Project at a Glance

Title: Crop losses from air pollutants: a computer and field-based assessment program and crop and forest losses from air pollutants: an assessment program.

Principal Investigator / Author(s): Mutters, Randall & C. Ray Thompson

Contractor: UC Riverside

Contract Number: A033-174 & A933-190

Research Program Area: Economic Analysis, Ecosystem & Multimedia Effects

Topic Areas: Agriculture, Costs, Ecosystem Impacts


The ARB - supported Crop Loss Assessment Program is the only source of information available that quantifies potential losses in agricultural productivity associated with ozone, in terms of yield, and is suitable for input into economic models. Using existing sources of information and Geographical Information System technology (GIS), statewide yield loss estimates were made with aggregated county statistics, and at a subcounty resolution for the southern San Joaquin Valley.

Interpolations of statewide seven-hour mean ozone concentrations were done within air basins delimited by a 2000-foot altitudinal barrier. Statewide crop loss assessments were calculated using 2.72 and 2.50 pphm ozone as background seven-hour and 12-hour seasonal means, respectively. Statewide yield losses for 26 crops were estimated using aggregated countywide agricultural production statistics. Estimated yield losses were greatest in bean (17%), cotton (20%), grape (23%) and orange (16%). Greatest losses occurred in the southern San Joaquin Valley, and production areas in and around the South Coast Air Basin. Percent loss in most crops was comparable between 1989 and 1990.

A regression approach was employed to examine relationships between ambient concentrations of ozone and cotton yield in Kern County. Interpolated values were used in predictive yield loss equations to estimate yield gradients. In a survey of cotton growers in Kern County, information about the number of acres planted, location, cotton variety, planting date, and yield were requested. Data were geographically registered on a sectional basis using a GIS. Cotton yield losses in Kern County ranged from 14% near Buttonwillow to 22% near Arvin. Crop loss predictive models, using statistics averaged over an entire county cannot predict the amount of variability in yield loss within a county. Significant regressions of yield vs. ozone concentration, soil characteristics and cotton variety were observed in Kern County. However, r2 values were low.

A field survey was conducted at 11 sites to identify the extent and severity of ozone injury to cotton, almond, and grape in the Central Valley. The incidence of foliar ozone injury was greatest in the southern portion of the Central Valley for cotton, almond and grape. Principal component analysis demonstrated that among the leaf conditions monitored (dead, injured and green) the number of green leaves retained was the best indicator of the degree of injury. No significant relationships between yield from the observation plots and the presence of foliar lesions were detected.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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