Purdue University Graduate School
Dissertation_Sandler_3-1-19.pdf (1.51 MB)

An agronomic and social perspective of industrial hemp adoption by organic farmers in the Midwest

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posted on 2019-06-10, 17:21 authored by Leah N. SandlerLeah N. Sandler

Hemp (Cannabis sativa L.) is an annual crop used to produce a wide range of products including foods, beverages, nutritional supplements, fabrics, and textiles. Hemp has long been conflated with marijuana and has not been grown in the United States for decades. Due to recent legislation, the legal restrictions on growing hemp seem likely to be lifted. However, although interest is high, industrial hemp has not been grown in the U.S. for nearly 80 years and research on virtually all aspects of hemp production in the U.S. is in its infancy. We lack fundamental knowledge regarding cultivar performance, interactions with pests, particularly weeds, and nutrient requirements. Research is needed to address this knowledge gap and potential production issues as well as to determine the attitudes, perceptions and concerns of farmers regarding the potential adoption of this “new” crop. Importantly, research should be conducted before the crop becomes widely available so that farmers can make informed decisions and avoid costly mistakes. My dissertation consists of four chapters. In Chapter 1, I examine the literature for weed management in hemp production and identify research gaps. In Chapter 2, I investigate the complex legal framework that surrounds Cannabisand the resulting complications for hemp production. In Chapter 3, I present research conducted to determine the attitudes, perceptions, interests and concerns of organic farmers regarding the reintroduction and potential adoption of hemp was completed through survey research. Finally, in the fourth chapter, I present research conducted to characterize the growth and phenology of industrial hemp cultivars and identify cultivars suitable for growing conditions in the Midwest, and to determine the effect of delayed planting on the phenology and growth of seed and fiber hemp varieties in the Midwest.

Weed control and weed management in industrial hemp production is a surprisingly understudied field. Few peer-reviewed field studies on hemp exist on any subject and in particular, weed control and weed management is understudied. Specifically, only three studies designed to address a weed management issues exist in the literature dating back to 1900. Most commodity crops have extensive literature discussing weed management, and such an extensive gap in the hemp literature suggests that research needs to be conducted to determine the impacts of weeds on hemp production. Discrepancies among state laws and current federal drug legislation have created a convoluted, confusing, and impractical framework currently surrounds hemp production in the U.S. The building of pesticide regulation and product safety systems that are specific to the many end uses of Cannabis have yet to occur in the U.S. Interactions between producers, state and federal government, and third-party testing laboratories need to be facilitated to build regulation systems along with educational programs to train growers appropriate best management. Organic farmers are generally considered less risk adverse than the general farming population and often considered early adopters of technology. I surveyed organic farmers in seven Midwestern states and found that 98.5% of the respondents were generally open to new technologies, but that demographics variables explained little of the variation for respondents’ level of innovativeness as well as their openness to hemp.The respondents were generally open to hemp production (88.2% agreed with the statement that they were open to trying hemp production on their farm) and found that attributes of hemp production that conferred relative advantage and were compatible with existing systems were important. Delayed planting of hemp generally reduced the onset and duration of female flowering and the time to seed formation but the magnitude of these effects varied among cultivars. Seed, stalk, and total above ground dry weight yields varied across cultivar and planting date which may have been impacted by inconsistent stand densities stemming from heavy rainfall and wet soils. Results from this dissertation suggest that hemp is an understudied crop in the U.S., but that interest in its production among organic farmers exists. Field results support the importance of both planting date and cultivar for hemp phenology discussed in previous literature and so research needs to be conducted to explore best hemp production practices in the U.S.


Ceres Trust


Degree Type

  • Doctor of Philosophy


  • Botany and Plant Pathology

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Dr. Kevin Gibson

Additional Committee Member 2

Dr. Zhao Ma

Additional Committee Member 3

Dr. Bryan Young

Additional Committee Member 4

Dr. Janna Beckerman

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