Implement Underground and Edge-of-Field Practices to Fight Back Against Nutrient Loss

The pressures farmers face on an everyday basis can be daunting, as any producer will tell you. But come planting season, this hits new heights. There’s a fine balance between using fertilizer applications to boost yields and increase production yet navigate the challenges of nutrient loss and nitrate runoff that come along with it.

“[In the United States,] we have a lot of agriculture production. Even when we use the best nutrient management, we lose some nitrates,” said Matt Helmers, Iowa State University Professor of Agricultural and Biosystems Engineering and Director of the Iowa Nutrient Research Center. “Farmers need to look at how they can improve what they’re doing on the landscape, like tiling, but then also implement edge-of-field practices to treat the water before it gets to the stream.”

According to the U.S. Environmental Protection Agency, an estimated 330 million acres of land across the nation are devoted to row crops, with the remaining 785 million acres invested in pasture, rangeland and grazed forestland. It’s here within the rows of corn, soybeans, wheat and other commodities where producers can find opportunities to improve their field conditions, minimize nutrient loss and manage water quality with edge-of-field practices.

From the Ground Up

Drainage tile is known to hold a host of benefits for many types of soil and climates. Whether farmers use it to drain out wet areas or improve a field’s yield patterns, a tiled field makes the soil more porous, creating healthier root structures in crops and lowering the water table. What’s more, drainage tile stabilizes a field’s absorption of fertilizer application, reducing variability. With less guess work involved, there’s less chance for fertilizer to run-off into nearby waterways.

“Water, just like it’s the driver of nitrate down our tile drains, it’s also the driver of nitrates in our atmosphere,” said Helmers. “When we improve our drainage, we reduce those atmospheric losses of nitrogen, and we keep much more nitrogen in the system. We also improve soil health and that is what allows us to apply less nitrogen for higher corn yields in a well-drained system.”

Helmers also suggested cover crops and no-till crops as practices to keep soil erosion at bay. Realistically, it may only be feasible for farmers to implement one or two nutrient reduction strategies at a time.

Stopping Runoff Before It Starts

Fertilizer loss, nitrate leaching, soil erosion and manure runoff are key factors in poor water quality, which has been a point of concern around the country. And there’s only so much each farmer can do with constraints of budget, time, field conditions and Mother Nature factored in.

With edge-of-field practices, farmers are encouraged to take the sides of the field that are typically unused for crop production and turn them into filters for runoff. Used alongside tile, they can positively impact water quality and help prevent nutrient loss by managing water flow.

The two main forms of edge-of-field practices are saturated buffer strips and bioreactors.

Buffer Strips vs. Bioreactors

As technical as a bioreactor sounds, it’s easily explained as a buried trench at the field’s edge. Within the trench, a water control structure is hooked up to an existing tile main and the entire trench is then filled with wood chips. The wood chips are a carbon source that treat the nitrates found in field run-off, essentially cleaning the water before it reaches streams and rivers. The typical bioreactor removes an average of 43% of nitrates from drainage water.

Depending on how fast they break down, woodchips in bioreactors don’t need to be replaced for nearly a decade.

“In bioreactors, woodchips degrade over time and require replacement about every 10 years after you lay the first batch,” said Jeppe Kjaersgaard, a research scientist for the Minnesota Department of Agriculture focused on agricultural conservation practices. “I also recommend adjusting the water control structure a few times a year to make sure the flow rate is working effectively.”

As edge-of-field practices have gained popularity, farmers in Iowa, Ohio and numerous other states have taken advantage of state and county programs that remove the barriers to installation to maximize the number of bioreactors.  These programs, which greatly reduce or eliminate the cost of installation and provide startup guidance have been key for farmers to adopt a new practice.

“Water quality is obviously something that impacts everyone, and bioreactors are specifically designed for subsurface agricultural drainage to be a leader in that effort,” said Kevin Kingery, an ADS territory manager. “We know bioreactors work. The next step is to ramp up installation.”

An even lower-maintenance option is a saturated buffer strip, which is a highly vegetated area between the field and the nearest waterway. Here, the vegetation does the work to absorb the excess nitrates and is further managed by using a water control structure.

Saturated buffer strips are typically chosen by farmers installing their first edge-of-field practice because they are easier to install and require a lower upfront cost than bioreactors. Ongoing maintenance for both practices is mostly hands off; farmers don’t need to worry about adding to their already hefty workload.

“Once these practices are installed, you can usually walk away and let them work their magic,” said Kjaersgaard. “For example, you can mow the saturated buffer, but it’s not necessary.”

Edge-of-Field Investments Earn Incentives

Edge-of-field practices are a worthwhile investment for farmers looking to maintain their land for future generations. And they don’t have to break the bank.

Ben Porepp, Conservation Program Coordinator for the Iowa Agriculture Water Alliance (IAWA), encourages farmers to research state and federal resources to help add conservation practices to their fields.

“These practices might sound expensive, but there are plenty of resources and incentives out there that can clear the red tape and speed up the process for you,” Porepp said. “Implementing these practices is an investment in your farm’s future, so offsetting that initial cost can help farmers take the first step in improving the water management on their farms.”

To learn more about edge-of-field practices and reimbursement options, contact your local NRCS service center. For questions about adding edge-of-field practices to fields with existing tile lines, reach out to your ADS sales representative.