Principal Investigator:
Michael J. Singer
Department of Land, Air and Water Resources
University of California
Davis, CA 95616
Duration of the Project: 2 years
This proposal addresses the first three priority areas of the Kearney Foundation
call. Published data and our preliminary data strongly suggest that the potential
to sequester inorganic carbon in semi-arid and arid regions using treated wastewater
is far larger than the potential to sequester organic carbon. We hypothesize
that with proper irrigation management, carbonate accumulation can become an
important mechanism for carbon sequestration in these regions. Our objectives
are to 1) examine the extent of carbonate precipitation in effluent irrigated
fields through reconnaissance surveys. 2) identify factors that control soil
carbonate dissolution/precipitation under effluent irrigation. 3) determine
die effluent irrigation management that maximizes inorganic carbon sequestering
in arid region soils, and 4) test the conceptual model presented here. To determine
die extent of carbonate precipitation we will do a reconnaissance soil survey
and sample collection to depths up to 6 meters in up to ten effluent-irrigated
and "sweet-water" irrigated fields within California. By sampling
along a climate transect from fields that have been irrigated for various time
periods, we can effectively extend the duration of the study period well beyond
the two years of funding. To address the remaining objectives, we will establish
a lysimeter study using 200L containers filled with sand and a carbonate-sand
mixture. The lysimeters will be irrigated with either treated effluent from
the UC Davis wastewater treatment plant or normal irrigation water at 80% and
120% of potential evapotranspiration. Solid, liquid and gas phases will be sampled
over the 18 month period that the lysimeters will be in operation in order to
determine the effectiveness of the treatments in sequestering carbon. The results
of this research will show that inorganic carbon is an effective means to sequester
carbon and will determine the most effective irrigation scheme based on a new
understanding of the basic soil processes.