By Lim Li Ching, Researcher,
Third World Network (November 2008)
A key question that is often asked
about ecological agriculture, including organic agriculture, is whether
it can be productive enough to meet the world’s food needs.
While many agree that ecological agriculture is desirable from an
environmental and social point of view, there remain fears that ecological
and organic agriculture produce low yields.
This short paper will summarise
some of the available evidence to demystify the productivity debate
and demonstrate that ecological agriculture is indeed productive.
In general, yields from ecological
agriculture can be broadly comparable to conventional yields in developed
countries. In developing countries, ecological agriculture practices
can greatly increase productivity, particularly if the existing system
is low-input, which is the largely the case for Africa. This paper
will focus mainly on evidence from developing countries.
Evidence from global modelling
A recent study examined a global
dataset of 293 examples and estimated the average yield ratio (organic
: non-organic) of different food categories for the developed and
developing world (Badgley et al., 2007). For most of the food categories
examined, they found that the average yield ratio was slightly less
than 1.0 for studies in the developed world, but more than 1.0 for
studies in developing countries.
On average, in developed countries,
organic systems produce 92% of the yield produced by conventional
agriculture. In developing countries, however, organic systems produce
80% more than conventional farms.
With the average yield ratios,
the researchers then modeled the global food supply that could be
grown organically on the current agricultural land base. They found
that organic methods could hypothetically produce enough food on a
global per capita basis to sustain the current human population, and
potentially an even larger population, without putting more farmland
Moreover, contrary to fears that
there are insufficient quantities of organically acceptable fertilizers,
the data suggest that leguminous cover crops could fix enough nitrogen
to replace the amount of synthetic fertilizer currently in use.
This model suggests that organic
agriculture could potentially provide enough food globally, but without
the negative environmental impacts of conventional agriculture.
Evidence from reviews
of ecological agriculture projects
In a review of 286 projects in
57 countries, farmers were found to have increased agricultural productivity
by an average of 79%, by adopting “resource-conserving”
or ecological agriculture (Pretty et al., 2006).
A variety of resource conserving
technologies and practices were used, including integrated pest management,
integrated nutrient management, conservation tillage, agroforestry,
water harvesting in dryland areas, and livestock and aquaculture integration
into farming systems. These practices not only increased yields, but
also reduced adverse effects on the environment and contributed to
important environmental goods and services (e.g., climate change mitigation),
as evidenced by increased water use efficiency and carbon sequestration,
and reduced pesticide use.
The work built on earlier research,
which assessed 208 sustainable agriculture projects. The earlier research
found that for 89 projects for which there was reliable yield data,
farmers had, by adopting sustainable agriculture practices, achieved
substantial increases in per hectare food production - the yield increases
were 50-100% for rain-fed crops, though considerably greater in a
number of cases, and 5-10% for irrigated crops (Pretty and Hine, 2001).
Disaggregated data show:
Average food production per household
rose by 1.7 tonnes per year (up by 73%) for 4.42 million small farmers
growing cereals and roots on 3.6 million hectares.
Increase in food production was
17 tonnes per year (up 150%) for 146,000 farmers on 542,000 hectares
cultivating roots (potato, sweet potato, cassava).
Total production rose by 150
tonnes per household (up by 46%) for the larger farms in Latin America
(average size 90 hectares).
The database on agricultural
sustainability (comprising the 286 projects) was reanalyzed to produce
a summary of the impacts of organic and near-organic projects on agricultural
productivity in Africa (Hine and Pretty, 2008). The average crop yield
increase was even higher for these projects than the global average
(79%): 116% increase for all African projects and 128% increase for
the projects in East Africa.
For Kenyan projects, the increase
in yield was 179%, for Tanzanian projects 67% and for Ugandan projects
54%. Moreover, all case studies that focused on food production in
this research where data have been reported, showed increases in per
hectare productivity of food crops, which challenges the popular myth
that organic agriculture cannot increase agricultural productivity.
Evidence from specific
ecological agriculture interventions
Data from the Tigray Project
in the Tigray Region in Ethiopia, where a project on ecological agriculture
has been carried out since 1996, concretely demonstrate the benefits
of compost on productivity. Preliminary data collected in 1998 had
already shown that using compost gave similar yield increases as chemical
fertilizers. Data collected in 2002, 2003 and 2004 showed that, on
average, composted fields gave higher yields, sometimes double, than
those treated with chemical fertilizers (Araya and Edwards, 2006).
In a new paper written for the
UN Food and Agriculture Organization (FAO), statistical analysis on
a larger data set over the years 2000 to 2006 inclusive confirms that
compost use in Tigray has increased yields in all the crops analysed
(Edwards et al., 2008). In total, data was collected from 974 fields
from 19 communities. Grain and straw yield data were obtained for
barley, durum wheat, finger millet, hanfets (a mixture of barley and
durum wheat), maize, sorghum, teff, faba bean and field pea.
Except for field pea, the compost
generally doubled the grain yield when compared to each respective
check (crops grown without any inputs). (For field pea, the increase
in yield was approximately 28%.) The difference was significant (95%
confidence limit). The application of compost also increased straw
yield compared to the check, but not to the same extent as it increased
The use of compost also gave
higher yields than the use of chemical fertilizer, though differences
in the yields from compost and from chemical fertilizer were not as
great as the differences between the use of compost and the check.
For sorghum and faba bean the yields from the use of compost and chemical
fertilizer were similar. But the yield difference for all the other
crops was greater with that from the compost treatment being always
higher than that from the use of chemical fertilizer. The results
also showed that compost not only increases the overall biomass yield,
but also increases the proportion of the grain to straw in the yield.
Since 1998, the Bureau of Agriculture
and Rural Development of Tigray Region has adopted the making of compost
as part of its extension package and by 2007 at least 25% of the farmers
are making and using compost. A reflection of the success of this
approach is that between 2003 and 2006, grain yield for the Region
almost doubled from 714 to 1,354 thousand tonnes. Since 1998, there
has also been a steady decrease in the use of chemical fertilizer
from 13.7 to 8.2 thousand tonnes.
There are many other specific
examples of increased yields following the application of ecological
agriculture practices, some of which are summarized below (Hine and
Pretty, 2008; Parrott and Marsden, 2002; Pretty and Hine, 2001; Scialabba
and Hattam, 2002).
Soil and water conservation in
the drylands of Burkina Faso and Niger have transformed formerly degraded
lands. The average family has shifted from being in cereal deficit
of 644 kg per year (equivalent to 6.5 months of food shortage) to
producing an annual surplus of 153 kg.
In Ethiopia, some 12,500 households
have adopted sustainable agriculture, resulting in a 60% increase
in crop yields.
In Tigray, Ethiopia, yields of
crops from composted plots were 3-5 times higher than those treated
only with chemicals.
Projects in Senegal promoted
stall-fed livestock, composting systems, green manures, water harvesting
systems and rock phosphate. Yields of millet and peanuts increased
dramatically by 75-195% and 75-165% respectively.
In Kenya, 500 farmers on some 1000 hectares have seen maize yields
improve from about 2 to 4 t/ha following the application of soil conservation,
soil fertility and organic agriculture methods.
A range of biological pest management
methods together with legumes, cover crops and green manures for soil
fertility improvement resulted in a doubling of beans and groundnut
yields from 300 to 600 kg/ha in western Kenya.
In eastern and central Kenya, smallholder farmers have been trained
in natural soil fertility management; integrated environmentally friendly
weed, pest and disease protection; on-farm soil and water conservation
techniques; and farm level seed conservation, with a resulting 50%
increase in productivity and 40% increase in income.
More than 1000 farmers in low
soil fertility areas in the North Rift and western regions of Kenya
increased maize yields to 3,414 kg/ha (71% increase in productivity)
and bean yields to 258 kg/ha (158% increase in productivity) as compared
to traditional agriculture, by incorporating soil fertility management,
crop diversification and improved crop management.
Integration of pond fish culture
into low-input farm systems with some 2000 farmers in Malawi increased
vegetable yields from 2700 to 4000 kg/ha, with the fish ponds producing
the equivalent of 1500 kg/ha of fish, a new source of food for households.
In Latin America:
45,000 families in Honduras and
Guatemala have increased crop yields from 400-600 kg/ha to 2000-2500
kg/ha using green manures, cover crops, contour grass strips, in-row
tillage, rock bunds and animal manures.
The states of Santa Caterina,
Paraná and Rio Grande do Sol in southern Brazil have focused
on soil and water conservation using contour grass barriers, contour
ploughing and green manures. Maize yields have risen from 3 to 5 tonnes/ha
and soybeans from 2.8 to 4.7 tonnes/ha.
The high mountain regions of
Peru, Bolivia and Ecuador are some of the most difficult areas in
the world for growing crops. Despite this, farmers have increased
potato yields by three fold, particularly by using green manures to
enrich the soil. Using these methods, some 2000 farmers in Bolivia
have improved potato production from about 4000 kg/ha to 10-15000
In Brazil, use of green manures
and cover crops increased maize yields by between 20-250%.
In Peru, restoration of traditional
Incan terracing led to increases of 150% for upland crops.
In Honduras, soil conservation
practices and organic fertilisers have tripled or quadrupled yields.
In Cuba, there are more than
7000 organic urban gardens and productivity has grown from 1.5 kg/m2
to nearly 20 kg/m2.
Participatory irrigation management
in Philippines has increased rice yields by about 20%.
Yield increases of 175% were reported from farms in Nepal adopting
In Pakistan, yields of mango and citrus fruits increased by 150-200%
after adopting organic agriculture techniques such as mulching, no
till production, composting and planting the fruit trees in double
It is clear that ecological agriculture
is productive and has the potential to meet food security needs, particularly
in the African context. The International Assessment of Agricultural
Knowledge, Science and Technology for Development concurs that an
increase and strengthening of agricultural knowledge, science and
technology toward agroecological sciences will contribute to addressing
environmental issues while maintaining and increasing productivity
(IAASTD, 2008). Moreover, ecological agricultural approaches allow
farmers to improve local food production with low-cost, readily available
technologies and inputs, without causing environmental damage.
Araya, H. and Edwards, S. 2006.
The Tigray experience: A success story in sustainable agriculture.
Third World Network Environment and Development Series 4. TWN: Penang.
Badgley, C., Moghtader, J., Quintero,
E., Zakem, E., Chappell, M.J., Avilés-Vázquez, K., Samulon,
A. & Perfecto, I. 2007. Renewable Agriculture and Food Systems,
Edwards, S., Asmelash A., Araya,
H. and Egziabher, T.B.G. 2008. The impact of compost use on crop yields
in Tigray, Ethiopia, 2000-2006 inclusive.
Hine, R. and Pretty, J. 2008.
Organic agriculture and food security in Africa. United Nations Conference
on Trade and Development (UNCTAD) and United Nations Environment Programme
(UNEP): Geneva and New York.
IAASTD. 2008. International Assessment
of Agricultural Knowledge, Science and Technology for Development.
Parrott, N. and Marsden, T. 2002.
The real Green Revolution: Organic and agroecological farming in the
South. Greenpeace Environment Trust: London.
Pretty, J. & Hine, R. 2001.
Reducing food poverty with sustainable agriculture: a summary of new
evidence. UK: University of Essex Centre for Environment and Society.
Pretty, J.N., Noble, A.D., Bossio,
D., Dixon, J., Hine, R.E., Penning de Vries, F.W.T. & Morison,
J.I.L. 2006. Resource-conserving agriculture increases yields in developing
countries. Environmental Science and Technology (Policy Analysis)
Scialabba, N.E-H. and Hattam,
C. (eds). 2002. Organic Agriculture, Environment and Food Security.