Project Number: 5347-11000-008-02
Project Type: Specific Cooperative Agreement

Start Date: Mar 07, 2005
End Date: Dec 31, 2007

Objective:
One objective of this specific cooperative agreement is to determine the effects of long-term (16 years) exposure of sour orange trees to elevated CO2 on the colonization and hyphal lengths of arbuscular mycorrhizal fungi (AMF). Second and third objectives are to determine the effects on glomalin (a soil protein produced by AMF and strongly associated with soil aggregate stability) production and on soil aggregate water stability.

Approach:
Four sour orange trees have been grown since 1987 at 300 ppm CO2 above ambient in open-top chambers by USDA-ARS, U.S. Water Conservation Laboratory (USWCL) peronnel at Phoenix, Arizona, as well as four control trees at ambient CO2. In February 2005, the experiment is scheduled for termination with a final massive harvest of all above- and below-ground plant tissues. At that time, soil and root samples will be taken and transported to the University of Montana, Missoula MT (UofM). Root colonization by AMF will be determined, and measurements of soil hyphal length will be made. Glomalin will be extracted and quantified. Soil aggregate water stability will be determined by sieving. Documents SCA with U. of Montana. Formerly 5344-11000-007-05S (2/05).