Impacts of Crop Management and Climate Change on Hydrology Across the Wisconsin Central Sands

View the project final report

• 2014 annual report

Commodities

• Agronomic: corn, millet, potatoes
• Vegetables: peas (culinary), sweet corn

Practices

• Crop Production: cover crops, crop rotation, irrigation
• Education and Training: on-farm/ranch research
• Production Systems: agroecosystems
• Soil Management: soil physics
• Sustainable Communities: sustainability measures

Pumping for irrigation in regions with strong ground-surface water connectivity can impact aquatic resources, leading to groundwater governance dilemmas. Recent hydrologic stresses and the decimation of local trout populations have created a groundwater governance dilemma between agricultural and aquatic stakeholders in the Wisconsin Central Sands, an ecological region with strong ground-surface water connectivity that has experienced changes in regional climate over the past 60 years. Sustainable agroecosystems in the Wisconsin Central Sands will maximize potato and maize production, while providing farmers with feasible irrigation strategies to protect prized freshwater lakes, streams, and wetlands. To this end, agricultural and aquatic stakeholders have continually met with scientists from academic institutions and government agencies to test assumptions, gather information, and develop conceptual models of regional hydrology. These community forums have identified an increase in evapotranspiration (ET) resulting from groundwater pumping for irrigation as a hypothesized mechanism of regional surface water depletion in the Wisconsin Central Sands. However, collective uncertainty exists as to the rate and magnitude of ET from potato and maize agroecosystems under different management scenarios (e.g. cover crops, tillage, irrigation).             The goal of proposed research is to quantify the coupled water-energy balance through the groundwater-soil-plant-atmospheric continuum under different irrigation, tillage, and crop rotation schemes typical to the Central Sands using biophysical field methods. This project is conceptualized, designed, and performed with Isherwood Family Farms, a sixth-generation, 1500-acre farm with 250 acres of woodland and 7 km of stream edge located in Plover, WI, in the heart of the water-stressed region of the Wisconsin Central Sands. Field-generated estimates of groundwater recharge and ET will parameterize and validate a dynamic, agroecosystem model, Agro-IBIS, simulating hydrological responses to climate and land use changes of the past 60 years. All field and modeling results will be presented to the preexisting stakeholder network of farmers, aquatic conservationists, property owners, and policy makers in the Wisconsin Central Sands. Short-term outcomes will improve collective understanding of seasonal fluctuations of water quantity and its vulnerability to regional climate change for more informed groundwater policy. Intermediate-term outcomes will assist farmers in developing precision-irrigation strategies in order to pump and irrigate at time scales that will maximize crop productivity, minimize stress to groundwater-fed lakes and streams, and adapt to a changing climate.

The overarching goal of proposed research is to determine how agricultural land use impacts surface water quantity in the Wisconsin Central Sands in response to scientific uncertainties identified by regional stakeholders utilizing trans-disciplinary modeling and field approaches. This work will assess the impact of varied groundwater pumping, irrigation, and crop rotation schemes on groundwater discharge to surface waters in the Wisconsin Central Sands by determining coupled water-energy budgets of potato and maize agroecosystems. Field-generated estimates of ET, groundwater recharge, and biophysical fluxes will parameterize and validate a dynamic, agroecosystem model (AgroIBIS) simulating regional surface water responses to climate and land use changes of the past 60 years. Aquatic and agricultural stakeholders will use modeling results to guide regional water policy. The specific objectives are: 

(1) Utilize monitoring wells, vadose zone lysimetry, soil moisture/temperature sensors, porometry/gas exchange, biophysical, and ecological field measurements in potato and maize cropping systems to quantify coupled water and energy budgets associated with crop type, irrigation, tillage, and cover crops.

(2) Expand, parameterize, and validate an agroecosystem model (AgroIBIS) and link groundwater recharge to aboveground processes by capturing coupled land use, water, and energy exchange in a model that can be used at a continuum of scales from field to continent.

(3) Inform aquatic and agricultural stakeholders using modeling simulations, sensitivities, and estimates to build adaptive management plans and identify remaining areas of uncertainty/road blocks for regional water rights and land use policy.