Working to Reduce Farm Nutrient Loss in Iowa

By: Malcolm Robertson, Program Coordinator and Lecturer, Iowa Nutrient Research Center, Iowa State University

From Getting Into Soil and Water 2018

The Iowa Nutrient Research Center (INRC) was established in the College of Agriculture and Life Sciences at Iowa State University by the Iowa Board of Regents in response to legislation passed by the Iowa Legislature in 2013. More information is available at

The center pursues a science-based approach to nutrient management research. Through its work, the performance of current and emerging nutrient management practices is evaluated, new nutrient management practices are developed and recommendations are initiated for implementation of nutrient management practices.

The primary role of the center is to fund science-based research that explores innovative approaches that identify gaps and needs in nitrogen (N) and phosphorus (P) research to address Iowa’s water quality issues.

Center research evaluates the performance of current and emerging field practices and develops tools to help farmers and landowners adopt effective management practices. Successful research outcomes will minimize the loss of nutrients into Iowa surface and groundwater. Through this research, the INRC will test the performance of current and advanced farmland management, land use and edge-of-field practices on reducing N and P loss.

The center will also develop tools that aid in decision-making and promotions for the adoption of new technologies and creative solutions for more sustainable management practices.

Working with researchers and farmers, the Iowa Nutrient Research Center funded more than 50 research projects from 2013 to 2017, led by more than 80 scientists at Iowa’s three Regents universities. The center’s competitive grants program has awarded nearly $6 million for research since 2013.

These funds are highly leveraged by water-quality scientists, who have successfully brought in over $17 million in grants from many federal and state agencies across five years. Some key results from center-funded research to date include:

  • Field and lab experiments are improving the understanding of winter cover crop management and impacts on corn yield.
  • Saturated buffers are evaluated to better assess their ability to remove nitrates from tile flow.
  • Research is evaluating the effectiveness of practices implemented around the edges of fields, such as planting strips of prairie and restoring stream banks.
  • Work is underway to better understand farm profitability impacts of precision conservation and grazing cover crops.
  • Intensive research at a watershed in Boone County is providing new insights on the contributions of stream bed and bank erosion to phosphorus transport.
  • Research is more precisely examining the movement of nutrients to surface waters.
  • How trading nutrient credits may benefit cities and farmers – and water quality – is explored in a pilot project watershed near Dubuque.
  • Work on research farms and in farmers’ fields is evaluating types of native perennials for prairie strips to reduce soil erosion and nutrient loss.
  • Research is seeking to improve performance and reduce costs of bioreactors, the practice that filters field drainage water with wood chips

In 2017 the center funded 12 projects with a total award value of almost $550,000. Below is a list of the projects awarded in 2017:

  • Total Phosphorus Loads in Iowa Rivers and Estimation of Steam Bank Phosphorus Contribution
  • Water Quality Evaluation of Prairie Strips across Iowa
  • Woodchip Bioreactors for Improved Water Quality
  • Limiting Nitrogen Immobilization in Cover Crop Systems • Amounts and Forms of Dissolved Phosphorus Lost with Surface Runoff as Affected by Phosphorus Management and Soil Conservation Practices
  • Delivery-Scale Evaluation and Modeling of Nutrient Reduction Practices • Improving the Effectiveness of Conservation Programs through Innovative Reverse Auctions and Sensible Enrollment Restrictions
  • Baseline Assessment of Geisler Farm Site: Collection of Pre BMP Monitoring Data
  • Does Quantity and Quality of Tile Drainage Water Impact In-stream Eutrophication Potential? Evidence from a Long Term Biofuel Cropping Systems Experiment
  • Successful Voluntary Watershed Improvement Projects: Do Short-Term Adoption and Outreach Lead to Attitude Changes and Long-Term Sustainable Practice Adoption?
  • Impacts of Cover Crops on Phosphorus and Nitrogen Loss with Surface Runoff
  • Evaluation of Measurement Methods as Surrogates for Tile Flow Nitrate-N Concentrations

In addition to these projects, the center also allocated $367,000 to the University of Iowa to fund a network of water-quality sensors deployed throughout eastern Iowa. These advanced remote sensors collect water-quality data that are relayed back to IIHR Hydroscience and Engineering every few minutes. The data are disseminated on a public website.

The Iowa Nutrient Research Center is dedicated to supporting impactful research in nutrient reduction. As new information, data and science become available, the center believes that the adoption of in-field and edge-of-field practices will increase, resulting in improved water quality through reduced nitrogen and phosphorus losses.

Background to the Iowa Nutrient Research Center’s Work

Scientifically Proven Effective Practices. Iowa leads the nation in corn and soybean production. Research has shown that a variety of management practices can mitigate the loss of nutrients from crop field soils. The goal is to get more of these scientifically proven practices implemented. The Iowa Nutrient Reduction Strategy science team, led by Iowa State University scientists, developed a list of in-field and edge-of-field practices that could reduce nutrient loss from farm lands ( Nutrient and soil management practices conducted within field boundaries to mitigate nutrient loss from row-cropped acres, and are known as in-field nutrient management.

Nutrient Loss Reduction – Nitrogen. There are a number of practices that reduce nitrogen loss, including in-field nitrogen management practices such as fertilizer application timing, fertilizer source, application rate, nitrification inhibitors, cover crops and living mulches. Additional in-field practices that reduce N loss include land use changes such as the addition of perennials, extended rotations and pastures for livestock. Edge-of-field practices may take a variety of forms and include practices and/or structures such as drainage water management, shallow drainage, wetlands, bioreactors and buffers.

Nutrient Loss Reduction – Phosphorus. There are a number of in-field phosphorus management practices that may be adopted to reduce P loss, include fertilizer application, source and placement; erosion control or land use change practices such as tillage, crop choice, perennials and terraces. Wetlands, buffers and sediment control are edge-of-field practices that have been shown to reduce phosphorus loss

2018 One Water Summit – Iowa’s Commitment

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Melissa Miller, Associate Director of the Iowa Water Center at the One Water Summit in Minneapolis, MN.

Miller presented Iowa’s commitment to water during closing remarks at the 2018 One Water Summit. Iowa had a conference delegation of over 50 people representing agencies, non-profits, and educational institutions who make an impact on water.

“Water connects us all. This core belief drives our work in Iowa, one we’ve seen in action over the last five years and one we focus on in the year to come. We celebrate the fifth year of the Iowa Nutrient Reduction Strategy, strengthened by the $97 million Iowa Watershed Approach to reduce flooding and improve water quality, as well as the Conservation Infrastructure action plan that brings together public and private sector partners to scale up those practices recommended by the science-based strategy. This next year, we commit to significant progress towards healthier watersheds as measured by conservation practices on the ground.”

-Melissa Miller, Associate Director of the Iowa Water Center


The Iowa Nutrient Reduction Strategy Farmer Survey: Tracking Changes in Knowledge, Attitudes, and Behaviors

Post written by Laurie Nowatzke and J. Arbuckle

The Iowa Nutrient Reduction Strategy (NRS) aims to reduce Iowa agriculture’s nitrogen loss and phosphorus loss by 42 and 29 percent, respectively. A major component of the NRS is to encourage the voluntary adoption of conservation practices on Iowa farms. Practices that can reduce nitrogen and phosphorus loss include cover crops, nitrogen management, and perennial vegetation, among others.

Decision and behavioral theory generally view awareness of a problematic situation and attitudes toward potential solutions as important predictors of behavior change. In tracking progress toward achieving NRS goals, we ask the questions: “What are farmers’ knowledge of and attitudes toward the NRS?” and, “How do these factors affect the use of conservation practices?”

Iowa State University Extension and Outreach, with support from the Iowa Department of Agriculture and Land Stewardship, is conducting a five-year survey of farmers to help track the progress of the Iowa Nutrient Reduction Strategy by examining trends in farmers’ knowledge, attitudes, and behaviors related to nutrient loss reduction. At the Iowa Water Conference on March 20, 2018, in Ames, we will present analysis and highlights from the first three years (2015-2017) of the survey.

Following an innovative “semi-longitudinal” structure, the project surveys two HUC6 watershed each year; one that was surveyed during the previous year, and one new one. Thus, each HUC6 watersheds is surveyed two years in a row to allow measurement of changes in farmers’ knowledge, attitudes, and conservation practice use. A sample of farmers in the Iowa HUC6 is surveyed every year. By the end of the five-year survey, the majority of the state will have been surveyed, and two years of data will be available for all major HUC6 watersheds in Iowa (Figure 1b).

Figure 1 The rotating survey areas for the Iowa Nutrient Reduction Strategy Farmer Survey, with a) HUC6 watersheds that, as of 2017, have been surveyed for a least two years, and b) the HUC6 watersheds that will have been surveyed at the end of the project in 2019. The Iowa HUC6 watershed is surveyed every year.

With three years of the annual sampled watershed (the Iowa HUC6) completed, and with two consecutive years surveyed in two other HUC6 watershed, our presentation at the Iowa Water Conference will present trends over time in each of those watershed areas (Figure 1a). The presentation will examine trends in the following survey variables:

  • Knowledge and awareness of the NRS
  • Information sources where farmers learned about the NRS
  • Attitudes toward the NRS and related activities
  • Concerns about agriculture’s impacts on water quality
  • Involvement in watershed groups
  • Use of conservation practices, including cover crops, springtime nitrogen application, and no-till
  • Use of cost-share funding and technical assistance for conservation practices


Laurie Nowatzke is the Measurement Coordinator for the Iowa Nutrient Reduction Strategy, in Iowa State University’s College of Agriculture & Life Sciences. She has a MA in International Relations & Environmental Policy from Boston University, and a BS from Wright State University. She is currently pursuing a PhD in Sociology at Iowa State University.

J. Gordon Arbuckle Jr. is associate professor and extension sociologist at Iowa State University. His research and extension efforts focus on improving the environmental and social performance of agricultural systems. His primary areas of interest are drivers of farmer and agricultural stakeholder decision making and action related to soil and water quality. He is director of the Iowa Farm and Rural Life Poll, an annual survey of Iowa farmers.

Measuring Progress of the Iowa Nutrient Reduction Strategy: The 2017 Annual Progress Report

Written by Laurie Nowatzke, Measurement Coordinator for the Iowa Nutrient Reduction Strategy, College of Agriculture & Life Sciences at Iowa State University

This week, the 2017 Annual Progress Report for the Iowa Nutrient Reduction Strategy was published. The report is the fourth annual progress evaluation of the NRS, and represents the continued improvement in communicating Iowa’s steps towards its goal of reducing annual nitrogen and phosphorus loss by 45%. For the first time, a summary infographic has been developed to pare down the in-depth report to its highlights.

Organizations across Iowa—public agencies, private entities, NGOs, and universities—form vital partnerships and have taken strides in the work toward meeting NRS goals.

  • Funding for NRS efforts totaled $420 million in 2017, an increase of $32 million from the previous year.
  • Annual outreach events reported by partner organizations effectively doubled in the last year, reaching 54,500 attendees in 2017.
  • Wastewater treatment plants and industrial facilities continue to make commitments to improve their nutrient removal processes. Of the 151 facilities required by the NRS, 105 have received new permits; of those, 51 have submitted feasibility studies on potential technology improvements.

These increased efforts represent early inputs into the Strategy, allowing work to ramp up and begin influencing tangible change in the state.

Increased funding and outreach, along with the continued dedication of other inputs by partner organizations, are having an impact on the Iowa landscape.

  • Cover crop acres have increased drastically, from just 15,000 estimated acres in 2011 to more than 600,000 acres in 2016.
  • During that 2011-2016 time period, 36 nitrogen removal wetlands were constructed, treating 42,000 acres.
  • Also since 2011, a net increase of 155,000 row crop acres have been retired under the Conservation Reserve Program, with total CRP land retirement nearing 1.7 million acres.

At this point, the extent of conservation practices in Iowa pales in comparison to what is likely needed to meet NRS goals. However, these steps forward represent very early change resulting from statewide NRS efforts.

The water quality impacts of these efforts will continue to be assessed. At least 88% of Iowa’s land drains to a location with a nitrate sensor, allowing researchers to evaluate Iowa’s annual nitrogen loss and detect potential changes in the nitrogen load reaching the Mississippi River. Ongoing research aims to provide similar estimates of annual phosphorus loads beginning in 2018. In addition, using models developed for the NRS Science Assessment, the Annual Progress Report provides an annual estimate of the nutrient reductions affected by the conservation practices installed across the state.

The Annual Progress Report, and other NRS documents, can be found at

Nowatzke_photo thumbnailLaurie Nowatzke is the Measurement Coordinator for the Iowa Nutrient Reduction Strategy, in Iowa State University’s College of Agriculture & Life Sciences. She has a MA in International Relations & Environmental Policy from Boston University, and a BS from Wright State University. She is currently pursuing a PhD in Sociology at Iowa State University.