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Open Access Publications from the University of California


California Agriculture is a quarterly peer-reviewed journal reporting research, reviews and news on California’s agricultural, natural and human resources.

Volume 73, Issue 3, 2019

Special Issue: Cannabis

Issue cover
Cover Caption:A close-up of a cannabis flower on an outdoor farm. Photo by Danaan Andrew Pacleb, ShutterStock.

Research and Review Articles

First known survey of cannabis production practices in California

Legalization of cannabis production has daylighted a unique and highly valuable crop in California agriculture. State and regulatory agencies must now address the ecological, social and agricultural effects of cannabis production, but little is known about how growers produce this crop. Using an online survey, we gathered information from growers in July 2018 on their production practices. According to responses from about 100 growers, most cannabis was produced outdoors or in greenhouses, relied primarily on groundwater and used biologically based inputs for pest management. Many farms employed seasonal workers paid at fixed piece rates. Regulatory compliance varied according to farm size. Beginning to document growing practices will help scientists formulate key environmental, social and agronomic questions and develop relevant research and extension programs to promote best management practices and minimize negative environmental impacts of production.

Characteristics of farms applying for cannabis cultivation permits

Cannabis producers in California can now participate in a regulated supply chain — but little is known, despite considerable speculation, about which types of producers are likely to seek legal status. Growers' decisions about joining the legal market are central to questions about how formalization will transform cannabis production in California, and in particular whether small farms, which were encouraged under Proposition 64, can remain part of the industry. We combine data on the location and characteristics of cannabis farms in 2012 and 2016 with applications for cultivation permits from 2018 to investigate farm characteristics associated with cannabis formalization in Humboldt County. We find strong evidence that the farms most likely to start the permit process are larger, existed in 2012 prior to the start of the “green rush” and expanded at greater rates between 2012 and 2016. The evidence is consistent with concerns that formalization of the cannabis industry may lead to industry consolidation, as has been the trend in California's agricultural and timber industries more broadly.

Retail cannabis prices in California through legalization, regulation and taxation

Traditional sources of retail price information, such as scanner data and government price surveys, are not available for cannabis. To help fill this gap, between October 2016 and July 2018 the UC Agricultural Issues Center collected online retail price ranges for dried cannabis flower and cannabis-oil cartridges at retailers around California. During this 21-month time period, the legal landscape of the California cannabis market underwent three broad regulatory changes: adult-use decriminalization, licensing and regulation and mandatory testing. This article provides unique primary data on legal cannabis prices in California before and after each of these three changes. Our data are imperfect but do provide a glimpse of the patterns of California cannabis prices at different times. For dried cannabis flower, we observe relatively stable retail prices over the 21-month period at both the top and bottom ends of the price range. For cannabis-oil cartridges, we observe relatively stable prices at the bottom end but increasing prices at the top end between November 2017 and July 2018.

Watering the Emerald Triangle: Irrigation sources used by cannabis cultivators in Northern California

Water use by cannabis cultivators represents an emerging threat to surface flows in Northern California's sensitive watersheds. To date, however, no data has been available to formally assess where cannabis sites source their water. This study analyzed data from annual reports, covering the year 2017, submitted by 901 cannabis cultivators enrolled in the Cannabis Waste Discharge Regulatory Program administered by the North Coast Regional Water Quality Control Board. The analysis identified cannabis cultivators' most common sources for water extraction, monthly patterns for each water source and differences between sites compliant and not compliant with the cannabis program. The most commonly reported source of water was wells (58% of sites), with most extraction from wells occurring during the growing season (April through October). Surface water diversions (22% of sites) and spring diversions (16% of sites) were the most common sources after wells, with extractions from these sources distributed much more evenly across the year. Although nearly one-third of noncompliant sites (33%) used wells, this source was more than twice as frequently reported among compliant sites (68%), indicating that wells may become increasingly common as more sites become part of the regulated cannabis industry.

Costs of mandatory cannabis testing in California

Every batch of cannabis sold legally in California must be tested for more than 100 contaminants. These contaminants include 66 pesticides, for 21 of which the state's tolerance is zero. For many other substances, tolerance levels are much lower than those allowed for food products in California. This article reviews the state's testing regulations in context, including maximum allowable tolerance levels — and uses primary data collected from California's major cannabis testing laboratories and several cannabis testing equipment manufacturers, as well as a variety of expert opinions, to estimate the cost per pound of testing under the state's framework. We also estimate the cost of collecting samples, which depends on the distance between cannabis distributors and laboratories. We find that, if a batch fails mandatory tests, the value of cannabis that must be destroyed accounts for a large share of total testing costs — more than the cost of the tests that laboratories perform. Findings from this article will help readers understand the effects of California's testing regime on the price of legal cannabis in the state — and understand how testing may add value to products that have passed a series of tests that aim to validate their safety.

Perceptions of cannabis among Humboldt County timberland and ranchland owners

Cannabis is often grown on agricultural and forest lands in California, but little is known about the adjustments that traditional agriculture and timber producers are making to their livelihoods as cannabis becomes legal under state law. Our goal in this research was to better understand how larger landowners, whose families have often produced timber and cattle for generations, are experiencing increased cannabis production in their areas — and also to better understand these landowners' perceptions of the impacts of cannabis, whether positive or negative, on their communities. To accomplish this, we surveyed landowners who owned at least 500 acres in Humboldt County, an area that — more than 40 years ago — became one of the first California counties to begin experiencing expansive cannabis cultivation. Of the 211 landowners we invited to complete a survey, 71 responded, providing insights into their experiences with and perceptions of cannabis production. Many survey respondents reported illegal cultivation on their properties, problems with shared roads and other direct negative effects of cannabis production. Most landowners also reported that cannabis production has increased the cost of labor, though they acknowledge that it has increased the value of their property as well. Survey respondents, however, have not changed their views of cannabis with legalization. The findings of this study illustrate some of the challenges involved in developing land use ordinances and other policies that can support multiple industries whose interests may be in competition.

“We can't just be a county that supports inebriants”: Voices of the noncannabis agricultural community

Legalized recreational cannabis poses uncertainty and challenges for the noncannabis agricultural and ranching community in Northern California, including what it might mean in terms of the price of farmland and ranchland and the effects on the regional culture of diverse crop production. In-depth interviews in Humboldt, Mendocino and Sonoma counties with noncannabis farmers, ranchers and key individuals closely tied to the community revealed insight and an overarching concern about the future for noncannabis producers in those counties. The research was conducted in the summer and fall of 2017, when the state and counties were ramping up development and implementation of recreational cannabis cultivation policies. Interviewees expressed concern about land prices, potential crop shifts, and outside investment in the cannabis sector, and recognized the parallels and emerging alliances between wine and cannabis producers. They also identified opportunities for diversifying their production and for improving the environmental impacts of cannabis production.

Growers say cannabis legalization excludes small growers, supports illicit markets, undermines local economies

H. Bodwitch is Postdoctoral Fellow, Department of Natural Resource Sciences, McGill University, Quebec, Canada; J. Carah is Senior Freshwater Ecologist, The Nature Conservancy, San Francisco; K.M. Daane is UC Cooperative Extension Specialist, Department of Environmental Science, Policy, and Management, UC Berkeley; C. Getz is Associate Cooperative Extension Specialist, Department of Environmental Science, Policy, and Management, UC Berkeley; T.E. Grantham is Assistant Cooperative Extension Specialist and Adjunct Professor, Department of Environmental Science, Policy, and Management, UC Berkeley; G.M. Hickey is Associate Professor, Department of Natural Resource Sciences, McGill University, Quebec, Canada; H. Wilson is Assistant Cooperative Extension Specialist, Department of Entomology, UC Riverside.

Cannabis farmers or criminals? Enforcement-first approaches fuel disparity and hinder regulation

Since California's cannabis legalization, localities have played a central role in determining the regulatory terms of where, how and within what legal bounds cannabis cultivation occurs. Siskiyou County, a rural, conservative and majority white county in Northern California, chose not to recognize cannabis cultivation as agriculture. It drew up highly restrictive cannabis cultivation regulations, largely under the purview of law enforcement rather than civil agencies. Hmong-American cultivators, made highly visible through enforcement practices, policy forums and media discourses, have borne the brunt of this regulatory regime. Cannabis policy, especially in its ethnic-racial dimensions, has become symbolic of broader anxieties about cultural and agricultural change. We employed ethnographic methods to research the formation and enforcement of Siskiyou's restrictive cannabis cultivation regulations, and their differential effects across local populations. We found that the county's law enforcement–first regulatory approach blurred civil and criminal lines, made some cultivators more visible and vulnerable to enforcement, and promoted criminalizing approaches to cultivators, even among civil regulatory agencies. These developments hinder the ability of agencies (including the California Department of Food and Agriculture and the California Department of Fish and Wildlife) to ameliorate negative social and ecological effects of cannabis cultivation through civil regulation, support and services.

News and Opinion

Special Issue: Cannabis

In this special issue, California Agriculture presents research articles on cannabis production, the economics of California's cannabis industry, and the social and community impacts of cannabis.

California cannabis regulation: An overview

In 2016, Proposition 64 decriminalized the possession and use of cannabis by anyone in California aged 21 or over. But the 2015 Medical Marijuana Regulation and Safety Act had begun the process of regulating cannabis in the state.

A concise cannabis guide: History, laws and regulations

An overview of key cannabis laws and regulations in California.

Restrictions and opportunities for UC cannabis research

Cannabis is legal in California but illegal in the United States. The plant's ambiguous status cuts off many avenues of cannabis research — but leaves other approaches wide open.

The rapid evolution of UC cannabis research

At campuses across the UC system, cannabis researchers are grappling with questions that have accompanied legalization.

CalCannabis: Regulating a previously unregulated industry

An interview with Richard Parrott, Director of the California Department of Food and Agriculture's CalCannabis Cultivation Licensing Division.

Science and law enforcement teaming up to help “critters”

An interview with Scott Bauer, Senior Environmental Scientist, California Department of Fish and Wildlife

“Like every other industry” — An on-the-ground perspective on Proposition 64

An interview with Amanda Reiman, Vice President of Community Relations, Flow Kana