The price premium is significant for almond and alfalfa . However, organic almonds suffer from an average 20% of yield loss, which hinders the transition . For alfalfa, the price depends on the organic status as well as quality, which is hard to control for organic growers due to weed and pest pressures . The z-test results in Table 1.3 and Table 1.4 show that the coefficients of Organicare similar to or larger, in absolute value, than those in the full sample estimation, which implies that the difference between two production systems are larger in the sub-sample than full sample.Differences in environmental impacts between organic and conventional production vary across crops. The full-sample regression is estimated for selected crops individually, except for lettuce where an additional time dummy is added to split the sample in half, to highlight important patterns of pesticide use in conventional and organic production. The specifications without grower or field fixed effects provide similar results and therefore results are not presented here for individual crops. The PURE index values are plotted for conventional and organic lettuce fields in Figure 1.4. The risk index from pesticides used in conventional lettuce fields decreased since growers have gradually transitioned from organophosphates to pyrethroid and neonicotinoid insecticides over the past twenty years and organophosphate insecticides are more toxic than their pyrethroid and neonicotinoid alternatives . Prior to 2005, diazinon was the most used insecticide in conventional lettuce production while the usage of lambda-cyhalothrin , was limited in lettuce.
However, by 2015, blueberry grow bag size lambda-cyhalothrin was the most used insecticide in conventional lettuce fields while fewer than 30 acres of lettuce were treated with diazinon. Consistent with these changes, in Table 1.5, the coefficients for Organic × 06_15 are significant and positive showing that the difference in the environmental impacts from pes-ticides use between conventional and organic lettuce production decreased in the second half of the study period. In Table 1.6, differences in environmental impacts between conventional and organic strawberries are largely driven by the environmental impacts of pre-plant soil fumigation, which is used by conventional but not organic strawberry growers. Soil fumigation is a common practice for managing pathogens, nematodes, and weeds in conventional strawberry fields. While soil fumigants are most commonly regulated because of their negative effects on human health via the impact on air quality and ozone layer, most soil fumigants are also highly toxic to earthworms . Accordingly, the PUREindex for soil is large. Consequently organic strawberry production achieves a 78% reduction in the environmental impact on soil. Conventional strawberry production also poses higher impacts on surface water because several AIs are highly toxic to fish and aquatic invertebrates , including abamectin for controlling spider mites , malathion for white flies , and pyraclostrobin for gray mold . As a result, the coefficient of Organic for surface water is larger than average. The difference in the PURE index for air is smaller because azadirachtin and clarified neem oil, two primary AIs contributing to VOC emissions in the nonattainment area of Ventura , a major strawberry producing county, together accounted for 18% of treated acreage for organic strawberries.
Comparing the results in Table 1.7 with other tables in this section, organic processing tomato production reduces the environmental impact on air by a larger percentage than all organic production on average. The key difference between processing tomatoes and other crops is that processing tomatoes are more threatened by diseases than by insects or nematodes . The two most common diseases are powdery mildew and bacterial speck, which are treated with sulfur and copper hydroxide respectively in organic production . In 2015, the acreage treated with these two AIs accounted for 42% of total acreage treated for organic processing tomatoes. In comparison, the share of sulfur-and copper hydroxide-treated acreage is below 10% for production of lettuce and strawberries and 25% for all organic crops. These two AIs have lower VOC emissions than other AIs used in organic production such as pyrethrins, azadirachtin, and clarified neem oil, which together accounted for nearly 30% of treated acreage for organic lettuce and strawberries, 18% for organic processing tomatoes, and 18% for all crops. However, the impact is increasing as indicated by the positive coefficient for the variable Organic × Year. Wine grape production occurs in many regions in California, and pest and disease pressures vary across production regions due to different climate and soil conditions. In the North Coast production region, which includes Napa and Sonoma counties among others, powdery mildew is a common disease because the fungus prefers a cooler temperatures, ideally around 21◦C, to grow . Measured by treated acreage, 9 out of the 10 most used AIs are fungicides targeting powdery mildew in this area. In the San Joaquin Valley, in contrast, powdery mildew is rarely seen because of high temperatures. Due in part to the large number of frost-free days per growing season, insects are the primary concern .
For wine grapes, the most used AIs beside sulfur are abamectin targeting spider mites, imidacloprid targeting vine mealybugs, and methoxyfenozide targeting lepidoptera . These insecticide AIs aremore toxic for humans, earthworms, and honeybees and have larger VOC emissions than the fungicides used for powdery mildew , so the estimated intercept in Table 1.8 is larger in the San Joaquin Valley than in Napa and Sonoma counties and the state as a whole for groundwater, soil air, and pollinators. Powdery mildews in grapes are often treated with sulfur . In 2015, table, wine, and raisin grapes accounted for 77% of acreage treated with sulfur among all crops. To control powdery mildew, organic growers also rely on bio-ingredients such as Bacillus pumilus and Bacillus subtilis, which have larger VOC emissions than sulfur and mineral oils. Thus, organic wine grapes growers in Napa and Sonoma counties only achieve a 38% reduction in the PURE index for air while the reduction in the San Joaquin Valley is 45%.Using a consistent index, this essay quantifies the environmental impacts of pesticide use in conventional and organic fields and how they have changed over time. Information from this analysis could benefit organic crop production worldwide because California is an important production region with a diverse set of crops and environmental conditions. Previous studies rarely focused on the use of specific AIs or the change in the structure of pesticide use when evaluating the environmental impact of organic agriculture. To the best of my knowledge, the PUR database has never been used to compare pesticide use for conventional and organic production. The U.S. organic agriculture sector has grown significantly over the past two decades, after the launch of the NOP in 2002. Organic farming has the potential to continue to ex-pand in the future. Pesticides are essential for both conventional and organic crop production. However, pesticide use is not static. The pesticide portfolio changed dramatically for both farming systems in the study period. Based on field-level pesticide application information, this essay shows that the environmental impact of pesticide use on air increased in organic fields due to the adoption of new chemicals and the reduction in the use of sulfur, which has zero VOC emissions. Pesticides used in organic agriculture had lower environmental impacts per acre on surface water, groundwater, soil, air, blueberry box and pollinators depending on the pesticide portfolios for conventional and organic growers. However, the difference between two systems is decreasing over time for all five dimensions. Notably, they had almost the same level of VOC emissions in 2015. In both production systems, increases in growers’ total acreage were associated with increases in the environmental impacts of pesticide use in all dimensions. Increases in grower experience were associated with increases in the environmental impacts of pesticide use to surface water and groundwater, and decreases in the impacts on soil, air, and pollinators. The magnitude of effects of these two variables is smaller than the effect of the organic status of the field. Pesticide use in organic agriculture has evolved to have greater environmental impacts over time. This is consistent with findings in Läpple and Van Rensburg , who showed that late adopters, those who adopted organic farming after the launch of government supporting program, are more likely to be profit-driven and less likely to be environmentally concerned than early adopters. New policy instruments could alter the current situation.
When reviewing pesticide and fertilizer AIs used in organic agriculture, the NOSB could focus on environmental criteria such as VOC emissions, which has not been considered previously. Such policy instruments could partially offset the negative environmental impacts of pesticide used in organic fields. Whether organic farming is the most cost-effective way to reduce the environmental impacts of agriculture remains unclear because the changes in PURE index values does not directly translate to a one-dimensional environmental or food safety benefit that is comparable across commodities or farming methods. An alternative approach to reducing environmental impacts is to regulate pesticide use directly, which could have a significant cost. For example, the ban of methyl bromide was estimated to result in an annual revenue loss of $234 million and a 10% revenue loss for the strawberry industry in California . However, as the result shows, the PURE air index for strawberry did not decrease in conventional production after the ban. In addition, the groundwater index value increased because alternatives to methyl bromide have a greater impact on groundwater. In previous studies, demographic variables, such as gender and education, were shown to be determinants of the adoption of organic farming . Here, these characteristics are addressed by using time-invariant grower fixed effects. More information regarding the determinants of pesticide use decisions might be revealed if those characteristics data were available. Future research could focus on impacts on human health rather then the environment and cal-culate the monetary value of reduced mortality and morbidity of converting to organic production. And, estimating the value of improved environmental quality associated with organic agriculture, identified in this essay, is another research direction. While pesticide use remains important for both farming systems, another caveat is that this essay does not investigate the environmental impacts of non-chemical pest management practices, such as biological, cultural, and mechanical/physical controls. However, if one were to pursue that direction by collecting data on non-chemical practices, the analysis would necessarily be done on a relatively small scale, unlike the comprehensive data used here.Organic agriculture has been proposed as an essential part of sustainable food systems . In 2016, over 5 million acres of land were certified organic in the United States, which generated over $7.5 billion worth of agricultural products. California is the leading state as a producer of organic crops in the United States, accounting for 12% of organic cropland and 51% of crop sales value in 2016 . According to Willer and Lernoud , the United States is the largest market for organic products and accounted for 43% of global organic retail sales in 2017. Organic land use data for California have been collected for a limited number of years by two government agencies, the United States Department of Agriculture and the California Department of Food and Agriculture . Farm-level acreage and location information are not publicly available from either source. Detailed crop acreage data would facilitate further investigation of key topics such as the spatial distribution of organic fields, which previously could be studied only at a very small geographic scale using other data sources . In this context, California’s unique Pesticide Use Report database serves as an alternative source of very detailed and long-term data, which allows the identification of individual organic fields based on their historical pesticide use records. The PUR database contains information on all commercial agricultural pesticide use in California since 1990, including information on the chemicals used, crops and acreages for millions of individual applications. Pesticide use patterns for organic fields and their environmental impacts have not been studied previously. Existing studies often evaluate the environmental performance of organic agriculture as a system, rather than focusing on specific farming practices . To the best of my knowledge, no study has quantitatively described pesticide use in organic agriculture or assessed its environmental impacts for ecosystems on a large scale across numerous crops and over a long time period .