[SANET-MG] Agroforestry and sustainability

[jcummins <jcummins@UWO.CA>]

http://www.i-sis.org.uk/SMFAAE.phpISIS Press Release 27/04/05
Sustainable Multi-cultures for Asia & Europe
Agroforestry and other multi-cultures increase productivity and
sustainability Prof. Bob Orskov

A referenced version of this article is available on ISIS members’
website. Details here

In Asia, the pressures of population have presented particular
challenges on how best to increase production in a sustainable manner;
and that’s where agroforestry has shown the most surprising promise.

Free grazing in coconut plantations
I first became involved with agro-forestry in a research project in Sri
Lanka carried out in collaboration with the Coconut Research Institute
in Lunawila. Large areas of Sri Lanka are covered with coconut
plantations owned by large industries and by small farmers. Coconut
trees do not form a dense canopy so it is always possible to grow other
plants under the trees. Cattle are often seen grazing under the coconut
trees, but the owners of the coconut trees are frequently not the owners
of the cattle. The cattle belong to small poor farmers, and the owner of
the coconut trees typically allows them to graze for free.

We set up an experiment to graze cattle under the coconut trees at a
high stocking rate. In fact, the animals had much less food than they
needed for maximum growth and reproduction (see Table 1).

The animals were old at calving, calving interval was long and milk
yield was low. Supplementing the feed with imported rice straw improved
the animals’ reproductive performance and when they were also given rice
bran, performance was further increased so that the calving interval was
normal at 13 months.

Table 1. Effect of grazing and supplement of female cattle under coconut

  Age at calving month
 Calving interval
 Milk yield kg/d

Grazing
 57
 20
 0.87

Grazing + rice straw
 47
 18
 1.53

Grazing + rice straw + rice bran
 40
 13
 2.36


These results may be expected, but the unexpected was the beneficial
effect on coconut yield (see Table 2).

Table 2. Effect of grazing on annual coconut yield and soil water
holding capacity

  Nuts/palm
 Copra/palm (kg)
 Water holding capacity (mm/m)

Non grazing
 41.1
 11.1
 16.9

Grazing
 47.9
 13.3
 18.3

Grazing + rice straw
 50.6
 14.2
 18.9

Grazing + rice straw + rice bran
 57.4
 16.7
 17.6


Grazing alone was sufficient to increase coconut yield by about 15%. No
wonder the owners of the coconut trees were quite happy for the small
farmers’ animals to graze under them! This was due to a rapid turnover
of biomass and the effect on soil quality seen here as water holding
capacity. Bringing nutrients for the cattle from outside further
increased coconut yield, as a result of the N, P and K etc contained in
the feed (see Table 3).

Table 3. Effect of grazing and supplement on coconut leaf composition
after 6 years

  Content in coconut leaf (%)

  N P K
Non grazing
 1.89  0.15 1.21
Grazing
 1.86  0.15 1.18
Grazing + rice straw
 1.92  0.16 1.48
Grazing + rice straw + rice bran
 2.23  0.18 1.76

The increased yield in coconut due to the animals is effectively an
animal product; but that is often ignored. Since then, whenever I see
animals grazing under trees or tied to trees I have often asked the
question, what is the effect on production from the trees be it mango,
coconut, durian or other fruit or on wood production e.g. teak. But
there is seldom an answer.

Oil Palm plantations
The effect of grazing animals on socioeconomy became very apparent to me
recently on a visit to an oil palm plantation in Bengkulu province of
Sumatra, Indonesia. The Indonesian company owning the plantations
employed workers to collect palm fruit bundles from the plantation and
carry them to a road passable by trucks. The employers had taken the
initiative to give to the workers a Bali cattle (Bos banteng), for
pulling a small cart that could hold about 15 to 20 bundles instead of
the one carried by the worker. This increased the capacity of a worker
to attend to 15 rather than 10ha. The feed for the cattle was plants
growing under the trees plus leaves and core from the palm fronds, which
had to be cut down before a palm bundle could be cut off. At night, the
cattle were also given some palm sludge from the factory. It soon
transpired that there was much more feed than one animal could eat so
the farm workers were allowed to take several animals with them during
the working day in the plantation. At the moment, an average of six
animals come with each worker in the morning. What is the possible
stocking rate under palm oil trees? I was told maybe 2/ha even with full
canopy. If so, many millions of cattle could be fed under oil palm trees
in the world. These could provide a secure living for many families.
Similar effects on oil palm production were observed some years ago (see
table 4).

Table 4. Effect of mixed cattle and goat grazing on annual yield of
fresh fruits in oil-palm plantations in Malaysia

Year
 Grazed area
 Non-grazed area
 Difference

Fresh fruit bunches (metric t. /ha)

1980
 30.55 (C)*
 25.61
 4.94

1981
 17.69 (C)*
 15.87
 1.82

1982
 25.12 (C & G)
 22.97
 2.15

1983
 23.45 (C & G)
 18.29
 5.16


*C = cattle: C & G = cattle and goats.

There were consistent increases in oil palm yield of some 15 to 20% as a
result of grazing with cattle and goats in the plantation, probably a
result of increasing turnover of biomass and soil water-holding
capacity. The positive effects of livestock in agroforestry are not
unique to the tropics. Recent work showed that productivity of sheep
grazing under trees in Scotland was similar, and in dry years greater
than sheep grazing a similar area in open land. Evidently the growth of
the trees was a bonus and soil fertility improved.

Reforestation with the aid of small farmers and their complementary crops
In Indonesia where many forests have been illegally cut, the government
is trying to re-establish the forests with the aid of small farmers
living nearby. These farmers are given the right to cultivate and plant
complementary crops between the trees, in this case teak and eucalyptus
trees, until the full canopy has formed. One may question if the full
canopy is necessary for optimal growth and quality of the trees. Less
than full canopy could give small farmers continuous access to grazing
and other complementary crops and maybe also to better quality trees.
Interplanting with leguminous trees and bushes for animal feed could
capture N also for the forest trees. The way silvopastoral systems
should be developed or perhaps more precisely redeveloped will vary
environmentally according to climate, type of trees, type of animals and
socioeconomic circumstances. What’s important here is not always the
maximum production of trees, but the best total production of all the
components in the system. An added advantage is that such systems will
be much more sustainable than monoculture tree systems and special
animal systems. Chickens and pigs after all were forest animals and not
designed for large intensive stall-fed and battery-fed systems. The
trees will also accumulate carbon from atmospheric CO2 and therefore
help in slowing down climate change. The relentless push to monoculture
promoted recently by herbicide resistant GM crops cannot be the solution
from environmental and socio-economic points of view.

Advantages of multi-culture
In many tropical areas in developing countries, multi-culture has been
used for many years particularly in densely populated areas. This
involves both combinations of forests with arable crops or grazing
animals and a mixture of arable crops. Often three crops are grown
together. Leguminous crops such as groundnut, soya bean and peas are
frequently grown together with non-leguminous crops such as maize,
cassava and wheat. The nitrogen captured by leguminous plants can be
used also by non-leguminous plants. These crops are not harvested at the
same time. Cassava for instance is generally harvested only once a year
while other plants that have a much shorter season can be replanted.
Combine harvesters cannot be used in harvesting; but as labour is
typically not a problem, labour-saving devices provide no solutions and
often create unemployment and poverty. Multi-culture systems such as
these are sustainable and help to maintain soil fertility and high
yields of crops.

Problems of monoculture
The negative effect of monoculture was recently demonstrated in rice
production. Here herbicides had been recommended for use in the paddy
fields; but instead of herbicides ducks were introduced (see Table 5).

Table 5. Integrated system of rice, rice plus duck, rice plus fish, and
rice plus fish and duck on net benefit for farmers (Mill.Vietnam Dong/ha)

Systems
 Rice
 Duck Rice
 Fish Rice
 Duck Fish Rice
 Layer Duck Fish Rice

Inputs:

For rice

6.62

3.92

7.36

3.92

3.92

For duck
 -
 8.70
 -
 8.70
 52.92

For fish
 -
 -
 15.58
 13.90
 13.90

Total
 6.62
 12.62
 22.94
 26.52
 70.74

Outputs:

From rice
 8.56
 8.03
 9.23
 9.85
 10.44

From duck
 -
 14.50
 -
 14.50
 68.02

From fish
 -
 -
 22.22
 46.39
 47.92

Total
 8.56
 22.53
 31.45
 70.74
 126.38

Net benefit
 +1.94
 +9.91
 +8.51
 +44.22
 +55.64


The ducks ate the weeds and the insects and increased the yield of the
paddy. As the young ducks were also fed at night they essentially
brought some fertiliser to the paddy in the form of faeces. Now fish
have also been introduced to consume the plankton grown in the paddy
fields as a result of the ducks fertilising the paddy. The total income
per ha increased by 50 times.

There are so many possibilities for increasing production in ways that
are sustainable.

Prof. Bob Ørskov OBE is head of International Feed Resource Unit,
Macaulay Institute, Aberdeen, Scotland, Fellow of the Royal Society of
Edinburgh & Fellow of the Polish Academy of Science

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