The text that follows is a PREPRINT.
Please cite
as:
Fearnside, P.M. 1985. Agriculture in Amazonia. pp.
393‑418 In: G.T. Prance & T.E. Lovejoy (compiladores) Key
Environments: Amazonia. Pergamon Press, Oxford, UK. 442 pp.
Copyright: Pergamon
Press, Oxford, UK.
The original publication is available from: Pergamon Press,
Oxford, UK.
AGRICULTURE IN AMAZONIA
Philip
M. Fearnside
Department of
Ecology
National
Institute for Research
in the Amazon‑INPA
Caixa Postal 478
69011 Manaus,
Amazonas
BRAZIL
April
10, 1982
Revised: Mar. 10, 1983
Jan.
24, 1993
Manuscript for G.T. Prance and T.E. Lovejoy
(eds.) Key Environments: Amazonia. Pergamon Press Ltd., Oxford, U.K.
(1985)
ABSTRACT
21.1
AGRICULTURAL TYPES: PATTERN AND
TRENDS
21.11 Terra Firme: the vast Uplands
21.111 Shifting Cultivation
21.112 Pioneer Smallholder Annual
Crops
21.113 Cattle Ranching
21.114 Perennial Crops
21.115 Mechanized Annuals
21.116 Horticulture
21.12 Várzea: Amazonian
Floodplains
21.121 Annual Crops of
Smallholders
21.122 Mechanized Rice
21.123 Horticulture
21.124 Fiber Crops
21.125 Cattle and Water Buffalo
21.2
ALTERNATIVE MANAGEMENT: IMPEDIMENTS AND PROSPECTS
21.21 Fertilizers and Continuous
Cultivation
21.22 Diversity and Sustainable
Management
21.23 Farm Size and Agricultural
Populations
21.3
LIMITS TO AGRICULTURE: HUMAN CARRYING CAPACITY
REFERENCES
ABSTRACT
The
varied habitat types of Amazonia, and the varied cultural backgrounds of the
region's inhabitants, are associated with a wide range of approaches to
agriculture. Agricultural types differ
greatly in their yields to humans, their production constraints, and their
future prospects. Soils, topography, and
other agriculturally important features of the landscape vary tremendously on a
microscale, as well as between the two principal zones into which the region is
divided: the upland terra firme and the seasonally flooded várzea.
Agricultural
patterns are changing rapidly. In terra
firme areas the traditional shifting cultivation practiced by indigenous groups
has been replaced by other forms as quickly as the groups themselves retreat
and disappear. Caboclos, the poor
Portuguese‑speaking inhabitants born in Brazil's Amazonian interior,
practice a form of cultivation similar in many ways to indigenous methods, but
also differing in important respects.
Far more different is the pioneer agriculture practiced by the waves of
recent arrivals to the region, resembling the traditional shifting cultivation
only in the initial slash‑and‑burn method of land preparation. Pioneer planting of annual crops is usually,
in one way or another, supplanted by low‑yielding cattle pasture. Pioneer farmers often plant pasture
themselves, and pasture is planted at an even faster rate by others who buy or
take the land from the pioneers. In
addition to pioneer farmers who follow annual cropping with pasture, large
ranchers are rapidly converting vast expanses of virgin forest directly to
pasture. Speculation, even more than
generous government incentives, makes pastures highly profitable in spite of
low productivity and slight chance of sustainability. Soil degradation and invading weeds reduce
pasture yields after a few years. Fertilizers have been put forward as a
solution to declining yields, but serious doubts cloud the long term
effectiveness of this measure for sustaining pasture productivity.
Much
more restricted areas have been planted in perennial crops with the help of
government financing. Fungal diseases
and world market limitations for the products make it unlikely that a
significant part of the region's vast uplands will be planted in cacao, black
pepper, rubber and other perennials.
Mechanized cultivation of annual crops has also been introduced by a few
wealthy newcomers, but long term prospects are poor. Horticulture near large city markets has
proved profitable, as high market prices allow the use of expensive inputs.
The
Amazon floodplain, or várzea, has the advantage over terra firme
of more fertile soils, and far more importantly, the possibility of sustained
production since soil fertility is renewed by the silt deposited with each
year's flooding. Annual crops planted by
small farmers is the traditional use.
Mechanized cultivation of irrigated rice has been in one large‑scale
attempt to apply capital and resource‑intensive methods to the várzea.
Other forms of agriculture employed in the várzea include horticulture,
fiber crops such as jute, and the grazing of cattle and water buffalo.
Researchers
have followed a number of approaches in the search for more productive ways of
farming in Amazonia. One program hopes
to make annual cropping in terra firme into a continuous cropping system
by applying a delicate balance of chemical fertilizers. Both technical and human obstacles make the
system's widespread use unlikely. A
number of experimental agricultural systems are attempting to maintain some of
the diversity and other characteristics of natural vegetation and traditional
cultivation systems. Many of these use
different combinations of perennial crops, some combining silviculture and/or
perennials with annual cropping. Diverse
plantings are appropriate for promoting sustainability, security of yields, and
self‑sufficiency of farming communities.
Land
tenure arrangements have a profound effect on the types and intensities of
agriculture employed, and on the effectiveness of agriculture in supporting the
human population. The trend to more
concentrated land tenure is related to the spread of cattle pastures as the
dominant form of agriculture in the region.
Each
form of agriculture has limits to its ability to produce yields and support
human populations. Some, such as pasture,
are very low. Human carrying capacity,
the population density that can be supported indefinitely at a given standard
of living without environmental degradation (given a variety of assumptions),
is limited. Amazonia's twin illusions of
infinite size and infinite "agricultural potential" can easily
mislead development planners into promoting wasteful and unsustainable land
uses. The current rush of immigrants to
Amazonia from other can soon be expected to lead to exceeding carrying
capacity. Agriculture in Amazonia cannot
be expected to solve growing national problems.
Sustainable management of agriculture for the region's residents will
require a re‑orientation of agricultural research efforts and development
programs. No single land use choice can
ever be recommended for the entire
Amazon, but rather a patchwork of different uses to fill different needs and
accommodate different constraints.
Careful definition of goals is an essential first step in helping
agriculture fulfill its primary purpose: continued support of the human
population. In addition to sustainable
agroecosystems, the long‑term wellbeing of Amazonia's inhabitants
requires restraints on the concentration of land holdings, limited total
consumption, and maintaining the human population below carrying capacity.
AGRICULTURE IN AMAZONIA
21.1 AGRICULTURE TYPES: PATTERN AND TRENDS
21.11 Terra
Firme: the vast uplands
21.111 Shifting cultivation
Shifting
cultivation or swidden is the traditional method of farming Amazonia's vast
unflooded uplands known in Brazil as terra firme (Span: tierra firme). Indigenous populations have used such
"slash‑and‑burn" agriculture for many centuries as a
means of obtaining plant‑based foodstuffs from Amazonia's infertile
soils, with a minimum of human effort spent on fending off the relentless
competition of weeds and crop pests (Carneiro, 1960; Harris, 1971; Gross et
al., 1979). Large land areas
relative to the human populations have allowed employment of long fallow
periods, usually several decades, between brief farming periods of 1‑2
years. During the fallow period, woody
second growth (Port.: capoeira, juquira, or quisasa;
Span.: purma, rastrojo, or barbecho) takes over the
temporarily "abandoned" fields, accumulating nutrients in the tree
biomass, restoring the soil's porosity and other physical structure characters
degraded through farming, and increasing the organic matter content of the soil
as reduced soil temperatures shift the balance between accumulation and
decomposition of soil humus. Soil fauna,
greatly depleted during the farming period, returns with consequent resumption
of nutrient cycling and other roles in the forest ecosystem.
The caboclos,
or poor Portuguese‑speaking inhabitants of the Amazonian interior, also
employ a similar system (Wagley, 1976; Moran, 1974). Caboclos generally do not move their
residences together with their fields, as indigenous groups often do, but are
still able to move their plantings over sufficiently wide areas to have long
fallows. Most of the region's river and
stream banks now occupied by the caboclo population have only been
farmed by these racially and culturally mixed residents on the order of one
century, in contrast to the much longer history of occupation, very often of
the same choice riverside sites, by Amerindian groups. Caboclos lack the complex of cultural
mechanisms which have been found in many parts of the world to result in long
fallows among traditional practitioners of shifting cultivation.
When
either primary forest or a second growth stand is cut for farming in Amazonia,
it is essential that the downed vegetation be burned. Burning removes the physical obstruction of
the dead vegetation, releases needed plant nutrients into the soil (especially
phosphorus and cations such as calcium, magnesium and potassium), and of
particular importance, raises the soil pH.
The extremely acid soils of the region yield only stunted crops if
burning is poor. Low soil Ph has a
synergistic effect with the low phosphorus levels, reducing the availability to
plants of what little phosphorus exists.
During
the farmed period, crop yields usually decline as a combined result of
exhausted soil fertility and the increased inroads of weeds and pests. The relative importance of the different
factors depends on the initial fertility of the soil (Sánchez, 1976). Where soil is extremely infertile, as in the
white sand areas of the upper Rio Negro, the end of nutrient supply, especially
organic matter from decomposition of the thick mat of forest roots, is believed
to be critical (Herrera et al., 1978).
In rich volcanic soils of Central America the invasion of weeds is
credited with at least equal impact on yield declines (Popenoe, 1960). The question of what causes shifting
cultivators to "abandon" a given field can easily become a sterile
academic debate, as farmers themselves are not concerned with levels of
phosphorus, organic matter, or any other soil nutrient, but rather the net
result in terms of yield obtained from their labor. Increased labor demands of weeding, combined
with declining yields per area, make moving to a new location more and more
attractive as farmed period lengthens.
The per area yield declines are themselves the combined result of the
many individual agricultural setbacks, a kilogram lost to pests being just as
unavailable to feed the farmer as a kilogram lost to stunted crop growth.
Yields,
and their declines, are exceedingly erratic depending on weather, biological
problems, and many other factors.
Sometimes yields will be better in the second year than the first, or
vice versa, a large sample being needed to draw valid conclusions. Yields of some crops, such as maize, may
increase in the second year of cultivation in comparison with the first
(Jessup, 1981), although evidence is conflicting. Others report the more traditional view of
yields declining steadily from the first year (Penteado, 1967; Watters, 1971:
101, 106; Cowgill, 1962; Sánchez, 1976: 375; UNESCO, 1978: 472‑3). One contributing factor to an increase in the
second would be the disappearance, as the farmed period progresses, of downed
vegetation occupying some of the land area.
The soil itself may provide some explanation if allelopathic chemicals
released into the soil by the original forest trees have a role in inhibiting
crop growth in the first year after clearing.
Information on such possible effects is scant and conflicting.
It is
important to note that many indigenous groups are believed to move their
residences, with consequent "abandonment" of swidden fields, as an
adaptation to exploiting game and fish populations over a wide range of
territory (e.g. Gross, 1975; Roosevelt, 1980).
For many indigenous groups the distinction is often blurred between an
actively cultivated garden and an "abandoned" or fallow field, as
tree crops planted in the field (or spared the axe during the initial clearing)
may be harvested for many years after active cultivation has ceased.
Shifting
cultivation is condemned by many agronomists for its inability to provide
sufficient surpluses to allow its practitioners entry into the cash economy
(e.g. Alvim, 1978), as well as for its leading to deforestation and erosion
(United Nations F.A.O., 1957; Watters, 1966, 1971). Advantages of the system include its
successful record for supporting human populations during millennia (provided
population densities remain low), as well as its self‑sufficiency and
high productivity per unit of human labor (Leach,1959; Nye and Greenland, 1960;
UNESCO, 1978: 467‑476; Sánchez, 1973, 1976). It is well to point out that most clearing in
Amazonia today is the result of large‑scale cattle ranching rather than
shifting cultivation, although clearings from both large and small operators
have negative effects. Small clearings
with short farmed times regenerate far more quickly than large pastures (Uhl,
1982; Uhl et al., 1982), but true shifting cultivation with small
isolated clearings and long fallows is becoming a rarity in the region. With the present rapid disappearance of
indigenous groups (Davis, 1977; Hanbury‑Tenison, 1973; Goodland and
Irwin, 1975; de Oliveira et al., 1979), shifting cultivation can be
expected to disappear. Pioneer
agriculture by small farmers, both squatters and government‑sponsored
colonists, resembles shifting cultivation superficially but has profound
differences which render it unsustainable.
2.112
Pioneer Smallholder Annual Crops
The
thousands of pioneer farmers who have entered the Amazon in recent years from
other regions employ agriculture with many essential differences from the
traditional long‑cycle shifting cultivation of Amerindian and caboclo
populations. The new migrants come from
areas such as drought‑prone Northeast Brazil, and from the former coffee
and food‑crop lands of Paraná and other southern Brazilian states where
mechanized soybean and wheat cultivation, along with vast sugar cane
plantations for alcohol production, are driving out the former sharecroppers
and small land owners. In the case of
migration to the Amazonian portions of Bolivia, Peru, Ecuador, Colombia, and
Venezuela, newcomers come from Andean areas.
The flow of migrants has swollen as a combination of worsening
conditions in the source areas and the opportunity to obtain land in Amazonia
by taking advantage of the many new highways constructed in the region. Pioneers are settled in government‑sponsored
colonization areas, as well as both private and public lands where squatters
have entered on their own initiative.
The new arrivals fell and burn the forest, much as do traditional
shifting cultivators in the first step of a swidden cycle, but thereafter the
differences in the two classes of systems become more apparent. A few of the pioneers are from caboclo
backgrounds in other parts of Amazonia; these carefully select the land to be
cleared based on indicator tree species present, and plant a diversified array
of crop plants (Moran, 1979a). They also
are more skillful in timing the felling and burning operations to obtain the
best burns, as well as in making the many agricultural decisions from deciding
how much to plant of crops like rice (Oryza sativa) requiring intensive
periods of seasonal labor as compared with more traditional staples like manioc
(Manihot esculenta) which spread the labor requirements over much the
year (Fearnside, 1978, nd‑a).
Most of
the new arrivals from other ecological regions find adaptation to the new
environment difficult. Many of the
responses lead them gradually to adopt some of the solutions long practiced by
the area's residents (Moran, 1981). The
speed and path of the adaptation process varies greatly, however, depending in
part on the colonist's background before arrival (Moran, 1979b, 1981; Fearnside,
1980a).
Pioneer
farmers do not plant the wide variety of crops employed by traditional shifting
cultivators (Smith, 1978, 1981a,b). The
more homogeneous and larger fields planted are both more susceptible to pest
and disease problems, and represent a more devastating blow when problems do
arise. The Transamazon Highway
colonists, for example, suffered a severe setback when virtually the entire
rice crop failed in 1973, as a result of an untested rice variety distributed
by the government colonization agency.
Colonists in government‑sponsored areas such as the Transamazon
Highway expand their planting far beyond what their family's labor supply would
permit, through hired hands for felling and harvesting paid by bank
financing. The bureaucratic delays and
other institutional problems associated with financing can often result in
colonist's agricultural efforts failing both agronomically and economically
(Wood and Schmink, 1978; Moran, 1981; Bunker, 1980; Fearnside, 1980a, nd‑a). Good burn qualities, largely predictable
based on meteorological data, and felling and burning dates, are critical to
obtaining a good yield (Fearnside, nd‑a, nd‑b); delayed felling for
bureaucratic reasons, or ignorance of the associated risks, can often result in
poor burns and failed crops.
The
most striking difference between pioneer agriculture and traditional shifting
cultivation is lack of the cultural traditions which lead swidden farmers to
leave their fields in second growth for long periods before returning for a subsequent
crop. Pioneers clear young second growth
only one or two years of age with frequency, not a practice that could be
expected to continue for long. Colonists
have no intention of using a sustainable cycle of shifting cultivation as the
basis for their agriculture. Rather,
annual crops planted in the early years of settlement are seen as a temporary
solution to their immediate needs for cash, while the settler waits for a
change to other sources of income such cattle pasture, perennial crops, or selling
the land at a good price to someone else who will develop one of these longer‑term
uses. By far the greatest share of the
land area, both in areas of small colonists and in large land holdings, is
rapidly being converted to cattle pastures.
Annual
cropping by small farmers cannot continue indefinitely in its present pattern,
given the unsustainable features of the system.
Traditional long‑fallow shifting cultivation also becomes
impossible when population density increases, as is rapidly occurring in
Amazonia.
21.113
Cattle ranching
Cattle
ranching, by far the most important agricultural activity in Amazonian
rainforest, is growing at such a rate that it can be expected to dominate Amazonian
landscapes in all parts of the basin (Fearnside, 1982). Even in areas where intensive government
programs promote perennial crops, such as colonization projects in Rondônia,
much greater areas are planted to pasture every year.
Ranching
is widespread both on the 15 million hectares of "natural" upland
grasslands and in the rapidly increasing areas of planted pastures. Beef productivity is low, but, far more
importantly, it is unlikely to prove sustainable in the planted pastures
(Fearnside, 1979a). The dry weight of
pasture grasses produced per hectare per year is small largely due to poor
soil, available phosphorus having been found to limit grass yields in several
locations on typical OXISOLS and ULTISOLS (Serrão et al., 1971; Koster et
al., 1977; Serrão et al., 1979).
Pastures are quickly invaded by inedible weeds, better adapted than the
grasses to the poor soil, in addition to being spared the grazing pressure of
the cattle (Serrão et al., 1971: 19; Simão Neto et al., 1973;
Fearnside, 1979a). Of 2.5 million
hectares of planted pastures in the Brazilian Amazon by 1978, 20% were
considered "degraded", or invaded by second growth (Serrão et al.,
1979: 202).
The
question of how soils change under Amazonian pastures is one of more than academic
importance in Brazil. Massive
governmental programs subsidizing pasture in the region have received impetus
from claims that pasture improves the soil, and, by implication, is sustainable
indefinitely. In 1974 the head of the
principal government agricultural research institute in the Brazilian Amazon
announced that comparisons of soils under virgin forest with soils under
pastures of various ages both on the Belém‑Brasília Highway at
Paragominas and in ranching areas of northern Mato Grosso had shown that:
Immediately after burning (of forest) the acidity is neutralized, with
a change in pH from 4 to over 6 and aluminum disappearing. This situation persists in the various ages
of pasture, with oldest pasture being 15 years old, located in Paragominas. Nutrients such as calcium, magnesium, and
potassium rise in chemical composition of the soil, and remain stable through
years. Nitrogen falls immediately after
the burn but in a few years returns to a level similar to that existing under
primitive forest. (Falesi, 1974: 2.14; my transl.)
The soil changes led to the conclusion that:
The formation of pastures on latosols and podzolics of low fertility is
a rational and economic manner in which to occupy and increase the value of
these extensive areas. (Falesi,1974: 2.15, my transl.)
The data on which these conclusions were based
(Falesi, 1976), when examined more closely, reveal that soil does not improve
from the point of view of pasture growth.
Available phosphorus, the element limiting pasture growth in these
areas, decreases over the period (Fearnside, 1980b). A more detailed study of soil change in the
Paragominas ranching area also confirms that the soil degrades, rather than
improves, from the point of view of pasture growth (Hecht, 1981, 1982b). Brazilian government agencies concluded in
1977 that the soil improvements they had noted were not sufficient to maintain
pasture productivity without the addition of phosphate fertilizers but that
adding 50 kg/ha of P2O5 (about 300 kg/ha of superphosphate)
would solve the problem of nutrient deficient growth limitation (Serrão et
al., 1979; Serrão and Falesi, 1977; Toledo and Serrão, 1982).
Adding
phosphorus is not in itself sufficient to render pasture sustainable, as other
soil characters continue to deteriorate until they limit production. Soil compaction is a major problem. Exposure of the soil to sun and the trampling
of cattle in pastures quickly results in the soil becoming hard and dense, with
reduced pore volume and water infiltration capacity (Schubart et al.,
1976; Dantas, 1979). Success has often
not been great in fertilized pastures in other tropical areas. In Peru researchers found that "with
time, these mixed pastures lose productivity because of soil compaction by
animal hooves, disease in legumes and probably deficiencies of nutrients not
provided by single superphosphate. The
proposed management alternative considered is to revert back to crops,
fertilize heavily and start the cycle over again" (Sánchez, 1977 citing
results of Peru, IVITA, 1976). Pasture
growth is reduced as the compacted soil restrains the plants' roots, and soil
erosion increases as rain water runs rather than sinking into the soil. Vital to the phosphorus fertilization program
has been heavy subsidization of its cost by the government, through attractive
loans with long grace periods and negative interest rates in real terms.
Brazilian
government recommendations regarding cattle ranching have changed several times
as additional problems have come to be known.
After the 1974 theory of self‑improving pastures was changed to
one of pastures sustainable with limited phosphorus inputs, the drawbacks of
Guinea grass (Panicum maximum), the recommended species occupying 85% of
the planted pasture area in the Legal Amazon by 1977 (Serrão and Falesi, 1977)
became evident. The grass's
disappointing performance on the poorest soils, inability to reseed itself
under many conditions, and bunchy habit facilitating invasion of second growth
(as well as erosion), led to the official change to promoting creeping signal
grass (Brachiaria humidicola) in about 1979. Brachiaria humidicola has the
advantage of forming a low dense cover, but has low yields and is not, as was
at first believed, immune to the attacks of the homopteran bug known as cigarrinha
(Deois incompleta, Cercopidae) that destroyed many pastures planted with
the congeneric species signal grass (Brachiaria decumbens) along the
Belém‑Brasília Highway in the early 1970's (de Brito Silva and Magalhães,
1980; Hecht, 1982b).
Would
phosphate fertilization, as recommended by the Brazilian government (Serrão and
Falesi, 1977), make cattle ranching a sustainable undertaking in Amazonian terra
firme? The question is a vital one given the continued rush to convert
forest to pasture. If fertilized pasture
is unsustainable, or is sustainable only with the present government subsidies
of fertilizer purchase and application, then the possibility of fertilizing may
prove to be little more than an illusion.
Planners may be led to advocate continuation of the rush to pasture on
the assumption that areas can always be made productive at a later date. Phosphate applications produce immediate and
dramatic improvement in degraded pasture but it is well to remember that the
number and magnitude of nutrient deficiencies to be supplied, as well as the
cost of steps needed to counter the deterioration of soil physical structure,
will increase as pasture use is prolonged.
Ultimately, the cost and availability of the inputs needed to maintain a
significant portion of Amazonia as fertilized pasture may restrain reliance on
fertilizers. Even with generous
subsidies available for pasture fertilization, most ranchers presently prefer
to concentrate their resources on clearing larger areas rather than improving
their pastures. A survey done in 1977 of
92 ranches in northeastern Pará found only one ranch (1.08% of the sample)
using any kind of fertilizer on pasture (Homma et al., 1978: 18).
Pasture
is attractive to landowners for a number of social and institutional reasons,
production of beef often being a minor consideration. A major factor is pasture's capacity to
occupy a large land area quickly with a minimum labor and capital expenditure. Amazonia's land tenure system is based almost
entirely on physical possession of the land.
Formal documentation of land titles normally occurs only after the
"owner", or his representatives, have occupied the claimed area. Violence and fraud are commonplace in
eliminating less powerful competitors for claims, especially small farmers or
Amerindians (Mueller, 1980, 1982; Martins, 1980; Davis, 1977; and many others).
Clearing
land is considered a "betterment" (benfeitoria), and pasture
is the easiest means of keeping land from reverting to secondary forest once
cleared. Land has a tremendous value as
a speculation, which accrues both to large land holders drawn to the region by
potential capital gains and to smaller farmers who come with the intention of
making a living through agricultural production. Pastureland prices in northern Mato Grosso
increased at a rate of 38% annually during the 1970‑75 period, after
discounting inflation (Mahar, 1979: 124).
No agricultural production system can match these rates of return. Even small farmers who do not view themselves
as speculators are tempted to sell their holdings to receive the financial
reward obtainable for having occupied a site--a reward which is usually much
more than they have ever made through their farming efforts. The lure of speculative profits hinders
agricultural development by raising land prices to a point where more
productive small farmers are excluded, and by channeling land use decisions
toward unproductive pasture rather than intensive management of smaller areas. Ironically, it is the lower price of land
(relative to other inputs) which leads to extensive use patterns and little
concern for sustainability. Land prices
rise to levels far higher than would be justified by the value of land as an
input for production (cf. Found, 1971).
The skyrocketing prices are partly due to the land's function as a store
of value, providing protection from Brazil's triple digit inflation. Expectation of future price increases is an
immediate motivation for many purchases; the anticipation of uninterrupted
expansion and improvement of road access, as well as the continued influx of
new arrivals in the region, underlie these hopes. In the case of pasture developed with
governmental incentives, the value of land as a key giving access to this rich
trove of tax exemptions and concessionary financing adds greatly to its value.
Incentives
for pasture projects approved by Brazil's Superintendency for Development of
the Amazon (SUDAM) are a major contributing factor to deforestation for
ranching (Mahar, 1979; Fearnside, 1979b).
Approved projects allow their owners to invest up to 50% of the income
tax these individuals or firms would have otherwise had to pay to the
government. The decision to invest is
logical for tax reasons alone for anyone with significant income from other
sources in the developed southern part of the country, even if the pasture
schemes are economic failures when viewed separately. In addition, an approved project allows
borrowing from the government‑supported Bank of Amazonia, Anonymous
Society (BASA) with no interest, although principal is adjusted yearly to
compensate for inflation (usually by a percentage below real inflation). No payments need be made during a grace
period of five years; formerly the grace period extended for seven years. Moreover, inspection of the remote ranching
projects is lax, allowing many to invest substantial parts of the subsidized
financing in more profitable ventures elsewhere.
The generous
terms of incentive arrangements not only offer a pull to attract investors to
Amazonian lands but are themselves a contributor to the inflation that pushes
investors to seek shelter in real estate.
Brazil's agricultural incentives are viewed by economists as one of the
major factors in the country's notorious inflation, according to former
Brazilian finance minister O.G. de Bulhões (Gall, 1980). Inflation occurs any time large amounts of
money are spent on unproductive endeavors, thereby putting money in the pockets
of consumers without contributing a corresponding flow of products to the
economy to satisfy resulting demand.
A
change of policy in 1979 has restricted new incentivated ranching projects to
parts of Legal Amazonia outside the area defined as "high
forest". Contrary to popular
belief, the change in SUDAM policy has not halted the subsidized expansion of
ranching. The hundreds of SUDAM projects
already approved for the "high forest" area continue to receive their
full incentives, and most of these have hardly begun to clear their forested
area. At the same time, new projects are
approved for the large areas classified as "transition forest" along
the southern fringe of Amazonia, already the focus of the most intensive
ranching activity.
Many
forces leading towards the rapid spread of ranching suggest that this land use,
of dubious sustainability, will continue to predominate in the expanding
clearings in Amazonia.
21.114 Perennial Crops
Perennial
crops, such as cacao (Theobroma cacao), coffee (Coffea arabica),
rubber (Hevea brasiliensis), and black pepper (Piper nigrum), are
seen by many planners as holding great promise for producing sustainable yields
in Amazonia (e.g. Alvim, 1978, 1981).
Other perennial crops in earlier phases of expansion as commercial
planting include African oil palm (Elaeis guineensis), various native
and introduced fruit trees, and guarana (Paullinia cupana), the
Sapindaceous woody climber used in a Brazilian soft drink and as a sex
stimulant. Sugar cane (Saccharum
spp.) is also officially classed as a perennial crop due to its ability to
sprout back for subsequent croppings after harvest, although its herbaceous
nature and need to be re‑planted after every 2‑3 crops in order to
maintain full productivity make it more like an annual crop in ecological
terms, while its highly seasonal labor requirements make it more like many
annual crops in social terms.
Principal
reasons for hopes that perennials will prove sustainable are that (1) the
products' value, in contrast to annual crops such as rice and maize, justifies
the cost of supplying nutrient requirements through fertilizers, rather than
relying on the small and quickly exhausted stocks in the soil (Alvim, 1973),
(2) plant nutrient losses are minimized as compared with annual crops, due to
better recycling within the agroecosystems, since leaves fall to the ground to
contribute to soil fertility in plant root zones, and (3) the soil is protected
from direct impact of sun and rain in the case of tree crops such as cacao and
rubber. In the case of black pepper, a
vine crop grown on posts in the open sun, erosion and other effects are much
more akin to annual crops than is case with arborescent crops like cacao
(Fearnside, 1980c).
Perennial
crops are affected by a variety of diseases, raising serious doubt about some
of the plans for large plantations of these crops. "Permanent crops," as perennials
are euphemistically designated in Brazil, are often anything but
permanent. Rubber is the best known
example. This native Amazonian tree
grows wild as scattered individuals.
Wild trees dispersed throughout the rainforest are susceptible to the
fungus Microcyclus (formerly Dothidella) ulei, causing
South American leaf blight, or "SLAB," but the impediment of many
trees of other species separating each individual rubber tree from others of
its own species prevents the disease from ever reaching epidemic
proportions. Susceptibility to pest and
disease attacks of monospecific stands in comparison with scattered individuals
in a diverse forest has been hypothesized as a selective pressure leading to
the evolution of rainforest tree species equipped to reproduce and disperse
themselves while present in such sparsely distributed patterns (Janzen, 1970a). When rubber is planted in monocultural
plantations, the fungus passes easily from tree to tree, resulting in death or
low productivity of susceptible plantations in regions favorable to the
fungus. Fordlandia, the Ford Motor
Company's plantation begun on the Tapajós River in 1926, was attacked by Microcyclus:
it became uneconomic in the mid‑1930's, was carried on a few years due to
Henry Ford's persistence plus the advent of World War II when rubber was
produced at all costs to compensate for supplies unavailable from Southeast
Asian plantations. After World War II
the Fordlandia plantation was abandoned, and the second Ford plantation at
Belterra 100 km downstream, begun in 1934 in an attempt to avoid the fungus,
was turned over to the Brazilian government as a money‑losing proposition
(Sioli, 1973). Although attacked by Microcyclus,
Belterra still functions today, with continual government subsidy and a
constant battle of grafting and spraying to combat losses to the fungus. The best solution to the fungus problem has
been found to be locating plantations in areas where a sufficiently harsh dry
season causes the trees to lose their leaves once a year, combined with the
expensive process of grafting resistant tops to high yielding root stock, and a
battery of fungicides to control the disease.
Brazil, once the world's principal source of rubber, is forced to import
two‑thirds of its natural rubber needs from Southeast Asia, despite a
sustained program of research, extension, and government subsidies to encourage
production in the Amazon region.
Black
pepper, introduced to Amazonia by Japanese immigrants in 1933 (Loureiro, 1978:
282‑84), produced large and valuable harvests in areas of Japanese
settlement in the 1950's and 1960's. The
fungus Fusarium solani f. piperi first appeared in 1960 at Tomé‑Açú
(de Albuquerque and Duarte, 1972), later spreading to other pepper‑growing
locations in the Brazilian Amazon. The
result has been devastation of the crop at one location after another, now
affecting the most recent plantations on the Transamazon Highway (Fearnside,
1980d). As long as pepper prices
remained high, re‑planting or moving to new locations was a practical
means of dealing with the disease. No
resistant varieties have yet been found, and spraying has proved unsatisfactory
as a means of control. Falling world
market prices for pepper have contributed to making pepper less attractive,
although many government financed pepper plantings exist.
Cacao,
a native Amazonian plant, is also susceptible to local fungal diseases. Witches' broom disease (Crinipellis
perniciosa, formerly Marasmius perniciosus), attacks plantations,
even those of relatively resistant seed varieties produced by government
breeding programs in the State of Bahia, the traditional cacao producing region
of Brazil located outside of Amazonia and away from the native range of the Crinipellis
fungus. Breeding programs for resistance
to fungal disease suffer from the disadvantage of such programs for any tree
crop, in that the much shorter generation time of the fungus in relation to the
tree allows the disease organisms to evolve ways of breaking the resistance
faster than trees can evolve new means of resisting attack, even with the help
of plant breeders (Janzen, 1973).
Witches' broom was a major factor in the demise of cacao production in
the State of Pará at the end the nineteenth century (Pará, SAGRI, 1971 cited by
Morais, 1974). The recent government
financing and extension programs for cacao on the Transamazon Highway and in Rondônia
have resulted in marked increases in planted areas. Witches' broom attacks have led to some
farmers abandoning their plantations, to some following government advice to
spray and remove affected branches and fruits, and to many others to taking an
attitude of waiting to see how the disease will progress.
Disease
will undoubtedly be a major factor affecting the extent to which cacao and
other perennial crops spread in Amazonia.
Disease attack can be expected to have a synergistic effect with falling
market prices to restrict the spread of cacao.
The world price of cacao has been falling since the peak reached in
1977. World Bank estimates of the future
course the decline indicated FOB cacao prices dropping, in constant 1980 US
dollars, from the observed $3,489/metric ton in 1979 to a projected $2,837 in
1984 and $2,037 in 1989 (International Bank for Reconstruction and Development,
1981: 100). Increased world cacao
production, partly from expanding plantations in Amazonia, is one factor
contributing to the expected decline (Skillings and Tcheyan, 1979), as is
anticipated progress in producing substitutes for cacao in chocolate
(International Bank for Reconstruction and Development, 1981: 79). Since controlling witches' broom is
expensive, requiring both a large amount of labor to remove affected branches
by hand and costly copper‑containing fungicide sprays, growers can be
expected to have less motivation to incur these expenses as cacao prices
fall. Once disease foci become well
established in neglected plantations, losses and control costs can be expected
to increase in surrounding areas, further weakening motivation to control the
disease. Disease and pest problems can
also be expected to increase as the size of monocultures of perennial crops
increases.
Irrespective
of the biological problems of perennial crops, economic limits are sure to
prevent these land uses from occupying a significant portion of the vast area
of Amazonia, although the relatively small area that could be planted to these
crops without saturating world markets could provide a significant income for
the region.
21.115
Mechanized Annuals
Mechanized
cultivation of annual crops in terra firme has been increasing in recent
years but still represents only a tiny fraction of the total planted to such
crops as rice and beans. Wealthier
newcomers to the region arriving from areas in southern Brazil where tractors
and other machinery are commonplace have increasingly brought with them the
cultural orientation and knowledge, as well as the machinery and financial
resources, needed to employ this form of technology. Mechanization avoids the headache of
obtaining hired hands to do manual labor at the seasons of peak labor demand. Since most people come to the area with the
intention of staking out their own claim rather than working for others, the
relatively few workers available for hire find a sellers' market for their
labor. Mechanization has disadvantages
as well. The isolated settlers find much
higher costs for obtaining spare parts and skilled maintenance for the
equipment than they had experienced in the highly developed South. At the same time, farm gate prices of cereal
crops are lower, since the cost of transportation to distant markets is far
greater. Use of tractors is also
difficult in much of the Amazon where land is dissected into steep slopes,
contrary to the popular illusion that the area is as flat as it appears from
the air. Removing rainforest tree stumps
and partially burned trunks is a costly prerequisite for using tractors in
agricultural operations. Destumping
almost always requires bulldozing the land, thus removing the most fertile
upper layer of soil, as well as contributing to soil compaction (Van der Weert,
1974; Seubert et al., 1977; Uhl et al., 1982b). Plowing the fields has the disadvantage of
bringing less fertile lower layers to the soil surface, in contrast to many
temperate zone farming systems where topsoil is deep and lower layers consist
of relatively unweathered material rich in plant nutrients.
The
influx of southern Brazilians to the Amazon can be expected to increase the
number of these new arrivals wanting to apply their capital to
mechanization. Improved transportation
and urban infrastructure, as with the paving of the Cuiabá‑Porto Velho in
1983, will make today's frontier areas increasingly more attractive to these
wealthy farmers. Better transportation
will make the products more marketable, as will the progressive disappearance
of staple food crops from Brazil's South, where these land uses are now being
quickly replaced by export crops such as soybeans. At the same time, rising land values will
make investing capital in equipment more attractive than in land clearing as
currently occurs. Forces that can be
expected to hold any explosion of mechanization in check include continued
migration of manual laborers to the region, presumably to lead in a drop in
wages from present levels which are far above those in other rural areas of
Brazil. Increasing fuel costs as fossil
fuel supplies dwindle will also slow mechanization, as will the disadvantages
of soil and topography already mentioned.
The tremendous amount of capital that would be required to convert any
significant portion or Amazonia to mechanized agriculture insures that cheap,
quickly installed land uses like pasture will dominate for the foreseeable
future.
21.116
Horticulture
Growing
vegetables has become a profitable venture for enterprising farmers located
near large cities in the Amazon. Market prices
for such commodities as tomatoes are as much as seven times higher in Manaus
than in São Paulo, and much of the produce sold is actually flown in from São
Paulo, over 2600 km away. Around major
cities such as Belém and Manaus, as well as many smaller towns such as Altamira
on the Transamazon Highway, farmers specialized in horticulture are often of
Japanese origin. These farmers have a
cultural tradition of intensively cultivating small areas, together with liberal
use of fertilizers, pesticides, and other costly inputs, practices foreign to
most of Amazonia's other inhabitants.
The high price of inputs has been compensated by high value products,
and the ventures have often proved economic successes.
Horticulture
is much more difficult in the tropics than in other regions, due to greater
losses to diseases and pests. Rural
residents grow what few green vegetables they include in their diet in raised
windowbox‑like structures called hortas. The legs of the hortas are protected
against rats (Rattus rattus), and sometimes against leaf‑cutter
ants (Atta spp.) as well. Soil in
the box is fortified with ash, black "Indian earth" (terra preta
do índio), or other nutrient-rich supplements. Production of green onions (Allium cepa),
collard greens (Brassica oleracea var. acephala), and other
vegetables is meager, but supplies an important addition to the usual meal of
manioc flour, rice and, when available, beans.
Commercial
horticulture must combat plagues of insects, slugs, rats, and other pests, as
well as disease‑causing fungi, bacteria, and viruses. One successful system for growing tomatoes is
employed commercially by a Seventh Day Adventist agricultural school 92 km from
Manaus. Open‑sided greenhouses
with polyethylene roofs shield the crop from rain, thus avoiding removal of
heavy doses of pesticides and fungicides from the leaves and fruits. The greenhouses also buffer the crop from
rapid changes in temperature and humidity, believed to be the cause of tomatoes
grown in the open having a tendency to split before ripening. Soil in wooden troughs containing the plants
is sterilized prior to planting, and irrigation is done by periodic flooding of
small ditches in the soil in each trough, to prevent loss of protective
chemicals and to avoid creating disease‑ favoring humid conditions for
the aerial portion of the plant. Division of the plantation into separate
greenhouses also helps prevent the spread of diseases, as do elaborate
procedures for disinfecting and controlling use of garden tools. Large quantities of reasonably well‑qualified
but low‑paid labor from students is required.
Another
commercial scale horticultural enterprise near Manaus is run by the municipal
government. Settlers have been assigned
individual small plots in Iranduba, on land fertilized with processed garbage
from the city of Manaus. The scheme
provides for irrigation, transportation, supply of chemical inputs, agronomic
advice, marketing arrangements, and housing in a planned village. Tomatoes (Lycopersicon esculentum),
cabbage (Brassica oleracea var. capitata), green peppers (Capsicum
annum), and other vegetables are grown for marketing at a cycle of weekly
markets in different parts of the city of Manaus. Yields and product quality are somewhat lower
than under the Seventh Day Adventist system, but the product forms an important
addition to the city's food supply.
The
many Japanese immigrants engaged in raising vegetables near Amazonian cities do
so with intensive application of fertilizers and manure, especially chicken
manure often obtained from poultry raising ventures on the same farms. Chickens are raised on a diet of pre‑mixed
food grains imported from southern Brazil.
Land is often tilled with micro‑tractors or hand‑pushed
motorized tillers. Pesticide use is
extremely heavy. Japanese embassy staff
offer technical support, conducting surveys and giving farmers Japanese
language computer outputs with individualized reports and advice. More important to the success of these
farmers is the close‑knit network of information exchange and mutual
assistance offered by the Japanese immigrant community itself. Cultural emphasis on thrift, sober planning,
and hard work have also been essential to the accumulation of capital and
information needed to pursue this form of agriculture.
21.12 Várzea:
Amazonian Floodplains
21.121
Annual Crops of Smallholders
In the
past, Amazonian indigenous populations made extensive use of the Amazon's várzea,
or floodplain, during the period of each year when river water level is low
(Lathrap, 1970; Meggers, 1971; Denevan, 1966; Gross, 1975; Roosevelt,
1980). Várzeas have been used to a far
lesser extent by caboclos occupying these areas since most riverside
Amerindian populations disappeared in the years immediately following European
contact. Várzea soils are more
fertile than almost all terra firme soils, but the most important
difference is not that várzea yields are higher when a crop is
harvested. Far more significant is the
possibility várzea offers for a sustainable yield without the lengthy
fallows (or heavy fertilization) required to make annual crops produce for more
than one or two years on terra firme.
Annual flooding in the várzea deposits a fresh layer of fertile
silt and leaves the land virtually free of weeds and pests at least once per
year, at the moment when the water recedes: "the river is the plow."
Várzea
areas can be subdivided into horizontal zones such as mud bars, levees,
backswamps, and beaches (Denevan, 1982).
Only the levees are unflooded year round. Soils, crops, and timing of agricultural
activities differ for each zone. Bergman
(1980) describes a typical crop zonation from a Shipibo village on the Ucayali
River in Peru: rice and beans on the beaches; maize, sugar cane, and jute on
the levee foreslope; bananas, manioc, and fruit trees on the levee tops; jute
and sugar cane on the levee back slopes; and beans and pasture in the
backswamps farthest from the river. Caboclo
exploitation of várzea in the Guamá River near Belém has a similar
zonation of crops; the addition of on associated zone with supplementary
plantings of perennial crops on nearby terra firme has been suggested as
making the pattern a model for Amazonian settlements (Camargo, 1958).
The
timing of the rise and fall of water levels dominates every aspect of várzea
agriculture. Years when the water level
begins to rise earlier than normal, or rises to higher than normal flood
levels, can be disastrous to várzea cultivators. These uncertainties have been hypothesized to
explain a wide array of cultural adaptations of indigenous várzea
groups, as well as limits to várzea as a base for "cultural
development" (Meggers, 1971: 149), although not all anthropologists agree
with this interpretation (Roosevelt, 1980: 23).
The
continuing deforestation of Amazonia can be expected to result in higher and
less regular flooding. Indeed, some
evidence exists that such changes may have already begun in the upper Amazon
(Gentry and Lopez‑Parodi, 1980, but see Nordin and Meade, 1982; Gentry
and Lopez‑Parodi, 1982). Among
many negative effects, these changes will make cultivation of annual crops in
the Amazonian várzea increasingly more difficult.
21.122
Mechanized Rice
Mechanized
cultivation of irrigated rice is being pursued commercially in one location in várzea
of the lower Amazon as a part of the Jari project (Fearnside and Rankin, 1980,
1982, 1985). The potential, or lack of
potential, of this form of capital intensive high yield agriculture is a question
with importance far greater than the relatively insignificant area of the
present 3062 ha under cultivation, or the 14,165 ha to which the plantation is
eventually expected to expand if probable ownership changes do not alter the
previous planning. The rice project is
not included in U.S. shipping magnate D.K. Ludwig's sale of silvicultural and
mining operations at Jari to a group of Brazilian firms (Veja, 27
January 1982: 92).
Rice is
currently grown on a rolling schedule, with different fields being planted and
harvested at different times. Any given
field produces two crops per year, although experiments underway may eventually
permit about 30% of a full crop's yield to be harvested from a ratoon or
stubble crop during the interval between the two crops planted from seed. Yields in most years have been on the order
of eight tons of rice (with husks) per hectare per year. A drop to around seven tons/ha/year in 1979
caused great concern among the technical staff and company officials.
Several
drops in yield have occurred and for the most part been countered by management
changes. A sulfur deficiency was
discovered (Wang et al., 1976) and corrected by changing the nitrogen
fertilizer used from urea to ammonium sulfate.
Iron toxicity contributed to a sharp fall in yields in 1979 to about
seven tons/ha/year. Various insect
pests, especially army worms (Spodoptera frugiperda) and stink bugs (Oebalus
poecilus), are also believed to have contributed to the drop. When completed, an improved canal system and
regrading of fields are expected to allow the fine‑water management
needed to minimize these problems. Rice
variety changes, increased pesticide use, and greater attention to a host of
management details are hoped to reverse the decline. In the future, yields are expected to improve
with the construction of a canal to allow changing the irrigation source from
the Araiolôs River to the less acid and more nutrient‑rich Amazon. A variety of insect pests, mites (Acari),
nematodes, weeds, and fungal diseases extract some toll on rice
production. Perhaps more important are
the diseases, weeds, and pests that have not yet arrived at Jari's rice project
in São Raimundo. The rice plantation has
been enjoying the honeymoon from coevolved pest and disease organisms that has
been a repeating pattern for newly introduced species throughout the world (see
Janzen, 1973; Elton, 1958). Neighboring
countries have biological problems in irrigated rice which can eventually be
expected to reach Jari, such as "hoja blanca" virus in Venezuela and
two major graminaceous weeds in Surinam (Leptochloa scabea and Ischaemun
rugosum). Jari was able to use the
IR‑22 rice variety as its mainstay for six years, even though this high‑yielding
variety is highly susceptible to rice blast (Piricularia oryzae). When the fungus arrived, IR‑22 was
already being phased out in favor of more resistent varieties. The most effective response to disease
problems is generally a switch to more resistant varieties, chemical treatments
representing only a temporary measure.
Managing large monocultures is a constant race, pitting human efforts to
breed, identify and propagate appropriate varieties against the ever‑changing
array of biological problems. The
outcome of this contest is never guaranteed.
Irrigated
rice of the type planted at Jari fails to take advantage of the Amazon várzea's
major advantage: the annual renewal of soil fertility by flooding and
siltation. Instead, the fields are
isolated from the river's water level fluctuations by polder--a dike
surrounding the fields, into which water must be pumped both in and out. The soil enclosed in the polder has
essentially been being mined for nutrients in these early years since many
nutrients have been removed in the crop without being fully replaced through
fertilization, in the same way that the mining of ore deposits removes the
resource without replacement.
Compensating increases in fertilizer‑supplied inputs can restore
the balance, but at an increased cost.
The
dependence of mechanized agriculture on nonrenewable resources may prove to be
a long‑term problem making it less attractive in the future.
21.123
Horticulture
Várzea
areas near urban markets are increasingly being cultivated for vegetable
production. The farmers are usually from
caboclo backgrounds, with many changes in their agricultural methods in
comparison with the traditional largely subsistence agriculture of the
scattered caboclo residents of more remote areas. Many have come to these areas from other
parts of the region. Government
extension agencies provide advice to producers within ready boating distance of
the agents' posts. The agencies also
help in obtaining seeds, insecticides, sprayers, and other necessities. Impact of extension agencies appears to be
much greater with introduction of this novel and demonstrably profitable
technology than are similar efforts with subsistence crops more familiar to the
farmers. Horticulture among these well‑located
várzea residents is generally profitable and is expanding, although many
failed attempts at individual plantings can also be seen. Defending these crops against diseases and
pests requires a large store of knowledge to be able to recognize and treat a
given problem as soon as it arises, as well as stocks of chemical remedies
readily at hand.
21.124
Fiber Crops
Jute (Corchorus
spp.) and malva (Malva rotundifolia) are common várzea crops
among small farmers. Jute was first introduced
to the region in 1934 by Japanese immigrants (Soares and Libonati, 1966),
although most jute farmers today are not of Japanese origin. Jute is most prominent in the várzeas of the
middle Amazon, while malva is most common in the tidally influenced várzeas in
the Zona Bragantina of Pará, as well as in the floodplains in the lower
portions of the Solimões (Upper Amazon) River.
Malva is sometimes also planted on terra firme, but it exhausts
the soil quickly and does better in the fertile floodplain. Jute and malva can be processed into bales of
saleable fibers by hand labor, can be stored and transported without spoilage,
and can be sold for cash.
21.125
Cattle and Water Buffalo
Zebu
cattle (Bos indicus) are grazed on natural várzea grasslands in
many parts of the Brazilian Amazon, especially in the lower part of the Rio
Solimões (Upper Amazon) and in the várzeas near the Amazon's mouth. Productivity is quite low in part due to poor
quality fodder, but more importantly due to stress in months when water level
is high and grazing land nonexistent.
During this critical period the cattle are herded together either on
isolated hilltops still above water, on raised wooden platforms (marombas),
or on floating barges. The cattle
tenders bring as much fodder as possible, carrying by boat or towing loads of
macrophytes cut from the river's "floating meadows," from
semisubmerged grasses along the river margins, or from terra firme. Cattle become emaciated and frequently die
during the flood period. Cattle tenders
try to sell as many animals as is practical as the water level rises in order
to keep their herds at a manageable size during the flooded period. When water levels fall again, there is a
superabundance of pasture area.
Water
buffalo (Bubalus bubalis) were first introduced to Brazil from Asia in
1895, and since the early 1960s the population of these animals has been
exploding at an estimated 10% per year (do Nascimento, 1979). The várzeas of the enormous Ilha do
Marajo at the mouth of the Amazon have been the focus of most water buffalo
ranching. Water buffalos are better
adapted than Zebu cattle to the wet conditions of the várzea, being well
equipped for swimming and wading during the flood season. Much of the Marajo herd is raised for meat,
but Brazilian government agricultural research efforts both in Pará and
Amazonas states are most enthusiastic about water buffalo as a source of dairy
products such as milk, butter, and cheese.
Water buffalo milk is richer and produced in larger quantities per
animal than is cows' milk, and each liter yields 50% more cheese or 43% more
butter (do Nascimento, 1979). It is well
to note, however, that water buffalo in commercial operations, such as those in
much of the Jari Project's várzea area, are noticeably less fat and
healthy than are those in government experiments. Nevertheless, replacing the Zebu cattle
presently grazed on várzea grasslands with the clearly superior water
buffalo could significantly increase the production of dairy products in the
region.
21.2 ALTERNATIVE MANAGEMENT: IMPEDIMENTS AND
PROSPECTS
21.21 Fertilizers
and Continuous Cultivation
Agronomists
working at Yurimaguas, near Pucalpa in Amazonian Peru, have directed their efforts
towards devising a system that would permit continuous cultivation of annual
crops by small farmers in terra firme (North Carolina State University
Soil Science Department, 1975, 1976, 1978, 1980). The system developed has produced two crops
per year from the same field over a ten year period using a rotation of upland
rice, maize, and soybeans (Nicholaides et al., 1982).
Although
the Yurimaguas experimenters are enthusiastic about the system's potential for
implementation by small farmers over vast expanses of terra firme
(Sánchez, 1977; Nicholaides et al., 1982; Sánchez et al., 1982;
Valverde and Bandy, 1982), several drawbacks may make any such expansion more
difficult and less rewarding than imagined.
The system requires continuous inputs of fertilizers. Although present prices for these inputs in
Peru are apparently low enough to be justified by the yields so far, the long‑term
costs and availabilities of these are a major cloud on the horizon for
fertilizer‑based agriculture worldwide.
Projections of global trends from 1976 indicate potash being exhausted
by the year 2062 and minable phosphate rock by the year 2027 (United States,
Council on Environmental Quality and Department of State, 1980; see also
Institute of Ecology, 1972). Although
the trends of the recent past cannot continue through all of this period due to
other restraints on population and cultivated area (Wells, 1976), unprecedented
price increases can be expected as supplies of these resources, non‑renewable
on a human time scale, dwindle.
Nitrogen, generally the major nutrient deficiency for tropical
agriculture (Webster and Wilson, 1980: 220), is an element whose supply depends
heavily on the world's vanishing reserves of fossil fuels if plant requirements
are to be met through fertilization.
A major
practical problem in implementing the "Yurimaguas Technology" on a
wide scale in Amazonia is the need for a continuous input of technical
information. As soil nutrients are
exhausted in any given field, the balance of nutrients added must be
continuously changed. After eight years,
the experimental plantings require supply of all essential elements with the
exception of iron and chloride (Nicholaides et al., 1982). Soil samples must be taken every year from
every field, chemical analyses performed, and the results interpreted and
explained to the farmer in terms of fertilizer requirements. Even the staff of qualified agronomists at
Yurimaguas have experienced sharp yield declines in years when nutrient
balances were not spotted and remedied in time.
The prospect is slight of semiliterate farmers doing as well when
dependent on a frail chain of poorly qualified extension agents as their link
to information sources on constantly changing input requirements. The present infrastructure of soil analysis
laboratories in the Amazon has difficulties in processing a few thousand
samples for research purposes; the barriers to expanding this infrastructure
sufficiently to cope with the millions of samples needed to apply the Yurimaguas
system to a significant portion of Amazonia would be tremendous in the
foreseeable future.
In the
long term, agronomic problems other the nutrient deficiencies encountered in
the present scheme are likely to become increasingly difficult to solve. Soil compaction is one such problem
(Cunningham, 1963; Baena and Dutra, 1979), as is the decline in organic matter
indicated in the Yurimaguas data (Nicholaides et al., 1982). Erosion, apparently not a significant problem
on the "flat Ultisol" of the Yurimaguas station, is likely to be a
major problem if extended to much of Amazonia where many areas of intensive
settlement are far from flat. The
experimenters point out that the system has "low erosion hazard except
during periods of intense rainfall" (Nicholaides et al., 1982), but
just such periods of intense rainfall are characteristic of Amazonia.
Profitability
of the system, even in the short term, may well be less than the Yurimaguas
results would indicate. The substantial
costs of supplying the technical information required to maintain the system,
including performing soil analyses and communicating their results and
significance, are not included in calculations of the system's
profitability. Also, both the experiment
station staff and the 11 farmers described as "respected farm
leaders" who have tried the system can be expected to obtain better
results than the masses of less well qualified farmers that would use the
system if expanded on a large scale.
The
problem of devising annual cropping systems for terra firme is an
important one deserving intense research.
It is essential to remember that a practical and sustainable system of
this type has yet to be devised. One should
be wary of placing faith in the future development of such technology to save
tropical peoples from the consequences of unwise forest clearing and land use
decisions being made today.
21.22 Diversity
and Sustainable Management
Most of
the history of human agricultural development has been one of finding ways to
reverse or arrest the process of ecological succession (E.P. Odum, 1971). "Climax" communities, usually
diverse forest, are replaced with earlier successional stages such as low‑diversity
stands of herbaceous crop plants or pasture grasses. Earlier successional stages offer the
advantages of quicker yields, of higher net primary productivity, and of a
greater share of the plant's energy budget being allocated to producing the seeds
and fruits that humans are interested in harvesting. An additional advantage of the simplified
crop stands is the ease of applying energy supplements, such as fossil fuel
inputs for mechanization. This strategy
can prove a cruel illusion. In Howard Odum's
(1971: 115‑16) classic statement: "A whole generation of citizens
thought that the carrying capacity of the earth was proportional to the amount
of land under cultivation and that higher efficiencies in using the energy of
the sun had arrived. This is a sad hoax,
for industrial man no longer eats potatoes made from solar energy; now he eats
potatoes made partly of oil."
Such
simplification has many other disadvantages (see Dickenson, 1972; Janzen,
1970b, 1973; Fearnside, 1983b). The
direct contribution of the farmer's production to his own diet is reduced,
obligating him to rely on expensive, uncertain, and often lower quality
products purchased through middlemen from other distant monocultures. The single stratum of the monoculture has
less complete utilization of the space and incoming sunlight, as bare earth is
often unoccupied by photosynthetic material.
Land is also left bare between crops.
The unshaded soil leads to greater weed competition and labor (or fossil
fuel) requirements to achieve control, as well as to soil erosion. Open nutrient cycles allow greater losses of
soil nutrients, in contrast to the relative effectiveness in minimizing
leaching afforded by the deep roots and well‑developed cycling of trees
and their litter communities.
Concentration on a single crop exposes farmers to international market
fluctuations beyond their control, whereas having a variety of agricultural
products gives them the insurance of income from the other crop species should
the market plummet for any particular species.
The same disadvantage applies to the farmer's hardship when faced with
crop losses from bad weather, pests, or diseases. The chance of pest and disease outbreaks is
itself increased by removal of both natural chemical defenses and the
protection afforded by spatial heterogeneity.
Labor requirements for maintaining monocultures are usually far more
seasonal than those for diversified plantings, thus making less use of family
labor and fostering less socially attractive systems of migrant labor. The concentration of management and marketing
decisions in distant elites can also prove a profound social disadvantage, as
sugar cane growers on the Transamazon Highway have discovered during a decade
of worsening relations with a series of three successive mill management
concerns. Frequent disagreements over
acceptability, price, and payment schedules for cane, usually settled to the
disadvantage of the producers, have led to a climate of mistrust and violence
in the cane-producing area.
Although
as yet only in its infancy as a field of research, attempts are being made to
develop sustainable and diverse crop associations for tropical areas (e.g.
Bishop, 1978, 1979, 1982 in Ecuador; Gleissman et al., 1978, 1981;
Gleissman, 1979 and Alarcón, 1979 in Mexico; May and Momal, 1981 in
Indonesia). In the Brazil Amazon,
systems are under development by the Brazilian Enterprise for Research in
Agriculture and Cattle Ranching: EMBRAPA (de Andrade, 1979), the Commission for
Promotion of Cacao Growing: CEPLAC (Bazán et al., 1973), and the
National Institute for Research in the Amazon: INPA (Arkcoll, 1979). Many are based on the modification of
traditional systems which have had the benefit of centuries of trial and error
by indigenous populations (see Clarke, 1976, 1978). Better designs of polycultural systems are
needed (Kass, 1978), especially including effects which reduce insect attacks
through increased diversity (Root and Tahvanainen, 1972; Risch, 1980). Theoretical approaches can help save time and
resources needed for trial‑and‑error testing of possible
intercropping combinations (Vandermeer, 1981).
Increased agricultural intensity and decreased diversity (Pool, 1972)
and decreased interfield spacing (Janzen, 1972) also increase vulnerability to
insect attack. The presence (Popenoe,
1964; Janzen, 1972: 5) or absence (Price, 1976 cited by Gliessman, 1979;
Janzen, 1974) of nearby woody vegetation can increase agricultural pest
problems depending on their role as reservoirs for populations of insect pests
or biological control agents.
Some
attempts have been made at modifying shifting cultivation to produce higher
returns. Suggestions include eliminating
some of the fallow period (Guillemin, 1956; Andreae, 1974; Ahn, 1979). The "corridor system", begun by
Belgian administrators in Zaire before independence (Martin, 1956; Ruthenberg,
1971) has not been tried elsewhere or continued after the end of Belgian rule
in its original site. Unfortunate rigidity
in the planning of the scheme brought on many problems avoided by the
flexibility in locating and timing cropping that is the hallmark of traditional
systems. Social pressures also led to
overly shortened fallow periods, the Achilles' heel of shifting cultivation in
many locations (e.g. Vermeer, 1970 in Nigeria; Freeman, 1955 in Sarawak, see
also Nye and Greenland, 1960; Watters, 1971; UNESCO, 1978). Adding carefully chosen "modern"
inputs, such as herbicides, has also been suggested as a way of "bringing
the green revolution to the shifting cultivator" (Greenland, 1975).
Interest
has been high in variations of the taungya system, or agri‑silviculture
(King, 1968; Mongi and Huxley, 1979; Hecht, 1982a; Dubois, 1979). Taungya, a system with a long history of
application in Southeast Asia, involves planting annual crops together with
silvicultural tree species such as teak (Tectonia grandis). The trees take the place of growth in the
shifting cultivation cycle, giving a valuable yield at the end of each cycle
although they do not supply the ash of burned secondary vagetation as in
unmodified shifting cultivation. The
necessity of clearing forest for taungya has environmental costs which limit
the extent to which this or other systems requiring clearcutting should be
promoted, but advantages exist for employing agri-silvicultural systems on land
already cleared for low productivity uses such as pasture (see Fearnside,
1983). Taungya and systems like it are
far from ideal: serious erosion can easily result over the long term (UNESCO;
1978: 464; see Bell, 1973 on erosion under teak plantations in Trinidad). One of the important features of taungya for
supporting human populations is its appropriateness for use by small farmers. Farm size is itself one of the major
determinants of land use choices, and the ability of agriculture to support
human populations.
21.2.3 Farm
Size and Agricultural Populations
The
question of land tenure distribution lies at the root of any discussion of
agricultural land use and production in Amazonia. Land tenure in Brazil has traditionally been
extremely skewed, with most of the land in a small number of large properties
or latifundios. In 1975, 0.8% of
Brazil's "rural establishments" were over 1000 ha in area and
represented 43% of the land, while 52% were under 10 ha representing only 3% of
the land (Brazil, IBGE, 1980: 314‑16).
Regional differences in land quality make the concentration even greater
in terms of its ability to support agriculture: the National Institute for
Colonization and Agrarian Reform (INCRA) cadastre for 1972 revealed that 72% of
all farms were minifundios, or establishments with less than one
"rural module" of land, a unit unique to each region, officially
defined as the size required to absorb the year‑round labor of the farmer
and his family, while large enough to permit "social and economic progress
of the domestic unit" (with supplementary hired labor) (da Silva, 1978,
cited by Wood and Wilson, 1982). The
degree of land concentration varies between the regions of Brazil, being highest
in the Northeast and in Amazonia. Within
Amazonia great variation exists: properties over 1000 ha in area account for
85% of the total farm area of Mato Grosso, but only 33% in Rondônia (Mahar,
1982). Within Rondônia, the state where
the most government colonization projects have been located, land concentration
varies from areas of 100 ha colonist lots in the older settlement projects (50
ha in the ones now being implemented), to areas where 3000 ha ranches area
auctioned from public lands, to areas of much larger holdings. The Gini coefficient, an index of land tenure
concentration, has been increasing in Brazil, rising from 0.842 in the 1950 ‑
1960 period to 0.844 in 1970 and 0.855 in 1975 (Wood and Wilson, 1982). High indices, of around 0.86, dominate in
ranching areas in the Amazonian parts of Goiás and Maranhão, while low indices
of around 0.28 are typical of old areas of small farmer settlement in the Zona
Bragantina near Belém (Hébette, and Acevedo, 1979: 117‑21). Forms of agriculture employed vary with the
size of the holdings. Large land owners
are more likely to engage in ranching, while smallholders are more likely to
plant annual crops.
As a
general rule, small properties do not produce consistently more or less per cultivated
hectare than large properties on land of the same quality planted with the same
type of crop, but produce far more per unit of total area, according to a World
Bank study of six tropical countries including Brazil (Berry and Cline, 1976,
cited by Eckholm, 1979: 17‑18).
The smaller units produce more because of cultivating a greater fraction
of the land area, as well as by more intensive techniques such as double
cropping in some areas. In northeast
Brazil, where land tenure concentration is notorious, the World Bank study
argues that redistribution of the land small holdings would give an 80%
increase in agricultural production. A
similar situation appears to be developing in Amazonia, where "replication"
of northeast Brazilian land tenure arrangements has been noted by many social
scientists (e.g. Ianni, 1979a,b). The
process is only one of several in changing land tenure patterns in Amazonia,
others including the breakup of large claims of rubber "barons" (see
Cardoso and Muller 1978: 74‑76), a statistic largely an artifact of
boundary readjustments and the subdivision of farmers' small plots into ever
smaller minifúndios as the land is divided through inheritance (Hébette
and Acevedo, 1979; Martine, 1980).
Unevenness of land tenure can be expected to increase in much of the
region once the first wave of pioneers has passed. Land tenure concentration occurs through the
takeover of squatters' claims by large ranches, as occurred along the Belém‑Brasília
Highway (Valverde and Dias, 1967; Mahar, 1979: 78), or through a process that
does not appear in government statistics: the purchase in the names of wives,
children, or other relatives of a number of adjoining or nearby properties by
wealthier newcomers as in colonization areas like those on the Transamazon
Highway. Concentrated land tenure
results in both lower overall production and the favoring of crops not eaten
locally, in addition to a greatly reduced contribution of what is produced to
supporting the human population (Durham, 1979 for an excellent example from
Central America).
21.3 LIMITS TO AGRICULTURE: HUMAN CARRYING
CAPACITY
Human
carrying capacity refers to the density of a people that can be supported
indefinitely in an area at an adequate standard of living without environmental
degradation, given appropriate assumptions concerning productive technology,
consumptive habits, and criteria for defining an adequate standard of living
and acceptable environmental degradation.
Criteria can include adequate security of a given family meeting the
standards in any year. Since exceeding
carrying capacity leads to failure to maintain adequate levels of consumption
and environmental quality, achieving a balance at a density below carrying
capacity is of supreme importance for the long‑term future of the
region's inhabitants. Intense flows of
migrants are currently entering the Amazon region especially in Rondônia. The population of Rondônia rocketed by 331% from
116,620 in 1970 to 503,125 at the 1980 census (Brazil, IBGE, 1981: 5). The northern region (Rondônia, Acre,
Amazonas, Roraima, Pará, and Amapá) grew by 65% while the country as a whole
grew by 28% during the same period. The
rapid increase in population in areas like Rondônia, combined with the
exclusion of settlers from much of the land area by owners and other claimants
already there, mean that population densities can be expected to quickly exceed
carrying capacity in settled areas.
The
individual agricultural systems discussed in previous sections of this chapter
all have finite limits, as does agriculture everywhere. That the limits are often lower than recent
arrivals to the region or overly enthusiastic government planners envision is
far less important than the fact that limits exist. Amazonia is a land of many illusions, both of
infinite area and of infinite agricultural "potential." These illusions lead governments to propose,
and the public to accept, roadbuilding and agricultural colonization as
solutions to such national problems as poverty and social unrest due to
overpopulation, highly unequal land tenure distribution, and rural unemployment
precipitated by coffee‑killing frosts and changes in agricultural
patterns to mechanized agribusinesses.
The
combination of overpopulation and skewed land tenure had been noted as a prime
motive for the migrations to colonization areas in the Amazonian portions of
Bolivia (Nelson, 1973), Peru (Aramburu, 1982), Ecuador (Uquillas, 1982), and
Colombia (Carrizosa U., 1982), in addition to alleviating social tensions in Northeast
Brazil in prompting Brazil's National Integration Program for establishing the
Transamazon Highway colonization schemes (Kleinpenning, 1975, 1979; Ianni,
1979). Despite the fanfare often
accompanying the launching of colonization initiatives, their role in absorbing
displaced populations has been minimal, being dwarfed by migration to urban
slums. In Brazil, the National
Integration Program absorbed only 7,839 families, or 0.3% of the rural exodus
during the 1970s (assuming that the virtually paralyzed program absorbed no
more net immigration after 1977), while the 24,242 families settled in the
entire Northern Region during the decade represent less than one percent of the
rural exodus during the period (Wood and Wilson, 1982).
The
notion that agricultural development in Amazonia is capable of providing
long-term solutions, the "Solution for 2001" as the Transamazon
Highway was enthusiastically christened (Tamer, 1970), has been doomed from the
start. If one were to make the
improbable assumption that all of Brazil's Legal Amazonia were distributed as
100 ha (1 km2) lots in the manner done in colonization areas along
the Transamazon Highway, only five million families, or about 25 million
people, would fill the entire region.
This represents less than eight years of growth for Brazil's 119 million
1980 population increasing at the current 2.4% per year.
In
discussing the merits of different forms of agricultural development, one must
be very clear about what the objectives of development are. Conflicting objectives is the most common
cause of divergent views on what forms agriculture are most appropriate. Many proposals for Amazonia are directed at
solving problems outside the Amazon Region, such as alleviating rural poverty
in migrant source areas, urban squalor aggravated by the flow of new arrivals
in cities like São Paulo, providing products for markets in other parts of the
country, producing export earnings to lessen national debts, and providing
investment opportunities for speculators and businessmen from more capital‑rich
regions. Farming the Amazon is a
difficult and poorly‑understood challenge, and supplying the needs of the
Amazon's residents alone is not an easy task if it is to be done on a
sustainable basis. The suggestion has
been made that Brazil's development effort be directed to other regions, such
as the central Brazilian scrubland or cerrado (Goodland et al.,
1978; Goodland, 1980). At the least, I
would suggest, the portion of the agricultural development effort in Amazonia
motivated by problems outside the region should be applied instead to
addressing the problems directly in those regions.
Exponentially
growing national problems cannot be solved for long by exploiting a finite
resource such as Amazonia. Even problems
which do not grow can only be solved if the agricultural systems employed are
sustainable. Recognizing the limits of
agriculture is the first and most essential step in redirecting development
policies as a whole such that the human population can be maintained at an
adequate standard of living on a sustainable basis. Estimating human carrying capacity is an
essential element in any such redirection (Fearnside, 1979c, 1983d). Devising sustainable agroecosystems is also
essential, and is a task which will require a sharp reorientation of the
present emphasis in agronomic research priorities. Presently, agricultural research usually aims
at obtaining higher and higher crop yields, or, more accurately, at producing
higher monetary returns on money invested in agriculture. Producing the greatest profits is not
necessarily consistent with sustaining production (Clark, 1973, 1976;
Fearnside, 1979b). Researchers should
strive to produce sustainable systems, even if yields and profits are
lower. Agroecosystems also need to serve
the needs of family consumption, producing the diverse array of products
required for local consumption, and doing so with a premium on the security of
obtaining an adequate harvest. Technologies
that increase yields at the cost of security may make sense to government
planners who see only aggregate statistics, or to wealthy investors who can
afford to gamble on risky ventures to maximize "expected monetary
value" (see Raiffa, 1970), but such risky agricultural choices are far less
wise for the small farmer who depends on the yield to feed his family from year
to year. When a crop fails on an
agricultural experiment station, the agronomists in charge receive their
salaries at the end of the month as usual, but when a small farmer's crop fails
his family goes hungry. The difference
in perspective needs to be incorporated into decisions about research
priorities and the promotion of new technologies.
The
available development choices for Amazonia, both agricultural and non-agricultural,
have widely differing prospects in terms of agronomic and social
sustainability, competitiveness without subsidies, self‑sufficiency,
fulfillment of social goals, retention of development options, effects on other
resources, and macro‑ecological effects (Fearnside, 1983b). What is needed is a patchwork of areas in
different land uses, fulfilling different needs and restricted by different
standards for environmental quality (cf. Margalef, 1968; E.P. Odum, 1969; Eden,
1978; Fearnside, 1979b). Agricultural
development must be pursued in the context of an interlocking system of
components, no one of which can be changed without affecting the others, and no
one of which alone can be expected to achieve goals such as sustaining an
adequate standard of living for the region's population. Agro-ecosystems must be sustainable,
concentration of land holdings must be limited, total consumption must be
limited, and the population must be maintained below carrying capacity.
ACKNOWLEDGEMENT
I thank
Judith G. Gunn for her careful reading and correction of the manuscript.
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