Tone Ag Consulting uses a two step process to map soil salinity. First,we use Veris to measure the electrical conductivity (EC) of the soil across the field. Then we select areas of the field with high, medium, and low EC and take soil samples. These samples are sent to a soils laboratory to measure their salinity levels. The EC reading and the soil salinity measurements are then reconciled to produce an equation which is used to convert EC to soil salinity across the field.
There is no universal EC to soil salinity conversion because factors such as soil texture and moisture can affect the EC readings. As a starting point, PFRA has found that the following are good correlations for loamy soils.
| Salinity Level | EC Reading |
| None (0-2 dS/m) | 0-75 |
| Weak (2-4 dS/m) | 76-110 |
| Moderate (4-8 dS/m) | 110-175 |
| Strong (8+ dS/m) | >175 |
This electrical conductivity (EC) based on saturated soil extract is measured as deciSiemens/m or dS/m and normally ranges from less than 1 (very low salt for saturated paste method) to 10 or more on very saline soils.
A lot of our salinity work has dealt with the effects of salinity on irrigated potatoes. Potatoes have a threshold soil salinity tolerance of 1.7 dS/m, the level for which there is no loss of yield. For every increase in soil salinity of one unit of conductivity above this threshold, the yield potential decreases by 12 percent. A value approaching 4 dS/m in the soil would result in a 28% decrease in potential yield. If you are interested in the relative salt tolerance of crops grown in Manitoba, see MAFRI’s Crop response to salinity table.
If you suspect that salinity is an issue in some of your fields, give us a call and we can map out your fields and advise you on what to do to minimize its effects.
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