Several Buchanan County farmers intend to find out exactly what comes out of their tile lines.
Members of the Lime Creek Watershed Improvement Association are engaged in a project that will measure the tile-line delivery of nitrogen and phosphorus from 10 differently managed, tile-drained fields in a 27,000-acre sub-watershed of the Cedar River.
This project is “especially timely” following the recent release of the Iowa Nutrient Reduction Strategy, a controversial state program that promotes voluntary adoption of practices to reduce delivery of nitrogen and phosphorus, said Chad Ingels, an Iowa State University Extension watershed specialist who is coordinating the research.
“We have several dozen water quality improvement projects but nothing quite like this,” said Bill Northey, secretary of the Iowa Department of Agriculture and Land Stewardship, which provided a $74,000 grant to the project.
“This project brings the scale down to a single field so we can see what works and what doesn’t,” said Coe College chemistry professor Marty St. Clair, who with his students will collect water samples for analysis from each of the 10 fields.
Northey said he thinks the research findings will increase Iowa farmers’ confidence in the ability of specific practices to reduce losses of nitrogen and phosphorus, which change from fertilizer to pollutant the instant they leave the farm field.
Iowa’s agriculture and natural resources departments, in conjunction with Iowa State University, last year inaugurated the state’s Nutrient Reduction Strategy, a science and technology-based plan to assess and reduce the nutrient load in Iowa waterways.
Both critics and supporters acknowledge the plan won’t work unless farmers embrace the plan’s voluntary conservation measures.
Ingels, who works with four voluntary watershed associations, said he believes farmers will get onboard if they have “real-world data” showing the nutrient reductions they can expect using various practices.
“Farmers want to improve water quality and save money by using fertilizer more efficiently,” he said.
St. Clair, who has been working with farmers in the Lime Creek watershed since 2006, said the project will be a good test of practical conservation. “Farmers are trying to make a living. If they can’t do that, nothing else is going to matter,” he said.
High levels of nitrogen and phosphorus in the state’s surface waters illustrate the struggles farmers have had in applying fertilizer at the right rate in the right place at the right time, said Richard Sloan, president of the Lime Creek Watershed Association.
“A field-by-field analysis, correlated with each field’s individual management practices, should give us a better idea of what practices work best,” said Sloan, who farms 720 acres in the Lime Creek watershed.
Sloan is one of 10 farmers who have volunteered a field for the project. Field management will vary by farm, ranging from continuous corn, corn-soybean rotation, other rotations, cover crops, and various nutrient applications.
The watershed association members have been working to improve Lime Creek since organizing in 2006. They have used performance measures such as the Iowa phosphorus index, soil conditioning index and cornstalk nitrate test to evaluate how their management affects nutrient use and loss. They have also monitored Lime Creek to see how management changes affect nutrient concentrations in the stream.
“With six years’ experience addressing nitrogen and phosphorus leaching into our surface waters, we felt we still wanted more accurate measurements of the results of our attempts to control these losses,” said Sloan.
“Iowa’s new Nutrient Reduction Strategy will rely on farmers believing that cover crops, reduced tillage and biofilters will work on their farms. We designed our project to help our producers have confidence in the science behind the strategy,” he said.
First steps will be the installation of tile-line monitoring sites at the edge of each of the fields and as part of a denitrifying bioreactor and associated monitoring station at a separate site.
Coe College students, who have been taking stream samples in the watershed since 2006, will take grab samples through the growing season while tile flow will be automatically collected. Other information, such as field-level management, precipitation and temperature, also will be recorded.
The Lime Creek Watershed Association is an active member of the Cedar River Coalition.The lower half of the 16-mile stream has been designated as “impaired” with siltation and nutrients among the factors eroding its ability to support aquatic life and primary contact recreation.