Author: Mallika Arudi Nocco

Publisher:

Published: 2017

Total Pages: 0

ISBN-13:

The Central Sands conflict over irrigated agriculture and freshwater degradation is one of the greatest environmental problems facing Wisconsin. Resource management will continue to be challenging because of the diversity of stakeholders, scientific complexity, and political divisiveness over Wisconsin's waters. Moreover, it is likely that similar challenges will present themselves throughout other regions in Wisconsin, Minnesota, and Michigan, where irrigated agriculture continues to grow. Though irrigation-induced impacts to water quantity and climate are well-understood in arid and semi-arid regions, there is still a great opportunity to understand irrigation-induced impacts to water and energy cycles in humid climates. My interdisciplinary work addresses four questions related to the Central Sands conflict: (1) How can scientists and farmers improve communication with one another? (2) How much water do irrigated crops use? (3) Could precision irrigation be a viable water conservation strategy? And, (4) how is irrigated land use altering regional climate? I collaborated with Isherwood Farms (Plover, WI), the Wisconsin Potato and Vegetable Growers Association groundwater task force, 28 private landowners, and the Wisconsin Department of Natural Resources to conduct four studies corresponding to the above research questions. My first study draws on my observations of farmers and scientists to identify different types of knowledge exchange. My second study quantifies potential recharge and evapotranspiration (ET) from irrigated agroecosystems on Isherwood Farms using twenty-five passive capillary lysimeters. The third study combines high resolution apparent electrical conductivity (ECa) and ET maps to assess the variability in crop water supply and use. The fourth study uses a 60 km, W-E transect of 28 temperature and humidity stations to investigate irrigation-induced climate changes in the Central Sands. My dissertation improves our understanding of the impacts of irrigated agriculture on water resources and climate in the Central Sands. This body of work also identifies several opportunities for better water management such as crop rotational strategies, precision irrigation, and boundary work amongst stakeholders. Future work could improve ET and recharge estimates at different spatial scales, test precision irrigation interventions, quantify historical impacts, and investigate whether communication training for scientists could improve farmer-scientist relations in the Central Sands.