Many farmers struggle with soil salinity and its effect on how crops, forages, shelterbelts and lawns produce and survive.
Len Hingley, a soil and water technician at Alberta Agriculture’s Crop Diversification Centre South near Brooks, said that’s why the centre has compiled a summary of its recent salinity research.
The centre’s studies included salinity tolerance ratings for four groups of plants: forage and turf grasses; ornamental trees and shrubs; dry beans; and potatoes.
Ornamental trees and shrubs
On land with variable soil salinity, 28 varieties of trees and shrubs were tested for salinity tolerance, using an EM38 electromagnetic induction meter and a hand held computer. The EM38 measures soil salinity levels using electrical conductivity readings through the soil.
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The Siberian salt tree and the Russian olive were the most saline tolerant species. The least tolerant were hawthorn and bur oak.
The Northwest poplar was the fastest growing tree, but its growth declines sharply in higher soil salinity. Caragana and Brooks poplar showed relatively good resistance.
Forage and turf grasses
Turf and forage grasses were tested in a series of two by 150 metre strips, set perpendicular to a salinity gradient.
Twenty-six grasses were tested near Brooks under irrigation, while 20 varieties received similar tests under dryland conditions at a site near Hanna, Alta.
Nine yield samples from each of four replicates were taken, for a total of 36 yields for each grass species, each year.
In the grass trials, Hingley said one irrigated test site had a steep graded hill with about a five m drop from the top to the bottom.
He said the slope showed low salinity levels at the top of the hill and higher salinity levels as the slope dropped. The grass plots were seeded across and down the slope.
Under irrigation, the wildryes and wheatgrasses showed the greatest tolerance to salinity, while Kentucky bluegrass was the least saline tolerant of the grasses tested.
At the dryland location, weeping alkaligrass yielded best in highly saline conditions, but is considered unpalatable as a forage.
Russian and Altai wildrye, along with some of the wheatgrasses, were more tolerant than other grasses tested.
Dry beans
A dry bean test was carried out on a quarter section of irrigated land near Bow Island, Alta. A yield map was generated using a global positioning system and a yield monitor on the combine.
A second map, identifying salinity levels, was developed using an EM38 unit plus a GPS system.
When the two maps were overlaid, a relationship was established indicating how higher yields corresponded with salinity levels less than three dS/m (decisiemens per metre, the international standard for measuring salinity).
Comparing yield as a function of salinity at corresponding points within the field produced an obvious maximum yield that corresponds to a given level of salinity.
Potatoes
For the potato study at Vauxhall, Alta., an EM38 was mounted on a sled and pulled across the field using an all-terrain vehicle. A GPS receiver on the ATV allowed the complete field to be mapped for salinity.
Tuber samples were hand dug at 62 locations across a range of salinity levels, with readings taken at each sample location.
“With the dry bean research, when you move from a salinity reading of zero to four dS/m, you don’t see any visible salinity, but you do see about a 39 percent decline in maximum achievable yield for that crop.
“Potatoes were similar. From one to four dS/m, we saw a 43 percent decline, without any visible salinity,” said Hingley.
“I know a lot of producers do have some hidden salinity that they’re not aware of. You don’t see any white crusting on the soil, visible salinity, until you get about five dS/m. But it makes a big difference, especially for crops like dry beans and potatoes.”
With potato acreage increasing in southern Alberta, Hingley said some producers are moving onto marginal land.
“Producers are pushing the threshold of what’s good land and what’s not. We want them to be aware that (hidden salinity) is a problem and they should probably have a salinity map done prior to working this land.”
Hingley said the centre does salinity maps only for research. Farmers must hire private companies or individuals to carry out the work.
