Like many farmers, John Swaine worked hard to control the runoff coming from the 1,800 acres of row crops he farms in Talbot County. He put in cover crops to absorb the excess nitrogen in the soil. He stopped tilling much of the Maryland farm’s soil to stem erosion, and he used integrated pest management to minimize his spraying of pesticides.
Still, after a rainstorm — a prolonged one or just one of the 20-minute gushers common during summers on the Eastern Shore — the water in his drainage ditch ran turbid. Swaine thought maybe he could do something more.
“I live right here,” he said, pointing to a farmhouse two miles from the Oxford-Bellevue Ferry in Royal Oak. “It bothered me. It still bothers me. But some of it is beyond what we’re capable of controlling.”
When Swaine learned of a practice called the two-stage ditch that might control more of the runoff, he signed up to be one of the first Maryland farmers to adopt the practice. Two-stage ditches are more common in the Midwest; Indiana alone has 52 projects in 21 counties, for a total of 23 miles of ditch. Data from Notre Dame University, where researchers have been monitoring the two-stage ditch projects, have shown the practice can reduce nitrate in the ditch’s water by 31 percent and phosphorus by 50 percent, compared with a conventional ditch.
A two-stage ditch works by essentially becoming the farm’s wastewater system. A regular ditch is trapezoidal in cross section. Water comes over the side and falls to the bottom, where it flows along to the stream. A two-stage ditch is more like a split-level staircase. The water flows down the sides gradually and collects in a bench on each side of the trench, before gradually filtering down to the bottom of the ditch. The bench is filled with vegetation that slows the flow of water and uses it. That means nutrients in the runoff enrich plant life on the bench instead of polluting the waterway. The ditches also trap sediment, blunt storm surges and collect nitrate.
When used in conjunction with cover crops, grass waterways, no-till and integrated pest management, a two-stage ditch returns the contours of the land to what it was, and brings back a floodplain of sorts. Together, the practices act as a natural sponge.
The Nature Conservancy paid for Swaine’s two-stage ditch, and he agreed to maintain it. The organization has been helping to implement the practice in the Midwest as well as helping to develop a targeting tool that showed where the practice would be most effective in Talbot County.
The two-stage ditches can also control runoff from roadways. Stormwater control falls to the counties, which are often looking for innovative and inexpensive ways to solve the problem.
“I don’t think there’s any silver bullet out there that’s going to meet the needs that we have,” said Amy Jacobs, the Conservancy’s watershed restoration director. “I would say the farmers here are doing a lot of great things. They are implementing new practices as they learn about new opportunities. But to meet the goals of the TMDL and local watershed implementation plans, or WIPS, will require some additional work, and that’s hard, because we have done the easier things.”
With 300 miles of ditches in the county, Jacobs said, Talbot was a good place to try to implement the two-stage ditch and other practices to collect or slow runoff. Working with Alan Girard of the Chesapeake Bay Foundation, the Conservancy helped find $3 million in loan programs that would allow the expansion of the two-stage ditch throughout the county. Talbot leaders opted not to do that, but they did acquire $500,000 from the Chesapeake Bay and Atlantic Coastal Bay Trust Fund and will use it to put best management practices in place for the 25 spots identified in the tool.
Talbot has two other two-stage ditch projects on county land as demonstration projects; Swaine’s is the only one thus far on a working farm, but it is not in the target area. Swaine’s ditch is also not a true two-stage, as the berm is only on the farm side and not on the road side. Though Swaine would like the ditch monitored, the Conservancy will not be monitoring. With limited funding, Jacobs said, they had to pick two sites, and chose the ones on county land.
The ditches are gaining popularity across the Midwest, particularly in light of Lake Erie’s continuing algae blooms stemming from excess phosphorus in the heavily agricultural Maumee watershed. But they haven’t taken off in the Chesapeake Bay, despite pressure in the form of the Total Maximum Daily Load to reduce pollution.
“When it runs through a crop field, it’s a tough sell,” said John Rhoderick, special projects and research coordinator with the resource conservation office at the Maryland Department of Agriculture.
Instead of two-stage ditches, he said, the department has been helping farmers implement other practices that focus more broadly on drainage control and replicating natural systems. Those include planting wooded areas to intercept water before it reaches a ditch, and creating flood areas that the ditch can seep into and slowly trickle its water into the ground instead of releasing it to a stream all at once.
Other organizations, such as Mid-Shore Riverkeeper, are working on bioreactors that use wood chips and other living matter to “digest” the pollutants from the runoff before depositing them into the ditch.
Rhoderick said these drainage projects are not new to the state’s agriculture department, but they’ve gotten renewed interest as recent studies by the U.S. Geological Survey have shown that the majority of the nitrogen from Eastern Shore fields sinks into the groundwater, rather than running off the surface. Much of that groundwater, and nitrogen, bypasses ditches and is carried directly to streams.
As a result, Rhoderick said, it makes sense that drainage systems seek to control nitrogen as much as possible before it ever reaches a ditch or other surface water.
Drainage issues are “not new to us, but for the average Joe out there, just like stormwater, it’s out of sight out of mind — they don’t necessarily get what these drainage systems are, that they short-circuit the natural functions,” Rhoderick said.
But Girard, of Chesapeake Bay Foundation, thinks the two-stage ditch will gain traction in specific areas where it has shown results.
“What farmers like about this project is that it’s targeted,” he said. “There is science to say, ‘here is the best place for a BMP.’”