A salinity risk index for soils of the Canadian Prairies

Agricultural land use can impact the sustainability of inherent soil quality by its influence on the extent, severity, and dynamics of soil salinity. To assess this impact, a salinity risk index was developed and applied to the agricultural region of the Canadian prairies, utilizing land-use data sets for 1981 and 1991. The analysis is presented in map form. The total extent of moderate or more severe salinity for the prairie region, as determined from a summation of each provincial map, is 1.4 million hectares. The risk assessment based on 1991 land-use data indicates that 62.2 percent of the farm land has little to no risk of a change in salinity, 27.9 percent has a moderate risk, and 9.9 percent of the land has a high risk. A comparison of the risk index classes for the 1981 and 1991 land-use data indicates that risk of salinity for the majority of the land (92 percent) had not changed, whereas less than 7 percent of the land had a lower risk class, and approximately 0.5 percent had a higher risk class in 1991. This approach could be utilized periodically to track the impacts of changes in land and thus serve as an indicator of agri-environmental sustainability. This information could be applied by upper levels of government to develop programs and to define agricultural policy.