October 31, 2013
Dryland Soil Nutrients Will Be Disrupted Due To Warming Climate
April Flowers for redOrbit.com - Your Universe Online
A landmark study conducted by an international collaboration of scientists reveals that an increasing aridity due to global warming will disrupt the balance of nutrients in the soil and cause a reduction of productivity in the world's drylands.
The study, published in Nature, investigated 224 dryland sites in 16 countries on every continent except Antarctica.
University of New South Wales Adjunct Professor David Eldridge studied woodland sites near Mildura, NSW, Australia. Other sites around the world include regions of the Negev Desert in Israel, the Pampas lowlands in Argentina and the Altiplano highlands of Peru. Average rainfall for the sites ranged from four to 31 inches per year. The same laboratory in Spain analyzed soil samples from all the sites.
The results reveal that the increasing aridity is associated with a reduction in carbon and nitrogen in the soil, and an increase in phosphorus.
"Drylands cover about 41 per cent of Earth's land surface and support more than 38 per cent of the world's population," says Professor Eldridge, who also works for the NSW Office of Environment & Heritage.
"As the world's population grows, people will increasingly rely on marginal lands – particularly drylands - for production of food, wood and biofuels. But these ecosystems will be severely affected by imbalances in the cycle of carbon, nitrogen and phosphorus."
Scientists have predicted a global decrease in soil moisture ranging from 5 to 15 percent for the 2080-2099 period. Phosphorus, which is released into the soil from rocks and sediments by weathering, is predicted to increase as soils become drier and erode more.
Reductions in carbon and nitrogen are expected to accompany the increase in phosphorus. Carbon and nitrogen are more dependent on biological processes such as litter decomposition, photosynthesis and nitrogen fixation, so reduced plant cover will exacerbate this effect.
"Plants need all of these elements, in the correct amounts and at the right times, but increasing aridity will upset this balance, leading to a breakdown in essential soil processes," says Professor Eldridge.