Irrigation Growth Requires Research and Monitoring to Protect Water
By Bruce Seelig, Water Quality Program Monitor
NDSU Extension Service

At a recent meeting at North Dakota State University on irrigated agriculture in North Dakota, a number of participants expressed the importance of understanding and minimizing environmental impacts from irrigation.

 

"Although most of the discussion at the meeting was directed toward agricultural production, it’s significant that producers and others involved in irrigation development are raising these issues so they can be addressed," says Bruce Seelig, a water quality specialist at North Dakota State University.

 

Irrigation has been associated with groundwater contamination in several states, Seelig notes. Evidence shows a connection between irrigation and high nitrates in some aquifers in Minnesota and Nebraska. Studies done in the Oakes aquifer in North Dakota also show that irrigation can contribute to elevated nitrates in groundwater. Recently the incidence of high nitrate in some monitoring wells in the Englevale aquifer in Ransom County has led to the suggestion that irrigation may be responsible.

 

Incidences of pesticide contamination in North Dakota are sporadic and have no relationship to the type of farming system. However, aquifer contamination with the insecticide aldicarb was shown to be directly related to irrigated potatoes in Wisconsin and New York.

 

Another concern is the observation of increased levels of sulfate and total salts in some monitoring wells. Elevated sulfate salts in groundwater can result in water that no longer meets drinking water quality standards. Salts can also build up in some irrigated soils, resulting in poor growing conditions for crops.

 

"Although it is extremely difficult to predict impacts of irrigation on groundwater at a specific site, we understand enough about contaminant translocation and fate to identify important factors that influence these processes," Seelig says. "We can use those factors to identify aquifer sensitivity. Once we know the potential for contamination to occur at a particular site, we can take steps to protect the groundwater by implementing appropriate management practices which may include modifications to existing irrigation systems."

 

Seelig says research is needed in North Dakota to demonstrate which irrigation management techniques are most effective at specific sites. "Accounting for aquifer sensitivity during the planning and implementation of irrigation research projects allows irrigators with similar site conditions to adapt tested practices to their management systems."

 

Specifically, research is needed to improve nitrogen use efficiency, particularly in areas of high contamination risk, Seelig says. "Research projects that improve our understanding of the denitrification process in various aquifers should be expanded. Improved knowledge of the interactions between soil properties and irrigation water quality remains an important area of scientific study."

 

Although groundwater usually is the focus of most environmental concern surrounding irrigation, soil conservation and surface water protection also need to be addressed. "Soils that are best for irrigation also are often most prone to erosion," Seelig says. "Control of sediment losses and the movement of associated nutrients and pesticides from irrigated fields is often difficult because of the crop rotations thought to be most profitable. We need to identify crop rotation alternatives that preserve both the soil and profitability."

 

Monitoring by the state’s Water Commission and Department of Health indicate that impacts to North Dakota water resources from agricultural activities have been minimal. However, incidents of contamination do occur, and many water resources are threatened by potential contamination.

 

There continues to be a need to further understand processes and factors important to contaminant movement and fate under North Dakota environmental conditions, Seelig says. "As our knowledge of these processes and factors improve, so will our efforts to develop and implement management practices that protect water resources."