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18 June 2010

World Day to Combat Desertification 2010

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Six to ten inches (18-25 cm) of topsoil are all that stand between us and extinction.

June 17, 2010. Message from Luc Gnacadja, Executive Secretary

There’s far more to this than food. The things that live in and grow from this irreplaceable and finite resource also keep us clothed, the air and water clean, the land green and pleasant and the human soul refreshed. Only now are we starting to comprehend how the tiny life forms in soil sustain productivity and the greater environmental balance.

Already, we know that the species that live in soil are far more abundant than first thought. Microbes in the soil make up most of the biomass of life on earth. They may lack the charisma of the tiger or the orang-utan, but the sheer prevalence of soil-dwelling fungi, archaea, bacteria, rotifers and nematodes alone puts other species in the shade. If we placed all the microbes found in soil on one side of a scale and all surface-dwelling animals on the other, the soil microbes would quite literally outweigh them. Understanding just what their function is thus vital to our broader grasp of environmental management, climate change and human development.

Rain-making bacteria Soil microbes and the tiny animals in earth provide a wide array of ecosystem services, including nutrient cycling, nitrogen fixation, decomposition and pest control, pollination, soil moisture retention, drainage, carbon sequestration, waste recycling and more. They even play little-known but major roles in climate regulation. Research provides growing evidence that, along with dust and other particles, certain bacteria from the soil are swept up by wind to high altitudes, where ice crystals form around them to make rain. Thus, healthy, bacteria-rich soil might well encourage rainfall.

Land degradation and desertification spell the gradual death of soil’s complex web of biota. The disappearance of just a single species from this web can be devastating. Among soil’s “free services” is the harbouring of the larvae of pollinating wasps, beetles, flies and bees. Their contribution to farming alone is extraordinary. The Food and Agricultural Organization (FAO) estimated in 2005 that of the slightly more than 100 crop species that provide 90 percent of the food for 146 countries, 71 are bee-pollinated. If we lose these “keystone” species, whole edifices will collapse.


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