Measuring Nitrate Levels in Irrigation Water Key for Farm Productivity and Water Quality

Kansas State University researchers emphasize the importance of testing irrigation water to optimize fertilizer use and protect drinking water sources.

Published on Feb. 19, 2026

Got story updates? Submit your updates here. ›

Researchers from Kansas State University are highlighting the importance of measuring nitrate levels in irrigation water, not only for farm management decisions, but also for protecting the quality of drinking water. They say recognizing nitrate contributions from irrigation water can help improve nutrient efficiency in crop production while also reducing the risk of excess nitrogen reaching water used by consumers.

Why it matters

Nitrate is highly soluble and can easily leach into aquifers, which are a primary source of drinking water for many rural communities. Excess nitrate in drinking water can cause a dangerous condition called methemoglobinemia. By testing irrigation water for nitrate levels, farmers can better manage their fertilizer applications and limit the amount of nitrate reaching groundwater.

The details

According to the researchers, many producers have historically focused on soil testing without accounting for nitrate contributions from irrigation water, which can represent a significant amount of applied nitrogen over a growing season. They say that recognizing the nitrate in irrigation water allows producers to credit that amount toward their total crop needs, improving efficiency while advancing water quality goals.

  • The U.S. Environmental Protection Agency has established a maximum contaminant level of 10 milligrams per liter (mg/L) of nitrate-nitrogen in public drinking water systems.

The players

Micah Cameron-Harp

K-State assistant professor in the Department of Agricultural Economics.

Matt Kirk

Professor of geology at Kansas State University.

Got photos? Submit your photos here. ›

What they’re saying

“Many producers are not considering the amount of nitrate already being applied through their irrigation water. When you measure what's there, you may be able to reduce fertilizer applications, which saves money and helps limit excess nitrate from moving into groundwater.”

— Micah Cameron-Harp, K-State assistant professor (americanagnetwork.com)

“Every well and every water source is different. The only way to know how much nitrate is present in your irrigation water is to test it. Once you have that information, you can incorporate it into your nutrient management plan.”

— Matt Kirk, Professor of geology (americanagnetwork.com)

What’s next

Producers interested in determining nitrate levels in their irrigation water can submit samples to commercial laboratories across the state or through Kansas State University testing services. Results can then be used alongside soil test data to fine-tune fertilizer recommendations.

The takeaway

By testing irrigation water for nitrate levels, farmers can optimize their fertilizer use and reduce the risk of excess nitrogen reaching groundwater, which is a critical drinking water source for many rural communities. This proactive nutrient management approach benefits both farm profitability and community health.