By Matt Reese
The 100-bushel soybean yields at Louie Rehm’s Wayne County farm have been getting quite a bit of attention this fall for their performance above the ground, but that is largely due to what was happening below the ground. The big yields were boosted by the installation of a controlled drainage system this spring that provided the moisture the crop needed through the dry conditions this summer.
“The rest of our beans are running in the high 40s or low 50s — nothing like this field,” Rehm said. “This spring we tiled the field and we decided we wanted to install the blocks to hold back the
water. It really helped this year. Even in the drought this summer, the beans never wilted once because of the water they had in the soil where we blocked the tile. It was incredible. They just kept growing and growing.
“They held the water all summer. We dug a hole down one day and we had moisture 14 inches down. We had very minimal rain like everyone else and in these bottoms that moisture really paid off this summer. We planted these beans May 10 and from then on, they just kept growing.”
The 30-acre field of muck soils mixed with some clay is tiled every 20 feet, with some of those lines tying into natural springs on the farm.
The situation in this flat, low-lying field is unique, and fit well with a controlled drainage system. The water control structures at the outlets of Rehm’s subsurface drainage system allow the drainage outlet to be artificially set at any level between the ground surface and the drain depth. Blocking the water can benefit crops during the growing season and also can be used to recharge the water table between growing seasons.
Brian Orr, with Orr Construction, Inc., worked on the installation of Rehm’s system.
“It is kind of rare in this area because of the rolling ground to be able to put those structures in. It needs to be pretty flat to put these structures in where they will do any good,” Orr said. “We plan out the drainage system before we start and we knew we were going to put these structures in ahead of time. It was not challenging to install them at all. In this field, we wouldn’t have tiled it any differently to put these structures in. In some fields that is not the case and we would want to change the tiling system a little bit. It depends where your water source is. In this field, there were so many springs above the bottom ground that it made it pretty easy to tile this. We have three structures for the three different mains that drain this field. They are right at the end of the outlet pipe at the edge of the field right at the ditch.”
The springs create a tremendous advantage in dry years.
“With all of these strong springs, he was able to keep the water table up,” Orr said. “I don’t know that we were the driest part of that state around here, but I know we weren’t the wettest either.”
The addition of the control structures in this field made clear economic sense.
“A rough number for the cost of the structures is about $1,000 per structure,” Orr said. “With the dry year we had, he easily paid for those structures this year.”
And, with increasing scrutiny on nutrient management in fields, the control structures offer some additional benefits.
“As soon as Louie gets harvest done, he will put those stops back in and keep those nutrients in the ground through the winter,” Orr said. “Then in the spring, depending on the weather, he’ll drain the water back own to the bottom of the tile when he is getting ready to work ground in the spring.”
While there are some clear nutrient management benefits with controlled drainage, the specifics of many of those benefits is not yet fully understood or quantified by science. Extension and USDA Agricultural Research Service research has found that controlled drainage may provide some reduction in nitrate losses and other water quality benefits.
“It’s known that less tile water is leaving a field due to the fact tile are blocked or restricted for a good part of the year. Benefits related to reduced flow are reduced stream ‘flashiness,’ or the rapid rise and fall of stream levels, and reduced downstream flooding,” said Mark Wilson, with Land Stewards, LLC in Marion. “Moreover, any time you reduce flow, in theory, you also reduce overall nutrient loading because of the concentration factor. It’s known that nitrogen, specifically nitrate, in tile water leaving a field with drainage control structures is less due to reduced flow, and because of denitrification which occurs within the soil profile. Widespread water quality testing in Ohio and throughout the Midwest has confirmed the nitrogen reductions.”
The dissolved phosphorus that is getting much of the blame for water quality problems in Lake Erie and other bodies of water, though, is less understood at this point with regard to many aspects of management, including controlled drainage.
“Unfortunately, dissolved reactive phosphorus leaving the field in tile water is not as well understood. The general theory on dissolved reactive phosphorus follows the results associated with nitrogen — less flow, less dissolved reactive phosphorus,” Wilson said. “But there’s limited research in Ohio, or the Midwest for that matter, on the issue of dissolved reactive phosphorus in tile flow. USDA-ARS has some research underway in Ohio’s Big Walnut watershed, north of Westerville and Dr. Kevin King is currently expanding his research to several other locations in Ohio. Unfortunately, it will take a few years until these additional sites start to generate meaningful data.”
Any uncertainties about the nutrient management aspects of the controlled drainage system in his field, though, have done little to diminish Rehm’s extreme excitement about his massive soybean yields this fall.
“The yield is unbelievable this year. The drainage system just did a tremendous job for us,” Rehm said. “It is incredible. I’ve even seen it and I still don’t believe it.”