Date of Award:

8-2024

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Committee Chair(s)

Matt Yost

Committee

Matt Yost

Committee

J. Earl Creech

Committee

Bruce Bugbee

Committee

Burdette Barker

Committee

Grant Cardon

Abstract

The Western U.S. looks for water optimization and conservation as agriculture is the largest water diverter, and resources are pressured by urban growth, winter snowpack instability, and drought persistence. Agricultural producers have several potential options to optimize water use with different investments associated with them. Options with varying levels of risks and known management practices include alternative crops, soil wetting agents, and crop biologicals.

An alternative crop that grew incredibly fast in popularity was industrial hemp (Cannabis sativa) despite limited agronomic knowledge for best management practices. Field trials occurred (2020-2022) near Logan, UT to test a total of 17 common regionally available hemp cultivars. The cultivars producing the best yields and quality included Abacus Improved, Trump, and Royal South. However, high performance variability of cultivars indicated that more testing may be required as stability in cultivar stock occurs.

A two-year (2020-21) hemp trial examined combinations of three hemp cultivars, four sprinkler irrigation sprinkler technologies, and four irrigation rates. The three hemp cultivars responded similarly to irrigation management, although there was high plant variability. This research suggested that floral hemp could be irrigated less than other common region crops to maintain yield in the region and potentially control THC concentrations.

An online grower survey gathered responses from 85 licensed Utah hemp growers to understand practices implemented in the beginning years, representing 72% of Utah counties and covering outdoor and indoor growing conditions. Results indicated opportunities for improved fertilizer, irrigation, and pest best management practices for hemp to refine product quality, production costs, and revenues.

Similar studies were conducted to test soil wetting agents and bio-stimulants. Both product types were tested in silage corn (Zea mays), alfalfa (Medicago sativa), and small grain forage (Triticum aestivum, Hordeum vulgare, and Secale cereale × Triticum aestivum). Trials were conducted from 2019 to 2023 for wetting agents, and 2022 to 2023 for biologicals at Logan, Vernal, and Cedar City, Utah. Yield and forage quality parameters were rarely enhanced by product application. Based on these results, tested soil wetting agents nor biologicals should not be used as drought protectors in soils with limited soil restriction.

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