Groundwater

Who can make a difference?

• Agricultural producers
• Rural and urban homeowners
• Public area maintenance personnel

Farmers, home gardeners, nurseries, commercial landscapers, golf course crews, and sports field maintenance staff all add nitrogen fertilizer to the soil to encourage healthy plant growth. Regardless of the form of nitrogen added--chemical fertilizer, an organic mix, manure, or sewage sludge--soil organisms convert it to nitrate before plants take it up.

Nitrate leaches through soil very easily. If too much nitrogen fertilizer is applied, the extra nitrate ends up in groundwater.

A new issue: Some fertilizers contain additives or industrial waste products that might contaminate groundwater. Not much is known about the potential risk of these compounds. Until these chemicals are proven to pose little risk to groundwater, they must be considered a potential contaminant.

Causes of groundwater contamination

• More fertilizer applied than plants can use
• Over-watering after fertilizer is applied
• Timing of fertilizer application that does not match plants needs
• Additives in fertilizers

What can you do?

Individual action

• Check with the OSU Extension Service for fertilizer recommendations for lawns, gardens, and agriculture.
• Test your soil and adjust pH before adding fertilizer.
• Consider the potential of nitrate to leach to groundwater when deciding fertilizer quantity, timing, and application method.
• Reduce the size of your lawn and let it go dormant in the summer.
• Select the right landscape plants for your climate and soil type; they usually need less fertilizer to stay healthy.
• If at all possible, avoid fertilizer products that might contain potential contaminants.

Community action

• Promote the use of fertilizer application rates and timing based on plant needs by providing incentives and recognition for farmers and homeowners who set good examples.
• Support educational programs for people who use fertilizers.
• Set up a lawn and garden demonstration site illustrating success without over-fertilization.
• Ensure that those responsible for maintaining public places, such as school grounds, parks, and sports fields, consider leaching potential when making fertilizer decisions, and promote this fact in the press.

To learn more

OSU Extension Service

Download publications (fertilizer guides, gardening information, and more) from the Web. See especially:

• Gardening and Water Quality Protection: Understanding Nitrogen Fertilizers

• Gardening and Water Quality Protection: Using Nitrogen Fertilizers Wisely

• Request a catalog.

Water testing labs

Contact a water testing lab to have your private well tested for nitrate.

• Oregon Health Division (503-731-4010) for a list of Certified labs

Oregon Department of Environmental Quality

Contact your regional DEQ office to find out if there is a problem with high nitrate levels in your region's groundwater.