Washington

The growing intensity of agriculture around the world is destroying soil quality, wasting water, demolishing forests and adding to greenhouse-gas emissions, according to a report by the International Food Policy Research Institute (IFPRI) and the World Resources Institute (WRI).

The Pilot Analysis of Global Ecosystems: Agroecosystems is billed by its authors as the first comprehensive audit of agriculture's global ecological impact. It argues that as much as four-fifths of the world's farm land is being degraded by agricultural effects such as erosion, nutrient depletion, acidification and loss of organic matter.

The audit makes a good case for more investment in agricultural research, especially in the developing world, says Ian Johnson, chair of the Consultative Group on International Agricultural Research and a vice-president of the World Bank. The bank is expected to use the report in its own forthcoming assessment of global ecosystems.

Agricultural science and technology, including genetically modified crops and plant breeding, are critical to raising food production while protecting natural resources, adds Robert Thompson, director of rural development at the bank.

The report says that farmers withdraw 70% of the world's fresh water supply for irrigation, but more than half of this is lost through evaporation. Farm land has grown by around 130,000 square kilometres a year over the past 20 years, mostly at the expense of forests and grasslands, it says, and farming is also encroaching on many national parks and other protected areas.

The audit also finds that agriculture is the largest source of methane — a potent greenhouse gas — from human activities, responsible for 44% of all emissions. And it calls for more investment in the science of ecosystem monitoring.

http://www.ifpri.org