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


and globally.


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.

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