Crop loss assessment for California: modeling losses with different ozone standard scenarios

Crop yield losses were estimated for ambient O3 concentrations and for a series of potential O3 air quality standards for California, including the current statewide 1-h oxidant (O3) standard of 0.10 ppm (196 microg m(-3)), 12-h growing season averages, and other models. A model for statewide losses was developed using hourly O3 data for all sites in the State, county crop productivity data, and available O3 concentration-yield loss equations to determine potential yield losses for each crop in each county in California for 1984. Losses were based on comparison to an estimated background filtered air concentration of 0.025 or 0.027 ppm, for 12 or 7 h, respectively. Potential losses due to ambient air in 1984 were estimated at 19% to 25% for dry beans, cotton, grapes, lemons, onions, and oranges. Losses of 5% to 9% were estimated for alfalfa and sweet corn. Losses of 4% or less were estimated for barley, field corn, lettuce, grain sorghum, rice, corn silage, spinach, strawberries, sugar beets, fresh tomatoes, processing tomatoes, and wheat. Implementation of either a modified rollback to meet the current 1 h California O3 standard (0.10 ppm) or a three-month, 12-h growing season average of 0.045 ppm was necessary to produce large reductions in potential crop losses.     

A California air standard to protect vegetation from ozone

Evidence shows that the current national primary ambient air quality standard, if attained, would still permit substantial injury to vegetation. Thus, in March 1987, the California Air Resources Board (CARB) began consideration of the evidence for the effects of ozone (O3) on vegetation, and of several possible state ambient air quality standards designed to protect vegetation, especially crops, from O3 injury. In its review, the CARB addressed a number of issues relevant to such a standard. One issue considered by the CARB is the relationship of an ambient air quality standard to natural background levels of O3, which would greatly influence the practicality of attainment. Attainment of a standard close to natural background could entail excessive costs. Another issue considered is the occurrence of oxidants other than O3 that can damage vegetation. Throughout much of California, O3 accounts for over 90% of the oxidant air pollutants, and the CARB considered whether, in keeping with current practice, O3 should be used as a surrogate for total oxidant air pollutants. A major new piece of information presented to the CARB was an assessment of the economic effects of several potential standards. This assessment, produced by University of California scientists at Riverside and Davis, calculated the benefits of the potential standards in comparison to current O3 levels and estimated natural O3 background. This assessment was developed using field chamber response data, local crop data, and local O3 concentration data as inputs to the California Agricultural Resources Model, which accounts for both supply and demand effects. Because of California's varied climate, agricultural production occurs on a year-round basis, with overlapping growing seasons for many crops. Over long periods of time, O3 levels may vary markedly because of the influence of various factors, and a 1-h standard may not be an accurate indicator of growing season O3 exposure. A moving three-month averaging time has been proposed as a way to approximate the growing seasons of California's 200 crops. However, a sufficiently stringent 1-h standard would serve as a surrogate for a growing season standard. The CARB reviewed evidence supporting both long-term and short-term standards. Agriculture dominates the economies of some regions within California but is a minor components of other regional economies. Because the San Joaquin Valley is California's most important agricultural area, the CARB reviewed evidence for a regional standard for this area that would be more stringent than standards for other parts of the state.     

Economic assessment of crop damages due to air pollution: the role of quality effects

Biological research has established that air pollution can affect the yield and quality of agricultural crops. Economic assessments of crop exposure to air pollution have focused on the yield effect. This study illustrates the implications of considering crop quality effects in addition to crop yield changes for the case of O3 impacts on soybeans. An economic model of US soybean, soybean oil, and soybean meal markets is used to simulate the impacts of increased soybean yields due to reduced O3 concentrations with and without changes in soybean quality. The simulations with quality effects are richer in their distributional implications and show larger increases in economic surplus than the simulations with yield effects only.     

Economic Assessment of the Effects of Air Pollution on Agricultural Crops in the San Joaquin Valley

Physical and economic impacts of 1978 ambient levels of ozone and sulfur dioxide on 33 crops In the San Joaquin Valley are estimated. The field data regression approach Is used and evaluated for estimating yield losses. The effects of alternative air pollution measures and regression functional forms are evaluated. An economic model is employed that accounts for both farm and market responses to yield improvements from reduced air pollution. Economic damages were estimated to exceed $100 million in 1978 with the biggest losers being the producers of cotton and producers and consumers of grapes, a crop that has heretofore been Ignored in agricultural assessments of pollution damage.     

The health benefits of reduced tropospheric ozone in California

Californians are exposed daily to concentrations of ozone (O3) that are among the highest in the United States. Recently, the state adopted a new 8-hr ambient standard of 0.070 ppm, more stringent than the current federal standard. The new standard is based on controlled human studies and on dozens of epidemiologic studies reporting associations between O3 at current ambient levels and a wide range of adverse health outcomes. Clearly, the new O3 standards will require further reductions in the precursor pollutants and additional expenditures for pollution control. Therefore, it is important to quantify the incremental health benefits of moving from current conditions to the new California standard. In this paper, a standard methodology is applied to quantify the health benefits associated with O3 concentration reductions in California. O3 concentration reductions are estimated using ambient monitoring data and a proportional rollback approach in which changes are specific to each air basin, and control strategies may impact concentrations both below and above the standard. Health impacts are based on published epidemiologic studies, including O3-related mortality and morbidity, and economic values are assigned to these outcomes based on willingness-to-pay and cost-of-illness studies. Central estimates of this research indicate that attaining the California 8-hr standard, relative to current concentrations, would result in annual reductions of 630 cases of premature mortality, 4200 respiratory hospital admissions, 660 pediatric emergency room visits for asthma, 4.7 million days of school loss, and 3.1 million minor restricted activity days, with a median estimated economic value of dollar 4.5 billion. Sensitivity analyses indicate that these findings are robust with respect to exposure assessment methods but are influenced by assumptions about the slope of the concentration-response function in threshold models and the magnitude of the O3-mortality relationship. Although uncertainties exist for several components of the methodology, these results indicate that the benefits of reducing O3 to the California standard may be substantial and that further research on the shape of the O3-mortality concentration-response function and economic value of O3-related mortality would best reduce these uncertainties.     

The global impact of ozone on agricultural crop yields under current and future air quality legislation

In this paper we evaluate the global impact of surface ozone on four types of agricultural crop. The study is based on modelled global hourly ozone fields for the year 2000 and 2030, using the global 1°×1° 2-way nested atmospheric chemical transport model (TM5). Projections for the year 2030 are based on the relatively optimistic “current legislation (CLE) scenario”, i.e. assuming that currently approved air quality legislation will be fully implemented by the year 2030, without a further development of new abatement policies. For both runs, the relative yield loss due to ozone damage is evaluated based on two different indices (accumulated concentration above a 40 ppbV threshold and seasonal mean daytime ozone concentration respectively) on a global, regional and national scale. The cumulative metric appears to be far less robust than the seasonal mean, while the seasonal mean shows satisfactory agreement with measurements in Europe, the US, China and Southern India and South-East Asia.Present day global relative yield losses are estimated to range between 7% and 12% for wheat, between 6% and 16% for soybean, between 3% and 4% for rice, and between 3% and 5% for maize (range resulting from different metrics used). Taking into account possible biases in our assessment, introduced through the global application of “western” crop exposure–response functions, and through model performance in reproducing ozone-exposure metrics, our estimates may be considered as being conservative.Under the 2030 CLE scenario, the global situation is expected to deteriorate mainly for wheat (additional 2–6% loss globally) and rice (additional 1–2% loss globally). India, for which no mitigation measures have been assumed by 2030, accounts for 50% of these global increase in crop yield loss. On a regional-scale, significant reductions in crop losses by CLE-2030 are only predicted in Europe (soybean) and China (wheat).Translating these assumed yield losses into total global economic damage for the four crops considered, using world market prices for the year 2000, we estimate an economic loss in the range $14–$26 billion. About 40% of this damage is occurring in China and India. Considering the recent upward trends in food prices, the ozone-induced damage to crops is expected to offset a significant portion of the GDP growth rate, especially in countries with an economy based on agricultural production.     

Crop loss due to air pollution in The Netherlands

The extent of yield reduction and economic loss caused by air pollution has been estimated for The Netherlands. Based on available data on direct effects only, each species was designated as sensitive, moderately sensitive or tolerant. On a nationwide scale, only ozone (O3), sulphur dioxide (SO2), and hydrogen fluoride (HF) exceeded effect thresholds. Effects from pollutant combinations were assumed to be additive. Yield reductions were calculated, using 10 exposure-response relationships and concentration data from the Dutch air pollution monitoring network. Changes in air pollution levels result in changes in supply. By multiplying the supply with the current price, the so-called crop volume was calculated. Subsequently, changes in crop volume were converted into economic terms, taking into account demand elasticity. On the basis of these calculations, air pollution in The Netherlands reduces total crop volume by 5%:3.4% by O3, 1.2% by SO2, and 0.4% by HF. The slope of the nonlinear relationship between crop volume reduction and exposure level increases at higher concentrations. In general, air pollution causes relatively little loss to producers, since yield reductions are largely compensated by higher prices. If air pollution in The Netherlands would be reduced to background concentrations, consumers would experience a net gain of Dfl 640 million (US 320 million dollars). Although large amounts of data were attained through literature and our own experience for this study, many assumptions still had to be made to arrive at these conclusions. With the current available knowledge, validation of our results in the field is not yet possible.     

Effects of enhanced O3 and CO2 enrichment on plant characteristics in wheat and corn

The effects of CO(2) enrichment and O(3) induced stress on wheat (Triticum aestivum L.) and corn (Zea mays L.) were studied in field experiments using open-top chambers to simulate the atmospheric concentrations of these two gases that are predicted to occur during the coming century. The experiments were conducted at Beltsville, MD, during 1991 (wheat and corn) and 1992 (wheat). Crops were grown under charcoal filtered (CF) air or ambient air + 40 nl liter(-1) O(3) (7 h per day, 5 days per week) having ambient CO(2) concentration (350 microl liter(-1) CO(2)) or + 150 microl liter(-1) CO(2) (12 h per day.). Averaged over O(3) treatments, the CO(2)-enriched environment had a positive effect on wheat grain yield (26% in 1991 and 15% in 1992) and dry biomass (15% in 1991 and 9% in 1992). Averaged over CO(2) treatments, high O(3) exposure had a negative impact on wheat grain yield (-15% in 1991 and -11% in 1992) and dry biomass (-11% in 1991 and -9% in 1992). Averaged over CO(2) treatments, high O(3) exposure decreased corn grain yield by 9%. No significant interactive effects were observed for either crop. The results indicated that CO(2) enrichment had a beneficial effect in wheat (C(3) crop) but not in corn (C(4) crop). It is likely that the O(3)-induced stress will be diminished under increased atmospheric CO(2) concentrations; however, maximal benefits in crop production in wheat in response to CO(2) enrichment will not be materialized under concomitant increases in tropospheric O(3) concentration.     

Improved Ventilation of Open Top Greenhouses

Plant injury caused by air pollutants is a well recognized effect causing economic losses totalling millions of dollars. Farm crops, forest species, and ornamentals are all affected depending upon kind of plant and degree of exposure. Benedict¹ estimated the minimum annual agricultural losses in the U. S. to be $132 million in 1969-1971. Millecan² estimated California crop losses caused by air pollutants to be at least $25 million in 1972. Recent studies by Brewer³ in which conventional greenhouses were placed in the field over cotton gave results showing yields were reduced by 10-30% in the San Joaquin valley where significant levels of photochemical smog occur. However, these estimates of losses represent little more than educated guesses because the procedures available for obtaining the information are so imprecise.     

Modeling the impact of ozone x drought interactions on regional crop yields

The influence of soil moisture stress on crop sensitivity to O3 was evaluated for corn (Zea mays L.), cotton (Gossypium hirsutum L.), soybean (Glycine max L. Merr.), and wheat (Triticum aestivum L.) grown in the United States. This assessment was accomplished by using yield forecasting models to estimate the influence of soil moisture deficits on regional yield and a previously developed model to predict moisture stress x O3 interactions. Reduced crop sensitivity to O3 was predicted for those regions and years for which soil moisture stress reduced yield. The models predicted a drought-induced reduction in crop sensitivity to O3 of approximately 20% for the 1979 to 1983 period; i.e. a hypothetical O3-induced yield reduction of 5% for adequately watered crops would have been reduced to a 4% effect by the 1979 to 1983 distribution of soil moisture deficits. However, predicted drought effects varied between crops, regions, and years. Uncertainties in the model predictions are also discussed.     

An assessment of the impact of California's Phase 2 Reformulated Gasoline on ozone air quality

California's Phase 2 Reformulated Gasoline (CaRFG), introduced early in 1996, represents an important step toward attainment of ozone standards. Studies of vehicle emissions and ambient air quality data have reported substantial reductions of ozone precursors due to CaRFG. This study uses daily measurements of regional ozone and meteorology to estimate the effect of CaRFG on ozone concentrations in three areas of California. In each area, a regression model was used to partially account for the daily effects of meteorology on area-wide ozone maxima for May-October. The statistical models are based on combinations of air temperature aloft (approximately 5000 ft), surface air temperatures, and surface wind speeds. Estimated ozone benefits were attributed to CaRFG after accounting for meteorology, which improved the precision of the estimates by approximately 37-57% based on a resampling analysis. The ozone benefits were calculated as the difference in ozone times the proportion of the reductions of hydrocarbons and nitrogen oxides attributed to CaRFG by the best available emission inventories. Ozone benefits attributed to CaRFG (with approximately 90% confidence) are 8-13% in the Los Angeles area, -2-6% in the San Francisco Bay area overall with greater benefits in two major subregions, and 3-15% in the Sacramento area.     

Volatilisation of crop protection chemicals from crop and soil surfaces under controlled conditions--prediction of volatile losses from physico-chemical properties

Volatilisation of crop protection chemicals from soil and crop surfaces is one of a number of processes that may contribute to their dissipation in the environment. Therefore, information on the potential of a chemical to volatilise from these surfaces is required by international and national registration authorities. This paper reports the results of more than 190 experiments, which were carried out with 80 different crop protection chemicals under controlled conditions (laboratory and/or greenhouse) according to the BBA guideline. Percent loss values observed during 24 h after application are reported for 123 soil and 71 crop volatility studies. Generally, volatile losses from crop surfaces were found to be greater than from soil surfaces under comparable experimental conditions. It has been previously proposed that volatile losses from soil surfaces, from crops, and from aqueous systems can be estimated from physico-chemical parameters. The data are therefore analysed to determine whether a correlation exists between volatilisation and physico-chemical parameters, such as vapour pressure, Henry's law constant, water/air and soil/air distribution coefficients. It was found that these parameters can be used to make reasonable predictions of volatile losses from crop and soil surfaces, which can be expected for crop protection chemicals under controlled conditions. Vapour pressure was the best predictor of losses from soil and crops. The use of the soil/air distribution coefficient is an alternative for predicting/estimating the volatility potential of a chemical from soil. Based on direct measurements, no noticeable volatility can be expected from compounds with a vapour pressure below 10(-3) Pa from soil and 10(-4) Pa from crops, this is fully confirmed by indirect measurements. A tiered volatility testing scheme including appropriate trigger values is proposed.     

PLATIN (plant-atmosphere interaction) II: Co-occurrence of high ambient ozone concentrations and factors limiting plant absorbed dose

There is an ongoing debate as to which components of the ambient ozone (O3) exposure dynamics best explain adverse crop yield responses. A key issue is regarding the importance of peak versus mid-range hourly ambient O3 concentrations. While in this paper the importance of peak atmospheric O3 concentrations is not discounted, if they occur at a time when plants are conducive for uptake, the corresponding importance of more frequently occurring mid-range O3 concentrations is described. The probability of co-occurrence of high O3 concentrations and O3 uptake limiting factors is provided using coherent data sets of O3 concentration, air temperature, air humidity, mean horizontal wind velocity and global radiation measured at representative US and German air quality monitoring sites. Using the PLant-ATmosphere INteraction (PLATIN) model, the significance of the aforementioned meteorological parameters on ozone uptake is examined. In addition, the limitations of describing the O3 exposure for plants under ambient, chamberless conditions by SUM06, AOT40 or W126 exposure indices are discussed.     

The use of air quality forecasts to assess impacts of air pollution on crops: Methodology and case study

It has been reported that ambient ozone (O₃), either alone or in concurrence with acid rain precursors, accounts for up to 90% of US crop losses resulting from exposure to all major air pollutants. Crop damage due to O₃ exposure is of particular concern as ambient O₃ concentrations remain high in many major food-producing regions. Assessing O₃ damage to crops is challenging due to the difficulties in determining the reduction in crop yield that results from exposure to surface O₃, for which monitors are limited and mostly deployed in non-rural areas. This work explores the potential benefits of using operational air quality forecast (AQF) data to estimate rural O₃ exposure. Using the results from the first nationwide AQF as a case study, we demonstrate how the O₃ data provided by AQF can be combined with concurrent crop information to assess O₃ damages to soybeans in the United States. We estimate that exposure to ambient O₃ reduces the US soybean production by 10% in 2005.     

Amelioration of Indian urban air pollution phytotoxicity in Beta vulgaris L. by modifying NPK nutrients

Air pollution levels are increasing at an alarming rate in many developing countries, including India and causing a potential threat to crop production. Field experiments were conducted to examine the impact of urban air pollutants on biomass (yield) and some physiological and biochemical parameters of palak (Beta vulgaris L. var. All Green) that grew from germination to maturity at seven periurban sites of Allahabad city having different concentrations of air pollutants under different levels of nutrients. The 6h daily mean NO2, SO2 and O3 concentrations varied from 2.5 to 42.5, 10.6 to 65 and 3.5 to 30.8 microg m(-3), respectively at different locations. Levels of air pollution showed significant negative correlations with photosynthetic pigments, protein, ascorbic acid and starch contents and catalase activity of palak leaves. A significant negative correlation was found for total biomass with SO2 (r=-0.92), NO2 (r=-0.85) and O3 (r=-0.91) concentrations. The increased fertilizer application (N, P and K) over the recommended dose resulted in a positive response by reducing losses in photosynthetic pigments and total biomass. This study proved that ambient air pollution of Allahabad city is influencing negatively to the growth and yield of palak plants.     

Phytotoxic risk assessment of ambient air pollution on agricultural crops in Selangor State, Malaysia

The phytotoxic risk of ambient air pollution to local vegetation was assessed in Selangor State, Malaysia. The AOT40 value was calculated by means of the continuously monitored daily maximum concentration and the local diurnal pattern of O3. Together with minor risks associated with the levels of NO2 and SO2, the study found that the monthly AOT40 values in these peri-urban sites were consistently over 1.0 ppm.h, which is well in exceedance of the given European critical level. Linking the O3 level to actual agricultural crop production in Selangor State also indicated that the extent of yield losses could have ranged from 1.6 to 5.0% (by weight) in 2000. Despite a number of uncertainties, the study showed a simple but useful methodological framework for phytotoxic risk assessment with a limited data set, which could contribute to appropriate policy discussion and countermeasures in countries under similar conditions.     

An Assessment of the Economic Effects of Ozone on U.S. Agriculture

Past attempts to measure the economic consequences of ozone on agriculture have been based on limited plant science information. This paper reports on an economic assessment of ozone on U.S. agriculture using recent crop response data from the National Crop Loss Assessment Network (NCLAN). The results are derived from a U.S. agricultural sector model that includes major crop and livestock production as well as domestic consumption, livestock feeding and export uses. The economic effects of four hypothetical ambient ozone levels are investigated. The analysis Indicates that the benefits to society of moderate (25%) ozone reductions are approximately $1.7 billion. A 25% Increase in ozone pollution results in costs (negative benefits) of $2.1 billion. These estimates do not reflect compliance costs of achieving the ozone changes and hence are not net benefits.     

Economic damages of ozone air pollution to crops using combined air quality and GIS modelling

This study aims at presenting a combined air quality and GIS modelling methodological approach in order to estimate crop damages from photochemical air pollution, depict their spatial resolution and assess the order of magnitude regarding the corresponding economic damages. The analysis is conducted within the Greater Thessaloniki Area, Greece, a Mediterranean territory which is characterised by high levels of photochemical air pollution and considerable agricultural activity. Ozone concentration fields for 2002 and for specific emission reduction scenarios for the year 2010 were estimated with the Ozone Fine Structure model in the area under consideration. Total economic damage to crops turns out to be significant and estimated to be approximately 43 M€ for the reference year. Production of cotton presents the highest economic loss, which is over 16 M€, followed by table tomato (9 M€), rice (4.2 M€), wheat (4 M€) and oilseed rape (2.8 M€) cultivations. Losses are not spread uniformly among farmers and the major losses occur in areas with valuable ozone-sensitive crops. The results are very useful for highlighting the magnitude of the total economic impacts of photochemical air pollution to the area’s agricultural sector and can potentially be used for comparison with studies worldwide. Furthermore, spatial analysis of the economic damage could be of importance for governmental authorities and decision makers since it provides an indicative insight, especially if the economic instruments such as financial incentives or state subsidies to farmers are considered.     

An ozone budget for the UK: using measurements from the national ozone monitoring network; measured and modelled meteorological data,and a 'big-leaf' resistance analogy model of dry deposition

Data from the UK national air-quality monitoring network are used to calculate an annual mass budget for ozone (O3) production and loss in the UK boundary layer during 1996. Monthly losses by dry deposition are quantified from 1 km x 1 km scale maps of O(3) concentration and O(3) deposition velocities based on a big-leaf resistance analogy. The quantity of O(3) deposition varies from approximately 50 Gg-O(3) month(-1) in the winter to over 200 Gg-O(3) month(-1) in the summer when vegetation is actively absorbing O(3). The net O(3) production or loss in the UK boundary layer is found by selecting days when the UK is receiving "clean" Atlantic air from the SW to NW. In these conditions, the difference in O(3) concentration observed at Mace Head and a rural site on the east coast of the UK indicates the net O(3) production or loss within the UK boundary layer. A simple box model is then used to convert the concentration difference into a mass. The final budget shows that for most of the year the UK is a net sink for O(3) (-25 to -800 Gg-O(3) month(-1)) with production only exceeding losses in the photochemically active summer months (+45 Gg-O(3) month(-1)).     

Atmosphere and agriculture in the new millennium

Effects of changing climate (CO(2), O(3), aerosols, UV-B radiation, temperature and precipitation) on crops are predominantly based on univariate studies. Limited bivariate studies suggest rising CO(2) levels would be beneficial to crops but may be offset by adverse O(3) effects. Elevated UV-B and ambient crop yields are difficult to project due also to limited research. Climate warming concerns, using average daily temperatures may be less important than the effects of rising nocturnal temperatures on crop growth. Traditional approaches of examining air pollutant-induced visible foliar injury or the effects of single air pollutants on crop productivity need to be redirected to the analysis of integrated holistic systems. In that context, present and future agriculture in India and the USA are compared.