Warmer World Will Alter Soil Nutrient Cycle, To Detriment Of Plants And Crops
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What keeps soils alive, and productive, is the compost or humus of leaf litter, animal dung, withered roots and other decaying vegetation in the first meter or so of topsoil: this in turn feeds an invisible army of tiny creatures that recycle the nutrient elements for the next generation of plant life.
But these microbes also need water to thrive. The consortium of researchers predicted that as the soils got drier, biological activity would decrease, but geochemical processes would accelerate. That is, nutrients that depended on little living things in the soil would drain away, but other elements – phosphorus among them – would increase, because they would be winnowed from the rock by mechanical weathering or erosion.
The research team tested this argument with samples from 16 countries, including the Negev desert in Israel, the woodlands of New South Wales in Australia, the Altiplano of Peru, and the Pampas lowlands of Argentina. These regions could all expect from 3.9 inches of rainfall a year to 31.5 inches; all soil samples were analyzed in the same laboratory in Spain.
And as predicted, they revealed an increasing imbalance: more phosphorus, less carbon and nitrogen as they became drier. Such a trend would actually feed back into global warming: ideally, more vigorous plant growth would absorb more carbon dioxide. But if vegetation wilts, and soils turn to dust over large areas of already parched land, then the carbon dioxide levels in the atmosphere will increase even more.
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http://www.climatecentral.org/news/what-happens-when-the-world-dries-out-16687?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+climatecentral%2FdjOO+Climate+Central+-+Full+Feed