Principal Investigators:
Jeff
Mitchell, Department of Vegetable Crops and Weed Science, University of
California, Davis.
Willi Horwath,
Department of Soils and Biogeochemistry, University of California, Davis.
Project Collaborators:
Robert Flocchini, Crocker Nuclear Laboratory, University of California,
Davis.
Bob Hutmacher, Department of Agronomy and Range Science, University of California,
Davis. Shafter Cotton Field Station. 17053 Shafter Avenue, Shafter, CA 93263.
Bruce Roberts, Kings County Cooperative Extension, University of California.
680 N. Campus Drive, Suite A. Hanford, CA 93230.
Dan Munk, Fresno County Cooperative Extension, University of California, 1720
S. Maple Avenue, Fresno, CA 93702.
Ron Vargas, Madera County Cooperative Extension, University of California.
328 Madera Avenue, Madera, CA 93637.
Duration of the Project: 2 years
The implementation of conservation tillage (CT) practices in
California may be a means to develop soil carbon (C) sinks and sustain soil
resources. Despite a 300% increase in CT production in the Midwest during
the past decade, less than 0.3% of row crop acreage in California's San Joaquin
Valley (SJV) is currently farmed using CT practices. Adoption of CT in California
is perceived to be difficult because of furrow irrigation practices and the
notion that increasing soil C may be problematic in an arid, irrigated environment.
In addition, row-crop production in California has benefited from intensive
tillage practices to increase yield. An average of about 9 to 11 tillage-related
passes are routinely done during the fall-spring period to prepare the soil
for summer cropping. These passes represent not only considerable energy,
equipment and labor costs, but recent research indicates that tillage reduces
soil carbon as well. Conservation tillage systems may serve to increase soil
C levels, reduce production costs and improve soil and air quality in this
critically important agricultural production region. We will determine C loss
and stabilization and the effect of soil C management using reduced tillage
on N availability in a cotton-tomato rotation. This research will compare
conservation (ridge- and strip-) tillage and conventional tillage practices
in a crop rotation that is common to the SJV's West Side in terms of soil
carbon sequestration, farm productivity and profitability, and will widely
disseminate information related to the study's objectives and outcomes.