Over the past couple of weeks, our group has
been working to organize itself and focus in on our key ideas. My
recent research has focused primarily on Brazilian agriculture. I
have been trying to find details on agricultural practices, but these are
hard to come by. I have, however, found information about Brazil's
agricultural production and its past and present land use, and information
about agricultural practices in general.
These are some statistics on land use in Brazil, from the
Instituto Brazileiro de Geografia e Estatistica (IBGE)
. These numbers do not distinguish between land that is and is not
part of the Amazon, but they do give a decent sketch of the way land is
used in Brazil in general and they show how land use patterns have changed
over time.
1970 |
1975 |
1980 |
1985 |
1995-96 |
|
total (in millions of
hectares) |
294 |
323 |
364 |
374 |
353 |
permanent crops |
8.0 |
8.4 |
10.5 |
9.9 |
7.5 |
temporary
crops |
12.9 |
15.3 |
19.2 |
22.1 |
34.2 |
fallow land |
------- |
2.2 |
8.9 |
10.7 |
8.3 |
natural pastures |
103 |
125 |
113 |
110 |
78 |
planted pastures |
30 |
40 |
61 |
74 |
100 |
natural woods |
56 |
68 |
83 |
83 |
89 |
planted woods |
1.6 |
2.9 |
5.0 |
6.0 |
5.4 |
"productive land" not
in use |
33 |
31 |
25 |
24.5 |
16.4 |
Farm Products |
Area (in ha, rounded
to nearest 1,000)
|
||
harvest gathered in
2001 |
harvest to be gathered
in 2002 |
% change |
|
Total |
46,163,000
|
49,406,000
|
7.03
|
1) Soybeans (grain)
|
13,931,000
|
16,362,000
|
17,45
|
2) Corn (grain) 1st harvest
|
2,339,000
|
9,234,000
|
-7.81
|
3) Sugar cane
|
4,973,000
|
5,055,000
|
1.64
|
4) Rice (in husk)
|
3,142,000
|
3,178,000
|
1.15
|
5) Corn (grain) 2nd harvest
|
2,339,000
|
2,755,000
|
17.78
|
6/7) Coffee beans
|
2,354,000
|
2,378,000
|
1.05
|
7/6) Beans (grain) 1st
harvest
|
2,063,000
|
2,520,000
|
22.17
|
8) Wheat
|
1,728,000
|
2,096,000
|
21.28
|
9) Cassava
|
1,656,000
|
1,686,000
|
1.84
|
10) Beans (grain) 2nd
harvest
|
1,218,000
|
1,522,000
|
25.02
|
This week I did some independent research
on agricultural practices in the Amazon. I focused on this topic because
I found in my general research that one large contributer to deforestation
is ill-managed agriculture, so one way to reduce deforestation greatly could
be to find ways to make agriculture more efficient and environmentally friendly.
That way, necessary agricultural development could continue with
minimal damage to the ecosystem.
From Sustainable Settlement
in the Brazilian Amazon1
(1995):
High productivity farming tends to have two effects:
1) Retention of land is high, so deforestation is contained to a certain
area.
2) There is high deforestation on the plots that are occupied; the forest
will probably never grow back there.
The enviromental costs that arise from this sort of farming are loss
of biodiversity and erosion of soil. These things are difficult to
measure, but it is possible to identify the conditions under which they are
reduced. (For instance, when there is greater yield per acre of land,
enviornmental costs will be lower.)
Three measures that would promote sustainability
are:
1) Reduce environmental cost per private benefit.
2) Increase private costs of deforestation.
3) Decrease private cost of environmental alternatives such as
alternative tropical farming technology.
From Amazonia: Agriculture and Land
Use Research2(1982)
Little has been done to understand the Amazon's potential adaptability
for annual food crops. Some information suggest that, with adequate
scientific knowledge, it would be possible to gradually develop the Amazon's
agricultural potential, through the careful manipulation of existing conditions
and through the generation of an equilibrium between different types of
crops (annual, perrenial, forest).
Different agricultural methods:
"Shifting agriculture," commonly known as slash and burn, is
the most widely used method in the humid tropics. As you would expect,
it consists of cutting down the vegetation in an area, burning it, farming
the plot for 2 or 3 years until the soil is depleted, and then moving on
to a new plot. Unfortunately, when the population of an area increases
enough, this practice becomes disruptive of the ecological balance. Additionally,
its average yields are relatively low.
Mechanized clearing (i.e. bulldozing)
is even worse than slash and burn in many ways. In the slash and burn
method, ashes return to the ground and replenish the soil's (very important)
nutrients. This doesn't happen with the mechanized clearing. Mechanized
clearing also causes problems of soil compacting (causing water infiltration
rates to decrease from 10.5 cm/hr to only 0.5 cm/hr in one study), and disrupts
the fragile surface layer of soil.
A number of systems for continous
cropping of annual plants exist, which are all improvements over these two
methods.
Intercropping--the cultivation of multiple crop species simultaneously
in the same area.
Experimentally, implementations of this give figures such as 50% and
60% better yield per unit of land. This system minimizes competition
for light, water, and nutrients, allows for more efficient management of
diseases, insects, weeds, and soil, permits better diversity of crops, and
just uses land more efficiently. This works best on small farms, although
the author states that intercropping of annuals and perennials "offers
promising perspectives."
Relay system--the planting of a second crop before the flowering
or harvesting of a first
This gives better yields than intercropping because it reduces the periods
of competition between crops, but it also seems to create environments that
encourage the spread of pathogens.
Sequential rotational system for annual
crops
This is often used commercially, and is viable for an extended period
of time (7+ years in one study). Of these three systems, it seems
to be the most efficient and effective in large scale operations.
Regardless of the system, certain things
are always important, such as:
Conclusions that can be drawn are:
When population density is high enough,
agriculture with annual crops should be permanent and continuous instead
of shifting. The step from shifting to continuous agriculture requires:
Continuous cultivation in the Amazonia
is feasible if these things are all taken into account.
There is still much research that needs
to be done. Some relevant fields of research are better farming technology
and genetic studies/selection of other crops that could be grown sucessfuly
in the Amazon area.