THE EFFECT OF TILLAGE ON SOIL ORGANIC-MATTER USING C-14 - A CASE-STUDY

We compared four adjacent soil plots in an effort to determine the eff ect of land use on soil carbon storage. The plots were located at the High Plains Agricultural Research Laboratory near Sidney, Nebraska. We measured C-14, total carbon, total nitrogen and Ce-137 to determine t he size and turnover times of rapid and stable soil organic matter (SO M) pools, and their relation to land-use practices. Results were consi stent with the model produced by Harrison, Broecker and Bonani (1993a) in that the C-14 surface soil data fell on the time trend plots of wo rld C-14 surface soil data, indicating that the natural sod and non-ti lled plots had a rapidly turning over SOM pool, comprising ca. 75% of surface soil carbon, and the tilled plots had a rapidly turning over S OM pool, comprising only 50% of surface soil carbon.