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  • From: "Tradingpost" <tradingpost@gilanet.com>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Why sustainable agriculture
  • Date: Sat, 09 Oct 2004 10:16:21 -0600

The Institute of Science in Society Science Society
Sustainability http://www.i-sis.org.uk

General Enquiries sam@i-sis.org.uk Website/Mailing List
press-release@i-sis.org.uk ISIS Director m.w.ho@i-sis.org.uk
========================================================


Why sustainable agriculture

The debate over sustainable agriculture has gone beyond the
health and environmental benefits that it could bring in
place of conventional industrial agriculture. For one thing,
conventional industrial agriculture is heavily dependent on
oil, which is running out; it is getting increasingly
unproductive as the soil is eroded and depleted. Climate
change will force us to adopt sustainable, low input
agriculture to ameliorate its worst consequences, and to
genuinely feed the world.

But in order to get there, important changes have to be made
in international agencies and institutions, which have
hitherto supported the dominant model of industrial
agriculture and policies that work against poor countries,
where farmers are also desperately in need of secure land
tenure.

This mini-series is a continuation of many articles that
have appeared in our magazine, Science in Society since 2002
http://www.i-sis.org.uk/isisnews.php.


Feeding the World under Climate Change
http://www.i-sis.org.uk/FTWUCC.php
Sustainable Agriculture: Critical Ecological, Social &
Economic Issues
http://www.i-sis.org.uk/SACI.php Restoring
Degraded Soils a Matter of Urgency
http://www.i-sis.org.uk/RDS.php




ISIS Press Release 09/10/04

Restoring Degraded Soils a Matter of Urgency
********************************************

Lim Li Ching reports

Sources for this article are posted on ISIS members' website
http://www.i-sis.org.uk/full/RDSFull.php. Details here
http://www.i-sis.org.uk/membership.php.

Research has shown that declining crops yields are, in most
cases, exponentially linked to loss of soil quality. Soils
are threatened by water and wind erosion, nutrient depletion
and salinisation, among other things. Although, on a global
scale, soil loss is unlikely to be a major threat to food
security, the impacts are probably going to be felt acutely
at the local and regional levels. This is especially so
where farmers are too poor to curb or overcome the damage.
Mechanized agriculture has caused billions of tonnes of
carbon previously trapped in soil to be released to the
atmosphere as carbon dioxide and methane. Lack of carbon in
the soil makes crop production inefficient and constrains
yields.

Global warming is likely to make things worse. As the ground
heats up, organic matter decomposes more easily, reducing
soil fertility, releasing carbon dioxide and further
exacerbating the warming effect. In fact, soil erosion
already contributes to global warming, as some of the carbon
in soil-laden water running off fields inevitably escapes
into the atmosphere. Deserts are expected to expand as the
interiors of continents become drier, and erosion would
worsen if soils dried out and violent storms became more
frequent.

Inevitably, a hotter world is likely to have less organic
matter in its soils. This will have tremendous consequences
for farmers the world over, particularly for those farming
in the marginal areas of developing countries. Critical
regions of soil degradation and hence a high priority for
soil restoration and carbon sequestration (storing carbon in
soil securely so it is not immediately reemitted) include
sub-Saharan Africa, central and south Asia, China, the
Andean region, the Caribbean, and the acid savannas of South
America.

Fortunately, something can be done, by managing soils to
stem erosion and retain more carbon. Carbon sequestration
can potentially offset global fossil fuel emissions by 5-15%
each year, while raising yields. Once sequestered, carbon
can remain in the soil, for the next 20-50 years at least,
as long as appropriate management techniques are used.

One proven method of resisting erosion, restoring soil
fertility and boosting crop productivity is the use of
organic compost. Compost is a natural fertilizer, supplying
soils with vital plant nutrients, and aiding them to retain
water and air. It restores soil carbon, crucial in
maintaining consistent yields through improvements in water
and nutrient holding capacity, soil structure and biotic
activity. Compost improves soil texture and structure, and
helps control weeds, pests and diseases.

The implications of practices such as composting could be
enormous for food security. According to Rattan Lal of the
Carbon Management and Sequestration Centre at Ohio State
University, a one tonne increase of the soil carbon pool in
degraded soils may increase crop yield by 20 to 40 kilograms
per hectare (kg/ha) for wheat, 10 to 20 kg/ha for maize, and
0.5 to 1 kg/ha for cowpeas. In Ethiopia, farmers using
compost increased yields for various food crops, sometimes
doubling or even tripling yields. The yields from using
compost are comparable, and often higher, than those from
chemical fertilizer.

Already, agricultural experts are urging Malawian
subsistence farmers to use organic compost, instead of
manufactured fertilisers. Samuel Saka, agricultural
development officer for Nkhunga extension planning area in
Nkhota-Kota district in central Malawi said, "Based on the
successful demonstration plots we had, many farmers have
started implementing this method and the results speak for
themselves - high maize yields."

A nationwide campaign is being promoted, as prices of
manufactured fertilisers are skyrocketing, putting them
beyond the reach of most Malawian subsistence farmers. As
compost is affordable and can be prepared from a combination
of readily available material such as dry leaves, grass,
maize stalks and other biodegradable substances, it can be
made and used by poor farmers. There is no need to borrow
money, so farmers do not have to take credit and get into
debt as they often do when using chemical fertilizers.

The materials to make compost are mixed with soil and water,
then left to decompose for some time. The heat generated
during the process destroys most weed seeds, fungal
diseases, parasites and pests. Although farmers do have to
invest time and labour into making good compost, the rewards
are worth the effort. The positive effects of compost on
yields last for two or more growing seasons, so soil given
compost in one year need not be treated again the next year.
Other strategies exist for combating soil degradation, and
should be used together with compost. For example, in
developing countries, sowing cover crops, using green
manures and crop residues, and planting trees have restored
soil fertility and stemmed erosion. In general, recommended
strategies to rehabilitate degraded soils and increase soil
carbon are also sustainable agricultural practices. The
combined benefits of restoring soils, increasing yields and
helping limit climate change are too important to ignore.






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