Improving irrigation and fertilizer management strategies across the Wisconsin Central Sands under a changing climate

View the project final report

Commodities

Practices

• Crop Production: application rate management, irrigation, nutrient management, water management
• Education and Training: on-farm/ranch research
• Natural Resources/Environment: water quality
• Production Systems: agroecosystems

Project Title: Improving irrigation and fertilizer management strategies across the Wisconsin Central Sands under a changing climate

The Wisconsin Central Sands (WCS), a region characterized by its sandy soils, is a major vegetable producer in Wisconsin. Due to the sandy soil, regular irrigation is required - making the region prone to leaching and groundwater contamination. High levels of nitrate in groundwater across the WCS have been heavily documented, as well as the resulting human health impacts. However, it is unclear how nitrate (N) levels vary spatially and temporally across the region. As a result, there is additional uncertainty in determining how to credit the N applied through irrigation water, which is pumped from groundwater, in nitrogen management plans. Additionally, it is crucial that we understand how nitrogen use efficiency (NUE) and water use efficiency (WUE) vary under a changing climate in order to best mitigate nitrate leaching to groundwater and reduce our water use, while still maintaining crop production. Our research incorporates both field work and ecosystem modeling to begin answering these questions. Through our combined approach of field and modeling research, we hope to provide farmers, researchers, and policy makers with the tools to make management decisions that will aid in both improving groundwater quality and reducing water use, which will be of heightened importance as weather variability continues to increase.

The overarching objective of this project is to improve irrigation and fertilizer management in the WCS in order to address both water quality and quantity challenges, while still maintaining crop production and farmer livelihood. The actions we will complete are as follows: 1) Assess spatiotemporal variability of nitrate levels in groundwater 2) Determine the different physiological responses of potato varieties to nitrogen and water stress 3) Improve the agroecosystem model, Agro-IBIS to accurately model WUE and NUE of vegetable cropping systems in the WCS under a changing climate. The broader outcomes will be 1) reduced fertilizer use which will provide economic savings and aid in reducing nitrate leaching to groundwater 2) Improved management strategies for responding to a changing climate.

This project will generate a diverse range of both learning and action outcomes. Learning outcomes include: 1) Increased knowledge of nitrate levels in groundwater, and subsequently, irrigation water. 2) Increased knowledge of nitrate variability within season, and year to year. 3) Increased knowledge of spatial variability of nitrate levels in irrigation water across the WCS. 4) Increased knowledge regarding how different varieties of potatoes respond physiologically to nitrogen and water stress under a changing climate.

Action outcomes include 1) Farmers will credit the nitrate found in irrigation water in their nitrogen management plans, and as result, reduce the amount of fertilizer and they are applying. 2) Reducing fertilizer use will save farmers money while simultaneously decreasing nitrate leaching to groundwater. 3) Based on model results, farmers will adopt management strategies that improve WUE and NUE of their vegetable cropping systems.