March 25, 2026

2026 March Stewardship Advocate

Mapping structural conservation practices in Iowa

The Iowa Nutrient Reduction Strategy (INRS) was developed in 2013 by the Iowa Department of Agriculture and Land Stewardship (IDALS), Iowa State University (ISU) and the Iowa Department of Natural Resources (IDNR). The INRS is a science and technology-based framework to assess and reduce nutrients entering Iowa water bodies. It is designed to direct efforts to reduce nutrients in surface water from both point and nonpoint sources in a scientific, reasonable and cost-effective manner. A key element of the strategy is measuring progress over time and releasing progress reports to the public.

Using sensor technology, ISU assembled a baseline of practices from 2007-2010 of up to 40,000 acres of watershed level including: terraces, water and sediment control basins (WASCOB), grassed waterways, pond dams, contour strip cropping and contour buffer strips.

There are several conclusions to draw based on the mapping of these three practices:

1. Landowners and farmers have constructed many of these practices since the 1980s. This can be seen by comparing the density of practices in the Silver Creek HUC in northeast Iowa. For example, the miles of terraces (shown in orange on the maps) increased by 276% between the 1980s and 2016, while the miles of WASCOBs increased by 8400% in the same time period.

2. Researchers can now look at a watershed scale to not only determine where terraces and WASCOBs are currently located but can also identify areas on the landscapes that could benefit from constructing additional terraces and WASCOBs. Below is a map of the Wolf Creek watershed in southeast Iowa showing the location and length of terraces and WASCOBs. By using other digital technologies, it is possible to estimate the saturation of a practice and the potential to install additional terraces and WASCOBs. In this watershed, there are 353,000 feet of terraces and WASCOBs which is 91% of the possible locations suitable for these structures. This leaves only 33,500 feet of potential terraces that could still be built in the proper position in this watershed to achieve 100% coverage of terraces in the Wolf Creek watershed. This is a clear example of farmers and landowners recognizing the need to reduce soil and runoff and putting in terraces and WASCOBs to do so.

3. A third feature of the mapping project is identifying structural flaws in structures such as terraces and WASCOBs. The LiDAR image below shows a break in the third terrace that allowed upstream runoff to flow through the break potentially causing erosion and gulleys. The first and second terraces are functioning properly as indicated by pooling of water on the upstream side of the terraces. Images like this could inform landowners that a breach has occurred and allow them to repair it.

4. The installation of structural practices like ponds, terraces, WASCOBs and waterways has had a profound effect on reducing sediments in Iowa’s water bodies. Not only do they slow down runoff from heavy rain events, they also reduce soil erosion and trap sediments in the field instead of having sediment leaving the field and enter creeks, streams rivers and drainage ditches. One example is the sediment loading results from 1976 through 2024 in the Skunk River recording station near Augusta in southeast Iowa. The blue line on the graph below is the suspended sediment concentrations during the nearly 50 years of monitoring at Augusta. Despite the variability of year-to-year rainfall, there is a trend of lesser amounts of sediments in the Skunk River in the last 15-20 years compared to the levels in the 1970s through 2000. The lower levels of sediments in recent years are likely due to structure practices but also less tillage and use of cover crops by farmers in the watershed.

Sources: Iowa DNR and ISU GIS Department

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Rethinking Nitrogen for Short-Stature Corn

Farmer to Farmer: Joe Rowe

Joe Rowe started farming in 2008 in the New Haven area of Mitchell County, Iowa. His three sons help on the farm when they are home from school. Joe says, “I started out primarily with mostly corn on corn but over the years, I have transitioned to a corn/soybean/oat rotation.”

Legacy is important to Joe saying, “Farming is in my blood, growing up on a small farm, the lifestyle ingrained itself in me. When my father stopped farming in 1997 after I moved to ISU, it left a large void. The opportunity to farm in 2008 came as a surprise, and I jumped in with both feet. My goal is to retire with a fully paid off small farmland legacy that I can pass on to my own sons, so they will always have a connection point back. Someday, I’d like to transition to farming full time. Core to these goals is not only being a good caretaker of the land but improving it and leaving it healthier than when I started. It must be able to sustain future generations.”

Joe variable-rates his fertilizer when strip-tilling his fields and also uses management zones when planting his corn. Joe does not apply any nitrogen before planting other than MAP/DAP/AMS in the strips. He says, “With the planter, I apply a low salt – high ortho starter, a biological in-furrow, then also band to the side a blend of 32% UAN and ATS. I then come back and Y drop the balance of my nitrogen needs later during the primary growth phase of the corn.”

Joe is an avid fan of cover crops despite the challenges associated with their establishment and mixed crop results over the years. He says, “Overall the cover crops have benefitted my land and made my soil more resilient to weather extremes. Combining cover crops and strip till has led to a dramatic improvement in soil structure, carrying capacity, and enables me to get into the field a day sooner than I could when I was using conventional tillage. If there is an overwintering cover on corn, I will terminate at planting or a couple of days after. The strips give me physical separation, and the nitrogen-sulfur fertilizer blend provides the N needed for decomposition of that biomass. If it is a dry spring, I will terminate earlier based on past lessons. In a wet spring, the living cover significantly aids in soil condition at planting.”

Joe has lots of ideas as he looks ahead to his operation in 2026 and beyond. He plans to expand his rotation to add more oat acres to take advantage of a new mill under construction in Albert Lea. He also plans to add a summer manure application to his oat ground which will be a first for his operation. He then will seed a diverse cover crop to hold and digest the nutrients in preparation for the corn next year. Joe says, “That ground should be ripe to grow a phenomenal corn crop given the additional biological diversity it will have.” Joe also is experimenting with adding sugar to his corn fields, trials with carbon and biological products, and increasing his spray drone applications.

Joe is busy off the farm as a grain merchandiser for a bioethanol plant, where he’s been since 2004. Currently he is Chairman of AgVentures Alliance Cooperative, a farmer coop focused on farm technology and investment. He is also a new member of Iowa Corn’s Animal Agriculture and Environment farmer committee. His rationale for joining is clear saying, “I am participating to learn more about the organization and what it does. I am very interested in new technology and market development. These are the same reasons I ran to be a school board director – I want to help shape the future – so join and be part of it. Sitting on the outside won’t advance anything.”

When thinking about what Joe wants other farmers to know about the way he farms, Joe says, “I am a history buff, and we must understand it, but we really shouldn’t repeat all of it. Doing things the same way and expecting a different result will not result in a positive outcome. Learning, experimenting and analyzing seem to be key to improving situations and outcomes. The future of agriculture is bright if you’re willing to be a part of its growth and look towards the future and remember the lessons of the past. I don’t know if my own kids will farm directly, but there is a solid path for each to be a part of our agricultural economy through the life experiences they are sharing in now and the technologies we’re employing and developing.”