HR: 14:00h
AN: B23B-02    [Abstracts]
TI: Assessing Carbon Storage and Flux in Agricultural Soils
AU: * Lal, R
EM: Lal.1@osu.edu
AF: The Ohio State University, 2021 Coffey Rd., Columbus, OH 43210 United States
AB: The heightened importance of assessing carbon (C) storage and flux in agricultural soils is attributed to: (i) being a source of atmospheric CO2 since the dawn of settled agriculture 10,000 years ago, (ii) the large sink capacity for C sequestration vis-…-vis soils of other managed ecosystems, (iii) high risks of agricultural soils being a source of C because of seasonal perturbations associated with farming operations, (iv) hidden C costs of numerous input, (v) numerous ancillary benefits of C sequestration in agricultural soils, (vi) potential of increasing farm income through trading C credits, and (vii) a methodological challenge of assessing C storage and flux across a range of scales from an aggregate scale of a few mm to regional scale of thousands of km2. Agronomists have measured soil C pool as an index of soil fertility since late part of the 19th century. These measurements were usually made for the plow depth (20 cm) and reported in the units of concentration (g/kg, %). The significance of C storage and flux in agricultural soils, as a source or sink for atmospheric CO2 widely recognized since 1980s, has changed the boundary conditions of these measurements. In the context of climate change, soil C storage and flux must now be measured to at least 1-m depth (preferably to 2-m depth) and reported in the units of Mg/ha as pool and Mg/ha/yr as flux. In this regard, the new challenges faced by soil scientists are: (i) obtaining a sufficient number of samples to adequately represent the depth distribution of C, (ii) measuring soil bulk density for each layer, (iii) developing a sampling protocol to assess spatial and temporal variations in C pool and flux in relation to land use and management, (iv) aggregating the point data to soilscape, watershed and regional scales, and (v) relating C pool and fluxes to agronomic productivity on the one hand and to soil vs. climate processes on the other. Rapid progress is being made in addressing these new challenges by adapting traditional methods and developing innovative, cost-effective and time saving techniques.
DE: 1866 Soil moisture
DE: 1030 Geochemical cycles (0330)
DE: 1600 GLOBAL CHANGE (New category)
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting