A noticeable spike in PURE indices appeared in 1998 for organic agriculture caused by a single application of copper sulfate with an application rate of 150 lb/acre, which is ten times larger than the average application rate and clearly a data abnormality. The PURE index is a measure of environmental impacts on the per acre basis.One could use the yield difference between conventional and organic agriculture to adjust values in Figure 1.3 and transfer them to a measure of impacts per unit of output. Organic agriculture is found to have 10%-20% lower yields than conventional agriculture . If we use the 15% yield loss as an average to adjust the results for all crops, organic agriculture reduced the PURE index for surface water , groundwater , air , soil , and pollinators . The impact of organic practices on pesticide use is crop specific. This aggregate result is derived based on current crop mix in California. Each crop is susceptible to a different spectrum of pests, which are managed by a distinct pesticide portfolio as part of a broader pest management program. Comparing PURE indices for individual crops shows the benefit from pesticide use in organic agriculture varies significantly. Based on value, production region, and the acreage share of organic production, four crops are selected to illustrate this point: lettuce, strawberries, wine grapes, and processing tomatoes. Lettuce, strawberries, cannabis indoor grow system and wine grapes are the three highest-valued organic crops in California, with organic sales values of $241, $231, and $114 million in 2016 respectively .
Production of strawberries and lettuce is concentrated in the Central Coast region. Processing tomatoes are an important crop in the Central Valley. Wine grape production occurs in a number of regions across the state. In 2015, the acreage shares of organic production are 8% , 9% , 4% , and 2% for the selected crops.For my analysis, the unit of observation is a field-year, defined as a field with one or more pesticide applications in a given calendar year. In total, more than 3 million field-year observations are included in the PUR database from 1995 to 2015. Table 1.1 provides field-year summary statistics for key variables by crop. Overall, 3% of them applied only pesticides approved in organic agriculture. For all crops, conventional farms are significantly larger in size and have higher PURE indices. The average farm size in PUR is smaller than the average number in the USDA Census . One potential explanation is that one farm could have fields in different counties and apply for multiple pesticide application permits within in each county, which classifies it as multiple “farms” in the PUR. For all crops, lettuce, strawberries, and processing tomatoes, growers who operate conventional farms have significantly more experience, measured by years they are observed in the PUR. For wine grapes, conventional growers have less experience than organic growers. Ideally, farming experience is measured directly or researchers use age as a proxy. However, the PUR database does not contain any demographic information, which limited my ability to measure experience.
The PUR experience is smaller than the farming experience reported in the Census, which has many reasons. First, the PUR database I use started in 1995. Any farming experience before 1995 is not recorded. The Census is conducted every 5 years. Farms that entered and exited within the 5 year gap are included in the PUR database but not the Census, which reduce the average experience. Conventional strawberries have significantly greater impact on surface water and less impact on groundwater, measured by the PURE indices, comparing to other conventional crops. Organic strawberries, on the other hand, had a higher PURE index for air and a lower PURE index for soil than other organic crops. Pesticides used in conventional production of wine grapes have less impact on pollinators than pesticides used in other conventional crops. To identify the effect of organic agriculture on pesticide uses and associated environmental impacts, I must address the issues of selection bias at both the grower and the field levels. Compared to growers who utilize conventional practices, growers who adopt organic ones may have different underlying characteristics, such as attitudes toward environmental issues, which can also affect their pesticide use decisions directly. If grower characteristics are time-invariant, an unbiased estimation could be achieved by including a grower fixed effect in the regression. There is also time-variant heterogeneity that is associated with individual growers, due to factors such as farm size and experience, that simultaneously influences the adoption of organic production and pesticide use decisions. The identification concern here is that growers with more farming experience or larger farms, including both conventional and organic acreage, are more likely to operate organic fields and use less pesticides .
Therefore it is not reasonable to compare environmental impacts of pesticide use for growers without considering these characteristics. For each grower, annual total acreage and experience serve as measures of time-variant heterogeneity. Acreage and experience may alter the environmental impact of growers’ pesticide programs. As shown in Table 1.1, there is a significant difference for these two variables between conventional and organic growers. Alternative agriculture – or agriculture that is alternative to mainstream, industrial forms of agriculture – existed prior to the 1950s as the dominant form of agriculture worldwide . In the United States, alternative agriculture casts a wide umbrella of terms, and can include organic farming, sustainable farming, agroecological farming, diversified farming, indigenous agriculture, bio-dynamic farming, urban farming, conservation or regenerative agriculture, and/or permaculture – to name a few. Regardless of its form, a key feature of alternative agriculture is that it is inherently knowledge intensive . Farming alternatively requires that farmers support a knowledge infrastructure that is multi-faceted and context-specific, often informed by scientists, researchers, policymakers, government, and/or extension agents. Farmers who practice alternative agriculture amass a wealth and depth of knowledge that integrates multiple ways of knowing and that reflects diverse knowledge systems for thinking about evidence; perhaps most importantly, farming alternatively is based in practice and necessitates deep knowledge of the local . Farmer knowledge is thus an essential component of practicing alternative agriculture. Despite the central role of farmer knowledge in alternative agriculture, this knowledge has long been overlooked in US agriculture – considered “informal” knowledge – and therefore infrequently recorded or incorporated within the scientific literature . Since the 1950s with the introduction of chemical-based, input-intensive industrial agriculture, farming in the US experienced an increase in knowledge standardization, whereby technical farming knowledge has become highly transferable, scalable, cannabis equipment and independent of its local social or environmental context . The simultaneous consolidation of land ownership and shift toward widespread deskilling among farmers and farmworkers in industrial agriculture have also minimized the knowledge infrastructure, while increasing the technological infrastructure, required to farm . As a consequence, farmer knowledge of alternative agriculture in the US has declined and has also become increasingly undervalued . If these trends continue, farmer knowledge of alternative agriculture in the US may considerably decrease, or in some cases, become permanently lost . Given that the role of farmer knowledge in alternative agriculture research in the US is currently overlooked, it is essential that we begin to 1) understand the key features of farmer knowledge; 2) understand the substance of farmer knowledge; and 3) systematically document farmer knowledge in specific local contexts. Understanding the substance of farmer knowledge serves as a first step to sustain this essential knowledge base in practice; it is equally critical to document the particularities of farmer knowledge in local contexts. Farmer knowledge may provide an essential knowledge base that can inform and extend scientific research in alternative agriculture, and also potentially inform and extend the knowledge base of contemporaneous and future generations of farmers, policymakers, and agricultural industry experts.
Moving forward, there is a need to elevate the importance and legitimacy of farmer knowledge across disciplines within agriculture such that farmer knowledge is considered a valued knowledge base within alternative agriculture research, policy, and beyond . While other studies attempt to integrate the artificial binary between “formal” and “informal,” or “expert” and “non-expert” knowledge and view the two forms of knowledge as complementary , in this paper we maintain that farmer knowledge represents a systematic way of knowing, and therefore warrants formal, standalone documentation and incorporation within the scientific literature .Farmer knowledge is a type of local knowledge . As such, farmer knowledge, especially in the context of alternative agriculture, becomes relevant when linked to a particular local context . Broadly defined, local knowledge involves dynamic processes and complex systems of experiences, practices, and skills developed and sustained by people in their environmental and socioeconomic realties , which means that local knowledge is place-based and dynamic. Though other types of local knowledge, such as “traditional,” “folk,” or “indigenous” knowledge, may take generations to develop, Maltz contends that certain types of local knowledge – like farmer knowledge – may develop even within one or two generations of place based experience. This suggests that research on local farmer knowledge of alternative agriculture may be possible even in places where a long tradition of agriculture is lacking. In this sense, soil and on-farm management of soil presents a unique entry point for studying farmer knowledge in alternative agriculture, particularly in the US – because regardless of the length of a farmer’s tenure, developing local knowledge of soil is foundational to farming alternatively. Local knowledge of soil enables knowledge holders to farm productively and understand the local ecological systems upon which their farm operation depends . It is widely known that healthy soils are the basis for agriculture . At the same time, soil is heterogeneous across landscapes . For example, even at the scale of a single field, differences in soil micro-environments, management histories, inherent soil characteristics, and time of year can dramatically influence how a particular field can be most effectively managed. Addressing this challenge in soil management and understanding the nuances of soil management are fundamental to practicing alternative agriculture – where place-based knowledge of soil is an important aspect of building and sustaining healthy soils on-farm – and more broadly, resilient agriculture . In the U.S., there exists a handful of studies documenting rural local knowledge and rancher local knowledge . To date, most formal studies on farmer knowledge tend to focus on farmer decision-making as it relates to the adoption of new practices . Even fewer studies currently exist at the intersection of farmer knowledge, alternative agriculture, and soil management. Though there is documentation of farmer knowledge of soil management in sustainable agriculture, most studies focus within the “development” context outside of US alternative agriculture . Similarly, research on indigenous knowledge of soil is frequently approached from an ethnopedological or traditional ecological knowledge perspective , and lacks focus on production agriculture. To consider this gap, we focus this exploratory study on a significant epicenter for alternative agriculture in the United States: present day Yolo County, California, also referred to as the unceded tribal lands of the Cachil Dehe Band of Wintun Indians of the Colusa Indian Community, the Kletsel Dehe Wintun Nation, and the Yocha Dehe Wintun Nation. This agricultural region in northern California is unique in that it is among the handful of places in the country that emerged as a catalyst and knowledge hub for farming alternatively – specifically, the organic movement – and where a large concentration of diversified fruit and vegetable farms continue to thrive today. Due to a unique set of historical and ecological circumstances, the region experienced an influx of organic farmers beginning in the 1970s . During this decade, Yolo County – in combination with coastal Santa Cruz – became a significant node in the organic movement. Its emergence as a significant node was in part due to Yolo County’s proximity to the San Francisco Bay Area and to the University of California, Davis , and also partially due to the existence of largely prime agricultural lands combined with a temperate climate ideal for growing year-round. Yolo County became one of a few places where regulations for organic production first evolved and experimentation with organic farming first emerged .