Groundwater pumped from a shallow, unconfined aquifer for irrigation supports the farms, vegetable processing plants, and supplemental businesses that the Wisconsin Central Sands (WCS) economy hinges on. Groundwater from this aquifer simultaneously replenishes the lakes, streams, and wetlands in the region, supporting aquatic habitats valued by residents and tourists. Declining surface water levels and a declining trout population in the late 2000s stress the importance of balancing the needs of agriculture and aquatic ecosystems in the WCS. Two relatively untapped resources are available to growers to reduce consumptive groundwater use: irrigation scheduling and precision irrigation.
The two primary goals of proposed research are: (1) to quantify the effectiveness of irrigation management strategies (precision irrigation and irrigation scheduling) for reducing consumptive groundwater use while maintaining acceptable crop productivity in the WCS and (2) to identify key barriers to irrigation scheduling and precision irrigation adoption by improving our understanding of how WCS growers make irrigation decisions. This project will be conducted on and in partnership with Isherwood Family Farms, a sixth-generation, 1500-acre farm with 250 acres of woodland and 7 km of stream edge located near Plover, WI: the center of the water-stressed WCS. Paired field experiments, field observations, and remotely sensed landscape imagery will be used to compare spatiotemporal differences in water budget partitioning, crop growth, and yield between scheduled and intuitively-managed irrigation regimes, among precision irrigation management zones, and across model complexities. Grower interviews will provide insight into how growers use experience, intuition, or objective measurements to make irrigation decisions. Project outcomes will be evaluated using academic and outreach indicators and surveys.
Growers need to know if investing time and resources in these irrigation technologies will lead to reduced agricultural groundwater consumption (reserving more water to support aquatic habitats) and improved crop water use efficiency, while still maintaining the yields necessary to support grower livelihoods and the WCS economy.
Understanding the value of irrigation scheduling and precision irrigation strategies requires clear knowledge on the how and why behind intuitive irrigation decisions. This knowledge is crucial for scientists, conservation professionals, and legislatures in order to direct research, resources and policy in a way that balances the water needs of WCS stakeholders.
Project objectives from proposal:
Short term learning outcomes are (1) increased knowledge of how use of the Wisconsin Irrigation Scheduling Program (WISP) compares to intuitively managed irrigation practices in terms of yield and groundwater recharge on a commercial farm. Target audiences will (2) learn how precision irrigation management zones relate to intrafield differences in crop growth, evapotranspiration, and groundwater recharge. Research will (3) improve understanding of how WISP operates on-farm and guides irrigation management compared to a more complex agroecosystem model (Agro-IBIS). Grower interviews will (4) increase knowledge of how growers make irrigation decisions, identify any barriers to WISP/precision irrigation adoption, and identify information that growers want to know about WISP/precision irrigation to iteratively inform field data collection.
On-farm irrigation scheduling and comparison of data collected among precision irrigation management zones will inform the action outcomes of this project. Data collected will provide growers on-farm evidence to decide if irrigation scheduling and/or precision irrigation technologies are a worthwhile investment in the coarse WCS soils. Grower interviews will direct additional data collection (researcher actions) by identifying knowledge gaps for grower decision-making. In the long-term, research results may lead to actions by growers, residents, and legislators regarding strategies to conserve groundwater that we cannot concretely predict.
WCS growers are the primary target audience, with applicability to growers in areas of humid, irrigated agroecosystems with shallow depth to groundwater (e.g. Minnesota and Michigan). WCS residents, tourists, government, and researchers will also benefit from this project, as it ultimately explores how to produce more food with less water.