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Managing salinity with forages

Some saline areas can never grow a profitable annual crop. Two farmers share their experiences with seeding perennial forages instead

Some acres were never suited to annual crop production. As some farmers get a better handle on the profitability of each cropped acre, they are putting the most dismal of these acres back into perennial forages where they belong.

Salinity is a common reason for chronic underperformance. Severe saline areas are sickly white, rimmed with kochia and foxtail barley, and never worth the effort of an oilseed or pulse crop. Even cereals, which are somewhat more tolerant, suffer in mild to moderate salinity. There is a better way.

Taking land out of annual production is never an easy decision, and the notion raises a lot of questions for farmers who have never established a forage crop and don’t have the equipment to harvest hay or the animals to eat it. This article, arranged in Q&A style, provides practical tips from farmers and from a new guide called AC Saltlander: A salt-tolerant forage for Western Canada, by Cameron Kayter, Alan Iwaasa and others from Agriculture and Agri-Food Canada (AAFC). Search for it at publications.gc.ca.

The farmers are Ryan Heavin from the black soils of Melfort, Sask., and Ken Miller from the brown soils of Milk River, Alta. In 2017, the Heavins seeded 90 acres of poor-performing saline land to grass. The Millers are cattle producers and seed growers, and they have the license to produce AC Saltlander seed.

How to identify a severe saline patch

Ryan Heavin: Over the previous 15 years or so, wetter conditions lifted the water table and increased surface salinity. Average yields for the worst field were down to around 25 per cent of normal. “We were losing money the past 10 years on those 90 acres,” Heavin says. “Canola and peas were a complete disaster, and getting more negative all the time. Six-row barley was the only thing that would produce any kind of crop.” It was obvious that those 90 acres needed help.

Ken Miller: If you see kochia and foxtail barley taking over an area, that’s a good indicator that salinity is a problem. “Kochia thrives in areas where salinity leaves you with half a crop, and of all weeds, foxtail barley is the one cattle producers hate the most,” Miller says. “You don’t want to wait for severe salinity that is white and nothing grows.”

AC Saltlander guide: Use soil testing to supplement descriptive information like visible salts, poor crop production, or presence of salt-tolerant weeds like kochia or foxtail barley. Map salinity levels within the field. Detailed soil testing is recommended to supplement conductivity mapping (with EM38 or Veris scanners).

A note on soil sampling: Soil sample analysis usually includes a salinity reading. Growers would need various separate tests to identify the boundaries of a patch, but this may be worthwhile for knowing where to plant forages and where to keep going with annual production. Another option is the Veris or EM38 electrical conductivity (EC) map. Ask around for providers. CropPro, for example, is one company that offers this service. Units for EC are “mho” and Siemens. Millimho per centimetre is the same as milliSiemens per cm or deciSiemens per metre. Oilseeds and pulses will tolerate up to two units of salinity (ex. 2 dS/m or 2 mmho/cm). Cereals can tolerate up to four units. AC Saltlander can tolerate more than eight units. 

What to do with those patches 

Ryan Heavin: The Heavins reduced fertilizer and increased the seeding rate by two or three times to improve crop performance on the 90 acres. “This provided a marginal improvement, but it wasn’t a long-term solution,” Heavin says. They considered tile drainage, but it wasn’t really used in the area at that time (although Heavin says more is coming in now). Finally, they talked to Lyle Cowell, Nutrien’s manager of agronomy services for northeast Saskatchewan. Nutrien owns the Proven Seed brand, which has a long line of forage seed options. Cowell recommended seeding the field to SalineMaster, a blend of AC Saltlander green wheatgrass, tall fescue, smooth bromegrass and slender wheatgrass.

Ken Miller: He seeds saline acres to AC Saltlander, which he says will root down to seven feet. He harvests the seed for sale and leaves the straw for cattle.

AC Saltlander guide: Most crop and pasture plants do not establish or survive long in highly saline areas, allowing salt-tolerant weeds to invade. These non-productive areas are often ignored and unmanaged because rehabilitation is difficult and costly. A recommended practice is to establish permanent plant cover to reduce the impacts of salinity.

A note on tile drainage: Wet years bring the water table closer to the roots, and salinity wicks up to the soil surface. If this wicking action and evaporation of surface water exceeds the downward movement of water – or “infiltration” — from rainfall or irrigation, the result is increased salinity. “Tile drainage may fix salinity,” says Marla Riekman, soil management specialist with Manitoba Agriculture and Resource Development, “but it can take a decade or more to see major improvement unless you also have irrigation to increase water infiltration.”

A note on low-maintenance patch management: If a grower doesn’t want to take on forage harvest and feed marketing, a low-cost option is to use the weeds to manage the water table and keep a saline patch contained. “Mow them, don’t spray them, so they stay in a vegetative state but don’t set seed,” says Riekman, who adds that kochia has very good feed value. Alan Iwaasa, AAFC research scientist in grazing management and ruminant nutrition, agrees, but says to cut it early. “Crude protein and digestibility of the kochia are good prior to flowering. As the plant matures, it becomes very stemmy and the fibre content increases substantially,” Iwaasa says.

How to establish forages in a saline patch

Ryan Heavin: The Heavins harrowed just before seeding to smooth out ruts, then seeded with a SeedHawk 6010 on 10" row spacing. Salinemaster went through the seed opener at a depth of about 1/4". Barley went through the fertilizer opener along with 25 pounds of a starter fertilizer blend of 8-41-3. Seeding rates were 11 lb./ac. for Salinemaster, which worked out to $65 per acre. Barley was at four bu./ac., which is a higher than normal seeding rate. They ran the drill at three m.p.h. to make sure depth was consistent. “The Salinemaster came up very thin. It didn’t seem like we had much of a catch, but then we got optimal rains,” Heavin says. The barley gave them a cash crop in the year of establishment and provided some protection for the grass. The following year, they harvested 320 round bales (of 1,000 to 1,100 pounds each) from the 90 acres.

Ken Miller: The Millers use a John Deere disc drill, seeding AC Saltlander at five pounds per acre in moderate salinity and eight pounds in severe situations. He blends the lightweight grass seed with five to 10 lb./ac. of wheat seed to improve flow through the drill. Wheat plants also establish faster, providing some shelter for the establishing AC Saltlander. Miller will use tillage and packing before seeding to dilute salts at the soil surface and bury weed seeds. He also gives the field a pre-seed burnoff and applies broadleaf herbicide after AC Saltlander reaches the two-leaf stage. They usually seed in the spring, but Miller says AC Saltlander could be seeded in late fall (for spring germination) on land that is difficult to access when ground is too wet. He says AC Saltlander needs two leaves to survive the winter, so late-summer seeding usually fails.

AC Saltlander guide: The guide has many pages of useful detail on establishing the patch. In summary, it recommends two rounds of pre-seed glyphosate, harrowing (not tillage) to smooth the field, and a carrier or nurse crop mixed with the seed at a 1:1 ratio to improve seed flow. For slight to moderate salinity, seed AC Saltlander at five pounds per acre. For severe salinity, the guide recommends monoculture AC Saltlander seeded at 10 pounds per acre. It adds that mixes with other salt-tolerant forages may be an option for less saline areas.

Iwaasa adds that AC Saltlander has flooding tolerance better than smooth bromegrass. “It can survive fine in three to five weeks of flooding. This may be of interest to producers with spring flooding concerns with their low-lying areas,” he says.

This drone image shows the Heavin’s 90-acre field of Salinemaster. This was taken in 2019, two years after they converted the field from annual crops to perennial grass. photo: Courtesy Ryan Heavin

What to do with the forages

Ryan Heavin: Before seeding Salinemaster, the Heavins talked to a local cattle producer who said he could use the forage. “This made the decision a lot easier,” Heavin says. So far, the grass has reduced the kochia population, but foxtail barley is starting to show up. The Heavins spread some leftover urea on a few strips in 2020. “We didn’t notice a response,” he says. “The cattle producer who baled it says we likely wouldn’t see a response due to the abundance of fertilizer in the soil from years of underutilization.”

Ken Miller: His daughter and her husband live nearby and have a herd of 300 to 400 cows. They graze AC Saltlander fields after seed harvest, and their winter feed is mostly AC Saltlander. Miller says the variety has a hollow, fine stem that is soft on the mouths of cattle. As the exclusive seed grower, Miller sells AC Saltlander across the Prairies and Proven Seed is his biggest customer. Miller acknowledges that purity standards allow for some downy brome in seed lots, but he says he has zero downy brome seeds per 25 g for 2021. 

AC Saltlander guide: In addition to saline tolerance, AC Saltlander was bred for good palatability and nutritional qualities. This sets it apart from other salt-tolerant grasses. Forage quality and yield for AC Saltlander in saline patches are similar to smooth brome and orchard grass grown under non-saline conditions. AC Saltlander tolerates moderate grazing pressure and recovers well after defoliation — as long as moisture is available. The guide also says to review the seed analysis certificate before buying seed.

Conclusion

Farmers notice saline areas because they grow saline-susceptible crops in those areas. “If we didn’t have plants susceptible to soil salinity, we wouldn’t see a salinity problem,” says Riekman.

The easiest management solution comes down to crop choice. If farmers choose to grow saline-tolerant forages and leave them there, the salinity “problem” becomes something that can be managed. The right crop choice can stop economic losses and possibly make those acres profitable again.

When asked what he would have done differently with the 90 acres, if given the chance to start again, Ryan Heavin says: “In retrospect, we should have seeded the whole quarter to grass.”


How to solve salinity along the road

The Canadian Prairies have a lot of land that is just naturally saline. This is called “primary salinity.” The Prairies also have a lot of secondary salinity — the result of artificial changes in the flow of groundwater. Roads and ditches can cause secondary salinity, which is why, unfortunately, salinity is often worse right along the highway where everyone can see it.

Roads and their dense foundations block the natural movement of water, and the water in ditches raises the water table in that immediate area. With water near the soil surface, salts wick up and create a band of higher salinity. Soil salinity can continue to rise and spread farther into the field.

Farmers have a solution. Due to the physics of water movement, a narrow band of lesser or no salinity often occurs in a strip between the ditch and the saline patch in the field. Alfalfa seeded in this 15- to 20-foot strip along the ditch can take up that excess water and stop the expansion of salinity into the field. 

“The alfalfa needs to be permanent,” says Marla Riekman, soil management specialist with Manitoba Agriculture and Resource Development, “but this permanent strip can reduce salinity to improve productivity in those larger areas farther into the field.”

Because this strip of land has lower salinity, it does not require a more saline-tolerant forage like AC Saltlander. These grasses can work, says Riekman, but deep-rooted options like alfalfa will usually provide better results. Alan Iwaasa with AAFC adds that saline-tolerant alfalfas are available in Canada.

Alfalfa can also work around other secondary saline areas, like dugouts, and in primary saline areas around natural sloughs and wetlands. “When I used to manage the Manitoba Zero Tillage Research Association farm north of Brandon, we had some wetlands with saline rings around them and some without,” Riekman says. The wetlands without the saline rings (which extended into the field and reduced productivity) had willows growing in the space between the water and the field. “The willows intercepted the water and stopped it from causing salinity issues in the field,” she says. “A narrow strip of alfalfa serves the same purpose.”

Jay Whetter is communications manager with the Canola Council of Canada.

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Jay Whetter is communications manager for the Canola Council of Canada.

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