Project Number: 6420-11120-005-00
Project Type: Appropriated

Start Date: Mar 22, 2005
End Date: Mar 21, 2010

Objective:
Reduce uncertainty regarding: (1) the effects of rising atmospheric carbon dioxide concentration on crop and pasture production; and (2) the role of agronomic ecosystems in the sequestration of atmospheric carbon dioxide as organic carbon in soils, as well as the release of carbon dioxide and other greenhouse gases from soil, as affected by agricultural management practices. Specifically, determine effects of carbon dioxide on belowground processes which affect crop productivity, soil physicochemical/biological properties, carbon/nutrient cycling, and trace gas efflux from soil.

Approach:
Two-year rotational cycles of sorghum and soybean will be maintained under two cropping systems: conventional, using tillage without cover crops; and conservation, using no-till with winter cover crops in rotation (wheat, crimson clover, and sunn hemp). Each cropping system will be grown under current and projected levels of atmospheric carbon dioxide. In addition, a Southeastern pasture system study, using bahiagrass exposed to these carbon dioxide levels, has been initiated. Carbon flux to plants (growth, physiology, and yield) and soil will be determined with supporting data on soil physicochemical properties. Emphasis will be given to measuring soil carbon storage, root development patterns, characterizing the rhizosphere, and trace gas efflux from soil. The relationships of nitrogen to carbon dynamics and to water quality will be examined. Root growth, decomposition, and microbial community structure will be quantified in respect to carbon flow. The effects of carbon dioxide on agronomic systems is a critical, yet neglected, area of research. Integrating data from these studies will help provide a mechanistic understanding of the potential of agronomic systems to mitigated global change via sequestration of atmospheric carbon dioxide in soil.