Seed & Chemical
Straw and double seeding beating salinity
Ignoring salinity allows it to expand and get worse, making reclamation
more difficult. Working straw into the wet areas and double seeding lets this farmer get crops growing to use the excess water that causes the problem.
November 6, 2008 By Helen McMenamin
Ignoring salinity allows it to expand and get worse, making reclamation more difficult. Working straw into the wet areas and double seeding lets this farmer get crops growing to use the excess water that causes the problem.
|Lawrence Vandervalk fights salinity by spreading straw on affected areas.
Photo Courtesy Of Helen McMenamin.
Lawrence Vandervalk sees salinity as something you have to fight every year to prevent the problem from getting worse. His rolling land near Nobleford, Alta., has many low areas that hold water in the spring and show white salt crusts most of the year.
Vandervalk spreads straw in saline sloughs in the fall or winter. He uses straw by the semi-load from fields without salinity problems, 10 tons or more to the acre. A bale processor would be ideal for spreading straw, he says. But, he just breaks and spreads the bales with the tractor, then harrows to break up and spread the straw. It takes him a few dry days, working until the straw gets too wet and muddy for harrowing.
The following spring, he works the straw into the soil and seeds barley. He double or even triple seeds the wet saline areas, applying fertilizer each time. “That’s the key, to seed the crop really thick, with plenty of nitrogen to keep it growing,” says Vandervalk. “I want as many plants as I can get growing to take up the salts. In a saline area, germination may not be 100 percent, but even at 50 percent germination, my double or triple-seeding gives a strong stand. And my experience is that more nitrogen gets more crop growing. Barley is the best crop, by far for these areas.”
At harvest time, the heavily-seeded draws are ripe, rather than green and lodged as they would be in a wet draw seeded just once. “It’s not as tall or as lush as the crop right beside it,” he says. “But, it is ripe and we can combine right through it.”
The crop on saline areas often has quite a bit of kochia in it. Vandervalk harvests those areas separately at silaging time for his cattle, feeding it fresh as ‘green chop’. “We feed it to the cows and calves on pasture,” he says. “The cows eat that half and half mixture of kochia and barley like candy. That gets the calves eating too. And, we’re taking that kochia with its high salt content off the area where salt is a problem.”
Over the years, Vandervalk has used straw and thickly seeded barley as well as continuous cropping to eliminate standing water and cut the salinity in quite a few fields. “The saline areas are getting smaller,” he says. “We’ve combined right through draws that have been too wet to farm for years.”
Experts caution that Vandervalk’s approach may not be effective where salinity is severe. “Continuous cropping alone cuts down some salinity problems,” says Don Wentz of Alberta’s Reduced Tillage Linkages, formerly a provincial salinity specialist. “Putting straw into a saline area improves the soil structure by putting organic matter into the soil. In a saline area, with no plant growth to replace the organic matter that’s lost from the bare ground, soil loses its structure, it has no tilth.”
Working on the seep itself only helps for weakly saline areas, according to Wentz. But, he says it’s worthwhile, because ignoring salinity allows salt concentrations to increase and saline areas to expand. Where salinity has been allowed to build up, reclaiming the area is more challenging. Wentz recommends alfalfa as the long-term solution to severe salinization. If switching the whole field to forage isn’t attractive, he advises putting alfalfa above the seep, on an area about five to 10 times the size of the seep. “For 95 percent of prairie salinity, the excess moisture comes from hills and slopes above the seep. That’s the area that needs a deep-rooted crop that uses a lot of moisture. Unless you want to grow trees, alfalfa’s ideal.”
After about five years, hay yields generally drop because the alfalfa has lowered the water table beyond its reach. It has also reduced the flow of water into the saline seep so it will grow annual crops again. Vandervalk has improved productivity on eroded hilltops by spreading manure on them. That has improved the stand, so there’s more crop to intercept the moisture that led to saline seeps.
Salt tolerant grasses offer another alternative. Ken Miller, of Milk River, Alberta, grows Saltlander, a new grass developed by Agriculture Canada at Swift Current that is as salt tolerant as tall wheatgrass. It is a productive, leafy grass that is palatable to livestock and has a low growing point that allows it to regrow after cutting or grazing. Unlike bunch grasses like
wheatgrass, Saltlander spreads by aggressive rhizomes, crowding out invasive species like foxtail barley.
Miller has used Saltlander to reclaim some fields that had a lot of white areas. It’s taken about four years, but they’re now productive pastures. “We’ve made an asset out of the natural moisture,” he says. “The cost is minimal. Even if you give away the hay and only contain the problem, you’re further ahead than spending money on inputs and only getting half a crop.”
Vandervalk acknowledges his efforts may not pay in the short run, and that he does not make much progress in a wet year, but he has seen steady improvement. He believes investment in his land is worthwhile if only for the generation coming after him.
“It’s a good feeling to harvest a crop that’s almost as good as the rest of the field from a piece of ground that hasn’t grown anything in at least 20 years,” he says