Author ORCID Identifier

https://orcid.org/0000-0003-0921-9677

Date Available

8-1-2025

Year of Publication

2024

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department/School/Program

Agricultural Economics

First Advisor

Dr. Tyler B. Mark

Abstract

Since the Agricultural Improvement Act of 2014 and 2018 legalized Industrial Hemp (Cannabis Sativa. L), interest in grain, fiber, and floral hemp production has seen growing pains. As an emerging crop, there is a research gap in the impact of weather and agronomic conditions on hemp production including THC (Delta 9 Tetrahydrocannabinol) and pollen drift as risks in hemp cultivation. The first essay aims to measure the impact of weather and agronomic factors on hemp grain, fiber, and floral yields in Kentucky using a yield-weather model with information on field locations. The results show that heat conditions during the growing season negatively influence grain yield, while grain and floral can tolerate stressful heat conditions. However, fiber is vulnerable to changes in temperature. The results show that growing degree days benefit a fiber yield, while increases in stress degree days harm it. Drought conditions also adversely affect the yield of fiber in July. The yield of grain and floral decreases as extreme drought conditions increase. As a previous crop, corn negatively affects grain yield, and consecutive hemp plantings are not recommended to hemp growers for floral. The second essay assesses the impact of weather and agronomic factors on Kentucky's hemp production THC levels. Test results of THC levels are essential as a legal threshold because they determine whether hemp products can be sold to commercial markets. If hemp growers fail to meet a legal threshold on THC levels, they must destroy hemp products and they will lose all investment in farming hemp. An applied yield-weather model based on a spatial regression analysis is employed to analyze this essay. The results suggest that stress-degree days during the harvest season and severe drought conditions in July contribute to an increase in THC levels. Moreover, corn and soybean are not recommended as a previous crop before hemp cultivation due to higher THC levels than other types of crops. The third essay proposes a theoretical framework for cross-pollination between non-CBD and CBD hemp fields, focusing on how the relative cross-pollination rate varies over a change in wind direction. The case study using a simulation is established to measure the relative amount of non-CBD pollen above CBD fields, which varies the mean and variance of wind direction during the pollination season. The results show that the amount of non-CBD pollen reduces when the difference in an angle between wind direction and hemp field locations gets larger. This dissertation consists of three essays on industrial hemp production in Kentucky, the United States.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.273

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Available for download on Friday, August 01, 2025

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