Date of Award:

2016

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Jennifer Reeve

Abstract

Most of the western United States faces increasing water shortages in the coming years, which will prove a major challenge for maintaining sustainable farms. Incorporating an alternative crop that is well adapted to the projected climate could be a successful approach to increasing the sustainability of farms in the region. Quinoa, Chenopodium quinoa Willd., may be an ideal alternative crop to meet the demands of the Intermountain West. Before widespread adoption of this novel crop can occur, best management strategies need to be documented. This paper provides research on cropping systems, irrigation rates, and weed competition with quinoa. Additionally, the impacts of prior cropping history and compost addition on soil health parameters are presented. Quinoa responded to compost addition in an organic cropping system trial where low soil phosphorous was a limiting nutrient. Cover crops, 70% hairy vetch (Vicia villosa Roth.) and 30% winter wheat (Triticum aestivum L.), provided sufficient nitrogen inputs for the following quinoa crop. In response to a line source irrigation trial, varieties showed optimal irrigation rate from 23- 42 cm of water for biomass accumulation, although no seed was produced by any variety. In a greenhouse weed trial, quinoa was less impacted by the presence of any other species, lambsquarters (Chenopodium album L.), red root pigweed (Amaranthus retroflexus) and green foxtail (Setaria viridis), suggesting a high competitive advantage. Finally, organically managed soil increased soil health indicators, including microbial biomass and resistance to stress, regardless of compost addition. In addition, compost increased soil health indicators in conventionally managed soil. Seed set across all field trials was hindered by peak summer temperatures above 32°C, a known temperature sensitivity threshold during flowering for the varieties tested. Therefore, further work to select adapted varieties for the region must be accomplished before widespread adoption is feasible. An integrated approach involving a locallyadapted novel crop and soil health protection promises to increase future farm sustainability.

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