Healthy soil and sustainable growing

["Tradingpost" <tradingpost@gilanet.com>]

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.