Nitrate levels in some Nebraska wells keep climbing years after farmers adopted modern nutrient management, and a University of Nebraska-Lincoln research team believes the explanation sits far below the root zone. Two new grants totaling more than $1 million will fund work to measure that buried nitrogen and test a method to neutralize it before it reaches groundwater.
The National Science Foundation has awarded $496,722 over three years to support investigation of an understudied reservoir of organic nitrogen in the deep vadose zone, the soil layer separating the surface from the saturated aquifer below. The Nebraska Corn Board, drawing on corn checkoff dollars, added a separate five-year award of more than $570,000 to support evaluation of a proactive nitrate remediation approach.
Roughly 80 percent of Nebraskans rely on groundwater for drinking water, much of it pumped from aquifers beneath some of the world’s most productive farmland. Nitrogen fertilizer that leaves the root zone represents both a loss to the farmer and a threat to drinking water supplies.
Organic nitrogen nobody has counted
Nitrogen is an essential nutrient present in many forms and is applied as a fertilizer to crops like corn. While these plants take up the nutrients they need, any remaining nitrogen can convert into mobile nitrate. However, the process of particular interest to the Husker research team is if this mobile nitrate may react with soil carbon through microbes to become bound as organic nitrogen in the deeper soil layers. This reaction could potentially act as a slow-release reservoir that gradually breaks down and generates new nitrate years later in the deep vadose zone, moving toward the groundwater…