By Charlotte Ward, PAg, Agri-Environmental Specialist, Yorkton
Soil salinity is considered a threat to long-term sustainable production in many parts of the Prairies. Agriculture and Agri-Food Canada estimates approximately 5.52 million acres of agricultural land in Saskatchewan are at moderate to high risk of salinization.
Soil salinity levels range from non-saline (zero decisiemens per metre (dS/m)) to very severely saline (greater than 16 dS/m). As soil salinity levels increase, the stress on germinating seedlings also increases. Soluble salts prevent plants from taking up the proper balance of nutrients and water required for growth. In general, perennial plants can handle salinity better than annual plants.
Perennial forages have various levels of salt tolerance. Species such as tall wheatgrass, green wheatgrass, altai wildrye, Russian wildrye, slender and western wheatgrass have high salt tolerance (<16 dS/m). Slightly less saline tolerant forages include sweet clover, established alfalfa, tall fescue, and smooth bromegrass (<8 dS/m) as well as crested wheatgrass, intermediate wheatgrass and meadow bromegrass (<4 dS/m). Seedling alfalfa, white, red and alsike clovers have very low salt tolerance (2 dS/m). In comparison, barley has a salt tolerance of 8 dS/m.
Recent forage breeding programs have recognized the challenge salinity poses to agricultural production and efforts have been made to develop forage varieties or species with improved salt tolerance. For example, newly developed varieties of alfalfa and green wheatgrass exceed the salt tolerance levels of their predecessors.
As salinity can vary within a very small area, one strategy when establishing forages in saline areas is to seed a complex mix of grasses and legumes with varying levels of salt tolerance. The result is greater establishment success and lessens the likelihood of establishment for weedy species such as foxtail barley.
Late fall plantings are often the best time to establish forages in saline soils when drier soils permit machinery to cross with minimal difficulty. Seeds will germinate early the following spring. Once established, perennial forages can have water-depleting characteristics which can be used to draw down the water table, leading to decreased soil salinity near the soil surface.
The Ministry of Agriculture Farm Stewardship Program provides information and financial assistance for producers to implement beneficial management practices (BMPs) that enhance sustainability and resiliency in the sector. The Permanent Tame Forage BMP provides funding for the conversion of annually cropped acres where salinity is present and impacting crop production, to perennial forage production. For more details and eligibility requirements for the Permanent Tame Forage BMP, please visit the Farm Stewardship web page.