Organic Agriculture Fights Back
By Lim Li Ching (ISIS/TWN)
Organic farming largely excludes synthetic inputs – pesticides, herbicides
and fertilisers – and focuses instead on biological processes such as
composting and other measures to maintaining soil fertility, natural pest
control and diversifying crops and livestock. Organic agriculture gives
priority to long-term ecological health, such as biodiversity and soil
quality, contrasting with conventional farming, which concentrates on
short-term productivity gains.
Organic farming has been denigrated for being less efficient in land use and
having lower yields than conventional farming, and even accused of posing
potential health risks. According to a commentary in Nature by Anthony
Trewavas, Fellow of the United Kingdom Royal Society, “Although its
supporters assert that organic agriculture is superior to other farming
methods, the lack of scientific studies means that this claim cannot be
substantiated” [1].
But he is wrong, there are scientific studies, peer-reviewed and published,
documenting organic agriculture’s positive outcomes. Furthermore, certified
organic production is just the tip of the iceberg in terms of land managed
organically but not certified as such. De facto organic farming [2] is
prevalent in resource-poor and/or agriculturally marginal regions where
local populations have limited engagement with the cash economy (see
“Ethiopia to feed herself” on ISIS website). Farmers rely on locally
available natural resources to maintain soil fertility and to combat pests
and diseases. They are showing the way towards sustainable agriculture
through sophisticated systems of crop rotation, soil management, and pest
and disease control, based on traditional knowledge.
Similar or higher yields
The charge that organic farming is lower-yielding is misleading. Because
comparisons of conventional and organic agriculture show differences in
biological, chemical and physical characteristics that may affect yield,
studies simply evaluating the reduction or elimination of inputs in
conventional systems may not accurately represent conditions in alternative
systems. Furthermore, abstract comparisons made when farms have just turned
organic do not tell the whole story, as it takes a few years for yield to
increase. Thus, it is necessary to make long-term comparisons.
A study on conventional and alternative farming systems for tomatoes [3]
over 4 years indicate that organic and low-input agriculture produce yields
comparable to conventional systems. Nitrogen (N) availability was the most
important factor limiting yield in organic systems, and can be satisfied by
biological inputs.
Another experiment examined yield, vitamin and mineral content of organic
and conventional potatoes and sweet corn over 3 years [4]. Results showed
that yield and vitamin C content of potatoes was not affected by the two
different regimes. While one variety of conventionally grown corn
out-produced the organic, there was no difference between the two in the
yield of another variety of corn or the vitamin C or E contents. Results
indicate that long-term application of composts produces higher soil
fertility and comparable plant growth.
A review of replicated research results in seven different US Universities
[5] from Rodale Research Center, Pennsylvania and the Michael Fields Center,
Wisconsin over the last 10 years showed that organic farming systems
resulted in yields comparable to industrial, high input agriculture.
* Corn: With 69 total cropping seasons, the organic yields were 94% of those
conventionally produced.
* Soybeans: Data from five states over 55 growing seasons showed organic
yields averaging 94% of conventional yields.
* Wheat: Two institutions with 16 cropping year-experiments gave yields in
organic wheat that were 97% of the conventional yields.
* Tomatoes: 14 years of research on tomatoes showed no yield differences
between organic and conventional.
The most remarkable results of organic farming, however, have come from
small farmers in developing countries. Case studies of organic practices
show dramatic increases in yields as well as benefits to soil quality,
reduction in pests and diseases and general improvement in taste and
nutritional content [2]. For example, in Brazil the use of green manures and
cover crops increased maize yields by between 20% and 250%; in Tigray,
Ethiopia, yields of crops from composted plots were 3-5 times higher than
those treated only with chemicals; yield increases of 175% have been
reported from farms in Nepal adopting agro-ecological practices; and in Peru
the restoration of traditional Incan terracing has led to increases of 150%
for a range of upland crops.
Projects in Senegal involving 2000 farmers promoted stall-fed livestock,
composting systems, use of green manures, water harvesting systems and rock
phosphate. Yields of millet and peanuts increased dramatically, by 75-195%
and 75-165% respectively. Because the soils have greater water retaining
capacity, fluctuations in yields are less pronounced between high and low
rainfall years. A project in Honduras, which emphasized soil conservation
practices and organic fertilisers, saw a tripling or quadrupling of yields.
In Santa Catarina, Brazil, focus has been placed on soil and water
conservation, using contour grass barriers, contour ploughing and green
manures. Some 60 different crop species, leguminous and non-leguminous, have
been inter-cropped or planted during fallow periods. These have had major
impacts on yields, soil quality, levels of biological activity and
water-retaining capacity. Yields of maize and soybeans have increased by
66%.
Efficient production
The world’s longest running experiment comparing organic and conventional
farming pronounced chemical-free farming a success [6, 7]. The 21-year Swiss
study found that soils nourished with manure were more fertile and produced
more crops for a given input of nitrogen or other fertiliser. Nutrient input
in the organic systems was 34 to 51% lower than in the conventional systems,
whereas mean crop yield was only 20% lower over a period of 21 years,
indicating efficient production and use of resources. The ecological and
efficiency gains more than made up for lower yields. In the long term, the
organic approach was commercially viable, producing more food with less
energy and fewer resources.
The biggest bonus was improved quality of the soil under organic
cultivation.
Organic soils had up to 3.2 times as much biomass and abundance of
earthworms, twice as many arthropods (important predators and indicators of
soil fertility) and 40% more mycorrhizal fungi colonising plant roots.
Mycorrhizal fungi are important in helping roots obtain more nutrients and
water from the soil [8].
The increased diversity of microbial communities in organic soils
transformed carbon from organic debris into biomass at lower energy costs,
building up a higher microbial biomass. The findings support the conclusion
that a more diverse community is more efficient in resource utilisation.
The enhanced soil fertility and higher biodiversity is believed to render
the organic plots less dependent on external inputs and provide long-term
environmental benefits.
Better soils
Indeed, organic agriculture is helping conserve and improve farmers’ most
precious resource – the topsoil. To counter the problems of hardening,
nutrient loss and erosion, organic farmers in the South are using trees,
shrubs and leguminous plants to stabilise and feed soil, dung and compost to
provide nutrients, and terracing or check dams to prevent erosion and
conserve groundwater [2].
Field experiments conducted at three organic and three conventional
vegetable farms in 1996-1997 examined the effects of synthetic fertilisers
and alternative soil amendments, including compost [9]. Propagule densities
of Trichoderma species (beneficial soil fungi that are biological control
agents of plant-pathogenic fungi) and thermophilic microorganisms (a major
constituent of which was Actinomycetes, which suppresses Phytophthora) were
greater in organic soils. In contrast, densities of Phytophthora and Pythium
(both plant pathogens) were lower in organic soils.
While the study recorded increased enteric bacteria in organic soils, the
researchers stressed that this was not a problem, as survival rates in soil
are minimal. Critics of organic farming have disingenuously pointed to the
possible human health effects of using manure [1]. But untreated manure is
not allowed in certified organic culture, and treated manure (known widely
as compost) is safe – this is what is used in organic farming. Unlike
conventional regimes (where manure might be used), mandatory organic
certification bodies inspect farms to ensure standards are met [10].
Little yield difference was observed. In the first year, corn and melon
yields were no different in soil amended with either synthetic or organic
amendments at four of six farms. In the second year, tomato yields were
higher on farms with a history of organic production, regardless of soil
amendment type, due to the benefits of long-term organic amendments. Mineral
concentrations were higher in organic soils whilst soil quality on
conventional farms was significantly improved by the addition of organic
fertiliser.
Another means by which soil fertility is restored in organic systems is
through legumes. A 15-year study compared three maize/soybean
agro-ecosystems [11, 12]. One was a conventional system using mineral N
fertiliser and pesticides. The other two systems were managed organically,
depending on legumes for N fixation. One was manure-based, where grasses and
legumes, grown as part of a crop rotation, were fed to cattle. The manure
provided N for maize production. The other system did not have livestock; N
fixed by legumes was incorporated into soil.
Amazingly, the 10-year-average maize yields differed by less than 1% among
the three systems, which were nearly equally profitable. Soil organic matter
and N content (measures of soil fertility) increased markedly in the manure
system (and, to a lesser degree, in the legume system), but were unchanged
or declined in the conventional system. The latter also had greater
environmental impacts – 60% more nitrate leached into groundwater over a
5-year period than in the organic systems.
In Honduras, the mucuna bean has improved crop yields on steep, easily
eroded hillsides with depleted soils [13]. Farmers first plant mucuna, which
produces masses of vigorous growth that suppresses weeds. When the beans are
cut down, maize is planted in the resulting mulch. Subsequently, beans and
maize are grown together. Very quickly, as the soil improves, yields of
grain doubled, even tripled. Mucuna produces 100 tonnes of organic material
per hectare, creating rich, friable soils in just 2-3 years. Mucuna also
produces its own fertiliser, fixing atmospheric N and storing it in the
ground where it can be utilised by other plants.
No increased pests
Because organic procedures exclude synthetic pesticides, critics claim that
losses due to pests would rise. However, research on Californian tomato
production found that the withdrawal of synthetic insecticides does not lead
to increased crop losses as a result of pest damage [14]. There was no
significant difference in pest damage levels to tomato on 18 commercial
farms, half of which were certified organic systems and half, conventional
operations.
Arthropod biodiversity was on average one-third greater on organic farms
than on conventional farms. There was no significant difference between the
two for herbivore (pests) abundance. However, densities of natural enemies
were more abundant on organic farms, with greater species richness of all
functional groups (herbivores, predators, parasitoids). Thus, any particular
pest species in organic farms would be associated with a greater variety of
herbivores (i.e. diluted) and subject to a wider variety and greater
abundance of potential parasitoids and predators.
At the same time, research has shown that pest control is achievable without
pesticides, reversing crop losses. For example, in East Africa, maize and
sorghum face two major pests – stemborer and Striga, a parasitic plant.
Field margins are planted with ‘trap crops’ that attract stemborer, such as
Napier grass and Sudan grass. Napier grass is a local weed whose odour
attracts stemborer. Pests are lured away from the crop into a trap – the
grass produces a sticky substance that kills stemborer larvae [15]. The
crops are inter-planted with molasses grass (Desmodium uncinatum) and two
legumes: silverleaf and greenleaf. The legumes bind N, enriching the soil.
But that’s not all. Desmodium also repels stemborers and Striga.
Besides the obvious benefit of not using harmful pesticides in organic
agriculture, Korean researchers recently reported that avoiding pesticides
in paddy fields encourages the muddy loach fish, which effectively control
mosquitoes that spread malaria and Japanese encephalitis [16]. Fields in
which no insecticides were used had a richer variety of insect life. But
actual larvae numbers of the mosquito vectors were significantly lower in
organic sites.
Higher biodiversity
Maintaining agricultural biodiversity is vital to ensuring long-term food
security. Organic farms often exhibit greater biodiversity than conventional
farms, with more trees, a wider diversity of crops and many different
natural predators, which control pests and help prevent disease [2].
Proving with stunning results that planting a diversity of crops is
beneficial (compared with monocultures), thousands of Chinese rice farmers
have doubled yields and nearly eliminated its most devastating disease,
without using chemicals or spending more [17]. Under the direction of
scientists, farmers in Yunnan implemented a simple change that radically
restricted the incidence of rice blast. Instead of planting large stands of
a single type of rice, as they typically have done, they planted a mixture
of two different kinds of rice: a standard rice that does not usually
succumb to rice blast disease and a much more valuable sticky rice known to
be very susceptible.
The hypothesis is simple. If one variety of a crop is susceptible to a
disease, the more concentrated those susceptible types are, the more easily
disease spreads. The disease is less likely to spread if susceptible plants
are separated by other plants that do not succumb to the disease and that
act as a barrier. Rice blast fungus, which destroys millions of tons of rice
and costs farmers several billion dollars in losses each year, moves from
plant to plant as an airborne spore, which should easily be blocked by a row
of disease-resistant plants.
Resistant plants not only blocked the spores, but as more farmers
participated, positive effects began to multiply. Not only were spores not
blowing in from the next row, they were no longer coming from the next
farmer’s field either, rapidly halting the disease’s spread. The sticky rice
plants, which rise above the shorter, standard rice plants, enjoyed sunnier,
warmer and drier conditions that also discouraged the growth of the fungal
rice blast.
Furthermore, empirical evidence from a study conducted since 1994 shows that
biodiverse ecosystems are 2-3 times more productive than monocultures [18,
19]. In experimental plots, both aboveground and total biomass increased
significantly with species number. The high diversity plots were fairly
immune to the invasion and growth of weeds, but this was not so for
monocultures and low diversity plots. Thus, biodiverse systems are not only
more productive, but are less prone to weeds as well!
The last word – sustainability
Research published in Nature investigated the sustainability of organic,
conventional and integrated (combining organic and conventional methods)
apple production systems in Washington from 1994-1999 [20, 21]. All three
gave comparable yields, with no observable differences in physiological
disorders or pest and disease damage.
The organic system ranked first in environmental and economic
sustainability, the integrated system second and the conventional system
last. A sustainable farm must produce adequate high-quality yields, be
profitable, protect the environment, conserve resources and be socially
responsible in the long term. Specifically, the indicators used were soil
quality, horticultural performance, orchard profitability, environmental
quality and energy efficiency.
Soil quality ratings in 1998 and 1999 for the organic and integrated systems
were significantly higher than for the conventional system, due to the
addition of compost and mulch. Differences in annual yields were
inconsistent among the three systems, whilst tree growth was similar. There
were satisfactory levels of nutrients among all three. A consumer taste test
found organic apples less tart at harvest and sweeter than conventional
apples after six months of storage.
Organic apples were the most profitable due to price premiums and quicker
investment return. Despite initial lower receipts in the first three years,
due to the time taken to convert to certified organic farming, the price
premium to the grower of organic fruit in the next three years averaged 50%
above conventional prices. In the long term, the organic system recovered
initial costs faster. The study projected that the organic system would
break even after 9 years, but that the conventional system would do so only
after 15 years, and the integrated system, after 17 years.
The environmental impact of the three systems was assessed by a rating index
related to the potential adverse impacts of pesticides and fruit thinners:
the higher the rating, the greater the negative impact. The conventional
system index was 6.2 times that of the organic system. Despite higher labour
needs, the organic system expended less energy on fertiliser, weed control
and biological control of pests, making it the most energy efficient.
Conclusion
Comparisons between conventional and organic farming are actually not on a
level playing field because research input into organics is small compared
to the former. Organic research tends to be more diffuse, farm-based and
participatory, drawing on local knowledge and tradition. It also focuses on
public goods, resources and techniques that are not readily patentable. This
explains why organics attract little investment from private sources
compared to conventional and biotechnological approaches [2]. As such,
higher levels of public funding for organics is needed.
At present, growers of more sustainable systems may be unable to maintain
profitable enterprises without economic incentives, such as price premiums
or subsidies. But if external environmental and social costs are
internalised into economic accounting, currently profitable conventional
farming systems may well become uneconomical and unsustainable.
Incorporating the value of ecosystem processes would encourage food
producers to employ economically and environmentally sustainable practices
[20].
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