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[SANET-MG] dream farms
http://www.i-sis.org.uk/DreamFarm.phpISIS Press Release 09/06/05
Abundantly productive farms with zero input and zero emission powered by
waste-gobbling bugs and human ingenuity
Sustainable development is possible
Dr. Mae-Wan Ho
A fully referenced version of this paper is posted on ISIS members’
website. Details here
Environmental engineer meets Chinese peasant farmers
Doesn’t it sound like a dream to be able to produce a super-abundance of
food with no fertilizers or pesticides and with little or no greenhouse
gas emission? Not if you treat your farm wastes properly to mine the
rich nutrients that can support the production of fish, crops livestock
and more, get biogas energy as by-product, and perhaps most importantly,
conserve and release pure potable water back to the aquifers.
That is what Professor George Chan has spent years perfecting; and he
refers to it as the Integrated Food and Waste Management System (IFWMS).
Chan was born in Mauritius and educated at Imperial College, London
University in the United Kingdom, specializing in environmental
engineering. He was appointed director of two important US federal
programmes of the US Environmental Protection Agency and the US
Department of Energy in the US Commonweath of the Northern Mariana
Islands of the North Pacific. On his retirement, Chan spent 5 years in
China among the Chinese peasants, and confessed he learned just as much
there as he did in University.
What he learned was a system of farming and living that inspired him and
many others including Gunter Pauli, the founder and director of the Zero
Emissions Research Initiative (ZERI) (www.zeri.org).
Chan left China in 1989, and continued to work with Gunter and others in
ZERI through consultancy services. This work has taken him to nearly 80
countries and territories, and contributed to evolving IFWMS into a
compelling alternative to conventional farming.
The integrated farm typically consists of crops, livestock and
fishponds. But the nutrients from farm wastes often spill over into
supporting extra production of algae, chickens, earthworms, silkworms,
mushrooms, and other valuables that bring additional income and benefits
for the farmers and the local communities.
Treating wastes with respect
The secret is in treating wastes to minimize the loss of valuable
nutrients that are used as feed to generate further nutrients from
algae, fish, etc., that feed a variety of crops and livestock. At the
same time, greenhouse gases emitted during the first phase of waste
treatment are harvested for use as fuel, while the oxygen required in
the second phase of waste treatment - which gets rid of toxins and
pollutants - is generated by photosynthetic algae, so fish stocks are
not suffocated through lack of dissolved oxygen in the nutrient-rich
water entering the ponds.
Livestock wastes are first digested anaerobically (in the absence of
air) to produce biogas (mainly methane). The partially digested wastes
are then treated aerobically (in the presence of air) in shallow basins
that support the growth of green algae. By means of photosynthesis, the
algae produce all the oxygen needed to oxidise the wastes to make them
safe for fish. This increases the fertilizer and feed value in the
fishponds without robbing the fish of dissolved oxygen. All the extra
nutrients, therefore, go to improve productivity. Biogas is used as a
clean energy source for cooking, and also enables farmers to process
their produce for preservation and added value, reducing spoilage and
increasing the overall benefits.
IFWMS has revolutionized conventional farming of livestock, aquaculture,
horticulture, agro-industry and allied activities in some countries,
especially in non-arid tropical and subtropical regions. It has solved
most of the existing economic and ecological problems and provided the
means of production such as fuel, fertilizer and feed, increasing
"It can turn all those existing disastrous farming systems, especially
in the poorest countries into economically viable and ecologically
balanced systems that not only alleviate but eradicate poverty." Chan says.
Increasing the recycling of nutrients for greater productivity
The ancient practice of combining livestock and crop had helped farmers
almost all over the world. Livestock manure is used as fertilizer, and
crop residues are fed back to the livestock.
Chan points out, however, that most of the manure, when exposed to the
atmosphere, lost up to half its nitrogen as ammonia and nitrogen oxides,
before they can be turned into stable nitrate that plants use as
fertilizer (see Box 1). The more recent integration of fish with
livestock and crop has helped to reduce this loss.
The important addition of a second production cycle of nutrients from
fish wastes has enhanced the integration process, and improved the
livelihoods of many small farmers considerably. But too much untreated
wastes dumped directly into the fishpond can rob the fish of oxygen, and
end up killing the fish.
How volatile nitrogen is turned into nutrient for plants
Livestock manure contains large amounts of ammonia gas that must be
turned back into stable nitrate before it can be absorbed as nutrient by
plants. Nitrification is the process in which soil bacteria oxidize
ammonia (NH3) sequentially into nitrite (NO2) and then nitrate (NO3).
Ammonia is oxidized into nitrite by bacteria belonging mainly to the
genus Nitrosomonas, but also Nitrosococcus, Nitrosospira, Nitrosolobus
and Nitrosovibrio. Nitrite is then further oxidized into nitrate by
bacteria belonging mainly to the genus Nitrobacter, but also by bacteria
in other genera such as Nitrospina, Nitrococcus and Nitrospira.
In IFWMS, the anaerobically digested wastes from livestock are treated
aerobically before the nutrients are delivered into the fishponds to
fertilize the natural plankton that feed the fish without depleting
oxygen, thereby increasing fish yield 3- to 4-fold, especially with the
polyculture of many kinds of compatible fish feeding at different levels
as practiced in China, Thailand, Vietnam, India and Bangladesh. The fish
produce their own wastes that are converted naturally into nutrients for
crops growing both on the water surface and on dykes surrounding the ponds.
The most significant innovation of IFWMS is thus the two-stage method of
treating wastes; the anaerobic digester followed by the shallow aerobic
basins containing green algae. Livestock waste contains very unstable
organic matter that decomposes fast, consuming a lot of oxygen. So for
any pond, the quantity of livestock wastes that can be added is limited,
as any excess will deplete the oxygen and affect the fish population
adversely, even killing them.
Chan is critical of "erratic proposals" of experts, both local and
foreign, to spread livestock wastes on land to let them rot away and
hope that the small amount of residual nutrients left after tremendous
losses that damage the environment have taken place.
According to the US Environment Protection Agency, up to 70% of nitrous
oxide, N2O, a powerful greenhouse gas with a global warming potential of
280 (i.e., 280 times that of carbon dioxide) comes from conventional
agriculture. Nitrous oxide is formed as an intermediate in
denitrification, a process in which soil bacteria reduce nitrate
ultimately back to nitrogen gas. Denitrifying bacteria belong to two
main genera, Pseudomonas and Bacillus. Animal manure could be
responsible for nearly half of the N2O emission in agriculture in
Europe, according to some estimates; the remainder coming from inorganic
nitrate fertilizer. Thus, anaerobic digestion not only prevents the loss
of nutrients, it could also substantially reduce greenhouse gas
emissions from agriculture.
Chan further dismisses the practice of composting nutrient-rich
livestock wastes, for this ends up with a low-quality fertilizer that
has lost ammonia and nitrite. Instead of mixing livestock wastes with
household garbage in the compost, Chan recommends produce high-protein
feeds such as earthworms from the garbage, and using worm castings and
garbage residues as better soil conditioners. He is also critical of the
outmoded practice of putting manure in septic tanks for not much
financial or other benefits while the badly treated effluent is just as
dangerous as the waste itself.
Instead, the livestock waste digested anaerobically followed by
oxidation in open shallow basins with natural algae before letting the
treated waste effluent flow into the fish pond, can convert almost 100%
of the organic nutrients into inorganic nutrients that will not consume
any oxygen to deprive the fish. So, theoretically, the quantity of waste
input into the pond can increase 10-fold without the risk of pollution.
But, Chan cautions, the nutrients in the waste must be totally used by
both fish and crop culture, or the nutrients can create problems of
eutrophication – over-enrichment of plankton - that uses up all the
oxygen in the pond, thereby lowering productivity.
To close the circle, livestock should be fed with crops and processing
residues, not wastes from restaurants and abattoirs. Earthworms,
silkworms, fungi, insects and other organisms are also encouraged, as
some of them produce high value goods such as silk and mushrooms.
The digester can be as simple as a couple of concentric plastic bags of
5m3 capacity or 200-litre drums for a small farm, or a complex
reinforced concrete steel structure with an anaerobic sludge blanket to
collect the biogas for a big farm or industrial enterprise.
As the fresh wastes enter the digester, the waste-eating bacteria
transform the unstable ammonia (NH3) and nitrite (NO2) into stable
nitrate (NO3), which is ready for use as fertilizer. As more wastes are
added, the digester also produces an abundant and inexhaustible supply
of biogas - 2/3 methane (CH4) and 1/3 carbon dioxide (CO2) - a
convenient source of free and renewable energy for domestic, farming and
industrial uses (see Box 2). Big farms, meat and fish-packing plants,
distilleries, and various agro-industries are now self-sufficient in
energy, besides having big volumes of nutrient-rich effluent for
fertilizing fishponds, and ‘fertigation’ (fertilization and irrigation)
of many kinds of crops.
Formation of biogas 
Certain bacteria naturally present in manure produce a combustible gas
(biogas) when they digest organic matter anaerobically (in the absence
of oxygen). Biogas typically contains between 60 and 70 percent methane.
Anaerobic digestion involves two groups of bacteria. The first group of
ordinary bacteria produces organic acids such as acetic acid by
fermentation. The second group of bacteria, the methanogens (methane
makers), is special, it breaks down the organic acids and produces
methane as a by-product.
Methanogens cannot tolerate oxygen and are killed when exposed to
oxygen. Instead, they can use the dead end products of fermentation,
carbon dioxide or organic acids such as acetic acid, to generate methane:
Methanogens are found wherever oxygen is depleted, such as wetland
soils, aquatic sediments and in the digestive tracts of animals. Methane
formation is the final step in the decay of organic matter when carbon
dioxide and hydrogen accumulate, and all oxygen and other electron
acceptors are used up.
Proliferating lifecycles for greater productivity
The aerobic treatment in the shallow basins depends on oxygen produced
by the green alga Chlorella. Chlorella is very prolific and can be
harvested as a high-protein feed for chickens, ducks and geese.
When the effluent from the Chlorella basins reaches the fishpond, little
or no organic matter from the livestock waste will remain, and any
residual organic matter will be instantly oxidized by some of the
dissolved oxygen. The nutrients are now readily available for enhancing
the prolific growth of different kinds of natural plankton that feed the
polyculture of 5 to 6 species of compatible fish. No artificial feed is
necessary, except locally grown grass for any herbivorous fish.
The fish waste, naturally treated in the big pond, gives nutrients that
are used by crops growing in the pond water and on the dykes.
Fermented rice or other grain, used for producing alcoholic beverages,
or silkworms and their wastes, can also be added to the ponds as further
nutrients, resulting in higher fish and crop productivity, provided the
water quality is not affected.
Trials are taking place with special diffusion pipes carrying compressed
air from biogas-operated pumps to aerate the bottom part of the pond, to
increase plankton and fish yields.
Apart from growing vine-type crops on the edges of the pond and letting
them climb on trellises over the dykes and over the water, some
countries grow aquatic vegetables floating on the water surfaces in
lakes and rivers. Others grow grains, fruits and flowers on bamboo or
long-lasting polyurethane floats over nearly half the surface of the
fishpond water without interfering with the polyculture in the pond
itself. Such aquaponic cultures have increased the crop yields by using
half of the millions of hectares of fishponds and lakes in China. All
this is possible because of the excess nutrients from the integrated
Planting patterns have also improved. For example, rice is now
transplanted into modules of 12 identical floats, one every week, and
just left to grow in the pond without having to irrigate of fertilize
separately, or to do any weeding, while it takes 12 weeks to mature. On
the 13th week, the rice is harvested and the seedlings transplanted
again to start a new cycle. It is possible to have 4 rice crops yearly
in the warmer parts of the country, with almost total elimination of the
back breaking work previously required.
Another example is hydroponic cultures of fruits and vegetables in a
series of pipes. The final effluent from the hydroponic cultures is
polished in earthen drains where plants such as Lemna, Azolla, Pistia
and water hyacinth remove all traces of nutrients such as nitrate,
phosphate and potassium before the purified water is released back into
Processing for added value and nutrient release
One big problem with agricultural produce is the drop in prices when
farmers harvest the same crops at the same time. This is solved by the
abundant supply of biogas energy, which enable simple processing to be
done such as smoking, drying, salting, sugaring, and pickling.
Finally, the sludge from the anaerobic digester, the algae, macrophytes,
crop and processing residues are put into plastic bags, sterilized in
steam produced by biogas energy, and then injected with spores for
high-priced mushroom culture.
The mushroom enzymes break down the ligno-cellulose to release the
nutrients and enrich the residues, making them more digestible and more
palatable for livestock. The remaining fibrous residues can still be
used for culturing earthworms, which provide special protein feed for
chickens. The final residues, including the worm casting, are composted
and used for soil conditioning and aeration.
Sustainable development is possible
There has been a widespread misconception that the only alternative to
the dominant model of infinite, unsustainable growth is to have no
growth at all. I have heard some critics refer to sustainable
development as a contradiction in terms. IFWMS, however, is a marvellous
demonstration that sustainable development is possible.
The key is a balanced development and growth that’s achieved by closing
the overall production cycle, then using the surplus nutrients and
energy to support as many different cycles of activities as possible
while maintaining internal balance, rather like a developing organism.
The ‘waste’ from one production activity is resource for another, so
productivity is maximised with the minimum of input and little or no
waste is exported into the environment. It is possible to have
sustainable development after all; the alternative to the dominant model
of unlimited, unsustainable growth is balanced growth.
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