Introduction |
This slide series gives an
illustration of seven Indigenous Fallow Management Types found in Southeast Asia:Retention of Volunteer Species
Shrub-Based Accelerated Fallows
Herbaceous Legume Fallows
Interstitial Tree-Based Improved Fallows
Perennial-Annual Crop Rotations (or cyclical taungya
systems)
Permanent Agroforestry Systems
Integration of livestock in fallow systems
During the presentation it can be asked to
the audience, which of the illustrated systems focus on soil improvement and which
concentrate on increasing the direct economic advantages of the fallow
(products itself). |
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Narrative |
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Slide 1: Title |
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Slide 2: Depending on
the processes from a wider context (land pressure, linkages with urban areas) that
influence household decision-making on the management of the fallow, we distinguish seven
indigenous fallow management types between three poles. One pole is where soil fertility
functions of the fallow remain important, one where the economic value of the fallow
vegetation increases in importance, and one where livestock is an integral part of fallow
systems (either introduced or already existent, but increasingly important). The seven
different "systems" described here will be discussed. However, remember that
combinations of the systems may occur on farmland owned by one household. In reality, the
household usually does not specialise on just one strategy, but in an effort to spread
risks, a mosaic of economic valuable tree based systems may occur together with fallow
management for food cropping, and with or without the integration of livestock.
[taken by Paul
Burgers © ICRAF] |
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Slide 3. Title |
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Slide 4: Imperata
cylindrica is widely viewed as a problem weed that should be eliminated by an
effective fallow (ref. Slideseries on Reclamation of Imperata grasslands using
agroforestry). Potter L and Lee J challenge this thinking by highlighting case studies
where market demands have transformed Imperata into a carefully tended fallow
‘crop’, processed for roof thatching. Gianyar, Bali, Indonesia.
[taken by Justen Lee] |
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Slide 5: Swidden
fallows are favoured locations for hunting and gathering activities. Wildlife often comes
in search of crop remnants and is later attracted to the protective cover of dense fallow
regrowth. Mushrooms, wild food plants and other useful products are harvested from
fallows, depending on the season and stage of fallow succession (Burgers P; Mertz O;
Tangan FT; Tayanin D). Many of the items on offer at this fresh market in
Savannakhet, Lao PDR, are fallow products.
[taken by M. Cairns © ICRAF] |
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Slide 6: Ferns develop
as one of the pioneer species together with grasses and weeds during the early stages of
fallow. Ferns are often harvested as a food crop. With increasing demand in the city to
eat unsprayed, natural food, Dayak communities in Sarawak, East Malaysia are able to sell
ferns and other "forest vegetables" together with farm products on a weekly
basis in Kuching, the capital city of Sarawak.
[taken by Paul
Burgers © ICRAF] |
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Slide 7: Title |
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Slide 8: Austroeupatorium
inulaefolium provides continuous soil cover after crop harvest, suppresses invasive
grasses, and generates large quantities of leguminous biomass. This Minangkabau couple in
West Sumatra, are clearing a seven-year old A. inulaefolium fallow in preparation
for cropping. Despite the dense forest cover on the upper slope (providing a nearby source
for seeds), very few pioneer trees have penetrated in the dense A. inulaefolium
thicket. Its aggressive nature may be delaying regeneration of secondary forest (Cairns
MF).
[taken by M. Cairns © ICRAF] |
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Slide 9: This Calopogonium
mucunoides undergrowth is slashed in preparation to reopen a Tithonia diversifolia
fallow in Bukidnon, Mindanao, Philippines. This legume / shrub succession is completely
spontaneous and may offer a symbiotic combination of N-fixation and nutrient scavenging.
[taken by M. Cairns © ICRAF] |
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Slide 10: Mimosa
invisa that self-propagates in maize fields may be managed as a green manure intercrop
during the cropping phase, and then left to dominate the subsequent fallow succession. As
shown in this maize field in Bukidnon, the Philippines, this system is used for the same
function as the Austroeupatorium in West-Sumatra, illustrated before. Farmers in
Leyte, value thorny M. invisa for its ability to discourage invasion by
free-roaming livestock, and often consequent problems of overgrazing, biomass removal and
soil compaction (Balbarrino E et al.).
[taken by M. Cairns © ICRAF]However
others do warn against the invasive character of Mimosa invisa and the risk of
becoming a pest itself especially with regard to biodiversity (http://www.hear.org/pier/miinv.htm). |
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Slide 11: Title |
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Slide 12: Farmers in
upland areas of Northern Vietnam also relay-plant beans (Phaseolus carcaratus
Roxb.) into maize (Hao NT et al.). After maize is harvested in July, the
beans are left to climb up the stalks, and form a protective ground cover during the rainy
season.
[taken by Klaus Prinz] |
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Slide 13: The ground
cover of Phaseolus carcaratus Roxb. and its extensive root system, play a valuable
role in stabilising soils on steep slopes.
[taken by Nguyen Tuan Hao] |
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Slide 14: Pachyrhizus
tuberosus Lam. (Leguminosae) is a herbaceous climber often found in disturbed
(fallowed) areas in Northern Vietnam. Its vines are used as green manure and the fleshy
tubers are marketed as a vegetable.
[taken by Payong Srithong] |
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Slide 15: Take care for
its pods, which are poisonous!
[taken by K. Hairiah © ICRAF] |
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Slide 16: The genus,
widely known as ‘yam bean’ or ‘potato bean’ (Ind.
Bangkuang),
originated in the Neotropics but is now widely spread throughout S.E. Asia. Market on the
outskirts of Hanoi.
[taken by M. Cairns © ICRAF] |
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Slide 17: Mucuna
pruriens var. utilis (velvet beans) climbs over fences, trees or even crops
such as cassava on farm site in N. Lampung, Indonesia. This legume cover crop was widely
used as a green manure, before commercial fertiliser was widely available in the market.
[taken by Meine van Noordwijk © ICRAF] |
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Slide 18: It also gives a good soil cover and prevents Imperata
invasion. The pods are used for making "tempe" (fermented cake) to replace
soybean, which is popular among Javanese farmers.
[taken by K. Hairiah © ICRAF] |
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Slide 19: Title |
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Slide 20: The
agricultural landscape of Amarasi Subdistrict, West Timor, is dominated by Leucaena
leucocephala forest fallows, which are rotated with annual crops. In addition to soil
improvement, the Leucaena fodder is cut-and-carried to cattle. The Amarasi system
provides a promising model for the intensification of fallow management together with
livestock husbandry.
[taken by M. Cairns © ICRAF] |
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Slide 21: In
Yunnan,
many ethnic minority groups manage Alnus nepalensis as an improved. In a sequential
fallow system fallow (Guo H et al.). Trees are completely cleared when reopening
the fallow and the forest is re-established either through natural regeneration or
intentional planting. Tengzhong County, Baoshan Prefecture, Yunnan.
[taken by M. Cairns © ICRAF] |
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Slide 22: Casuarina
oligodon landscapes are a common sight in the highlands of Papua New Guinea, where an
estimated 1.3 million people plant Casuarina trees (Bourke RM). If Casuarina
is absent from the natural fallow composition, farmers collect wildlings from along stream
banks and transplant them into their yam gardens towards the end of the cropping phase.
Once established by this method, the Casuarina self-seeds and germinates from the
soil seedbank whenever farmers clear the fallow in preparation for planting. Management is
then limited to thinning Casuarina seedlings from areas of dense establishment and
gap-filling in other parts of the field. (Near Chuave District of Timba province, with
Mount Elim Bari in the background.) To reopen Casuarina fallows, several approaches
may be taken, depending on the intended use of the wood. Trees cut at waist height are
used for immediate fencing needs. Other times, trees may be killed by ring-barking
but left standing until eventually harvested for firewood.
[taken by M. Cairns © ICRAF] |
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Slide 23: If there is
not an immediate need for the wood, the side branches are often pruned back heavily
(shown) to return biomass to the soil and reduce shading, and the trees are
maintained through successive swidden cycles. (Timba province, Papua New Guinea
highlands).
[taken by M. Cairns © ICRAF] |
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Slide 24:
Title |
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Slide 25: In
Kerinci, West Sumatra, any rotation starts with the cultivation
of annual crops. Here, tobacco and chilli's are intercropped with resprouting cinnamon
trees, while coffee seedlings are planted. After two years annual crops are not planted
anymore, and the coffee harvest starts. After three years of coffee harvest the canopy
closes of the cinnamon trees. From this moment onwards a "fallow-period" occurs,
where the natural vegetation is allowed to grow with the coffee and cinnamon trees.
[taken by Paul
Burgers © ICRAF] |
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Slide 26: Due to rising
timber prices shifting cultivators in Luang Prabang province of Lao PDR converted
increasing areas of dryland fields into Tectona grandis plantations (Hansen P et
al.) applying the Taungya system. Farmers prefer to plant teak close to roads to
facilitate later log extraction. This has raised concerns that the highest potential
agricultural land may be tied up for forestry in the long term, forcing farmers to
cultivate more ecologically fragile areas further upslope. Although potential returns are
high, most farmers would have difficulty in waiting 20-30 years before harvest, tempting
them to sell the land or harvest rights to urban speculators.
[taken by M. Cairns © ICRAF] |
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Slide 27: In
Bukidnon, the Philippines, degraded grasslands are converted into valuable
timber stands. Paraserianthes falcataria seeds are distributed into Imperata
swards, before they are slashed-and-burned in preparation for cultivation. The fire
scarifies the P. falcataria seeds, causing them to germinate together with planted
food crops. Farmers selectively retain emerging tree seedlings during weeding operations,
but may do some thinning or transplanting to achieve the desired stand density. After crop
harvest, the P. falcataria dominates the fallow succession and can be harvested for
timber at 10-12 years. Midway through the fallow, P. falcataria flowers and
contribute to the soil seed bank so that after tree harvest, the subsequent burning of
remaining slash sets the cycle in motion again.
[taken by D. Magcale-Macandog] |
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Slide 28: A market for
pulp wood has persuaded many upland farmers in Yen Bai province of Northern Vietnam to
plant Styrax tonkinensis (shown) and Manglatia glauca into their swidden
fields in a taungya system. These tree crops can achieve marketable size within a fallow
of 10-12 years, after which the fallow is reopened and the logs sold to the pulp mill. In
this way, shifting cultivation has been transformed into de facto permanent land use with
a food crop-pulp wood rotation. The system has led to progressive reforestation of barren
hills and increased forest cover in the province.
[taken by M. Cairns © ICRAF] |
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Slide 29: Shifting
cultivators in Nam Bak District of Luang Prabang, Lao PDR, also manage Styrax
tonkinensis as a useful fallow species - but for tapping its resin ‘benzoin’
(Savathvong S et al.). Indigenous to the area, S. tonkinensis quickly
colonises disturbed land and can form almost pure stand under favorable conditions.
Slash-and-burn scarifies Styrax seed in the soil seed bank and accelerates
germination. Styrax then germinates together with the glutinous rice crop and after
a single year of cultivation, it is left to dominate the subsequent fallow succession.
Tapping (shown) begins when the trees are six years old - and can continue up until 10-14
years of age. This traditional system is however under threat due to falling resin prices
and shortening fallow periods.
[taken by M. Cairns © ICRAF] |
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Slide 30: In the
Kerinci area of West Sumatra, Indonesia, high cinnamon prices and a favourable land tenure
have stimulated many shifting cultivators to interplant Cinnamomum burmanii into
their fields in a taungya system (Suyanto et al.; Werner S). As in standard
practice, intercropping of food crops between the rows of trees is discontinued when
shading becomes excessive, leaving it as a pure Cinnamomum plantation, or mixed
with coffee when coffee is planted as well. The harvest is usually at around 8-12 years
after which the cycle starts again.
[taken by Suyanto © ICRAF] |
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Slide 31: Farmers in
several provinces of Northern Lao PDR harvest the inner bark of larger stems of Broussonetia
papyrifera (paper mulberry) for processing into a coarse-textured parchment.
Development of a local processing industry and opening of market channels have encouraged
many farmers to retain B. papyrifera growing in rice swiddens. The paper mulberry
fallows are able to produce a harvestable product even within the short 2-3 year fallows
that predominate across much of S.E. Asia’s uplands today.
[taken by K. Fahrney] |
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Slide 32: Title |
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Slide 33: In isolated highland areas a lot of tea, coffee and other tree crops with high
value, low volume and low perishability can be found. This tea plantation in Shangyun
Township of Tengzhong County, Baoshan District in Yunnan, is planted under an Alnus
nepalensis canopy. This innovation was a modification of the traditional Chinese
practice of growing tea under natural forest canopy. Farmers widely recognise alder as
having soil-building properties (Guo H et al.). This practice began as recently as
30 years ago when farmers observed that tea grown under an Alnus canopy had higher
productivity and less insect damage. Alnus logs, periodically thinned to regulate
the shading, are used as firewood in processing tea, for construction of tea boxes, and as
a substrate in culturing several kinds of mushrooms.
[taken by M. Cairns © ICRAF] |
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Slide 34: In mixed
garden with cacao and coconuts, Gliricidia sepium is used as a shading tree for
cacao, cassava and chili pepper (the latter not shown in photo). This system gives a good
soil cover, maintains soil moisture, and reduces soil erosion and weed growth. (N.
Lampung, Indonesia).
[taken by Meine van Noordwijk © ICRAF] |
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Slide 35: Gliricidia
sepium is also often used as a life pole for Vanilla in a home garden system, besides
its use as fodder in S. Sumatra.
[taken by Meine van Noordwijk © ICRAF] |
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Slide 36: Title |
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Slide 37: Upland farmers have a comparative advantage in producing tree products and
ruminant livestock - both commodities in high demand by Asia’s growing middle class.
Silvipastoral patterns, such as this Philippine example of grazing cattle under a Gmelina
arborea fallow (Magcale-Macandog D and Rocamora PM), may be a promising approach to
manage fallow land more productively. Research needs to identify ‘best-bet’
species that can both perform fallow functions and provide livestock fodder.
Claveria,
Misamis Oriental, Philippines.
[taken by M. Cairns © ICRAF] |
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Slide 38: In parts of
Java, Indonesia, farmers have found multiple uses of the "improved fallow"
species Tithonia diversifolia. It is mainly used as fodder for fattening goats.
Besides that Tithonia also accumulates a lot of biomass, the resulting litter is
beneficial for crop growth.
[taken by M. Cairns © ICRAF] |
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Slide 39: In Timor, the
fallow of Leucaena leucocephala provides a huge fodderbank for cattle fattening.
Cattle is kept in zero-grazing units to avoid crop damage by roaming cattle. The improved
fallow of Leucaena is rotated with maize, in a 2-4 year cycle. Bringing back the dung onto
the field, these fallow systems where cattle is integrated provide efficient nutrient
cycling to sustain food cropping. The sale of cattle provides a good cash income for the
farmer. In the 80'ies Leucaena leucocephala was widely promoted world wide as a
kind of wonder tree: a rapid grower, nitrogen fixing tree and a good fodder. Leucaena is
however prone to psyllids, which has also in Timor led to a massive die-back of the tree.
To avoid similar disasters in the future diversification of species remains the order
word. This could be done by intercropping different (leguminous) species (like Calliandra
and Sesbania) or look at what local species can offer.
[taken by Tony Djogo] |
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