Don’t Just Drain Excess Water Off Your Field – Reuse It
Recycling. It’s a practice that became mainstream during the 1970s. Focus centered on the three R’s of reducing, reusing, and recycling to increase sustainability. The hope was to decrease waste, conserve natural resources, and save money.
Today, farmers are faced with similar goals as they look to better manage water. Precipitation patterns are shifting, as rainfall events become more intense and less frequent.
“As our climate is changing, we’re going to see a lot of differences,” says Jerry Hatfield, director of the USDA-ARS National Laboratory for Agriculture and the Environment located in Ames, Iowa. “We’ve gotten increasingly wetter throughout the Midwest. It has not increased uniformly across the U.S.”
Across the Midwest, the current agricultural system was built on reliable summer rainfall.
“Our summer rainfall is going to become less reliable,” says Hatfield. “Precipitation patterns are changing with more spring rainfall and more variable summer precipitation.”
More and more rain is coming as heavy rainfall events. It’s not uncommon to see 6- to 8-inch rainfalls in one day, says Hatfield. As he sees it, this change leaves farmers with two choices.
- Change cropping systems
- Deal with variation
“We are losing 20% of yield 80% of the time due to short-term stresses,” says Hatfield. There are three main causes of yield gaps.
- Maximum temperatures during pollination
- Minimum temperatures during grain fill
- July and August precipitation
Retaining precipitation could make or break a crop. There are times when the plant needs another inch of rain, which adds stress to the plant. That’s where drainage water management comes into the picture.
Control the flow
“In the Midwest, farmers are mostly interested in getting water off of their land,” says Jane Frankenberger, Purdue University Extension agricultural engineer. “But if they can get that water back on the land when the crops need it, I think we’ll have people who have more and more interest in innovative water management.”
Controlling drainage isn’t new, says Charlie Schafer, president of Agri Drain. But there has been a shift in thinking because of weather variability and the hypoxia in the Gulf of Mexico with the voluntary measures to reduce nutrient loss. The use of practices like buffers is becoming more common throughout the Midwest.
“A lot of the momentum came through work with the Gulf of Mexico Hypoxia Task Force,” says Schafer. “People are generally getting more health conscious than they were in the past. Producers always want to do the right thing economically and environmentally, but it’s more on the front burner these days than it’s been previously.”
With the current economics, rather than expanding their operations, producers are opting to improve current acres, says Schafer.
These improvements make the ground more resilient and capable of handling intense rainfall events.
“Modeling studies suggest that there is often a yield loss from lack of moisture,” says Frankenberger. “Crops are not reaching their potential due to lack of water.”
Irrigation could result in yield benefits. “As our weather shifts toward more extreme events, rainfall will be more likely to come the wrong time and in heavier amounts,” she says. “It’s unlikely all the water will be able to infiltrate the soil.”
Frankenberger worries about predictions from climate scientists of increased drought pressure in the future.
To address water shortage expectations, Frankenberger leads a multistate project called Transforming Drainage. The collaborative effort looks at how farmers can use water storage practices and technologies to control drainage, store water, and then get that same water back on to the field – when the crop needs it.
“It’s expected that storing and recycling drained water will become more beneficial in the future, which is one of the reasons it’s important to look at it now,” says Frankenberger. “The goal is to increase water storage in the current agricultural landscape, so it’s available when it’s needed later.”
This article features three options – tailwater recovery systems, controlled drainage, and drainage water recycling – for farmers to control, store, and recycle water. Read on to see what ideas you may be able to adopt for your own farm.
Controlling water isn’t a new concept for all farmers. Jim Carroll of Brinkley, Arkansas, farms nearly 100% irrigated land. The fourth-generation farmer says water conservation has been a blessing for his operation.
Carroll, currently serving as secretary of the United Soybean Board, uses tailwater recovery systems to capture, store, and reuse water. This recycling system allows him to hold on to water and nutrients alike. “We’re all trying to use some conservation practices and not waste any water.”
A tailwater recovery system has a ditch at the edge of the field that allows irrigation water to be captured, held in the pit, and then pumped back onto the field.
“Most of the irrigating is done with a pump and an underground pipe,” says Carroll. “The tailwater recovery (pit) location is dependent on the slope of the field.”
He configures polypipes (lay-flat flexible irrigation tubing) to irrigate the entire field. Carroll uses a software program to configure individual field needs. He rolls out the polypipe the length of the field and connects it to the pump. Then Carroll punches holes in the pipe, and water flows down each row, watering the crop. For corn, the required size hole is punched for each row. Soybeans have a hole punched every other row.
The polypipe Jim Carroll uses costs $300 per ¼-mile roll. He spends $10 to $12 per acre with this system. The price per roll varies on the diameter and length of the polypipe.
The software tells Carroll how long it will take to irrigate the entire field; this depends on the size of holes in the polypipe.
“I have to know the flow of my well and coordinates of the field, then it can configure the size of holes I need and how long it will take to pump it. It gives me the basics to start. It’s really been efficient for me,” he says.
He wants to be precise. This method gives him the ability to control the flow so water doesn’t run straight off, too fast, or too slow.
“With this polypipe system, for example, I can set the pipe up on a ridge so the water flows two directions, and I know how much time it will take to irrigate the entire field. Say it takes 36 hours, then I know when to go cut the water off,” says Carroll.
This system makes it possible for Carroll to reduce the amount of irrigation water. “I can’t precisely tell when to shut off the water because of the difference in temperature and soil. But I get close,” he says. “The water is not just turned loose into the streams, and I’m ready to pump it back the next time I irrigate.”
This system requires a bit of labor up front, though. One of the tasks is land grading.
“I precision-grade to make my water more efficient,” says Carrol. “I’m trying to irrigate without pivots and without levees and dikes. I’ve gone away from pulling up levees to putting down polypipe. It’s the equivalent to a soaker hose used in a garden.”
With that comes a cost.
“When you cut the soil, you mess up the biology,” says Carroll.
He tries to make up for it with chicken litter. “When I cut this dirt, I go back and apply chicken litter to replace what I took off. There’s something magic in chicken litter,” he says.
He doesn’t worry about nutrient loss. “With my tailwater systems, I don’t have any nutrient runoff,” says Carroll. “If it goes off that field, I recapture it and put it back.”
The polypipe itself is not reusable, but that doesn’t bother Carroll. “This is the best thing to come for irrigation,” he says.
Carroll inspects fields to ensure the water flows in the direction it should. He occasionally places a barrel under a portion of the pipe to restrict or redirect the flow.
The pipe is never 100% empty. Thus, remaining water in the polypipe stays securely placed on the ground in the field. At the end of the season, Carroll rolls the pipe up, hauls it out of the field, and it’s picked up to be recycled.
Unlike a pivot, he likes that this system waters the entire field and doesn’t miss corners.
“I’m able to take the water and recycle it through the polypipe. I can utilize the water at the right time, and then I don’t have to worry about losing any water off of the field,” he says.
This system isn’t something Carroll was able to accomplish in one day. “This has been a 15-year-long process,” he says.
When he’s ready to build a tailwater recovery system on a new field, he starts by surveying his farm and making a total farm irrigation plan. “I’m lucky that the way I started helped my plan, and I’ve been able to add to it,” he says. “I should have been thinking about it years ago.”
Instead, the conservation-minded farmer learned on-the-go, consistently trying to improve new aspects as he went. “It’s been a lifetime of improvements,” he says.
Controlled drainage – drainage water management – uses water-control structures to control the water level in the field. The water-control structures hold water in the field during periods when drainage isn’t needed, and allow drainage when it’s necessary. Drainage water management uses a water-control structure in a main, submain, or lateral drain to vary the depth of the drainage outlet, says Charlie Schafer, president of Agri Drain.
While conventional drainage systems continuously remove excess water to the drain depth, controlled drainage allows retention of water in the soil profile. Controlled drainage can hold water in the field during the off-season when drainage isn’t needed – or any time you want to hold water.
Schafer has noticed a shift in the way farmers think about water when they have this system. Instead of thinking about it as a negative in the spring, they consider it as a resource and a benefit.
“Many become reluctant to let it go,” says Schafer.
how it works
To put it simply, the control structures control the flow of water. The water has to rise above the outlet level, which is set by the farmer, in order to drain from the field. During the growing season, it can allow growers to capture and hold water in their fields from timely rains.
“Water management can make a huge difference,” says Schafer. “On poorly drained soils, standard subsurface drainage will increase yields 30% to 35% over undrained soils. Subirrigation will increase an additional 30% to 35%. It’s a huge increase and risk reduction.”
“You can monitor water levels and flow rates and build a perfect-world scenario,” says Schafer.
Of course, that’s only when there’s plenty of moisture. “The top stop log establishes the high-water level during the fallow season,” says Schafer. “If water gets to that point in the field, it will flow over the top stop log.”
There’s also a slide gate down at the bottom of the automated structure to open and close on demand based on crop needs at that particular time of year, says Schafer.
For cases with a saturated buffer at the edge of the field, perforated tile will extend from the control structure. This lets water enter the buffer before it overflows out the tile drain.
There are manual and automated options available for farmers. The manual system requires farmers to adjust the stop logs inside of the control structures themselves. The automatic system allows farmers to set the level, and the valve is able to respond to the desired water level, says Schafer.
where is it suitable?
These systems are ideal for flatland with a 1% slope or less. If your field is relatively flat, this could be an option instead of the traditional subsurface drainage system, says Schafer. “It can be done on steeper fields, but it becomes more expensive and complicated.”
If you have an ideal field, instead of the traditional manner of installing a subsurface drainage system, he suggests a drainage water-management system that will give you more control over water management.
Agri Drain is able to plan and design water-management systems that comply with NRCS standards, says Schafer. That’s important so farmers are able to apply for financial assistance.
“We make sure that the designs we give farmers would be approved by USDA,” explains Schafer. “The discussion is elevated to go away from just an increase in production to multipurpose drainage management. We want to improve economic outcomes and reduce risk. Also, we look to see if we can create some habitat in the process of improving the water quality, too.
“We also build the option if the landowner desires to do subirrigation,” says Schafer. “We can control the pumps with these systems and add water back into the subsurface drainage system and reverse the drainage process – and feed that water from the bottom up.”
This process is efficient from an energy usage and water standpoint.
“There’s no evaporation,” says Schafer. “We don’t have to use high-pressure pumps; we just push it up to the highest point in the field and let gravity do the rest.”
What’s the cost?
The percent of slope will influence the cost of the system. At 1% slope, it’s much cheaper than if it’s steeper, he says.
“If you have 40 acres and you have a flat system where you only need one structure at the end of the field, it’s going to be about $1,000 to install the structure,” says Schafer. “That ends up being about $25 per acre.”
NRCS will pay for the conservation activity plan design, the structure, and, in most cases, the management fee for the producer to manage it, too, he says.
Some people have had the system pay for itself in one year, says Schafer. If it has more bells and whistles – like the automated system – it may take closer to seven or eight years.
“We’ve been building this type of structure for over 30 years, and they’re still in fields, still working,” says Schafer. “On standard ag ground, they look like they should last 50 years.”
Drainage Water Recycling
On-farm water storage takes the drainage control structures a step further by allowing farmers to recycle the water – not just hold it in the field. Instead of storing the water in the field, it is held in a reservoir or pond off the field.
“Taking a certain amount of land out of production to store water can be worthwhile,” says Jane Frankenberger, Purdue University Extension agricultural engineer. “The yield could be substantially increased on the remaining parts of the field.”
This system is similar to the tailwater recovery system, except that the water stored is from drainage due to excess precipitation rather than from irrigation.
You could drain water off your field during the spring when most tile drainage occurs. In the summer, when there are periods of insufficient moisture, the stored water can be recirculated onto the field.
“We’re trying to get a handle on the percentage of land you need for on-farm water storage,” she says.
More research needs to be done, says Frankenberger. But now, they’re looking at pond sizes between 4% and 10% of the field area, she says. So, if you have 100 acres you want to irrigate via a pond, the storage area would need to be between 4 and 10 acres.
“In addition to yield benefit, drainage water recycling can substantially reduce loss of nutrients to downstream waters,” she says.
Instead of going downstream, the nutrients would be recycled onto the field where they can be used by the crop. Systems can be set up for surface irrigation (such as sprinklers or a center pivot) or through subirrigation by flooding the drain tiles.
“In the past, it seemed like people were most concerned, at least in the Midwest, with getting excess water off their ground,” says Charlie Schafer, Agri Drain president. “That’s been the primary motivation. They didn’t think about the potential of irrigating with that water.”