By Mel Luymes
LaVerne Weber walks us across a rolling, 110-acre field in northern Illinois, dotted with control structures along the perimeter and down a grassed waterway running through the middle. There are 140 structures in total, each attached to a drainage tile main, to restrict the outflow as needed. Each structure has a tap into it; he is irrigating these crops through the drainage tile laterals, supplied through buried pressure lines, out of two 16 million gallon lagoons of wash water from a nearby soy and oatmilk processing facility.
This is called subirrigation (to differentiate it from sub-surface irrigation through drip tape) and while most of these systems are installed on flat ground and using clean water, LaVerne and his team at Grade Solutions have proven that it works, even on steep hills and even with nutrient-rich water.
After installing 400 acres of subirrigation for three separate processors, they have nearly perfected the control structures, which they assemble themselves, the electrofusion plastic welding for a perfect seal and precision installation with the latest construction-grade GPS technology. The drainage tile is installed at a flat grade, contoured around the hills at approximately 16-20 foot spacing, with a control gate backing up water every foot-and-a-half of drop in elevation.
On the hills near Rockford, the loamy topsoil is 20 to 40 inches deep on top of a tight clay layer and pulls water out of the tile and up through the soil profile through capillary rise. This feeds the growing crops in the summer months, and the farmers have seen a tremendous increase in yields, averaging about 60 bushels in corn. When the system is empty, the control “gates” are removed before the winter and the water lines are blown out to avoid freezing. This allows the pipes to function for drainage in the spring like usual, before the gates are installed in June and pumping begins again.
There are less than half a percent of solids in the wash water, says LaVerne, who well understands the nutrient levels in the effluent water and the importance of getting them to a living crop and not to a watercourse. The Illinois Environmental Protection Agency (EPA) has installed deep monitoring wells around and below the fields to monitor lateral flow and groundwater quality; so far, they have seen no change. Just in case, LaVerne has installed woodchip “bioreactors” at every outlet for additional treatment of nutrients before field water is released to a watercourse.
A bioreactor sounds a bit more complicated than it is. Basically, it is an area where drainage water leaves the pipe to move slowly through media that will clean the water. Woodchips host a variety of microorganisms that feed on nitrogen, while phosphorus removal would largely be done through a chemical treatment with iron filings or the like.
The alternatives to subirrigation, for these processors in Illinois, would be pivot irrigation or water treatment. Water treatment is an expensive alternative; it is a lot of work to get nutrients out of water, but that is what plants do best! As for pivots, they are difficult to operate on a rolling landscape and the wash water creates both odours and erosion. Subirrigation, on the other hand, can often get the water to the furthest reaches of a field, no matter what the shape and using tile drains that would need to be installed regardless.
Subirrigation is a win for both the processing plants and for the nearby farmers, with whom they have a long-term land agreement for irrigation. Grade Solutions installed the systems, but they also have a long-term contract to operate them.
This is exactly the space where LaVerne likes to work. For him, it is all about finding win-wins and pursuing a grander vision.
Raised on a farm near Rockford, IL, LaVerne knew that he didn’t want to be farming the rest of his life, but he has stayed quite close to the industry, as he started working for John Deere as soon as he could. When he later got into road construction, he made an important connection with fly ash, a byproduct of burning coal that improves the strength of concrete. He worked to make the connections to put fly ash into roads for a few decades, until he sold his contracts to LaFarge.
LaVerne knew he wouldn’t sit still for long, and when he met Bob and Jeremy Meiners, the father-and-son team at AGREM, he quickly saw another win-win. AGREM is another Illinois-based company with software and know-how to design controlled drainage systems on the contour. (They designed the drainage project that is now installed at the Huronview Demo Farm south of Clinton if you want to see for yourself!)
But let’s back up for a minute. To understand the importance of contoured drainage, we need to understand the basics of controlled drainage. Controlling drainage is just a matter of installing a restriction in the tile. It can keep more water stored in the soil and it will help crops get through a dry spell, but it needs to be managed well to not avoid flooding the crops. It is also promoted for water quality; inasmuch as it restricts water from leaving a drainage system, it is restricting the nutrients in that water from leaving as well. And these nutrients can then feed the plants for which they were originally intended.
There are many types of control structures. In the case of Agri Drain or Great Lakes Drainage Products control structures, they are a matter of pushing stop logs down into a riser, which will manage the maximum level of the water table. And for the ADS’ Nyoplast Water Control Structure, as well as the do-it-yourself versions that Laverne uses, a vertical pipe is used as the riser to restrict outflow. Agri Drain’s structures can also include a relief slide gate within the bottom stop log that can be operated automatically based on soil moisture levels, often powered by a solar panel at the control gate.
But controlled drainage only works to hold water behind it when the drainage system itself is relatively flat. It works quite well on flat fields, with one gate holding back several acres of water in the field. But, on sloped ground, like in Illinois or at the Huronview Demo Farm, the tile itself had to be installed at a very low grade and so it needed to snake around the hills. At Huronview, the contoured sections were installed at 0.1 per cent grade by Roth Drainage (in the front field) and Williams Drainage (in the back field), with a control gate installed on every lateral in the front field.
Subirrigation is simply a matter of running water into the back end of a control gate. It has been researched over the years and continues to be researched across the world. The federal research station at Harrow, Ontario had installed plots decades ago in Essex County’s flat clay soils. What we have learned so far is that soil type really matters. An important factor for maintaining water tables is the depth to a restrictive layer that will keep the water from dropping too far below the tile. In Ontario, the weight of the glaciers left us with a heavily compacted “glacial till” subsoil. This restrictive layer is why farmers here needed drainage in the first place, and its also a critical factor to making controlled drainage and subirrigation work.
But more research is needed. The University of Illinois has partnered with Nutrien Ag Solutions on their research fields south of Urbana and have installed six Agri Drain control structures with water taps and extensive monitoring. The flat field is tiled at 40-foot spacing, four feet deep. A small pump will be pulling 150 litres a minute from the Embarras River (just a stone’s throw from the plot) to keep the water table at a consistent 30 inches below the surface.
Caleb Bruhn is a doctoral student at the University of Illinois and will be researching nitrous oxide emissions from a fluctuating water table compared with the steady water table from the subirrigated plots. Working under the prestigious Dr. Richard Cooke, Caleb was named a 2023 Foundation for Food and Agricultural Research (FFAR) fellow, and the research is funded jointly by FFAR and Nutrien, the industry sponsor. Nutrien will no doubt be keeping an eye on the yields from the subirrigation plot to compare with the rest of their fields.
Perhaps the most complex subirrigation research plot, however, was installed by LaVerne Weber and Grade Solutions last year at the Highland Community College in Freeport, IL. On the contour, the research field is divided into nine plots with a separate water line to each and this will allow for research on various fertigation (yes, exactly what it sounds like) strategies down the road. Next to the college, this field is pulling from municipal water, and the manifold is in the basement of a new classroom facility that is sure to attract people from around the world.
Another farmer to take the plunge into field-scale subirrigation is Brian Goetz, of Riga, Michigan. With a relatively flat 105-acre clay-loam field crossed diagonally with a pipeline, he couldn’t get an outlet across his neighbour’s property for a drainage system. Instead, he dug out eight feet and built up eight feet for a 4.9-acre pond at the bottom end of the property, storing 20 million gallons of water. An electric pump lifts drainage water into the pond at a rate of 1000 gallons a minute in the spring and, around the beginning of August, he pumps it all back out to the field. Brian pumps to the top of the three sections of his drainage system, but, this time, the 16 Agri Drain control gates are shut and so the water floods through the laterals, spaced at 20 feet. The mains were also installed with Water Gate float-activated head pressure valves between the control structures to help hold water back in the drainage system.
It takes about a week of pumping non-stop to fill up the system, says Brian, who worked closely alongside Tom VanWagner, with Lenawee Conservation District, to design the system. It was installed by DeJonghe’s Farm Drainage in 2020, with some support from the Great Lakes Commission and The Nature Conservancy. The field, yields and water quality are being researched and monitored by Dr. Ehsan Ghane and his students at Michigan State University.
“The idea is to keep every bit of water that falls on the farm, on the farm,” says Brian. “And it should leave in the form of a crop that leaves in a truck.” Going from no drainage to drainage and irrigation, Brian has seen his yields more than double and is considering growing specialty crops on that field in the future. Irrigating from a pond that was filled with drainage water is often termed “drainage water recycling,” whether it is irrigated through a pivot, traveller or through the same drainage system it came from.
Closer to home, there are some tomato fields in Essex County with the ability to subirrigate and a few other farmers dabbling with it. However, we’ll soon be seeing results from the Upper Thames River Conservation Authority’s (UTRCA) new installation on their field near Wildwood Conservation Area. The Rural Voice caught up with Beth Wrona, Agricultural Stewardship Technician who walked us through the installation.
The 18-acre field is owned by UTRCA and is rented to a local farmer. The field is relatively flat, but with two knolls and a low draw going to the bottom corner where there is an existing wetland at the edge of the field. The field often had ponding issues, so the UTRCA used it as an opportunity to install a drainage water recycling system for demonstration and research.
They dug an additional pond (20 x 30 x 5 metres deep), in the bottom corner and have it overflowing to the existing wetland for additional water quality treatment. They hired McCutcheon Drainage to install contoured tile in the field at 25-foot spacing to drain into the pond, with three Agri Drain control structures on the main. A solar pump is installed to pull water from the storage pond and back to the top of the field during the summer months, where the water will fill up the top structure and laterals before cascading down to the next structure below and filling it as well.
This will be the second innovative drainage demonstration field for UTRCA; it follows their 58-acre Thorndale Demonstration Farm that includes a side-by-side comparison of contoured, controlled drainage vs. “free” drainage, a handful of erosion control berms and a blind inlet, as well as a StormTech® chamber system that was installed in 2024 at the bottom edge of the field. Most often used under sports fields or parking lots in urban settings, this open-bottom chamber functions like an underground wetland, capturing water from a tile and holding it there to percolate through the soil below. If it is full, it goes to the nearby creek through an overflow pipe.
The UTRCA hopes to host learning events at the Wildwood Demonstration Farm starting in the fall and anyone interested can stay tuned on their website or social media for more information.
Considering the investment and advancements in precision agriculture for seed and fertilizer, why are we still at the mercy of rains? Controlled drainage and subirrigation will likely be the next consideration and investment for agricultural areas to maximize efficiency, especially for areas like Ontario, with too much water in the spring and often too little water in the summer. Precision water management will be a win-win for both farm productivity and water quality, and it is exciting to see