All types of grapes , are combined in Figure 2.3C. The PUR database reported more organic acreage consistently. Abraben et al. Showed that organic labeling generates a meaningful price premium only for low-quality wine, while the price of high-quality wine is actually reduced by consumers’ perception of the organic label. This marketing issue creates an incentive for growers to intentionally avoid certifying their organic production in higher-end wine grape production. Therefore, we observe more grape acreage following the organic farming practices than certifying as organic. For tree nuts , the PUR database reported less organic acreage than the USDA and CDFA sources with a narrowing gap in recent years . Tree nut acreage has gone through a tremendous growth phase in California during the past two decades, with almond acreage increasing from 595,000 in 2000 to 1,110,000 in 2015, the period when Figure 1D indicates that the PUR database is missing large portions of organic acreage . Normally pesticide applications are not required for the first two years in a nut orchard , which makes the PUR database less reliable for capturing new organic tree nut acreage. While organic fields without any pesticide applications in a given year are missing from the PUR database, blueberry packaging box this appears to be only a minor limitation because organic acreage from the PUR database is not consistently smaller than that from the other two sources for all crops. This minor limitation is compensated by the major advantages of the PUR database, i.e., its fine spatial scale and comprehensiveness in terms of all crops, years and counties being included.
Due to the availability of information on the specific pesticides used, we are able to determine pesticide use patterns in organic agriculture in California. As discussed earlier, the lists from the Organic Materials Review Institute and the Washington State Department of Agriculture yielded 1,027 pesticide products and 216 AIs registered for use in organic production in California. Combined with entries from the National List, we are able to construct a list of 496 prohibited and 271 allowed AI substances for organic agriculture. From 1995 to 2015, a total of 1,428 distinct DPR-registered products were identified as allowed for use in organic agriculture. This list includes 550 insecticides, 454 fungicides, 35 herbicides, and 563 other minor pesticide types, which collectively represent a total of 272 different manufacturers. The top 15 AI/AI groups, ranked by acres treated in 2015, and their historical use from 1995 to 2015 are listed in Table 2.2. This Table reports “Acreage treated”, which is different from actual field area, because a single plot of land is counted multiple times when pesticides within the same AI/AI group were applied multiple times on the same field. Sulfur has been recognized as a soft chemical and it is the most widely-applied single AI in organic fields. Sulfur is an important plant nutrient, fungicide, and acaricide in organic agriculture . In 1995, organic growers treated 272,676 acres of land with pesticides and about 50% of them were treated with sulfur products.However, in 2015, sulfur was no longer the most widely-applied AI based on acreage treated, and it only accounted for 21% of acreage treated for all crops .
Powdery mildews in grapes and pome fruits are often treated with sulfur in California . Together organic table, raisin, and wine grape growers treated 109,736 acres with sulfur products in 1995 and 226,317 acres in 2015, which accounted for 80% and 69% of total acres treated with sulfur, respectively. In addition, during the study period the application rate of sulfur in organic grape fields decreased from over 15 lb/acre in 1995 to less than 9 lb/acre in 2015. One potential explanation is that growers may have reduced their sulfur application rate to avoidout breaks of spider mites. Sulfur products are known to decimate predatory mites, as reported in field studies for hop yards and vineyards, which can lead to secondary spider mite outbreaks . In addition, sulfur applications control powdery mildew, a food source for predatory mites, and can therefore lead to increases in the spider mite population . The rising usage of azadirachtin, clarified neem oil, and neem oil supports this theory, as all three of these AIs are recommended in the IPM guidelines to control spider mite in organic grape fields . Two other AIs worth mentioning, spinosad and Reynoutria sachalinensis, show how the progress of technology has shaped the pesticide portfolio for organic growers. Spinosad was registered for use as a broad-spectrum insecticide by the US Environmental Protection Agency in 1997, and was first used in cotton to manage pyrethroid resistant caterpillars . It is also recommended for looper and leafminer treatments, and it was quickly adopted by organic growers, becoming the third most heavily used AI in organic fields in 2015.
Reynoutria sachalinensis was first registered by EPA as a fungicide for greenhouse and non-food crop treatments in 2000. This ingredient, under the product name Regalia®, was first registered with OMRI for use in organic production in 2009, after which it became widely used by organic growers to manage powdery mildew. Changes in the pesticide portfolio will have consequences in the environmental performance of organic agriculture, especially as the sector grows.The PURE index values for organic fields are plotted in Figure 2.4. The noticeable increase in soil and air index values occurring in 1998 is due to a single application of copper sulfate in a rice field with an application rate of 150 lb/acre 1 , which is ten times larger than the average application rate, so it is clearly a data anomaly. The PURE index for air increased steadily from 1995 to 2015, at an average annual growth rate of 4%. Several factors probably contributed, related to overall application rates and the changes in the organic AI portfolio over the years. The PURE index for air is calculated by multiplying the AI application rate by its VOC emission potential, which is a physicochemical property related to its tendency to evaporate or sublimate into the surrounding air. During the study period, the average application rate across all pesticides for organic growers decreased from 9.1 lb/acre in 1995 to 2.9 lb/acre in 2015 in contrast to the increase in the value of the PURE air index. However, the pesticide portfolio changed significantly as organic growers diversified their pesticide AI options and relied less on sulfur products over time. Because dusting sulfur products have zero VOC emission, the increasing applications of virtually any other AIs would have contributed to a steady increase, as observed in the PURE index value for air. However, the results in Figure 2.4 should be interpreted with caution. The PURE index values are calculated based on site-specific information, such as the pesticide application rate, soil characteristics, and distances to groundwater and surface water. Therefore, aggregated results may not apply to individual fields. For example, in fields with sandy soil, instead of remaining in the soil, pesticides are more likely to move to groundwater due to irrigation or rainfall, blueberry packaging containers which would reduce the PURE index value for the soil and increase the index value for groundwater. Growers can achieve a better understanding of their own usage/impact considerations by combining aggregate results with site-specific information.Management of organic cropland has shifted toward larger farm operations during the study period. The acreage share of each size class remained relatively stable until 2001 when NOP introduced a national standard for organic crop production and established the foundation of the organic price premium nation-wide by protecting the integrity of the “organic” distinction . However, in later years the share of organic acreage operated by farms in larger acreage classes rose. For example, in 2015, 56% of organic cropland was operated by growers with at least 500 acres of organic cropland, up from 15% in 1995. At the other end of the spectrum, growers with 10-50 acres accounted for 18% of organic cropland in 1995, which dropped to 8% in 2015.As mentioned previously, the observation that organic farms are getting larger could be driven by the change in crop mix instead of the consolidation process. To examine that, we plot the acreage share of each crop category in Figure 2.6.
The acreage share of vegetables increased tremendously, from 30% in 1995 to 50% in 2015, while theacreage of grapes and field crops fell. Given that vegetables, such as lettuce and spinach, are produced at a smaller acreage scale than field crops, such as rice, the consolidation process in organic agriculture is profound as shown in the PUR database.Median crop acreage per grower is another common measure of farm size . By definition, half of growers operate less cropland than the median acreage value, while the other half operate more. Therefore, the median is a more meaningful statistic than the average because it not as sensitive to changes at the extremes. Acreages are not comparable across crops as the revenue per acre varies greatly. However, for any given crop, the change of median acreage over time reveals cropland shifts. Table 2.3 shows the median crop acreage per grower for the top 10 organic crops in 2015.Although larger farms continued to add cropland during the study period overall, such consolidation is not a universal pattern for all crops. Table 2.3 shows that by 2015, three out of ten crops actually had a decrease in median acreage per grower compared to 1995. Spinach growers had the most growth in median acreage, from 4 to 38 acres. Leaf lettuce production also consolidated with the median farm size increasing by 40 acres. The last row of Table 2.3 reports the median of total organic acreage per farm. For crops with a lower organic price premium, growers lack the incentive to expand production. Therefore, it is not surprising to see that median acreage decreased for the processed and staple crops in Table 2.3, particularly wine grape, rice, and processing tomato. Carrot has gone through the most significant growth of total organic acreage over the past two decades . However, as small farms have continued to join in the production of organic carrot, the consolidation process seems to have lagged behind other crops.Microbials are the most widely used pesticide category in organic agriculture . The number of applications per field and the application rate are significantly correlated with organic acreage. Growers with more organic acreage applied microbials less frequently but used more products per acre in each application. Overall, the use of microbials did not vary across growers in different organic acreage size classes. The use of spinosad, azadirachtin, and pyrethrins is similar to that of microbials. Farms’ organic acreage has a significant impact on the number of applications and application rate but in different directions, so the combined effect is not significant. For sulfur and fixed copper, the application rate is not correlated with my variable of interest. However, an increase in the organic acreage leads to an increase in the number of applications for those two AI/AI groups. Therefore, more sulfur and fixed copper products are used on farms with more organic acreage. Sulfur serves as a protectant fungicide for powdery mildew. Fixed coppers are often used to treat plant diseases caused by the genus Xanthomonas such as bacterial leaf spot and leaf blight. Therefore, both of these AI/AI groups must be applied preventatively and regularly to be effective . The observation that growers with more organic acreage used sulfur and fixed copper more frequently is one of the theoretical predictions in Zilberman et al. where growers use pesticides as a tool to mitigate uncertainty in production. Changes in sulfur and fixed copper use have environmental consequences because sulfur and fixed copper products are less toxic to earthworms and are more toxic to aquatic organisms than spinosad and pyrethrins. Using the PURE index values as the dependent variable in equation 1, we can identify the impact on the environment.The result of an increase in acreage on PURE index values is shown in Table 2.5. For surface water, the average index value is 4.35 and growers with more organic acreage have a greater impact. The major AIs/AI groups listed in Table 2.4 have varying toxicities to aquatic organisms. The toxicity is commonly measured by the half maximal effective concentration , which is the dissolved concentration needed for a response halfway between the baseline and maximum lethality. A larger EC50 is associated with a less toxic chemical.