Thursday, February 2, 2006
Sustainable Agriculture Increases Yields
EU Science for Environment Reports:
Sustainable Agriculture Increases Crop Yields
Unsustainable
agricultural practices have been recognised as key drivers of environmental
degradation at the global scale. Thus, promoting agricultural
sustainability by the use of technologies and practices that improve food
productivity without causing environmental damage is crucial in our pursuit
for a more sustainable and equitable development in Europe
In one of the
largest analysis of sustainable agricultural practices in developing
countries, an international group of scientists has examined 286 completed
and ongoing sustainable farming projects in 57 countries. In total, 37 million
hectares (3% of the cultivated area in developing countries) and some 12
million farmers were engaged in transition towards resource-conserving
agricultural practices. These included integrated pest and nutriment
management, conservation tillage, agroforestry, water harvesting, and
livestock and aquaculture integration in farming systems. Questionnaires
and published reports by project have been used in order to assess adoption
of sustainable practices and changes in yield production over time.
For the 360
reliable yield comparisons, the analysis has shown an average increase in
crop yields by around 64% since the 1990s. Half of the projects have shown
yield increases between 18 and 100% and 25% of the projects showed 100%
increase in yields. However, important differences have been noted between
various crops. Cotton and rice showed the lowest increases, while maize,
potatoes and some legumes (beans, pigeon peas, and others) demonstrated
more than 100% increases.
Though many technologies
and practices have been used in these “success projects”, the
authors suggest that the following three types of technological
improvements have probably played substantial roles in food production
increases:
1. More efficient water use;
2. Improvement in organic matter accumulation and carbon sequestration; and
3. Reduced pesticide use.
The paper notes
that all crops showed water use efficiency gains with the highest
improvement observed in rainfed crops. This is due to increase in water
productivity (i.e. kg of food per unit of water) as a result of certain
sustainable agricultural practices, viz. removing limitations on
productivity by increasing soil fertility; reducing soil evaporation
through conservation tillage; using more water efficient varieties;
reducing water losses to unrecoverable sinks.
By increasing
carbon sinks in soil organic matter and above-ground biomass, the farmers
have increased the amount of sequestered carbon by an average of 0.35
tonnes C/ha per year.
Regarding the analysis
of pesticide-use practices, 77% of projects with reliable pesticide-use
data have shown a decline in pesticide application by 71% while crop yields
grew by an average of 42%.
The authors
agree that in spite of the fact that sustainable agriculture alone will not
solve the problem of hunger and poverty in developing countries, their
findings give grounds for optimism. They also recall that the challenge
lays in finding the ways to improve the farmers’ access to
resource-conserving practices through international collaboration and
support.
Source: Pretty
J.N. et al. (2006)
“Resource-Conserving Agriculture Increases Yields in Developing
Countries”, Environmental Science and Technology on-line.
Contact:
jpretty@essex.ac.uk
http://lawprofessors.typepad.com/environmental_law/2006/02/sustainable_agr.html