ArticlePDF Available

Agriculture without burning: restoration of altered areas with chop-and-mulch sequential agroforestry systems in the Amazon region

Article

Agriculture without burning: restoration of altered areas with chop-and-mulch sequential agroforestry systems in the Amazon region

Abstract and Figures

Traditional shifting cultivation in the Amazon region has caused negative environmental and social effects due to the use of fire. This type of agriculture has been criticized because it results in emission of large amounts of carbon into the atmosphere and a loss of soil productive potential. Since 1991, Project SHIFT-Tipitamba has researched this type of agriculture and, in a subsequent phase, attempted to propose solutions that could be adopted in northeastern Pará, a region of ancient colonization in Amazon and highly anthropized based on an exclusively slash-and-burn agricultural system for more than 100 years. This paper presents some results obtained over two decades of research on these agricultural systems and proposes a method for the recovery or maintenance of the productive potential of these areas based on sequential agroforestry with secondary vegetation management and chop-and-mulch land preparation.
Content may be subject to copyright.
Global Advanced Research Journal of Agricultural Science (ISSN: 2315-5094) Vol. 3(12) pp. 415-422, December, 2014 Special
Anniversary Review Issue.
Available online http://garj.org/garjas/index.htm
Copyright © 2014 Global Advanced Research Journals
Review
Agriculture without burning: restoration of altered areas
with chop-and-mulch sequential agroforestry systems in
the Amazon region
Mauricio Kadooka Shimizu1* Osvaldo Ryohei Kato1, Ricardo de Oliveira Figueiredo2, Steel Silva
Vasconcelos1, Tatiana Deane de Abreu Sá1, Anna Christina Monteiro Roffé Borges1.
1Embrapa Eastern Amazon, Trav. Dr. Enéas Pinheiro, s/n, Belém, PA, 66095-100, Brazil.
2Embrapa Environment, Rod. SP 340, Km 127,5; Jaguariúna, SP, 13820-000, Brazil.
Accepted 08 December, 2014
Traditional shifting cultivation in the Amazon region has caused negative environmental and social effects due to
the use of fire. This type of agriculture has been criticized because it results in emission of large amounts of
carbon into the atmosphere and a loss of soil productive potential. Since 1991, Project SHIFT-Tipitamba has
researched this type of agriculture and, in a subsequent phase, attempted to propose solutions that could be
adopted in northeastern Pará, a region of ancient colonization in Amazon and highly anthropized based on an
exclusively slash-and-burn agricultural system for more than 100 years. This paper presents some results
obtained over two decades of research on these agricultural systems and proposes a method for the recovery or
maintenance of the productive potential of these areas based on sequential agroforestry with secondary
vegetation management and chop-and-mulch land preparation.
Keywords: Amazonia, shift cultivation, slash-and-burn,
INTRODUCTION
Shifting cultivation or slash-and-burn agriculture in the
Amazon region is an ancient tradition among the
indigenous and cabocla populations and represents an
extraordinary adaptation to tropical conditions (Shubart,
1983). The slash-and-burn system is perhaps one of the
best examples of an ecological strategy used to manage
agriculture in the tropics (Altieri, 2002). Despite advantages
of this agriculture, it has been considered a problem for
some Amazonian ecosystems due to population pressure
and changes in the use of natural resources (Nepstad et
*Corresponding Author’s Email: mauricio.shimizu@embrapa.br
al.,1999), which result in soils and agricultural systems
degradation.
Production system intensification based on secondary
vegetation has been the focus of research efforts on
finding sustainable alternatives; initiated in 1991, Project
Shift (Studies on Human Impact on Forests and
Floodplains in the Tropics) is an example of international
cooperation between the German and Brazilian
governments. The German participants include the
Universities of Bonn and George August Göttingen. The
Brazilian portion of collaboration has been led by Embrapa
Eastern Amazon (Rodrigues et al., 2007); partnerships
exist with other institutions, such as the Federal Rural
416. Glo. Adv. Res. J. Agric. Sci.
University of Amazonia, Federal University of Pará and
Emílio Goeldi Museum.
In the initial phase, studies consisted of exploratory
research to understand the impacts of traditional
agricultural practices on secondary vegetation and to
analyze the extent of ecological problems in Eastern
Amazon; it was expected that alternative systems would be
proposed (Denich et al., 2005).
The alternatives studied included increase the cultivation
period (allowing the highest number of annual crops in a
fallow/cultivation cycle) with mechanized area preparation
(chop-and-mulch), thereby replacing slash-and-burn (Kato
et al., 1999).
In early 2000, when Project Shift ended, actions were
continued with Project Tipitamba (Rodrigues et al., 2007).
Project Tipitamba’s main objective is to propose
technological, economic and environmentally sustainable
alternatives with a focus on the elimination of fire and
efficient use of natural resources and agricultural inputs to
family farming development.
In this context, this review aims to present some
experience obtained over more than two decades of
research on alternatives to the use of fire in sequential
agroforestry systems in the Amazon region.
The role of secondary vegetation in Amazonian
agricultural systems
Studies conducted primarily in recent decades have shown
the important environmental and socioeconomic role of
secondary vegetation as a component of land use
rotational systems adopted by many farmers in the
Amazon region, especially in northeastern Pará (Hedden-
Dunkhorst et al., 2003).
In the Amazon region, secondary vegetation is important
because it provides several beneficial functions for family
farming, including biomass and nutrient accumulation,
which ensures productivity in the following growing period
(Denich, 1991; Denich et al, 2005); the recycling and
recovery of nutrients from deep soil layers (Sommer,
2000); erosion control (Denich et al, 2005); weed
suppression (Gallagher et al, 1999); timber and firewood
supply (Sanchez, 1995) and biodiversity maintenance in
agricultural landscapes (Baar, 1997; Denich et al, 2005).
Studies conducted by Baar (1997) in the northeast of
Pará state; in 92 secondary vegetation areas aged
between 1 and 10 years, 673 plant species were found, of
which 316 were trees and shrubs.
The floristic diversity found in secondary vegetation
harbors a considerable number of species with different
abilities to accumulate essential nutrients that can sustain
plants during cultivation. This functional diversity was
studied by Denich (1991) in northeastern of Pará state; in
that study, the concentration of 11 bioelements (N, P, K,
Ca, Mg, Mn, Fe, Zn, Cu, Na and Al) was evaluated in
leaves and ligneous material of 81 species. This study
revealed sixteen groups of species with similar
concentrations of nutrients in their leaves through a cluster
analysis of 80 secondary vegetation species.
The accumulation of biomass by secondary vegetation
(Denich et al., 2004) is fundamental to slash-and-burn
system because this accumulation of nutrients (Denich,
1991; Sommer, 2000; Denich et al., 2004) is necessary for
the cultivation phase, when the nutrients are made
available to plants in ashes remaining from vegetation
burning during area preparation. Low amounts of
phosphorus accumulate in secondary vegetation biomass,
and this nutrient is one of the most limiting in tropical
regions.
The composition and nutrient concentration of litter
formed by secondary vegetation species (Cattanio, 2002)
influences organic matter availability because the
composition of this material influences the diversity and
concentration of mesofauna in soil (Denich, 1991) and
processes mediated by the mesofauna.
When primary forest is converted to pasture or
agricultural areas using the slash-and-burn technique, soil
nutrients and carbon are vulnerable to loss through various
mechanisms including combustion, faster soil organic
matter decomposition, soil chemical and microclimatic
changes, and changes in the quality and quantity of
nutrient cycles in forest replacement systems (Juo & Manu,
1996). In seven years of secondary vegetation burning in
the Bragantina region, northeastern Pará, 21.5 Mg carbon
and 372.0 kg nitrogen ha-1 were estimated to have been
lost (Sommer, 2000). In addition, between 45 and 70% of
typically less volatile cations, such as potassium (K),
calcium (Ca) and magnesium (Mg), are lost. Most of this
loss occurs through particle transport in smoke, and the
most worrying feature is the export of 63% of phosphorus
(P) stock, corresponding to 1.0 kg ha-1 (Sommer, 2000).
In secondary vegetation aged 7 years and with 31 Mg.ha-
1 of dry matter, Hölscher (1995) and Hölscher et al. (1997)
suggests losses of 98% of accumulated carbon in biomass
(143,78.0 kg C.ha-1), 96% of nitrogen (199.2 to 205.0 kg
N.ha-1), 48% of potassium (35.1 to 39.0 kg K.ha-1), 47% of
phosphorus (4.0 to 4.3 kg P.ha-1), 35% of calcium (102.0 to
107.0 kg Ca.ha-1), 40% of magnesium (17.1 to 18.0 kg
Mg.ha-1), 76% of sulfur (34 kg S.ha-1) and 30% of sodium
(5.6 to 6.0 kg Na.ha-1).
After several slash-and-burn cycles in the same area,
this type of agriculture exhibits a decrease in sustainable
levels, particularly when the fallow period is reduced
(usually the result of an increase in population pressure
and a reduction or elimination of secondary forest areas)
[Zarin et al., 2005; Lawrence et al., 2010]. The biomass
accumulation per cycle change is significantly lower in
young forests that have gone through a shorter fallow
period (Lawrence et al., 2010). Similarly, the nutrient
contribution to annual crops provided by secondary
vegetation is reduced (Kanashiro & Denich, 1998).
In recent decades, farmers have reduced fallow periods
Shimizu et al. 417
Figure 1. The chopping sequence for secondary vegetation. Stage 1: Reversed operation (a), (b) and (c). Stage 2: Forward operation (d), (e) and (f). (g)
Mulch resulting from stage 1. (h) Mulch resulting from stage 2. (i) Aboveground mulch.
from 20 to approximately 5 years, limiting accumulation of
plant nutrients needed to sustain crop productivity (Joslin
et al., 2011). The predominant adoption of increasingly
shorter fallow periods is associated with nutrient losses
during burning and is endangering the system stability of
both private lands and the wider landscape because when
fallow periods were long (7-10 years), systems based on
secondary vegetation management were sustainable.
Fire-free land preparation using the chop-and-mulch
system
Sustainability is threatened by proliferation of pastures on
family farms. Attempting to practice cattle ranching and
semipermanent mechanized crops increase, such as
passion fruit and black pepper, compromises the
regeneration of most species in secondary vegetation,
precluding the subsequent use of these areas for
agriculture. Unless high-cost techniques are adopted, the
situation becomes generally unfeasible for small farmers.
To reduce these limitations, family farming systems in
this region, which are dominated by secondary vegetation
of different ages, have been developed and validated;
agricultural interventions in eastern Amazon include the
replacement of slash-and-burn practices by the use of
chop-and-mulch during land preparation phase (Denich et
al., 2005).
Manual chopping of vegetation started with the use of
tools that are typically available in family production units.
For secondary vegetation with little biomass, forage
harvesters has also been tested. Despite its advantages,
this type of work was adopted at low levels due to the need
for highly intensive labor and difficulty experienced in
execution, which is arduous and unattractive to farmers. It
was necessary to develop a solution that could decrease
the rejection rate and facilitate adoption of the proposed
technology. Then, the mechanization process began (Kato
et al, 2009).
Current mechanized land preparation uses a branch
chopper, also known as a forestry mulcher trailer, which is
attached to a wheeled tractor (Denich et al, 2004). The
vegetation is chop to 5-10 cm of aboveground, so as not to
disturb the soil (a no-tillage system) and avoid damaging
the main regeneration system of secondary vegetation
(stumps and roots that remain intact in the area, ensuring
natural vegetation regrowth).
Two operations are required for adequate area
preparation (Figure 1). In first operation, secondary
418. Glo. Adv. Res. J. Agric. Sci.
vegetation is slashed, and vegetal material is partially
chopped; in second operation, large material is chopped,
and a soil mulch layer is standardized (Block, 2004).
Fallow vegetation performs an important role in
maintaining and restoring soil productivity in Amazonian
slash-and-burn agricultural systems. However, the intensity
of land use is dramatically reduced during the fallow
period. Therefore, soil quality must be restored more
rapidly (Cattanio, 2002).
Research has shown that chop-and-mulch and no-tillage
systems ensure secondary vegetation regeneration
because they avoids damage to root systems, and 70%
regeneration is guaranteed by the regrowth of stumps and
roots (Stevens, 1999).
Rodrigues et al. (2007) conducted a comparative study
of flora in areas under traditional slash-and-burn and
alternative chop-and-mulch systems and found no
significant differences in terms of the total number of
individuals and species richness, but in an alternative
system, a greater number of individuals and species
richness was found in the upper stratum (> 1.5 m high),
demonstrating faster regeneration and development.
This technique has shown positive economic and
financial results in northeast Pará (Mburu et al, 2007).
However, other solutions based on low external input
standards are required before this agriculture becomes
viable for small farmers (Costa, 2012).
This technology was also tested on semi-permanent and
permanent cultures in experiments (Kato et al., 2001) and
on cattle livestock subsystem for family farms (Bittencourt
et al, 2009).
Based on Projects Shift and Tipitamba results, three
options sequences for more sustainable land use were
available to farmers: 1) Land preparation with secondary
vegetation chop-and-mulch systems annual crops
perennial fruit crops in agroforestry; 2) Land preparation
with secondary vegetation chop-and-mulch systems
annual crops fallow with natural secondary vegetation
regeneration, and 3) Land preparation with secondary
vegetation chop-and-mulch systems annual crops
fallow enriched with fast growth species.
Aspects of fire-free land preparation in agricultural
production
Denich et al. (2000); Tippmann (2001) and Sommer (2001)
presented important data regarding above- and below-
ground carbon stocks in young secondary vegetation in
northeastern Pará. Denich (1991) demonstrated that
groups of secondary vegetation species have the
functional ability to accumulate major nutrients, whereas
Sommer (2000) offered evidence for a protective role
played by secondary vegetation roots (safety net) in
reducing nutrient losses resulting from lixiviation and in
reducing aquifer contamination (Wickel et al., 2002).
Regarding the sustainability of agricultural practices for
Amazonian agroecosystems, Leal (2002) demonstrated
that land preparation for cultivation using fire dramatically
reduces species richness; consequent increased fire
frequency can cause savannization, producing a landscape
predominantly comprising graminoids and herbs, and
reducing the presence of trees.
The development and maintenance of soil fertility is a
major challenge for researchers dedicated to sustainable
agricultural systems implementation in the humid tropics
because highly weathered soils with low cation retention
capacities coexist with a pluviometric index of more than
2.000 mm per year (Moura et al., 2008).
Alternatives biomass management strategies have been
studied, for example, the planting of fast-growing
leguminous and nitrogen-fixing trees in secondary
vegetation (Brienza Junior, 1999). Studies using
techniques based on this principle have been developed in
the Amazon region and have introduced species, usually
leguminous plants, in fallow enrichment techniques using
fast-growing species (Brienza Junior, 1999; Borges et al.,
2011; Rangel-Vasconcelos et al., 2012), green manure
(Aragão et al., 2012) and alley cropping (Moura et al.,
2008).
Nutrient cycling (the transfer of mineralized elements in
soil-plant systems) is effectively realized by leguminous
plants due to ability of these species to absorb nutrients
from deeper layers of soil and to promote their release at
the surface by roots decomposition , litter and pruning
waste (Alegre et al., 2000). More efficient nutrient cycling
during fallow periods contributes to ensuring production
during the shifting cultivation period.
Soil management is unquestionably important to the
development of agriculture in the tropics; however, there
are many limitations to achieving sustainable development.
One of the major limitations is related to distance between
researchers and small farmers, who have low financial
resources.
Only recently have researchers formed groups that work
more directly with small farmers. This allows the
consolidation of small producers confidence, providing
adequate information to supply their needs. Conversely,
deficiencies in research or in the adaptation of technology
that enables the use of sustainable production systems
that emphasize the maintenance of soil fertility with less
chemical input are limitations that need to be determined
and resolved.
Development of food crops in chop-and-mulch
systems
Land preparation using chop-and-mulch system does not
reduce production compared to slash-and-burn systems
with fertilization. A tendency toward increases in production
with crop intensification is observed in areas that are not
burned (Kato et al, 1999). When fertilizer is not used, the
first crop in burned areas is always greater than areas
Shimizu et al. 419
Figure
2
.
Aggregate production of three harvest periods (2001/2002) of passion fruit cultivation
Figure 2. Aggregate production of three harvest periods (2001/2002) of passion fruit cultivation (adapted from Cardoso Jr. et al. [2007]) and pumpkin
(unpublished data), according on land preparation method. CM - chop-and-mulch, BPH - burning, plowing and harrowing, B - burning, I - intercropping with
pumpkin. Means followed by same letter do not differ based on the Tukey test at 5% probability.
without burn. This difference between systems is due to
positive effect of ash in burned areas and nutrients
immobilization by decomposing mulch microorganisms
(which initially reduces nutrient availability) in unburned
areas (Cattanio, 2002). However, there is greater
production stability in lands that have been prepared using
chop-and-mulch land (especially for cassava roots).
Kato et al. (1999) observed that rice and cowpea
production was decreased in chop-and-mulch system
when compared to land prepared with fire; this is
unacceptable for small farmers. The solution is to use
fertilizers to compensate for production losses. Due
cassava is an undemanding crop with a cycle of greater
than 12 months, it benefits from nutrient release from
biomass in mulch form.
Fire-free land preparation wastes ted for passion fruit
culture intercropped with pumpkin cultivation. A significant
difference was observed between treatments regarding the
total production of passion fruit obtained from two crops in
the same year. Passion fruit production was higher in both
chop-and-mulch system and burning, plowing and
harrowing (Figure 2).
Intercropping reduced passion fruit production, possibly
due to competition with pumpkin crop for water and
nutrients. However, in burned areas and in areas that used
chop-and-mulch land preparation, intercropping allowed
greater aggregate production (passion fruit + pumpkin),
obtaining 19.11 and 23.02 t ha-1, respectively.
In slash and burn shifting cultivation, cassava is
traditionally the last crop, and more demanding crops, such
as rice, maize and cowpea, are planted immediately after
land preparation at the beginning of the rainy season to
utilize nutrients deposited by the ash produced by
vegetation burning. In systems that do not use burning, soil
fertility is not increased immediately after land preparation,
and use of fertilizer is recommended to compensate for low
nutrient availability in the initial phase (Kato et al., 1999).
The natural fertility of Amazonian soils is low, and
nutrients in slash-and-burn systems come from secondary
vegetation biomass. In chop-and-mulch systems, the
release of nutrients from secondary vegetation biomass
depends on decomposition of chopped vegetal material.
Chopped biomass is formed of ligneous material, and the
C/N ratio is high, indicating relatively slower
decomposition. Thus, in the initial phase after chopping
occurs, the decomposition of immobilized nutrients begins,
initiating decomposition of organic material deposited on
soil as mulch (Cattanio, 2002).
With low soil natural fertility and because nutrients
remain immobilized during the initial phase, fire-free
systems require the addition of nutrients as fertilizer to
neutralize this initial negative effects. Kato et al. (1999) and
Bunemann (1998) demonstrated that phosphorus is the
most limiting element in Amazonian soils (levels are below
1 mg dm-3), and a small amount is present in secondary
vegetation biomass (Denich, 1991). Although applying
small amounts of phosphate fertilizer produces a great
response in maize production.
When it is impossible to acquire fertilizer for application,
it is recommended to initiate the system with a cassava
crop because this crop demands less nutrients and exhibits
no productivity loss during the initial phase of chop-and-
mulch system. After growing cassava, when mulch
decomposition is more advanced and soil nutrient
availability is higher, more demanding crops, such as rice,
maize or cowpea are recommended.
The incidence of weeds in chop-and-mulch systems is
lower due to cover formed from chopped material
deposited on the ground. This coverage inhibits seed
germination, especially that of herbs and grasses. The
more secondary vegetation biomass is present, greater is
weed suppression. Weeds that emerge in these areas are
420. Glo. Adv. Res. J. Agric. Sci.
the initial regrowth of secondary vegetation species from
stumps and roots that remain intact in the soil.
Soil changes using the chop-and-mulch system
In humid tropical regions as Amazonia, which are
characterized by high pluviometric precipitation and high
temperatures, the use of chop-and-mulch systems based
on secondary vegetation should allow the efficient
maintenance of OM levels.
Thus, the maintenance of agroecosystem productivity
depends mainly on OM decomposition and, consequently,
on microbial biomass (Gama-Rodrigues, 1999), which
functions as an OM transformation agent in the nutrient
cycle and energy flows (Wardle, 1993).
Ground mulch formation is the main aspect that
differentiates chop-and-mulch from slash-and-burn
systems. Mulch has an important role in soil functioning
(Sayer, 2006) and positively affects physical, chemical and
biological soil properties.
The absence of burning and mulch formation in chop-
and-mulch systems should increase soil carbon (C)
concentration and storage. However, after 2 cultivation
cycles, there were no significant differences in C
concentration between secondary vegetation (4 and 10
years old), slash-and-burn and chop-and-mulch systems
(Denich et al., 2004). In another study conducted in a long-
term experiment at Igarapé-Acu, Pará state, after 2
cultivation cycles, total C concentration was significantly
higher at shallow depths (0-5 and 5-10 cm) in a chop-and-
mulch (C0-5 = 2.70%, C5-10 = 1.86%) than in a slash-and-
burn system (C0-5 = 1.65%, C5-10 = 1.47% ); in layers at 10-
20 and 20-30-cm depths, no significant differences were
observed between treatments (Sampaio, 2008). In same
study, the C stock at a 0-30-cm depth was greater in a
chop-and-mulch system (56.6 t C ha-1) than in a slash-and-
burn system (50.7 t C ha-1) [Sampaio, 2008], suggesting
the potential storage of C in soil in the system without
burning.
The high contribution of biomass in chop-and-mulch land
preparation systems can negatively affect greenhouse gas
emissions from soil. For example, high inputs of C and N
and higher soil moistures in chop-and-mulch systems can
generate favorable scenario for methanogenesis and
nitrification, stimulating the production of methane (CH4)
and nitrous oxide (N2O) emissions, respectively, from soil
(Davidson & Schimel, 1995). In fact, the levels of N2O and
CH4 emissions produced by chop-and-mulch systems are
higher than those produced by slash-and-burn systems
(Davidson et al, 2008). However, calculating the total
balance of CO2 equivalents emitted during crop cycles,
considering CO2 emissions from vegetation burning (in
slash-and-burn system) and fuel consumption in
mechanized chopping system, shows that the chop-and-
mulch system produces at least 1/5 of the CO2 equivalent
emissions as those produced by slash-and-burn system
(Davidson et al., 2008).
Rangel-Vasconcelos (2012), studying enriched fallow
systems, affirmed that the use of a chop-and-mulch system
in 23-month-old fallow vegetation, with fallow enrichment,
increases free light organic matter (F-LOM) and improves
soil quality.
Comte et al. (2012) compared the effects of traditional
slash-and-burn agriculture to crops and pastures, a crop
chop-and-mulch system with an enriched fallow period
using leguminous trees and a pasture chop-and-mulch
non-enriched fallow system; the authors observed that the
enriched chop-and-mulch system conserved soil density
and increased nutrient and organic matter concentrations
significantly compared to slash-and-burn and forest control
methods. In pastures, the use of chop-and-mulch non-
enriched fallow had minor impacts on the physical and
chemical properties of soil, with the exceptions of water
retention capacity and total P stock.
Despite the expected soil compaction due to tractor
weight, this effect was not observed by Comte et al.
(2012), possibly because the use of a large amount of
biomass as mulch reduced the effect of raindrops and
because the presence of organic matter promoted more
stable aggregates, resulting in soil density recovery over
the two years between analyses.
Chop-and-mulch systems support the maintenance of
soil moisture and prevent extreme fluctuations in soil
temperature compared to slash-and-burn systems. In
addition, increased soil OM content and improvements in
soil physical properties provided favorable environments
for soil fauna. Rousseau et al (2010) studied soil
macrofauna in environments with 20- and 40-year-old
secondary forests, chop-and-mulch systems with crops or
pasture, and traditional slash-and-burn systems with crops
or pasture; the authors observed that the Macrofauna
Index of Soil Health (MISH) was higher in a chop-and-
mulch system with agricultural crops; in particular, sub-
indices related to the presence of earthworms and other
invertebrates in the studied systems were high. These
results demonstrated that chop-and-mulch systems exist
closer to equilibrium, similar to a 40-year-old secondary
forest.
CONCLUSION
Fire-free agriculture based on secondary vegetation
management is an alternative to slash-and-burn agriculture
that allows the possibility of recovering sustainability that
has been affected by the loss/reduction of nutrients in
agroecosystems as the result of fire and reduced fallow
periods. The results obtained thus far indicate the
possibility of substantial change in family farming systems,
particularly in the region targeted in this study; such
change would allow farming without the use of fire and
based on secondary vegetation management, thus
ensuring a higher production of biomass and bioelements
and a period of time appropriate for current land use
pressures. At the same time, it can offer additional value
aggregation in the case of woody species that can also be
used partly for other purposes (e.g., as energy sources)
that are currently in demand due to the disappearance of
wood and coal sources in the Amazon region and
increases in petroleum derivatives prices.
REFERENCES
Alegre J, Arévolo L, Guzmán W, Rao M (2000). Barbechos mejorados
para intensificar el uso de la tierra en los trópicos húmedos de Perú.
Agroforestería em las Américas, 7:7-12.
Altieri MA (2002). Agroecology: the science of natural resource
management for poor farmers in marginal environments. Agr. Ecosyst.
Environ., 93:1-24.
Aragão DV, Carvalho CJR, Kato OR, Mourão Júnior M (2012).
Alternativas de recuperação da fertilidade de solo em sistema agrícola
de subsistência no Nordeste Paraense. Revista Brasileira de
Agroecologia, 7(1):111-120.
Baar R (1997). Vegetationskundliche und –okologische Untersuchungen
der Buschbrache in der Feldumlagewirtschaft im ostlichen
Amazonasgebiet. Gottinger Beitrage zur Land- und Forstwirtchaft in
den Tropen und Subtropen 121, Gottinger, Germany.
Bittencourt PCS, Veiga JB, Camarão AP, Rodrigues Filho JA, Azevedo
GPC (2009). Avaliação do corte-e-trituração da capoeira na utilização
de pastagens em igarapé-açu, estado do Pará. Amazônia: Ciência e
Desenvolvimento, 4(8):43-49.
Block A (2004). Göttinger Mähhäcksler Tritucap und Forstmulcher - Nicht
Brennende Flächenvorbereitung am Beispiel der Zona Bragantina,
Nord-Ost-Amazonien, Brasilien, Doctoral thesis, Fakultät fur
Agrarwissenschaften der georg-August-Universität Göttingen,
Göttinger, Germany.
Borges ACMR, Kato OR, Pinheiro HA, Shimizu MK, Rangel-Vasconcelos
LGT, Oliveira Júnior MM (2011). Crescimento e produção de fitomassa
de variedades de milho em diferentes manejos da capoeira. Pesquisa
Agropecuária Brasileira 46(2):143-151.
Brienza Júnior S (1999). Biomass dynamics of fallow vegetation enriched
with leguminous tress in the Eastern Amazon of Brazil, Göttinger
Beiträge zur Land- und Forstwirtschaft in den Tropen und Subtropen,
Göttinger, Germany.
Bunemann E (1998). Einfluß von Mulch und mineralischem Dunger auf
Zea mays und Vigna unguiculata in der Feldumlagewirtshaft
Ostamazoniens. Georg-August Universität Göttingen, Göttingen,
Germany.
Cardoso Júnior EQ, Kato OR, Kato MSA, Lopes SC, Sá TDA (2007).
Métodos de preparo de área sobre algumas características físicas do
solo e da produção do maracujazeiro (Passiflora edulis) no nordeste do
Pará (Boletim de pesquisa e desenvolvimento, 65), Embrapa Amazônia
Oriental, Belém, Brazil.
Cattanio JH (2002). Soil N mineralization dynamics as affected by pure
and mixed application of leavy material from leguminous trees used in
planted fallow in Brazil, Doctoral thesis, Georg-August-Universitat
Göttingen, Göttingen, Germany.
Comte I, Davidson R, Lucotte M, Carvalho CJR, Oliveira FA, Silva BP,
Rousseau GX (2012). Physicochemical properties of soils in the
Brazilian Amazon following fire-free land preparation and slash-and-
burn practices. Agr. Ecosyst. Environ., 156:108-115.
Costa MCG (2012). Soil and crop responses to lime and fertiizers in a fire-
free land use system for smallholdings in the northern Brazilian
Amazon. Soil Tillage Res., 21:27-37.
Shimizu et al. 421
Davidson EA, TDA, Carvalho CJR, Figueiredo RO, Kato MDSA, Kato
OR, Ishida FY (2008). An integrated greenhouse gas assessment of an
alternative to slash-and-burn agriculture in eastern Amazonia. Global
Change Biology, 14(5):998-1007.
Davidson EA, Schimel DS (1995). Microbial processes of production and
consumption of nitric oxide, nitrous oxide and methane. In: Matson PA,
Harriss RC (Eds.). Biogenic trace gases: measuring emissions from soil
and water, Blackwell Science, Oxford,UK, pp.327-357.
Denich M (1991). Estudo da importância de uma vegetação secundária
nova para o incremento da produtividade do sistema de produção na
Amazônia Oriental Brasileira, EMBRAPA/CPATU and GTZ, Eschborn,
Germany.
Denich M, Kanashiro M, Vlek PLG (2000). The potential and dynamics of
carbon sequestration in traditional and modified fallow systems of the
Eastern Amazon region, Brazil. In: Lal R, Kimble JM, Stewart BA
(Eds.). Global climate change and tropical ecosystems, , C.R.C. press,
Boca Raton, USA, pp. 213-229.
Denich M, Vielhauer K, Kato MSA, Block A, Kato OR, Sá TDA, Lücke W,
Vlek PLG (2004). Mechanized land preparation in forest-based fallow
systems: The experience from Eastern Amazonia. Agrofor. Syst.,
61:91-106.
Denich M, Vlek PLG, Sá TDA, Vielhauer K, Lücke W (2005). A concept for
the development of fire-free fallow management in the Eastern
Amazon. Agr. Ecosyst. Environ., 110:43-58.
Gallagher RS, Fernandes ECM, McCallie EL (1999). Weed management
through short-term improved fallows in tropical agroecosystems.
Agrofor. Syst., 47:197-221.
Gama-Rodrigues EF (1999). Biomassa microbiana e ciclagem de
nutrientes. In Santos GA, Camargo FAO (Eds.). Fundamentos da
matéria orgânica do solo: Ecossistemas tropicais e subtropicais,
Genesis, Porto Alegre, Brazil, pp. 227-244.
Hedden-Dunkhorst B, Denich M, Vielhauer K, Mendoza-Escalante A.
Börner J, Sousa Filho FR, Sá TDA, Costa FA (2003). Forest-based
fallow systems: a safety net for smallholders in the Eastern Amazon?.
In: Proceedings of the Conference Rural Livelihoods, Forests, and
Biodiversity, CIFOR, Bonn (CD-ROM).
Hölscher D (1995). Wasser- und Nährstoffhaushalt eines
Agrarökosystems mit Waldbrache im östlichen Amazonasgebiet. PhD.
Thesis, Universität Göttingen, Göttingen, Germany.
Hölscher D, Möller MRF, Denich M, Fölster H (1997). Nutrient input-output
budget of shifting agriculture in Eastern Amazonia. Nutr Cycl
Agroecosyst, 47:49-57.
Joslin AH, Markewitz D, Morris LA, Oliveira FA, Figueiredo RO, Kato OR
(2011). Five native tree species and manioc under slash-and-mulch
agroforestry in the eastern Amazon of Brazil: plant growth and soil
responses. Agrofor. Syst., 81:1-14.
Juo ASR, Manu A (1996). Chemical dinamycs in slash-and-burn
agriculture. Agr. Ecosyst. Environ., 58:49-60.
Kanashiro M, Denich M (1998). Possibilidades de utilização e manejo
adequado de áreas alteradas e abandonadas na Amazônia brasileira,
MCT/CNPq, Brasília, Brazil.
Kato MSA, Kato OR, Denich M, Vlek PLG (1999). Fire-free alternatives to
slash-and-burn for shifting cultivation in the eastern amazon region:
The role of fertilizers. Field Crops Research, 62:225-237.
Kato OR, Kato MSA, Silva WR, Cordeiro CJ, Vielhauer K (2001). Passion
fruit under slash-and-mulch land preparation - a sustainable crop? In:
Proceedings of the Deustscher Tropentag (Conference on International
Agricultural Research for Development), Universität Bonn, Bonn,
Germany.
Kato OR, TDA, Denich M, Shimizu MK (2009). Mecanização agrícola
em sistemas agroflorestais sequenciais: A experiência do projeto
Tipitamba sobre agricultura sem queima. In: Anais do VII Congresso
Brasileiro de Sistemas Agroflorestais, SBSAF, Luiziânia, Brazil.
Lawrence D, Radel C, Tully K, Schmook B, Schneider L (2010).
Untangling a Decline in Tropical Forest Resilience: Constraints on the
Sustainability of Shifting Cultivation Across the Globe. Biotropica,
42(1):21-30.
422. Glo. Adv. Res. J. Agric. Sci.
Leal EC (2002). Potencial de regeneração da capoeira após preparo de
área com queima e sem queima na região Bragantina, M. S. thesis,
UFPA-Centro Agropecuário/Embrapa Amazônia Oriental, Belém,
Brazil.
Mburu J, Bönner J, Hedden-Dunkhorst B, Mendoza-Escalante A (2007).
Feasibility of mulching technology as an alternative to slash-and-burn
farming in eastern Amazon: A cost-benefit analysis. Renewable
Agriculture and Food Systems, 22(2):125-133.
Moura EG, Silva AJF, Furtado MB, Aguiar ACF (2008). Avaliação de um
sistema de cultivado em aléias em um argissolo franco-arenoso da
região amazônica. Revista Brasileira de Ciência do Solo, 32:1735-
1742.
Nepstad DC, Moreira AG, Alencar AA (1999). Flames in the Rain Forest:
Origins, Impacts and Alternatives to Amazonian Fires, The Pilot
Program to Conserve the Brazilian Rain Forest, Brasília, Brazil.
Rangel-Vasconcelos LGT, Kato OR, Vasconcelos SS (2012). Matéria
orgânica leve do solo em sistema agroflorestal de corte e trituração sob
manejo de capoeira,” Pesquisa Agropecuária Brasileira, 47:1142-1149.
Rodrigues MACM, Miranda IS, Kato MSA (2007). Estrutura de florestas
secundárias após dois diferentes sistemas agrícolas no nordeste do
estado do Pará, Amazônia Oriental. Acta Amazonica, 37(4):591-598.
Rousseau GX, Silva PRS, Carvalho CJR (2010). Earthworms, ants and
other arthropods as soil health indicators in traditional and no-fire agro-
ecosystems from eastern Brazilan Amazonia. Acta Zoológica
Mexicana, special(2):117-134, 2010.
Sampaio ICG (2008). Biogeoquímica do carbono em solo de parcelas sob
trituração, sob queima e sob capoeira, M. S. thesis, Universidade
Federal do Pará-UFPA, Belém, Brazil.
Sanchez PA (1995). Science in agroforestry. Agrofor. Syst., 30:5-55.
Sayer EJ (2006). Using experimental manipulation to assess the roles of
leaf litter in the functioning of forest ecosystems. Biological reviews,
81(1):1-31.
Shubart HO (1983). Ecologia e utilização de floresta. In: Salati E (Ed.).
Amazônia: integração, desenvolvimento e ecologia, CNPq, Brasília,
DF, Brazil, pp. 132-133.
Sommer R (2000). Water and nutrient balance in deep soils under shifting
cultivation with and without burning in the Eastern Amazon, Cuvillier,
Göttingen, Germany.
Sommer R, Denich M, Vlek PLG (2001). Carbon storage and root
penetration in deep soils under small-farmer land-use systems in the
Eastern Amazon region, Brazil. Plant and Soil, 219:231-241.
Stevens AD (1999). Influência da agricultura itinerante na regeneração da
vegetação de pousio no leste da Amazônia, Deustsche Gesellschaft für
Technishe Zusammenarbeit, Eschborn, Germany.
Tippmann R (2001). Assessment of Carbon Sequestration in Landscape
under the Clean Development Mechanism of the Kyoto Protocol,
Doctoral thesis, ZEF Bonn/ Department of Geography - Universität
Bonn, Bonn, Germany.
Wardle DA (1993). Changes in the microbial biomass and metabolic
quotient during leaf litter succession in some New Zealand forest and
scrubland ecosystem. Functional Ecology, 7:346-355.
Wickel AJ, Van de Giesen NC, T, Vlek PLG, Vielhauer K, Denich M
(2002). Water and nutrien dynamics at various spatial scales of a
tropical agricultural watershed in Eastern Amazon, Brasil: first results.
In: Proceedings of the American Geophysical Union.
Zarin DJ, Davidson EA, Brondizio E, Vieira ICG, Sá T, Feldpausch T,
Schuur E. AG, Mesquita R, Moran E, Delamonica P, Ducey MJ, Hurtt
GC, Salimon C, Denich M (2005). Legacy of fire slows carbon
accumulation in Amazonian forest regrowth. Frontiers in Ecology and
the Environment, 3(6):365-369.
... This scenario has been observed in many parts of the Amazon, including the "Zona Bragantina" of the northeastern part of the Brazilian state of Pará. However, alternatives to using fire have been explored, especially through sequential agroforestry, prescribed secondary vegetation management, and chop-and-mulch land management [18]. Nutrient and water losses from soils can be avoided with chop-and-mulch; despite the relatively higher amount of rapidly decomposing surface mulch compared to slash-and-burn scenarios, this does not increase nutrient losses by leaching [19]. ...
... Furthermore, as noted earlier, a chop-and-mulching system can serve to help conserve soil moisture, reduce soil erosion, and attenuate the entry of agrochemicals in the hydrochemical flows of the basin [56]. Cutting fallow vegetation (secondary forest, called "capoeira" in Brazil) followed by shredding of this cleared vegetation can be used in place of fire to prepare the land for agriculture, as fire has negative impacts on soil, water, and air quality [18]. Results from two decades of research have shown this practice to have good result for agricultural production outcomes, together with conservation of soils and water resources [57]. ...
Article
Full-text available
Expansion of agriculture in the Brazilian Amazon has been driven not just by demands from traditional, rural producers, but also large agriculture and cattle producers, both of whom have put considerable pressure on remaining forests and their watersheds. Monitoring of these watersheds has been a focus of intensive study for the past 20 years and although this work has greatly increased our understanding, considerable gaps still remain in our ability to provide adequate recommendations for land management and associated public policies. In this study we present a summary of findings from these previous results. For small properties, the use of fire to prepare land for cultivation remains controversial, while in large properties, forest conversion to pasture and/or crop production has had a meaningful and adverse effect on water quality. Riparian forest conservation can make a significant difference in reducing impacts of land-use change. Secondary vegetation can also play an important role in mitigating these impacts. New types of sustainable agricultural production systems, together with incentives such as payments for ecosystem service can also contribute. Continued monitoring of these changes, together with robust sustainable development plans, can help to preserve forest while still addressing the social and economic needs of Amazonian riverine inhabitants.
... (iii) Improving farm-fallow systems has vast potential for sustainable economic restoration in the Amazon, as shifting cultivation is a pillar of traditional farming systems and common across the basin. Management options in farm-fallow systems include reducing fire-use by adopting techniques such as chop-and-mulch [39][40][41] , shortening the cropping periods, and increasing the fallow period to restore soil and agricultural productivity 42,43 . Extended fallow periods have additional benefits, as they can help protect biodiversity, facilitate connectivity, and improve ecosystem services such as hydrological functions. ...
Chapter
Full-text available
Key Messages & Recommendations 1) Restoration encompasses a broad suite of objectives related to the practice of recovering biodiversity and ecosystem functions and services, such as water quality, carbon sequestration, and peoples' livelihoods. It spans aquatic and terrestrial realms, and goes beyond natural ecosystems to include the recovery of socially-just economic activities on deforested lands. 2) Within terrestrial systems, site-specific restoration options include speeding up recovery after mining, reforesting the vast swathes of defor-ested land, facilitating the recovery of degraded primary forests, and the restoration of sustainable economic activities in deforested lands via sustainable intensification, agroforestry, or improving farm-fallow systems. 3) Restoring aquatic systems requires applying techniques to remediate polluted aquatic and terrestrial habitats, including those affected by min-a (Rio Branco/Porto Velho), Rio Branco AC 69900-970, Brazil ing, petroleum, and plastic; developing and enforcing rules to reinstate natural flow regimes; removing barriers that fragment rivers and disrupt connectivity, and implementing collabora-tive partnerships to recover fisheries and flood-plain habitats. 4) The high cost and complexity of many restoration options mean they should only be used as a last resort; for vast areas of the Amazon, the primary aim should be to avoid the need for future restoration by conserving forests and waterbodies. Abstract This chapter examines site-specific opportunities and approaches to restore terrestrial and aquatic systems, focusing on the local actions and benefits. Landscape and biome-wide considerations are addressed in Chapter 29.
... Improving farm-fallow systems has vast potential for sustainable economic restoration in the Amazon, as shifting cultivation is a pillar of traditional farming systems and is common across the entire basin. Restoration options in farm-fallow systems include reducing fire-use by adopting chop-andmulch and other techniques (Denich et al., 2005;Shimizu et al., 2014), and shortening the cropping periods and increasing the fallow period to restore soil and agricultural productivity (Jakovac et al., 2016;Nair, 1993). Extended fallow periods have additional benefits, provided they do not encourage additional clearance; they can help support the conservation of biodiversity and may improve hydrological functions and other ecosystem services (Chazdon and Uriarte, 2016;Ferreira et al., 2018). ...
Technical Report
Full-text available
This chapter examines site-specific opportunities and approaches for restoring terrestrial and aquatic systems, focusing on local actions and their immediate benefits. Landscape, catchment, and biome-wide considerations are addressed in Chapter 29. Conservation approaches are addressed in Chapter 27.
... Forest landscape restoration aims to simultaneously enhance ecological functioning, ecosystem service delivery and human wellbeing in degraded forest landscapes [2]. Agroecological approaches in general, and agroforestry in particular, are increasingly seen as essential tools for restoration interventions since they can provide a variety of ecosystem services while simultaneously contributing to food security and livelihood improvement [3][4][5][6][7][8]. In the IUCN guide to the Restoration Opportunities Assessment Methodology (ROAM) [9], the term 'agroforestry' is mentioned 48 times, showing that forest landscape restoration and agroforestry are increasingly considered complementary to each other. ...
Article
Full-text available
Agroforestry systems with a range of native and often neglected and underutilized tree species (NUS) are increasingly recognized for their potential role in restoration, simultaneously providing ecological and livelihood benefits. Successful adoption of these systems requires knowledge about beneficial species, system-level potential profitability, and barriers faced by farmers. Such information is essential but lacking for most NUS. We analyzed the economic potential of NUS in diverse smallholder-managed agroforestry systems in the Peruvian Amazon. Through semi-structured surveys with local stakeholders (n = 40), we identified 10 native Amazonian NUS fruit with ecological, nutritious and commercial benefits. We then simulated the potential revenue per species and system-level profit of an agroforestry system designed with the 10 NUS. Our projections suggest that a diverse NUS-based agroforestry system can outcompete most alternative land-uses in the region on a per hectare profit basis. This shows that including NUS in restoration efforts could provide economic benefits for smallholders. To realize this potential, we recommend adapted interventions, e.g., increased farmer access to planting material, technical support for production and capacity building with a focus on high-potential NUS.
... De maneira geral, a agricultura orgânica tem avançado bastante no âmbito da agricultura familiar como revisado e descrito por Peigné et al. (2007), o que de fato atenua a entrada de agroquímicos nos fluxos hidrogeoquímicos da bacia. Na agricultura familiar amazônica, por sua vez, a prática de preparo de área por meio do uso do fogo, o que promove impactos na qualidade do solo, água e ar, pode ser substituída pelo corte da vegetação de pousio (capoeira) seguida da trituração dessa vegetação derrubada (Shimizu et al., 2014). Alguns resultados de duas décadas de pesquisas têm apresentado bons efeitos na produção agrícola aliada à conservação dos solos e dos recursos hídricos (Figueiredo, 2009). ...
Article
Full-text available
Neste artigo da Série "Documentos / Embrapa Meio Ambiente" é abordada a complexidade dos desafios para que seja alcançada a sustentabilidade no setor agropecuário, no tocante à conservação dos recursos hídricos e respectivas bacias hidrográficas. A publicação trata da dinâmica de alterações nos processos biogeoquímicos e hidrológicos presentes nas bacias onde o ecossistema natural é modificado. Considerando também as variações temporais e espaciais distintas, dependendo das características biofísicas e biogeoquímicas originais da bacia, ao lado do uso da terra presente. Como fator importante relacionado ao uso da terra, destaca-se as atividades agropecuárias, as quais possuem potencial de promover significativas alterações em ecossistemas terrestres e aquáticos, incluindo os fluxos de nutrientes, carbono e água. Considerando, em especial em nosso país, certa carência de literatura técnico-científica que aborde o tema, pretende-se atender à demanda crescente para o planejamento de estratégias que visem uma agricultura sustentável. Dessa maneira, são discutidos de maneira breve os principais aspectos quanto aos desafios da sustentabilidade da Agricultura no tocante à conservação das bacias hidrográficas. Nesse escopo é observado como o manejo do solo e diferentes sistemas de produção, quando implementados sem as devidas considerações sobre suas ligações com fluxos de água e nutrientes nas bacias, não atendem à demanda por um desenvolvimento sustentável. Obviamente a conservação de recursos hídricos apresenta ainda forte relação com as mudanças climáticas em curso no Planeta, dada a dependência destes recursos das condições do clima relacionada, por exemplo, à pluviosidade e temperatura. Nesse contexto, os autores abordam como a bacia hidrográfica deve ser considerada como a unidade de estudo primordial nas análises ambientais no tema referido. São assim considerados os processos naturais, o manejo agropecuário sustentável, a necessidade de medições e simulações, assim como as mudanças do clima e do uso da terra e sua relação com a sustentabilidade. Dessa maneira, a presente publicação visa atender à geração de conhecimento relativa ao Objetivo de Desenvolvimento Sustentável 6 - Assegurar a disponibilidade e gestão sustentável da água e saneamento para todos - e em especial às metas 6.5 e 6.6 no que se refere à gestão integrada dos recursos hídricos e a proteção e restauração de ecossistemas relacionados com a água.
... A despeito da lenta adoção de práticas sustentáveis por parte das comunidades, elas vêm se expandindo. Entre tais pesquisas, assume papel de destaque o sistema de roça sem queima, prática que adota o corte e a trituração da vegetação secundária em substituição ao uso do fogo para o preparo de área durante a implantação de sistemas produtivos (KATO et al., 2004;SÁ et al., 2007;SHIMIZU et al., 2014). ...
Technical Report
Full-text available
Key Messages & Recommendations 1) Restoration encompasses a broad suite of objectives related to the practice of recovering biodiversity and ecosystem functions and services, such as water quality, carbon sequestration, and peoples' livelihoods. It spans aquatic and terrestrial realms, and goes beyond natural ecosystems to include the recovery of socially-just economic activities on deforested lands. 2) Within terrestrial systems, site-specific restoration options include speeding up recovery after mining, reforesting the vast swathes of defor-ested land, facilitating the recovery of degraded primary forests, and the restoration of sustainable economic activities in deforested lands via sustainable intensification, agroforestry, or improving farm-fallow systems. 3) Restoring aquatic systems requires applying techniques to remediate polluted aquatic and (Rio Branco/Porto Velho), Rio Branco AC 69900-970, Brazil terrestrial habitats, including those affected by mining, petroleum, and plastic; developing and enforcing rules to reinstate natural flow regimes ; removing barriers that fragment rivers and disrupt connectivity, and implementing collaborative partnerships to recover fisheries and floodplain habitats. 4) The high cost and complexity of many restoration options mean they should only be used as a last resort; for vast areas of the Amazon, the primary aim should be to avoid the need for future restoration by conserving forests and waterbod-ies. Abstract This chapter examines site-specific opportunities and approaches to restore terrestrial and aquatic systems, focusing on the local actions and benefits. Landscape and biome-wide considerations are addressed in Chapter 29.
Article
Full-text available
This paper presents the theoretical, operational and implementation premises that guide the development research agenda of the Center of Development Research (ZEF), exemplified by three agroforestry-related case studies. First, the importance, assumptions, conditions and priorities for development research in the context of developing countries are reviewed. Second, the three core premises of ZEF’s research approach, (1) transdisciplinary to carry out research on real-life problems, (2) symmetrical partnerships with local stakeholders to sustain ground activities and ensure implementation, and (3) capacity development to warrant future competences, are exposed. Third, these premises are exemplified and mirrored in three agroforestry-related case-studies: (1) slash-and-burn agriculture in the Brazilian Amazon, (2) socio-ecological management of coffee-agroforests in Ethiopia, and (3) afforestation with multipurpose tree species in Uzbekistan. The paper concludes by streamlining the theoretical and practical premises exposed with the presented case-studies, and confirming how these have guided ZEF in the planning, implementation and continuation of development research programs. Although ZEF’s approach to development research is dynamic and continuously subject to assessment, its core remains guiding even after two decades of implementation, appearing to be a suitable pathway for reaching development objectives.
Article
Full-text available
The north-east of Pará state in the Eastern Amazon of Brazil was settled over 100 years ago. Today the region is an agricultural landscape with variously-aged secondary vegetation and fields with annual cultures, plantation crops and pastures. The effect of these different land covers on carbon sequestration as well as on water and nutrient extraction remain subject of debate. Therefore, we assessed the importance of land use on soil carbon stocks by measuring various C fractions and root biomass (0–6 m) in slash-and-burn systems and (semi-) permanent cultures. An extensive root system down to at least 6 m depth was present under various secondary vegetation stands and slashed and burned fields recently taken into cultivation as well as under a primary forest. Shallower rooting patterns were evident under (permanent) oil palm (4.5 m) and (semi-permanent) passion fruit plantations (2.5 m). Carbon storage in soils of traditional slash-and-burn agriculture up to 6 m depth (185 t ha-1) was not significantly lower than under a primary forest (196 t ha-1) but declined significantly under (semi-) permanent cultures (to 146–167 t ha-1). Compared to above-ground C losses, soil C losses due to slash-and-burn agriculture may thus be small. This is an argument for maintaining the secondary vegetation as part of the agricultural land-use system, as the root system of its trees is conserved and thus C is sequestered also at greater depth.
Article
Full-text available
No trópico úmido, a construção e manutenção da fertilidade dos solos são os maiores desafios dos que se dedicam à implantação de sistemas agrícolas sustentáveis. O objetivo deste estudo foi avaliar um sistema de cultivo em aléias com guandu, associado à adição anual de calcário e de K, em um Argissolo de textura franco-arenosa, a fim de verificar a possibilidade do uso desse sistema como alternativa ao corte e queima na agricultura do trópico úmido. Foram utilizados, como leguminosa, o guandu (Cajanus cajan) e a cultura do milho. Os tratamentos foram os seguintes: T = testemunha, com solo desnudo; G2, G2,5 e G3, tratamentos com fileiras de guandu nos espaçamentos de 2, 2,5 e 3 m, respectivamente; G2K, G2,5K e G3K, tratamentos com guandu nos mesmos espaçamentos mais K; G2C, G2,5C e G3C, tratamentos com guandu mais calagem; G2KC, G2,5KC e G3KC, tratamentos com guandu mais K e calagem. A cobertura e o equilíbrio de nutrientes do solo foram os mais importantes fatores que influenciaram a produtividade do milho no sistema de cultivo em aléias com guandu; portanto, eles devem ser considerados como fundamentais para o manejo sustentável dos Argissolos de textura franco-argilosa do trópico úmido.
Article
Full-text available
O objetivo deste trabalho foi caracterizar e comparar a estrutura de florestas secundárias com quatro anos de idade, que foram formadas após a utilização de dois diferentes sistemas de eliminação da cobertura vegetal - o sistema alternativo (SA) que tritura a biomassa e o sistema tradicional (ST) que utiliza o fogo. O estudo foi conduzido na região Bragantina que está localizada no nordeste do Pará. Para tal, foram selecionadas três áreas amostrais para cada sistema de uso da terra. Dentro de cada área amostral foram alocadas aleatoriamente quatro parcelas de 15 m2 (3 x 5 m), totalizando 60 m² por área de estudo e 180 m2 por sistema de uso. Foi encontrada uma diversidade média (H') de 2,94 para o SA e 3,32 para o ST, a densidade média foi 459.556 ind. ha-1 no SA e 466.833 ind. ha-1 no ST, a área basal do estrato superior do SA foi de 8,48 m² ha-1 e a do ST 3,07 m² ha-1, a biomassa seca estimada para o SA foi de 6,68 ton ha-1 e 2,80 ton ha-1 para o ST. Ocorreram diferenças estatísticas (ANOVA; P < 0,05) em parâmetros da estrutura vertical e biomassa indicando que o SA facilita o desenvolvimento do componente arbóreo das florestas.
Article
Throughout the developing world, resource-poor farmers (about 1.4 billion people) located in risk-prone, marginal environments, remain untouched by modem agricultural technology. A new approach to natural resource management must be developed so that new management systems can be tailored and adapted in a site-specific way to highly variable and diverse farm conditions typical of resource-poor farmers. Agroecology provides the scientific basis to address the production by a biodiverse agroecosystem able to sponsor its own functioning. The latest advances in agroecological research are reviewed in order to better define elements of a research agenda in natural resource management that is compatible with the needs and aspirations of peasants. Obviously, a relevant research agenda setting should involve the full participation of farmers with other institutions serving a facilitating role. The implementation of the agenda will also imply major institutional and policy changes.
Article
1. The soil microbial biomass and microbial metabolic quotient (respiration:biomass ratio) was measured in 16 forest and scrubland ecosystems throughout New Zealand, on materials representing successional stages of plant litter and its subsequent incorporation into the F-H and mineral soil layers. 2. Microbial biomass usually peaked in the L<sub>1</sub> layer and then declined. The microbial carbon:organic carbon ratio decreased sharply between the F-H layer and the underlying mineral layer, indicating that a stress factor (possibly pH) reduced the proportion of organic matter immobilized in the microbial biomass at this stage. 3. The microbial respiration:biomass ratio declined between the L<sub>1</sub> and F-H stages. This was then followed by a statistically significant (and sometimes very large) increase in this ratio upon reaching the mineral layer, for 10 of the 16 sites. This increase is in contrast to the predictions of Odum's theory of ecosystem succession and probably occurs because increasing levels of stress (in the absence of disturbance) in the latter stages of this succession reduce microbial efficiency. 4. When the 16 sites were classified according to early- and late-vegetation successional stages, there was no difference between the two categories with regard to microbial biomass, respiration or the metabolic quotient, although the microbial biomass carbon:organic carbon ratio was significantly higher for the early-successional sites. However, the variance for the microbial biomass:carbon ratio and metabolic quotient was substantially lower for the late-successional than early-successional sites, indicating that as vegetation succession proceeds these variables both converge to a narrower range of values.
Article
RESUMO Na Amazônia, a prática de corte-e-trituração da capoeira, que prescinde do uso do fogo, apresenta a vantagem de enriquecer o solo com matéria orgânica. Avaliou-se o corte-e-trituração da capoeira como alternativa ao corte-e-queima, na utilização de pastagem em Igarapé-Açu, PA. Os métodos foram implantados em dois talhões iguais de uma capoeira de 12 anos. No corte-e-trituração, foi utilizada a máquina AHWI FM 600. O delineamento foi de blocos casualizados, com dois tipos de pastagens: BQ = braquiarão (Brachiaria brizantha cv. Marandu) + quicuio-da-amazônia (B. humidicola) e BQA = braquiarão + quicuio-da-amazônia + arachis (Arachis pinto cv. Amarillo). Três grupos de dois novilhos pastejaram as parcelas, um grupo, as três repetições da pastagem BQ e dois grupos, as seis repetições da pastagem BQA, em pastejo rotacionado de 18 dias de ocupação e 36 de descanso. A pastagem foi avaliada a cada 36 dias e os animais, pesados a cada 54 dias. A taxa de lotação utilizada foi de 1,2 a 2,2 Unidade Animal por hectare. A vantagem do corte-e-trituração sobre o corte-e-queima ocorreu na redução do crescimento da juquira, favorecendo o aumento da massa de forragem e a elevação do nível nutricional da pastagem, possivelmente devido ao efeito da matéria orgânica no solo. A melhoria do ganho de peso por animal foi apenas nos dois primeiros anos. Concluiu-se que o corte-e-trituração da capoeira substitui satisfatoriamente o corte-e-queima na exploração de pastagem em Igarapé-Açu, PA. Em termos de ganho de peso por animal, a vantagem do corte-e-trituração foi até o segundo ano de utilização da pastagem. Mas o potencial de adoção da prática de corte-e-trituração nos sistemas de produção animal da região vai depender de uma criteriosa avaliação econômica.
Article
The purpose of this study was to investigate the effects of lime and fertilizers in a fire-free system for land clearing. Four replications of the split-plot experimental design were used, and two treatments were chosen for the main plot: lime (1 t ha−1) or no lime. Fertilizer levels zero (1), low (2), and high (3) were evaluated in the subplots over a period of three years. In 2006 and 2008 treatments were evaluated while using corn (Zea mays L.) intercropped with rice (Oriza sativa); the evaluations of 2007 were carried out while cropping cowpea (Vigna unguiculata L.). In plots without lime on which fertilizer level 3 was applied, the soil pH decreased by 0.4 and 0.8 in 2006 and 2007, respectively. The effects of the fertilizer levels reducing the soil pH were observed in 2007 (plots without lime) and in 2008 (plots with or without lime). Organic soil matter increased with liming and fertilizer level 3. Soil calcium and magnesium increased with liming and fertilization, while available phosphorus increased only with fertilizer level 3. Lime and fertilization increased the nutrient content in plant tissue, however it did not lead to an equilibrium of nutritional status. The increase of corn and rice yields was related to the fertilizer levels rather than to liming, but the cowpea yield was responsive to both liming and fertilizers. The most positive financial balance was observed to with fertilizer level 2 (without liming) after three years; however, the difference between level 2, with or without liming, was small. Fertilization without liming is an option for the first year of a fire-free system for land clearing, assuming corn is intercropped with rice. Lime application from the second year on is important to allow better yields of subsequent crops and to avoid soil acidification by inorganic fertilizers.