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Field tour highlights MDA and SWCD research in nitrate reduction

By Carol Stender

Date Modified: 10/03/2013 4:33 PM

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WESTPORT, Minn. — Luke Stuewe is tall, but he couldn't reach the top of the metal frame with all its gadgets during last week's Nitrate Reduction Field Tour.

The structure is a weather station located at the Herman Rosholt Research Farm near Westport. It collects soil and air temperature, soil moisture and humidity data foruse by irrigators, said Stuewe, water advisor for the Minnesota Department of Agriculture.

Irrigators use the data and a scheduling tool to determine how much water the crops need and to avoid over-irrigation, whichcan move soil nitrates into groundwater.

The Westport stop was one of two sites that the more than 50 state lawmakers, farmers and commodity group representatives toured to learn more about nitrate studies and practices used to keep nitrates from leaching into groundwater and well water.

In Rice Township, the group learned about research efforts using Best Management Practices. Several MDA projects have received Clean Water Legacy funding. SWCDs also are involved in the research projects.

East Otter Tail Soil and Water Conservation District has used the weather station information for almost two decades. The SWCD put in its first weather station near Perham in the mid-1990s, said EOT SWCD district conservationist Darrin Newville. When farmers in the southern area of the county wanted information for their irrigation systems and crops, the SWCD installed three more weather stations at Wadena, Ottertail and Parkers Prairie. Four more sites will be added next year in Becker, Hubbard, Wadena and Todd counties, he said.

Use of the weather station information is a win-win for farmers, said Stuewe. They use less water, which reduces water costs and results in less soil nitrates moving into groundwater.

Rosholt Farm is also studying nitrogen movement in three large plots. The sites have water collection systems so researchers can check nitrate levels.

Three crop rotations are involved in the nitrogen fertilization study — corn on corn, corn following soybeans and soybeans following corn. Four different nitrogen forms have been applied at eight rates from zero to 28 pounds per acre. The plots are irrigated by a linear irrigation system.

Adaptive Nitrogen Management uses innovative tools for farmers. Precision equipment can be too expensive for many farmers, Stuewe said. The Adaptive Nitrogen Management program provides a lower cost in-field measurement of plant nitrogen uptake to demonstrate where excess amounts of N are available. The data demonstrates the value of management changes to improve the efficiency of N use.

The tool is centered around the basal stalk nitrate test. The test is available only for corn and evaluates the adequacy of the nitrogen program for the current growing season. It's a post-mortem test since stalk samples are taken after the grain is mature. While the information gathered on N uptake isn't valid for the current year, it provides insight into management options for upcoming years.

Soils at the two sites are sandy and nitrate leaching is a concern. Problems with high nitrate concentrations in private drinking water wells led to the development of the Central Sands Private Well Network.

There are two phases to the project. The short term goal is to determine the current N concentrations in private wells and the second goal, a long term one, is to determine N trends.