Nitrogen & Irrigation Management Outreach to Protect Groundwater in Central Minnesota.

Since 2010, the Minnesota Department of Agriculture has partnered with the East Otter Tail County Soil and Water Conservation District on a project to accelerate the use of irrigation and nitrogen management tools in Central MN.  Often irrigation water scheduling is associated first with conserving water quantity and this is certainly an important benefit of the practice; however an equally important goal of this project is to minimize the amount of nitrogen lost below the crop root zone to shallow groundwater (< 30 feet). The predominant geologic formation here is a deep outwash sand plain providing a large reservoir for groundwater. The accessible groundwater supply and predominantly well-drained soils have supported the development of highly productive irrigated land.  Potatoes, corn, dry beans, soybeans, and wheat are the major crops grown under irrigation and the use of nitrogen fertilizer is critical in these rotations. Groundwater is also the predominant source of drinking water for the cities and rural homeowners that live in this region and monitoring has confirmed that nitrogen levels above the safe drinking water standard of 10 mg/L exist throughout the region. To promote conservative groundwater use, winter workshops, a local network of weather stations, and an irrigation scheduling program are employed.  In-season aerial imagery, guided corn basal stalk testing, and annual winter meetings are tools used to promote efficient nitrogen use.  The irrigation scheduling program now has over 100 fields participating each year and the program success has led to the start of similar programs across MN.  This widespread and sustained enrollment appears to be having a positive impact with some local groundwater sampling data indicating nitrogen levels are not trending upward. Groundwater quality protection is critically important to the citizens of MN and this project is a great example of local problem solving to accomplish that goal.