Precision irrigation and nitrogen management for enhancing water-nitrogen use efficiency (Year 3)

Vasudha Sharma

Two critical challenges face Minnesota’s agricultural watersheds: (1) nitrate leaching into groundwater supplies, and (2) competition over a limited groundwater resource. These issues are predominant in the Central Sands region of Minnesota where irrigation makes row-crop agriculture highly productive due to the soil’s naturally low water holding capacity and rapid drainage rate. At the same time, the majority of communities depend on groundwater as their sole drinking water supply. Precision water management has the potential to strike a balance between groundwater use for irrigation and the maintenance of groundwater quality for drinking water. However, production-scale research on advanced precision irrigation and nitrogen (N) management techniques, such as variable rate irrigation (VRI) and variable rate N (VRN), has been lacking in Minnesota.

In this project, we will conduct a field study to quantify and evaluate the impact of VRI and VRN management in comparison to both conventional uniform rate irrigation (URI) and uniform rate N (URN) management. Specifically, we will quantify the effect of VRI and VRN on nitrate leaching, corn plant growth and development, grain yield, evapotranspiration, and N and water use efficiencies. An economic analysis of VRI and VRN management will be conducted to assess the economic feasibility of the system for greater adoption. The project will also focus on extension and engagement through field days, student mentoring, and conversations with farmers to disseminate the research results, promote VRN and VRI technologies among growers, and develop actionable strategies for adoption.