New global map reveals effects of wet and dry climates on soil pH

SANTA BARBARA, Calif., Dec. 8 (UPI) -- Scientists already knew soil in wet climes is generally acidic, while soil in dry climes is generally alkaline. But in the process of creating a global soil pH map, scientists realized the distinction was surprisingly stark.

"Our analysis was able to confirm that the transition between those two zones is very abrupt," Eric Slessarev, a Ph.D. student in the Department of Ecology, Evolution and Marine Biology at the University of California, Santa Barbara, said in a news release. "It only takes a small change in climate to achieve the switch from that acid zone to the alkaline zone and there are fewer soils with an intermediate pH."

Slessarev and his fellow researchers found -- less surprisingly -- the few regions of soil featuring an intermediate pH, places like Iowa and the Ukraine, are areas of intense agricultural production. Soil with a neutral pH is conducive to farming.

The new map is the result of a meta-analysis of data from soil surveys in the United States, China, Canada, Australia and Brazil, with additional data points provided by the International Soil Research Information Center.

The map and related findings were published in the journal Nature this week.

"One thing that we can draw from our analysis is that the parts of the world that humans depend upon the most for agriculture sit on an edge between wet and dry climates and between acid soils and alkaline soils," Slessarev said. "What's more, our work demonstrates that soil pH -- and therefore soil fertility -- is tightly linked to climate."

The findings are particularly relevant to farmers living and working in regions of transition.

"In fact, it's linked in a way that looks like a staircase, where a step exists between one space and another," Slessarev added. "For the parts of the world on the edge of that step, this means a very small change in climate could make a big difference in how the system functions."