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Soil salinity is a term used to characterize the accumulated soluble salts in a soil. In sufficient quantity it adversely affects plant growth and quality. The ability of a plant to withstand and flourish in saline soils is often referred to as its salinity tolerance.
A three year experiment (1991-93) on the salinity tolerance of turf grasses was conducted near Brooks (under irrigation) and near Hanna (under dryland conditions). Unlike traditional salinity tolerance testing, which is usually conducted in greenhouses under controlled conditions, this project was long-term and took place under field conditions, where soil moisture fluctuations and other environmental conditions were factors.
 | The irrigated plot site near Brooks: low soil salinity is found at the top of the slope and high soil salinity is found at the bottom. |
Soil salinity was measured with the EM38 salinity meter. It is a portable device that is set on or above the soil's surface and measures the soil's electrical conductivity. This measurement is then corrected for soil temperature, moisture and texture to determine soil salinity, equivalent to a saturated paste extract (with units of dSm-1).
The irrigated plot was on a slope with a salinity gradient from low (0.4 dSm-1) to high (17 dSm-1) salinity. Seven species of turf grass were harvested twice a year. There were 36 samples per species taken at each harvest. Salinity measurements were taken at each sample site immediately following harvest and classified into one of three salinity zones; low, medium and high.
The dryland plot was located on a relatively flat piece of land with variable salinity throughout, ranging from 0.4 dSm-1 to 28 dSm-1. Five species of turf grass were grown at this site and a single harvest was taken each year. Thirty-five samples per species were harvested. Salinity was recorded at each of the sample sites and classified into three salinity zones.
Species (Variety) | Scientific name | % Yield decrease per
1 dSm-1 increase |
Irrigated | Dryland |
| Tall fescue (Arid) | Festuca arundinacea Schreb. | 3.1 | 0.0 |
| Creeping red fescue (Boreal) | Festuca rubra L. | 4.0 | - |
| Hard fescue (Aurora) | Festuca ovina var. duriuscula (L.) Koch | 7.8 | - |
| Sheep fescue (Nakiska) | Festuca ovina L. | 7.8 | 6.1 |
| Kentucky bluegrass (Troy) | Poa pratensis L. | 8.1 | 4.8 |
| Creeping bentgrass (Emerald) | Agrostis palustris Huds. | 6.7 | -26 |
| Weeping alkaligrass (Fults) | Puccinellia distans (L.) Parl. | 2.7 | -5.0 |
The values in the table are based on three years data. The smaller the number, the greater the tolerance to salinity. Under dryland conditions, two varieties had negative values, indicating that the yields increased with increasing soil salinity. Saline soils usually have poor drainage and a greater water content is associated with greater salinities. This could explain the negative values as yield being a response to more to moisture than salinity.
Dry matter yields of turfgrasses
Tall fescue (Arid)
Under irrigation, tall fescue had good salinity tolerance. It had its highest yields under low salinity conditions (<3 dSm-1), but also did well in the medium salinity zone (3-9 dSm-1). The total yield decreased each year, regardless of soil salinity.
Under dryland conditions, yields were reduced considerably. They varied year by year and did not have the annual declining pattern shown under irrigation. Optimal yields were produced under medium soil salinity (4-9 dSm-1). Yields were similar under low and high salinity conditions and remained constant over the range of salinities. Tall fescue is recommended for turf use on saline soils, both irrigated and dryland.
Creeping red fescue (Boreal)
Creeping red fescue was only tested under irrigation. It had its highest yields in the low and medium salinity zones (<3 dSm-1 and 3-9 dSm-1). It had good salinity tolerance, with yields decreasing by only 4.0 % for each dSm-1 increase. Under favourable soil conditions (<3 dSm-1), the yields decreased by 17% each year. In the high salinity zone (>9 dSm-1) the yields remained relatively constant over the three years, but showed marked improvement relative to those in low salinity. Creeping red fescue is an excellent turfgrass but care should be taken if considering it for use in high salinity areas.
Hard fescue (Aurora)
Under irrigation, hard fescue yielded best under low salinity (<3 dSm-1) and also did well under medium salinity (3-9 dSm-1). In both of these salinity zones, the highest yields were obtained in the first year of the experiment. Yields decreased by 7.8 % for each dSm-1 increase, therefore hard fescue is not recommended for turf use on highly saline soils.
Sheep fescue (Nakiska)
Under irrigation, sheep fescue had consistent production in the low and medium salinity zones, but production was reduced considerably under high salinity. Results were similar under dryland conditions.
Under dryland, in the low (<4 dSm-1) and medium (4-9 dSm-1) salinity zones, the total yields increased over the course of the three years and remained about the same in the high (>9 dSm-1) salinity zone. Sheep fescue is not recommended as turf for use on soils with salinities greater than 9 dSm-1.
Kentucky bluegrass (Troy)
Under irrigation, the Kentucky bluegrass had moderate yields which decreased from 1991 to 1992 but then increased slightly in 1993. This may have been due to the large amount of rain received in 1993. Kentucky bluegrass had its lowest yields under high salinity.
Under dryland conditions, Kentucky bluegrass had yields which increased over time for all three salinity zones. Increasing from low (<3 dSm-1) to high (>9 dSm-1) salinity reduces yields by half. In a turf situation (irrigation or dryland), Kentucky bluegrass would not be recommended in an area where salinities exceed 9 dSm-1.
Creeping bentgrass (Emerald)
Creeping bentgrass is a very low growing turf species and this is reflected in its low yields. At the irrigated site, it produced well in low and medium salinities but yields were reduced by more than half in high salinity. The first year had the greatest yields for all salinity zones.
At the dryland site yields were poor over the full range of salinities because creeping bentgrass requires adequate moisture for growth.
Weeping alkaligrass (Fults)
Weeping alkaligrass had good salinity tolerance on both the irrigated and dryland plots. Yields were highest on medium salinity, except in 1993, where they were highest in the high salinity zone at both sites. Along with tall fescue, weeping alkaligrass was one of the most saline tolerant, based on its percent yield decrease per dSm-1 increase. It is recommended for turf use on soils where salinity exceeds 9 dSm-1. It is also an excellent low growing grass for reclamation purposes.
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