Soil salinity is the ugly duckling of agriculture that doesn’t attract much research funding, yet 5.5 million acres of land in Western Canada are classified as being severely affected, says Ken Miller, a grain and forage seed producer at Milk River, Alta.
Miller has been fighting soil salinity for the entire 40 years he’s been farming. While various methods of control — manure, calcium applications, tile drainage — have been tried over the years without great success, he has been reclaiming saline areas on his land for the past 15 years using NewHy wheatgrass as his saline fighter.
That led to his interest in AC Saltlander, a new variety of green wheatgrass bred by Dr. Harold Stepphun at Agriculture Canada’s Semiarid Prairie Agricultural Research Centre at Swift Current. In 2006, Miller Seeds received exclusive rights to increase the seed and commercialize the variety, which is now available through Viterra, his retail partner in Canada, and Producer’s Choice in the U. S.
Viterra markets Saltlander in a forage blend called Salinemaster, which includes 40 per cent Saltlander, 30 per cent tall fescue, 20 per cent smooth bromegrass and 10 per cent slender wheatgrass.
The diversity in the mix allows the stand to adjust to variable soil conditions within the field, Miller explains. Saltlander will have a definite advantage in saline areas, with its yield and quality being similar to smooth brome on non-saline soils. Slender wheatgrass has rapid establishment, but is short-lived. Tall fescue has some tolerance to salinity and can withstand longer periods of flooding than Saltlander.
Viterra promotes Salinemaster as its best blend for saline soils. Saltlander bumps it up a notch from the Saltmaster blend, which is 45 per cent tall wheatgrass, along with 15 per cent alfalfa, tall fescue, smooth bromegrass and slender wheatgrass.
Tall wheatgrass has long been recognized for its superior tolerance to soil salinity, however, being a bunch-grass, it isn’t very effective in suppressing foxtail barley. Perhaps one of its greatest drawbacks is its poor palatability.
NewHy wheatgrass and green wheatgrass are newer forages with much improved palatability developed from crosses between species of bluebunch wheatgrasses and quackgrasses. The quackgrass parentage contributes to persistence and the bluebunch parentage adds a quality component. NewHy originated as a manmade cross developed by the United States Department of Agriculture (USDA) and released there in 1989. Saltlander was developed in Canada from seed collected by the USDA from a natural cross between quackgrass and bluebunch grasses found in Turkey. Dr. Stepphun then selected for superior resistance to root-zone salinity along with winter hardiness, uniform plant colour, vegetative vigour, leafiness, seed set and freedom from plant pests.
The standard lab tests using sodium chloride and additional tests using sodium sulphate — the dominant salt in saline areas of Western Canada — were conducted at Canada’s salinity tolerance testing laboratory at Swift Current during the breeding program for Saltlander. The results show that Saltlander’s salinity tolerance is equal to that of Orbit tall wheatgrass and exceeds that of NewHy, which was recommended for areas with moderate salinity.
Miller’s daughter is the rancher of the family, so they have also been able to put Saltlander to the test under grazing pressure and in the wintering ration. “The seed head looks a lot like quackgrass, but the plant itself is finer-stemmed and leafier than quackgrass. The cattle relish it even after seed set,” Miller says. The aftermath from threshing is a palatable soft hay with adequate nutrition to keep cows through the winter.
Saltlander’s low growth point gives it the ability to readily recover after
defoliation, making it a flexible choice for grazing or haying. It spreads by seed and shoots from rhizomes that branch out underground to fill between the rows, pushing out the foxtail barley and other weeds that survive in saline soils. Foxtail barley is an opportunistic plant — it takes advantage of bare soil but doesn’t like competition.
Saltlander is adapted to all growing regions. Its drought tolerance is better than intermediate wheatgrass and meadow brome and it stays vegetative later into the fall than other wheat grasses, such as crested wheatgrass. Being an inter-species cross, or hybrid, seed yields are very low and somewhat temperamental as reflected in the price of the seed, Miller explains.
REHABILITATING SALINE SOILS
According to Alberta Agriculture, the extent of dryland salinity in Western Canada is difficult to establish because of the ability of salts to move to the surface and back into the soil. In Alberta alone, it’s estimated 1.6 million acres are affected by secondary salinity, resulting in a 25 per cent reduction in crop yields when averaged across the province. The problem is widespread in Saskatchewan with some 3.3 million acres affected, while estimates for Manitoba are 0.6 million acres.
The practice of summerfallowing has been a major contributor to salinity problems, Miller explains. When there is no plant growth to absorb excess moisture, the soil can become saturated, allowing the water to penetrate deep into the soil below the root zone where it dissolves the naturally occurring salt deposits.
There are several ways in which the groundwater can transport salts to the soil surface. In low-lying areas with high water tables, the moisture may be drawn up during dry spells, leaving the salts on top as it evaporates. If the recharge area (where the water originates) is on high ground, the groundwater can carry the dissolved salts downslope to discharge areas nearby or quite a distance away. This happens when the groundwater flows through a permeable layer of soil above a less-permeable layer. Sometimes the soil formations force it close enough to the surface that it seeps through in a wick-like fashion or bursts through an outcropping on the side of the slope, as in a spring. As the concentration of salt builds over time, the seep will develop the whitish crust characteristic of saline soils. Sometimes, patchy areas of poor crop will be your first indication of a saline seep.
“Saltlander has been a real boon because it can convert the nastiest land into a useful resource,” Miller says.
“Foxtail barley, kochia and dock are weeds that tolerate moderate to severe salinity. If these weeds are present in your saline areas, Saltlander will grow there. If nothing at all is growing, you shouldn’t expect Saltlander to grow there,” Miller explains. It takes a few years to rehabilitate these sterile areas with forages, but it is doable.
His strategy is to work from the outside, in by surrounding the area with a perennial crop that has tolerance to salinity. The forage crop uses moisture, preventing it from reaching the water table and perpetuating the problem. As the water table recedes, the salts slowly dissipate from the root zone, giving Saltlander a chance to spread into the dead zone until the entire patch is eventually filled with plant growth.
Miller has three critical recommendations for establishing Saltlander and Salinemaster.
Rate and depth: Under ideal conditions, five pounds per acre of living seed placed one-half to one inch deep is adequate. Additional seed is advisable because thin stands invite weed encroachment. Use a roller or harrow packer to firm the seedbed and avoid using seeding equipment that leaves steep furrow walls that could collapse and bury the seed too deeply.
Weed bank management: Salinized areas usually have substantial quantities of salt-tolerant weed seeds in the top two inches of the soil. To minimize weed competition, use tillage or a nonselective herbicide to control weeds for at least a season prior to seeding. In-crop weed control using mowing or herbicides recommended in your provincial crop protection guide will increase the vigour of the stand.
Sodic crusting: Salinized soils are the result of sodium-based salts accumulating at the soil surface. Salts often result in soil crusting, especially under hot, dry conditions that can prevent seedlings from emerging.
Mitigation measures include light irrigation (one-half inch) every five or six days; planting early in the spring before the hot weather; and dormant fall planting after it’s too cold for the seed to germinate so it will be there for very early spring germination.
For more information, visit the Miller Seeds website at www.miller-seeds.comor call Viterra’s help desk at 1-800-661-3334.
The Saskatchewan Forage Council’s fact sheet “Revitalization of Saline Soils Using Salt-tolerant Grasses” includes a table listing the relative salt tolerance of various forages as well as yield and forage quality information from trials carried out at Swift Current. It is online at www.saskforage.caor call 306-966-2148.