Anthony Seeman and Corey McKinney draw samples of water from a tributary of the Middle Cedar River to test for nutrients, dissolved oxygen and suspended solids.
Science of Water Monitoring ISA Lab Trusted Source of Data BY CHRIS HAY AND ANTHONY SEEMAN
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he Iowa Soybean Association (ISA) has been monitoring water quality for over a decade. The monitoring program has evolved over time and includes rivers, streams, individual tile outlets and edge of field practices located throughout Iowa. Water samples are analyzed in ISA’s certified water laboratory. The lab serves as a trusted source of water quality data for soybean farmers. Data is provided to participating farmers to help inform their management decisions. When aggregated with data from other farmers, it’s used to gain insight into impacts of management on water quality to make recommendations for improvement for all farmers. ISA and its partners also use this data to target areas for planning and implementing water quality projects
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and to evaluate the effectiveness of installed practices. Monitoring with Agriculture’s Clean Water Alliance, a consortium of ag retailers and support companies in the Des Moines and Raccoon river basins and ISA partner, showed that nitrate-nitrogen concentrations in the Boone and Raccoon Rivers in 2019 were some of the lowest since monitoring began. While low concentrations are good, they often occur with higher river flows, and the overall loss of nitrogen, measured as load (concentration multiplied by flow) is still high from the greater volume of water transporting nitrogen. In 2019, however, nitrate concentrations were low enough that nitrogen loads remained moderate despite higher than average river flows.
The interactions among soil, weather and management that influence nitrogen loss are complex. However, the 2019 results suggest that the cooler and wetter spring that delayed planting also delayed nitrogen mineralization into water-soluble nitrate that was available for loss early in the spring when nitrate concentrations are usually highest. The Miller Creek Water Quality Initiative (WQI) project is one of several WQI projects funded by the Iowa Department of Agriculture and Land Stewardship within the Middle Cedar River watershed in eastern Iowa. It provides an example of the impact of ongoing conservation practice implementation on water quality in a smaller watershed.
