I am re-posting the Trewavas article on organic agriculture again below
with the corrected reference numbers as the earlier posting did not show
reference numbers properly . There are two reference lists: one for the
organic article and a separate one for the "can ecological ideas be used
in agriculture". Also the article can be accessed on web site
From: Tony Trewavas
Urban Myths about Organic Agriculture.
There is a widespread belief that farming systems with lower yields and
lower use of inputs are more friendly to the environment, and more
sustainable than higher producing systems (10). Organic food is often
viewed as healthier and benign. However the information below rarely finds
its way into discussion on organic food but is essential for a critical
assessment. Compared to efficient conventional farming conducted with good
agricultural practices, organic farming has "no positive environmental
aspects at all" (41) and least sustainability (44 ).
Organic farming is an ideology and not a science (1).
Organic farmers assert on principle that organic sources of minerals
produce crops with superior quality to inorganic mineral fertilisers.
Manure is the permitted fertiliser but minerals from manure breakdown have
not been observed to produce crops with superior qualities (8, 9, 55).
Furthermore the nutritive value tested on children was higher in crops
grown on inorganic fertiliser than manure (33). Intensity of fertilisation
is more important, as is location of the farm to crop quality. Organic
fertiliser, soil type or synthetic pesticide are of little importance
(31). The availability of free N between different fields receiving no
fertiliser and under the same management varies by at least three fold.
Contrary to organic expectations, no relationship between the organic
content of the soil and freely available N was observed (32 and references
therein). A further organic assertion that inorganic fertilisers damage
soil structure has instead been shown to result from lack of crop rotation
(29). Organic associations claim that current unstable synthetic
pesticides are dangerous. Only natural pesticides like rotenone, (a
highly-toxic, fish-killing chemical) or Bt spores (which causes fatal lung
infections in mice (21-23)) are used to kill insects on organic farms.
Pyrethrum (a common fly killer) is also used; the more effective and
equally unstable, synthetic pyrethroids are banned. Any competitive
organic farmer will keep his cropped area as clean of insects as possible
by whatever means permissible (27). Studies in Texas showed that organic
insecticides can be used at 100 fold higher dose than conventional
products (64 ). Organic farmers use copper sulphate to treat plant disease
but this is to be banned by the EC. Bordeaux mixture, the organic form
used, has induced liver disease in vineyard workers, caused deaths and is
probably carcinogenic. Copper sulphate kills earthworms, fish and leads to
serious copper contamination of food (24). Use of this chemical by the
organic community for many years indicates the dangers of assertion rather
than knowledge. Organic ideology derives from the common assumption that
natural things are good and man- made things bad. But are tapeworms, lice
and malaria-carrying mosquitoes good and antibiotics, vaccines and
anesethetics obviously bad?
Is organic farming environmentally friendly? Organic farming offers no
solution to the prominent agricultural problems of soil compaction or soil
erosion. Current no-till conventional agriculture using herbicides is the
simplest means of dealing with erosion on sloping land. No-till increases
organic material in the soil surface, leads to increased earthworm
populations, less damage to ground insects and better soil structure.
Trace element accumulation is higher in organic soil particularly of
cadmium, a known carcinogen (1, 15). Inorganic fertilisers are now cleaned
of cadmium whilst use of crude phosphate rock containing variable amounts
of cadmium (56) by organic farmers gives cause for concern over further
heavy metal accumulations. The use of manure results in retention of N and
other minerals in soil with only slow mineralisation. Consequently mineral
release is not synchronised with crop growth as it should be (46). Failure
of sufficient mineralisation in spring, hinders early crop canopy
production, reducing yields . Mineralisation outwith the growing season
has led to higher overall N leaching rates than conventional farms, often
exceeding EC regulations (5,25,26, 29, 43). In Holland, Germany (1) and
the UK (26), excessive manure breakdown has led to eutrophication of lakes
and rivers; the volatile ammonia from fresh manure has damaged woodland
(5, 25, 31, 49, 64). Ploughing up grassland or legume leys, a necessary
stage in organic rotations to build up N, can cause serious aquifer
contamination from leached nitrate (4, 43). Microbial breakdown of manure
produces nitrous oxide and methane, the most potent global- warming gases
by orders of magnitude(25). Potent sources of methane production are from
cattle guts and anaerobic soil. Early leaching of minerals from
conventional soils (1, 28) reduces potential damaging nitrous oxide
production. Mechanical weeding by tractor is usually essential on organic
farms because herbicides are banned (29). Consequently fossil fuel
consumption can be doubled producing more global-warming carbon dioxide
and damaging NOx (41, 49). 70% organic produce is flown into the UK on
supersonic jets in part from mesoamerica, a part of the world still
destroying its rain forest . High flying jet aircraft are thought to
damage the ozone layer.
The dangerous bacterium, E.coli 0157 H7 is abundant in manure; deaths have
resulted from contamination of both organic and conventionally-produced
food (11,12, 18-20). Even though it is thought that feeding grass or hay
to cattle reduces E.coli contamination in faecal material, sheep and deer
fed only on grass have contaminated both water and food with these
Organic food and disease. Climate predictions indicate a more variable,
wetter climate for the UK (45). Plant disease will increase and become
more damaging. Agricultural technologies to deal with this problem should
be flexible and rigid organic rules are inappropriate. Organic farms may
currently survive disease outbreaks because other surrounding conventional
farms use effective fungicides to control disease (29). Is this not
similar to an irresponsible minority of parents who refuse to have their
children vaccinated relying on others to reduce disease spread? Recent
work shows that organic farms can act as reservoirs of disease (2, 36). If
further research confirms this trend then organic farmers could be sued by
conventional farmers for failure to adequately treat disease. A
consequence of disease problems is the reported higher contamination of
organic food by the mycotoxins, patulin (14, 53) and fumonisin (2, 40) and
by the chemical, dioxin (14). Disease often enters through insect damage
and failure to adequately treat pests may in part be responsible. Present
mycotoxin consumption definitely affects European cancer rates (63).
Synergism between mycotoxins and other life style factors is expected to
account for a measurable proportion of cancers in those under 65, (62, 63)
of which one third are diet related (52). New organic products to deal
with disease, in the pipe-line, will probably be made in GM bacteria.
Organic farming yields and mineral requirements. To feed a fast-growing
population without further destruction of our ecosystems, requires crop
land to be used much more efficiently (45 and references therein). In
organic farming the emphasis instead is on sustainability and recycling
rather than yield/ha. Thus the minerals that leave an organic farm as sold
produce, must be replaced by minerals generated only within the farm
itself. Organic farmers rely on (a) biological N fixation, whose annual
yields for legumes are well established and limited (16, 25), (b), an
uncertain, weak and variable supply of rainwater minerals (32), (c)
recycling of minerals through manure generated on the farm itself. Mineral
budgets of organic farms commonly reveal net deficits of certain minerals;
more goes out than comes in (6, 7). A continuous deficit will result in a
slow decline in fertility and plant health. Organic farms however
supplement their mineral supply by purchasing straw (providing K), animal
feed to produce mineral-enriched manure and composted manure, all from
conventional farms (6, 7, 42). If however all agriculture went organic,
the essential supplements from the non-ideological conventional farms
would not be available and crop deterioration would result. Because of the
self-imposed regulation on inorganic fertiliser use, organic yields are
lower than conventional farms. Direct comparisons on the same farm show
that 40-70% is common e.g. (5, 33,41,57); comparisons between different
farms cannot be used given the complexity of factors determining yield
(42). World wide, organic farming is the (usually-undesired) norm and crop
production is limited by the inadequate input of minerals from recycled
and resources and rain water. Western organic farming is a "land guzzler"
(35); a bad example to poorer countries who must use their land more
efficiently. Estimates suggest organic farming could feed no more than 3
billion people; we are already 6 billion in number (16, 34, 64).
Improve technology; don't reject it because of problems. Integrated crop
management (ICM) is a conventional agriculture using crop rotation,
resource recycling and integrated pest management (47). ICM does not
reject technology because problems arise. Instead, the difficulties are
solved and technology benefits retained. ICM skilfully, and flexibly,
optimises application of minerals, manure and pesticides without waste and
maintains environmental friendliness. Full use is made of detailed
information about each field and ICM requires high managerial skill.
Furthermore detailed reports show that whatever environmental friendliness
is claimed by the organic community this is shared by many other farming
systems including many conventional farmers (48, 49).
Are synthetic pesticide residues dangerous? The organic community makes
much of supposed pesticide residues in food. Each of us eats a quarter
teaspoon of potential carcinogenic pesticides /day, 99.99% of which comes
from natural plant pesticides (50,51). Synthetic pesticide residues, 0.01%
of this carcinogen total, are insignificant; the dose would have to be one
thousand fold higher to have any detectable effect (29). Organic food
contains on average about half the synthetic pesticide residues of
conventional food (51). Synthetic pesticides have been used for 50 years.
Average cancer rates have dropped by 15% and over 50% for stomach cancer
from 1950 onwards (38, 39). We live much longer and healthier thanks to
cheap, conventional food. People living over 100 years are now common
Organic food price, a major danger. Organic food is more expensive because
of its negative attitude towards technology. A diet high in fruit and
vegetables cuts cancer rates for those under 65 by half (51). Increasing
the price of these health-giving foods such as "going organic" will reduce
consumption, particularly in poorer families and increase premature death
and higher health bills. At present others may purchase organic fruits and
vegetables believing them to be better but consume less because of the
expense. Many scientific investigations comparing organic food with
conventional food fails to show it is healthier, more nutritious or better
tasting (e.g. 9, 13, 31, 33, 37, 61). The UK Advertising Standards
Authority recently struck down such claims of superiority for organic food
(58). Averaging 150 investigations show that organic products contain
slightly lower nitrate and have a lower protein content (33). Recent
information suggests that current nitrate consumption rates may be
innocuous contrary to old, poorly-established and misleading literature
Holistic descriptions of agriculture. Organic agriculture is often
described as holistic, an interlinked system, believed by some to indicate
an indivisible and thus un-examinable whole (3). But any proper system can
be subjected to a sensitivity analysis to identify internal constraints
(59). For others, holistic views represent a kind of mystique to indicate
superiority to reductionist or chemical agriculture. However the
philosophical divide between holistic views and reductionism is now
considered dead (60). The designation of conventional agriculture as
"chemical" omits consideration of the chemical complexity of manure. Many
of the individual chemical components of manure can be demonstrated to be
carcinogenic when injected into rodents (51).
Farms are land management systems not ecosystems (see appendix for
critique of ecological ideas in agriculture). Farmer activity replaces the
feedback constraints which normally impose stability on ecosystems because
the fundamental aim of farming is food production. Organic farming usually
requires detailed management and cost effective use of resources. Within
the imposed ideological constraints, good organic farming represents
efficient use of resources available. But ICM (and many other forms of
agriculture) ensures equally efficient use of resources without the
Any systems approach emphasises the importance of the context in assessing
the better course of action. Successful agriculture requires objectivity
in decision and flexibility as circumstances, disease and weather change.
In the face of definite climate change, organic associations offer obscure
rules, arbitrary regulations and inflexibility. Such are necessary to
ensure certification. In contrast ICM requires thought from the farmer to
optimise farm resource use, flexibly leaving decisions within the remit of
the individual farm (47).
Comparison of organic farming to conventional farming of the past which
operated purely under economic goals is misleading. A choice can be made,
to have agriculture with low yields or to farm part of it with much higher
yields and set aside the surplus land to forest , woodland or nature (45).
On every economic, environmental and biodiversity criterion used, this
form of modern agriculture with good practices outscores organic farming
(41) and is easily the most sustainable, even on theoretical grounds(44).
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Can ecological ideas really be applied to agriculture?
All forms of agriculture start with some form of soil disturbance. In this
respect farming mimics the Fen-Carr succession resulting eventually, if
left alone, to the regeneration of climax forest. The reproducible
characteristics of succession result from the different life histories of
the participating species. In fact many crop plants have identical
characteristics to the pioneer plants which populate openings in forests
as old trees die and collapse (Wood, 1998). The flush of free N and
increased water supply which accompanies the death and collapse of mature
trees in forests are mimicked by present agricultural approaches. However
if a field is left fallow, crops rapidly disappear, unable to compete with
weeds (Nuffield, 1999) and the climax succession is reinitiated. Critical
genetic characters essential for weed survival have been removed from
crops during domestication (Chrispeels and Sadava, 1994).
All farms are artificial constructs; they are managed landscapes. A farm
is not an ecosystem, lacking the fundamental controlling interactions
between different natural plants and animals. Instead the farmer
interpolates the necessary feedback controls with the ultimate goal of
food production. Removal of weeds, control of predators, growth of crop
monocultures, rotation and manipulation of soil fertility are unique and
non-ecological contributions by the farmer.
Although ecologists commonly regard agricultural monocultures as unstable,
Wood (1998) has indicated that the natural, stable monocultures of
phragmites, bracken, spartina, mangroves, wild wheat amongst others
indicates that we do not understand what underpins ecological stability.
Furthermore Wood (1998) suggests that crop plants might be better compared
to invasive exotic species managed by the farmer. Species numbers /unit
area was once thought to confer apparent stability to ecosystems. But
theoretical analyses (May 1973) suggest that increased complexity of
interaction between species might instead destabilise complex ecosystems.
The stability of tropical ecosystems may depend heavily on the high tree
canopy rather than the density of species. The canopy provides for a
stable ground environment. Stable, temperate boreal forests are often
species poor. The current heated controversy between ecologists concerning
ecosystem stability and species number indicates that understanding is
currently poor (Kaiser 2000).
Recent observations suggest that perhaps functional differences between
species may be more important than complexity of species number in
conferring ecosystem stability (Tilman et al., 1997). Sometimes
inter-cropping reduces disease (Zhu et al., 2000) perhaps supporting
ecological notions of disease resistance, but other combinations of crop
plants have been reported to potentiate the spread of disease (Matson et
al., 1997). But is stability (or sustainability) really what is needed in
crop production and growth? Stability implies strong buffering ability and
therefore resistance to any agricultural improvement (Wood, 1998). Climate
changes will require continual modification of farming activities if only
to maintain yields.
The emphasis on soil quality, sometimes mistakenly described as organic,
is shared by most farming systems (Mc Derron et al., 2000). Efforts to
maintain soil microflora and improve nutrient release and holding capacity
are of obvious importance to some crops (Matson et al., 1997). But this
suggests that manure should be used primarily to condition the soil; not
as the only fertiliser. Manure enriched soils have better water holding
capacity and less mineral run- off (Drinkwater et al., 2000). But growing
crops with more precise targeting of minerals could act to compensate for
these problems certainly in areas where heavy manure application may be
difficult. Also in these cases green manure may be advantageous and might
be claimed to be more ecological. However crops vary in their optimal soil
structure and there is no basis for assuming that heavy manure
applications are necessary or advisable given the breakdown to N2O. Vines
for example do best on poor stony soils.
Crop rotation is not obviously ecological but is instead physiological.
There is certainly managerial benefit because rotation increases yield/ha
over the long term. It is supposed that different crops require different
balances of minerals that can be optimised by rotation. Furthermore pests
to individual crops find survival difficult when other crops occupy the
field. Different crops may condition the soil in different ways,
particularly from chemicals exuded by the roots. Ecological ideas can be
helpful in aspects of agriculture, as in the use of Integrated Pest
Management (Thomas 2000); although the help might be very complicated.
Recycling and minimal use of resource inputs at the end of the day may
simply make good economic and sense (Chrispeels and Sadava 1994). However
the Haber process is perfectly sustainable. There is sufficient phosphate
rock to last thousands of years (Smil, 2000). Requirements for increased
food production cannot conceivably be met without increased nutrient
inputs (Matson et al., 1997). Unless of course new crop plants with more
efficient minerals sequestering abilities appear soon.
However good ecological science has been corrupted into an ideology called
environmentalism. There has been environmentalist emphasis on the
population bomb (Erhlich 1968) and statements that the carrying capacity
of the planet is six billion (Ehrlich et al 1993), a figure we have now
exceeded. However recently, other environmentalists now claim that
population figures have been grossly inflated (Hodgson, 2000 commentary on
Ho statements). This sudden change in emphasis may be because
environmentalists do not like GM crops and wish to imply that population
pressures are no longer a concern for world food production. Julian Simon,
an economist, won a wager with Paul Ehrlich, an environmentalist, over the
future price of natural resources between 1980-1990 (Simon 1996). This bet
exposed the narrow perspective of environmentalist views and the danger of
taking only such views into governmental decisions.
Given that we do not understand these properties well, using ecology as a
basis for agricultural policy could at present be extremely damaging (Tait
and Morris 2000). Most would welcome a clean sustainable environment but
see that other considerations are equally important. A balance between
social, economic and ecological goals to meet a broad range of human needs
in economic viability, with reduction of environmental harm and fulfilling
demands for increasing food supplies and landscape benefits stands in
contrast to environmentalist views. This "competing objectives" viewpoint
includes many more stakeholders in agricultural decisions than those with
narrow ideological agendas (Farrell and Hart 1998; Tait and Morris 2000).
It is clearly a real holistic assessment.
A pragmatic view is called for. Progress can be made by assessing which
aspects of current agricultural systems are least sustainable and
targeting these for improvement (Tait and Morris 2000). For example,
pesticide waste, destruction of non-target insects, lack of crop rotation,
use of virus infected crops, or waste of water can be regarded as unwanted
externalities in different agricultural systems and be reduced,
circumvented or eliminated. This approach takes account of variation in
agricultural systems without demanding fundamental changes. In Africa and
other third world areas, simple improvements in soil quality or crop
rotation can have substantive effects on yield/ha; in western
agri-systems, programmes on pesticide reduction and efficient use of
minerals become important targets for optimisation. Integrated crop
management systems probably represent the best compromise for the West
with the fundamental goal of precision in application (Lu et al., 1997).
However Smil (2000) has indicated that western crops fall well below their
yield potential and there is considerable room for improvement given
current agricultural knowledge. If it is indeed functional differences
between species, not species numbers per se, which confer ecosystem
stability, then a systems parallel might be effective. In that case, forms
of agriculture which complement each other and use different resources
might confer the holy grail of stability and sustainability on the
agriculture of individual countries. Whether such a policy would increase
yield/ha is far less certain.
Conventional approaches used with thought and the objectives above seem at
present to be perfectly sustainable (Tait and Morris 2000). But to
increase yield/ha on a large scale in western agriculture will need new
crops and the potential inherent in GM technology. Publicly funded GM
research needs to target areas of social need in farming by providing
viral and pest resistant crops, crops with enhanced uptake of N and P to
reduce leaching, reduced water requirement and better direction of
photosynthate to seed. Virus resistant crops are needed desperately in the
third world and GM technology holds out enormous promise to substantively
eliminate such problems.With requisite safeguards and adequate testing, GM
crops should help both population increase, global warming and
bio-diversity requirements to be met. By 2050 when the population
stabilises, the agricultural goals will change and mankind can then
concentrate on returning as much land as possible to wilderness; true
harmony, or at least a steady state with nature, can then become a
Chrispeels MJ, Sadava DE. (1994) Plants, Genes and Agriculture. Jones and
Drinkwater LE, Wagoner P, Sarrantonio M (1998) Legume based cropping
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