Understanding how much nitrate is present in irrigation water is important not only for farm-management decisions but also for protecting the quality of drinking water, according to research from Kansas State University.
Micah Cameron-Harp, Kansas State University assistant professor in the department of agricultural economics, and Matt Kirk, professor of geology, said recognizing nitrate contributions from irrigation water helps improve nutrient efficiency in crop production while also reducing the risk of excess nitrogen reaching water used by consumers.
“Many producers are not considering the amount of nitrate already being applied through their irrigation water,” Cameron-Harp said. “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.”
Nitrate is highly soluble and moves easily with water through the soil profile. When more nitrogen is applied than crops can use, the excess can leach into aquifers — a primary source of drinking water for many rural communities.
The U.S. Environmental Protection Agency has established a maximum contaminant level of 10 milligrams per liter of nitrate-nitrogen in public drinking water systems to protect human health. At levels of 10 milligrams per liter, nitrate can cause a condition known as methemoglobinemia, which prevents blood from carrying enough oxygen, causing bluish skin, headache, fatigue and difficulty breathing.
Kirk said that groundwater monitoring across Kansas shows variability in nitrate levels, making local testing essential.
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