthy growing season,
and maximizing on the soil moisture that is available.
So no-till is now the dominant form in which crops are planted throughout
Australia and certainly in the large rain fed field crops of wheat,
barley, canola, oats, and the pulses.
It is almost universally no-till cropping,
and that has been a great advantage to preserving
our soils as well as increasing crop productivity.
So no-till is a great success in Australian cropping.
Now no-till, of course,
also has its technological challenges and we would not have been able to develop
no-till cropping in Australia without the availability of herbicides.
Soil cultivation, soil tillage,
is a great tool,
since the dawn of agriculture, in managing weeds.
So when we switched from destructive soil cultivation to no-till,
we had to have a way to control the weeds which will infest our crop fields.
And the tool that became available that enabled no-till cropping was good,
modern, environmentally benign, and selective herbicides.
In the 1980s as we adopted no-till we
could do so because we had available to us herbicides
that could be applied both before the crop was seeded to remove
weeds at the time of crop seeding, so-called pre-emergent herbicides.
And very importantly, early in the crop's growth,
we could apply post-emergent herbicides that would
remove the weeds without adverse effect on the crop.
So no-till cropping has required the usage of herbicides and that has
been a very important part of conserving
our soils and enabling increased crop productivity in Australia.
But like all changes,
the adoption of herbicides and no-till
agriculture meant other challenges which had to be addressed.
And principally, the major challenge has been the emergence, the evolution,
of weeds that have evolved resistance to the herbicides which we have used.
In the 1980s, when we started
the widespread adoption of herbicide use and the introduction of no-till,
we did not have a sufficient appreciation that the weeds
would evolve resistance to the herbicides we were using.
We have a particular weed species called ryegrass,
species is lolium rigidum,
which is particularly able to evolve herbicide resistance.
It is very widespread across the nation,
it is very genetically diverse,
and it has all of the genetic capabilities to quickly
evolve resistance if there is over-reliance on herbicides.
So a major challenge in Australia to maintaining a no-till cropping,
with all of its environmental advantages,
a major challenge is to ensure the sustainability of
the herbicides which enable the no-till cropping.
In the face of the evolution of herbicide resistance,
we have had to learn to be much smarter with our use of the herbicides that we have.
We have learned that we must not over-rely on herbicides.
While they are essential to modern cropping in Australia with our no-till emphasis,
we must not over-rely on herbicides because if we do,
they fail due to the evolution of resistance.
We have had to realize the importance of diversity,
both in our choice of crops and pastures,
our choice of herbicides,
and the use of non-herbicide or non-chemical ways
to control weeds to complement our farming system,
to diversify our farming system,
to diversify our crops,
to have in many cases alternatives like pastures,
or hay crops, or other diverse tools so that we do not over-rely on herbicides.
If we use the same herbicide every
year we know that the weeds will evolve resistance to that herbicide.
We also know that if we have sufficient diversity in our farming system,
we can maintain the enormous advantages of no-till cropping and
still keep herbicides working to help no-till and crop productivity.
And that is our objective.
