In the 1890s the pioneering soil scientist R. V. Rizpolozhensky collected
"monoliths" slabs of soil, some of them more than a meter
deep from nearly 50 locations across Russia, ranging from the taiga
near St. Petersburg to the deserts of South Central Asia.
A century later Margaret Torn joined Russian scientist Andrei Lapenis, now at the State University of New York, in using Rizpolozhensky's collection to measure long-term changes in the soils of the vast Russian plains. Historic soil data are often inaccurate, and original sampling sites have been lost. However, with Rizpolozhensky's careful notes, plus computer-aided comparisons between new and old maps, the scientists relocated many of his sites within a few hundred meters. In some places, they found that land use hadn't changed since Rizpolozhensky's time; at one site, the pristine steppe has been preserved.
In five widely separated locations the scientists dug new pits and compared the soils directly with the historic monoliths. In forest soils, acid rain from power plant emissions and wind-blown phosphates from agricultural fertilizers had caused striking changes.
Torn's radiocarbon measurements showed that the amount of carbon in the soils had changed very little, however. Most of the carbon in the upper 20 centimeters of soil cycles every few decades as plants and soil organisms photosynthesize and respire, die and decay; deeper in the soil, carbon cycles at a slower rate.
"The central question," says Torn, "is whether soils like these will buffer the atmosphere against the massive injections of carbon from fossil fuels and other human activity or do the opposite, by releasing carbon and greatly amplifying human impacts."
The challenge is to learn how long the resilience of soils can last, and how to detect ominous changes early.