Edge-of-field initiatives gaining traction as farmers embrace effective nitrate-reducing practices. 

Iowa farmers are embracing innovative conservation strategies, showing parti­cular interest in edge-of-field practices installed through the creative “batch and build” model, which is gaining momentum across the state.

Saturated buffers — strips of vegetation alongside waterways that intercept tile drainage — or bioreactors, which use wood chips to treat tile water, are central to batch and build efforts. 

Both practices are showing effectiveness in reducing nitrates from drainage tile lines that move water from farm fields.

Farmers are taking notice and signing up to install these conservation practices along the edges of their fields to help prevent nutrient runoff from reaching creeks and streams.

Tanner Puls, Iowa’s statewide edge-of-field coordinator with the Iowa Department of Agriculture and Land Stewardship (IDALS), said the development of the batch and build model has sparked increased conservation enthusiasm and implementation across the state. Puls oversees projects designed to reduce nitrates entering waterways through a combination of emerging practices.

“Day to day, it’s mostly batch and build work that I sink my teeth into,” said Puls. “The end goal is to install a larger number of edge-of-field practices and treat more nitrates. It’s another tool in the toolbox.

“If we can do something to get more of these practices in that are proving to be cost-effective as far as pounds of nitrate removed per dollar, I think that’s what we should be doing.”


What is batch and build?

The batch and build concept originated in Polk County, where Puls first worked as a watershed coordinator roughly seven years ago. Local watershed plans had long included edge-of-field practices, but installations were slow, he said.

“We realized we needed a more efficient way to reach our goals,” he explained.

Who coined the phrase “batch and build” remains a mystery, but the approach generally bundles clusters of potential sites for edge-of-field practices into a larger project that streamlines installation and planning.

Batch and build projects are designed to be as hassle-free as possible for farmers. Landowners’ involvement is minimal, generally limited to granting initial permission for site surveys and signing a maintenance agreement. 

Once potential sites are identified, IDALS and its partners handle engineering, design and bidding, often grouping multiple sites into a single contract.

“Contractors find it more at­­tractive to bid on a package of several sites than a single small practice,” Puls said, noting that this approach saves time and mobilization costs.

Puls spent 3.5 years in Polk County before joining IDALS as the new edge-of-field coordinator. He’s seen the department’s efforts grow with the hiring of two additional employees — one handling contracts and one engineer — giving IDALS the capacity to bid out projects internally.

The program has expanded dramatically since its inception, growing from a small pilot in Polk County to having batch and build projects span 28 counties across the state. Original projects in Polk and Story counties are into their second and third rounds of construction, demonstrating the program’s staying power and scalability.

Projects in the Middle Cedar Watershed are continuing this year, with additional projects planned for 2026.  

IDALS also has announced new efforts, such as its streamside buffer pilot project targeting priority watersheds upstream from the Des Moines and Cedar Rapids metropolitan areas to improve water quality.


Funding, effectiveness

Edge-of-field practice funding comes primarily through the state’s Water Quality Initiative, part of the broader Iowa Nutrient Reduction Strategy. IDALS covers 100% of installation costs, removing financial barriers for farmers.

Puls described the growing farmer interest as a key success of the program. 

“In some of our batches, we’re getting upwards of 90% positive responses from landowners willing to let us survey their sites,” he said.

Research supports the effectiveness of these practices. Saturated buffers can reduce nitrate runoff by 40% to 60%, with potential reductions of up to 90% if water is fully routed through the system. Bioreactors achieve similar results, depending on design and site conditions.

Saturated buffers can last for years, while bioreactors typically need wood chips replaced after roughly 15 years to continue functioning effectively. Each practice comes with a 10-year maintenance agreement.

For farmers considering participation, Puls advises reaching out to local Natural Resources Conservation Service (NRCS) offices to explore available resources. 

Many IDALS programs can be combined with NRCS cost-share options to cover 100% of installation costs, providing a practical, low-risk opportunity to improve water quality while maintaining farm productivity.

A native of Poweshiek County, Puls majored in environmental science and sustainability at Iowa State University and has been immersed in Iowa’s water and conservation challenges for nearly seven years. He views his work as a long-term investment in the state’s waterways.

“I’m a big fisherman, so I like spending time on lakes and rivers, and I want to keep that for future people to enjoy,” he said.