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Video - Case study: conservation agriculture
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Из курса от партнера University of Western Australia
Agriculture, Economics and Nature
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The economics of land conservation
Week 4 focuses on evaluating land conservation practices, weighing benefits and costs correctly, non-economic factors, and provides an example in conservation agriculture.
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Professor David Pannell, BSc(Agric), BEc, PhDHead of School of Agricultural and Resource Economics
University of Western Australia
Jacob Hawkins, BA(Biol), MESM, PhDSchool of Agricultural and Resource Economics
University of Western Australia
[THEME MUSIC]
The aim in this segment is to illustrate
how economic analysis can help to understand farmer's
responses to a new farming practice
and which groups of farmers are more
likely to adopt a particular practice.
It's a relatively long presentation
compared to most of the other presentations in the course.
And it's longer because it goes into some detail
to help you to help you understand what is driving
the economics, and to help illustrate
how useful economics can be in this sort of study.
So start with some background.
Concerns about food security, farm profitability,
and land degradation in agriculture
are prominent in many developing countries.
And various practices have been developed and promoted
to try and address those issues.
In developing countries, at least in some of them,
a lot of emphasis has been given to promoting
a particular package of practices
called conservation agriculture.
And in the standard version of conservation agriculture,
there are three components-- the zero tillage,
or at least minimum soil disturbance, retention
of crop residues for soil cover, which is also sometimes called
mulching, and rotation, or intercropping
of cereals with legume crops.
While though this is being quite widely promoted
throughout developing countries, particularly
in Africa and South Asia, it really
hasn't been that widely adopted in those countries.
And this is a bit of a contrast to at least some parts
of the developed world.
There's quite a bit of this type of agriculture
in Australia and in North America, some in South America.
But in the small holder type areas,
areas with smaller farmers, smaller farms
in Africa-- southern Africa, particularly--
and South Asia, the adoption of these practices
has been quite disappointing.
There are a few success stories, but mostly disappointing.
So let's talk a bit about some of the factors
that are influencing the economics of conservation
agriculture that help to explain this disappointing adoption
level.
The first is around tillage.
So traditional tillage involves plowing and turning
over the soil, whereas in conservation agriculture,
farmers are encouraged to use approaches
like this particular photo which shows a jab planter, which
makes very little disturbance of the soil
when the seeds are planted.
So, zero tillage has a number of benefits.
It reduces soil erosion.
It can, in some situations, save labor and inputs
due to not tilling.
It can have yield effects in some cases.
Although, in most cases, it's likely
that it has relatively little effect on crop yields.
It also has some costs.
It requires extra effort to kill weeds,
so either farmers have to be willing to put
more labor into weed control or they
need to have the money to buy herbicides.
And in some areas, the herbicide's are not available.
And if weed numbers are high, then using labor
is a relatively costly way to do it.
So that could be quite unattractive in some cases.
The next element is crop residues.
And you can see from this photo an example
where residues of a corn crop have been left on the soil
surface to help retain moisture and reduce soil erosion.
So, as I said, those are some of the benefits-- reduced
erosion and retention of moisture in the soil.
But also, adding organic matter to the soil is another benefit.
The costs are that it may require additional nutrients
to be added.
The yields may get worse before they get better, particularly
if nutrients are not added and that crop residues that
are retained and left on the soil surface
are not available to be used for other things.
And the other thing that they're usually used for
is as livestock feed.
So crop residues can be, in some farming systems,
quite a valuable source of livestock feed.
Another barrier is that in some regions,
the local practice is to allow any animal in the village
to graze on the crop residues.
And farmers who grow crops have no fences
and they actually have no rights to exclude grazing animals,
anyway, even if they had fences.
The local custom is that they should
be allowed to graze on the crop residues.
So, if that is the local practice,
then full conservation agriculture
is simply impossible.
So that would explain why, in some areas,
it's not been adopted.
So there's a photo of some cattle
grazing on crop residues.
And you can see there's no fences in that area.
The next element to consider is legume rotations.
So, the benefits of the legume rotation in the farming system
are that it fixes nitrogen, which
becomes available to the next cereal crop.
It can provide a disease break, so
that there's less disease in the following cereal crop,
because cereal crops and legume crops have different diseases.
It can provide diversification and risk reduction.
And it can provide better quality food for livestock.
On the other hand, depending on the particular legume crop
in the particular location, it may result in less profit
than the farmers would have got from a cereal crop.
But that depends very much on the yields, the sale prices,
and the input costs, and also the affect
that the legume crop might have on subsequent cereal crops.
It might be more profitable.
It might be less profitable.
It'll depend on the local situation.
So what I'm going to do now is present results
from a particular case study.
This is from the Mbire District, which
is part of the Mid-Zambezi Valley in northern Zimbabwe.
And the farming system in this region
consists of maize, pigeon peas-- which
is the legume crop, and livestock.
And, although at the moment, this farming system is part
of a culture where livestock cannot be excluded from grazing
crop residues.
I'm going to assume that it may become
possible to exclude livestock in future.
As part of the study, I've got an economic model.
We obtained data on crop yields, production costs,
labor requirements, biological effects, and so on
from experts who'd done research in the area.
And the model was developed for four different farms sizes
because the economics are likely to be different depending
on whether the farm is relatively large, relatively
well resourced, and at least somewhat mechanized
compared to really small farmers who tend to lack resources.
And there is a research paper available for this study which
I'll give you information about on the website.
OK.
So let's look at some of the results of this study.
There are a lot of different results that we developed.
I'll select some of the more interesting and important
results.
So here's a table that shows you the results
for the economic performance of having a rotation that
includes the legume crop versus farming cereal
crops continuously every year.
There are two sets of results.
On the left hand side of the graph,
there's two columns where I've got the net present value,
and you've learned about what that
is, for three years and the two right hand columns
are for 10 years.
So these are included because some farmers have more capacity
to allow more time and to consider benefits and costs off
into the future, whereas for some small holder
farmers in developing countries, they really
can't afford to think that far ahead.
They've got pressing needs for food and income.
And so, for those farmers, we looked at a three year time
frame.
For some of those farmers, it might even
be a one year time frame that's the most relevant.
But here, we've looked at three.
And you can see that there are net present values presented
for cereal crops and for a rotation that
includes legumes as well as cereals.
So for the standard assumptions, the standard set
of data that we used, the key message
from this set of results is that the legume rotation
is worse than the continuous cereal farming
system on all four of the different farm types.
Farm type 1 is the really small farms.
Farm type 4 is the relatively large firms.
But in every case, for every farm size,
the legume rotation was worse than the continuous cereal
farming system.
And that was true for both the three year analysis and the 10
year analysis.
So that wasn't very encouraging for the legume system.
These are in a situation where we're
assuming that there is open access,
that farmers can't exclude livestock
from grazing their crop residues.
Then we decided to have a look at a case
where legume yields might increase in future.
There's research going on or there are different legume
crops available that might be able to perform better
in this farming system.
And we were interested to see whether it was conceivable
that in future, the legume crop system, the legume rotation
system, might become financially attractive option
for these farmers.
Now, these results are for the 10 year case.
So there's three columns of results.
Oh, sorry, there's four-- one for no legume rotation,
one for the best case legume yields, and then one for 30%
increase legume yields, and one for 50% legume yields.
And you can see that some of the sales
are now shaded a greener color.
And these are the ones where the legume rotation now
performs better than the system with no legumes
in the rotation.
So, with a small increase in legume yields,
we can get a legume rotation to become the most attractive
option, but only on the largest farm type, number 4.
You can see that at the bottom of that second-to-last column.
And then, in the last column, when
we've got quite a large increase in legume yields,
the legume rotation becomes the most attractive option
on most of the farms.
It's only on the very smallest farm
that it doesn't come into the best farming system.
Next, we're going to look at the tillage options.
So we're comparing in this case, again, three years and 10 years
analysis.
And we're comparing conventional cultivation with zero tillage.
And this is for the open access case
where farmers can't exclude other people from their village
from grazing livestock on the crop residues.
In this case, you can say that on the largest farms, farm type
4, the zero tillage option is at least as good.
It's about as good as the conventional cultivation option
when you look at it over only three years.
And it's slightly better if you look at it over 10 years.
But on the smaller farms, farm types 1, 2, and 3,
it's not as attractive.
And, in fact, on the very smallest farm,
farm type 1, its miles behind.
It's much less attractive to do a zero tillage farming
system than a conventional cultivation option.
And that relates primarily to issues of weed control.
Weed control problems are more costly on the zero tillage
option.
And for those small farmers, that's a real problem.
This time we're looking at several different farming
systems over 10 years and comparing
the economic performance of each of them.
For these results, I've shown the result
where whichever is better, either open access
or private access.
So the farmer has the option of fencing off their crop
residues, but it may or may not be
optimal to do that because it's an expensive thing to do.
So the results that have an asterisk next to them
are the ones where it's actually more
profitable not to fence off.
And the ones where there's no asterisk
are the ones where it's more profitable to fence off
the crop residues to exclude grazing.
OK.
So there's several columns of results here.
The first column of results is for conventional agriculture,
then the results for legume rotations,
then zero tillage, then the combination
of zero tillage and mulching, and finally--
the full conservation agriculture package
with legume rotation, zero tillage, and mulching.
Right.
So the first result to observe is that the most economically
attractive option, across all of these options for the smaller
farms-- farms 1, 2, and 3 -- is actually conventional
agriculture.
So, looking at these results, it's not that surprising
that small holders in these sorts of regions
are choosing not to adopt conservation agriculture.
But for at least some of these farmers,
they would actually lose money by doing so.
On the largest farm, it is economically attractive
to move away from conventional agriculture,
but not necessarily to the full conservation agriculture
package.
What turns out to be the most attractive option
is just to go to the zero tillage optional line,
not to do the mulching or the legume rotation.
At least not on this, legume rotation yields
could be increased.
But with the standard yields for legumes,
the best option for farm type 4 is just zero tillage.
So this is an important observation.
The promotion that's been done of conservation agriculture
has tended to promote all three of these items, all
these options, as a package.
But in reality, farmers tend to pick over packages like this
and choose the individual options.
They might choose one or two options
within a complex package that look best to them.
And these results show that, in some situations at least,
that can be a very sensible thing to do.
So, in conclusion, what can we learn from these results?
First of all, you can see that drawing conclusions
about a package like conservation agriculture
is a numbers game.
There are lots of numbers involved.
And what matters is how the numbers stack up
in a particular situation.
It's not possible to draw a very general conclusion usually
that one particular package is better,
one farming practice is better than another.
You've got to look at the numbers
and bring them together, do the economics properly,
and see which ones stack up best.
So what we found was that conservation agriculture
perform best on the well resourced larger
farms with longer time horizons.
But interestingly, it may not be compelling even then.
It wasn't always the case that conservation agriculture was
the best option, even on the largest farms with the longest
time horizon.
We also learned that selective adoption
of parts of the package are likely to be best, or at least,
may be best for some farmers.
Some farmers might choose to adopt the whole package.
But some will prefer to be selective and pick and choose
within the elements of the package.
So I guess it's important to note
that the results for this case study are not generalizable.
It's a particular case study with a particular set
of numbers for a particular region in a particular country.
So one shouldn't jump to conclusion
that the same specific results would apply in other cases.
But the more general observations,
like farmers might pick and choose within the package
and that smaller farmers might have more trouble than larger
farms finding these packages attractive.
Those sorts of more general results,
you would expect those to apply more generally.
The results indicate trends and principles quite well.
And they reinforce the suspicions
that you get from looking at the previous literature
on the economics of conservation agriculture.
It is a practice that can be attractive in certain cases.
But it may not be attractive.
And it's likely not to be attractive in every case.
So there you go.
There's a little bit of a more detailed look
at the economics of a particular case study.
And I think you'll agree that that's
been reasonably enlightening, even though it's only
a case study for one region.
[MUSIC PLAYING]
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