Soil salinity effects on germination of native and introduced grasses

Authors: Riedell, Walter

Submitted to: Soil/Water Research, Progress Report
Publication Type: Experiment Station
Publication Acceptance Date: 3/14/2011
Publication Date: 4/1/2011
Citation: Riedell, W.E. 2011. Soil salinity effects on germination of native and introduced grasses. Soil/Water Research 2010 Progress Report. Agricultural Experiment Station, South Dakota State University. https://www3.sdstate.edu/ps/research/soil-fertility/reports/upload/PR10-21-Riedell.pdf.

Interpretive Summary: Soil salinity on poorly drained and subirrigated soils in the James River valley in east central South Dakota has intensified over the past 20 years. Replacing water evaporation from the soil surface with transpiration through deep-rooted salt-tolerant perennial plant species may help remediate soil salinity by utilizing excess soil moisture which, in turn, will help leach salts through the soil profile. To develop such a strategy, grass species that germinate under saline conditions must first be identified. The objectives of this report were: 1) to characterize the soil salinity levels in a typical saline soil in the James River valley, and 2) to provide some preliminary information on greenhouse experiments designed to identify native and introduced grass species that germinate under saline conditions. Electrical conductivity levels of the saline lowland soil increased close to the soil surface, likely because of salt deposition as soil water evaporated from the surface of this poorly drained sub-irrigated soil. Three of the species that performed well in the greenhouse trials also did well under field conditions. In contrast, three other species, which also were highly ranked in the greenhouse study, had very poor establishment under field conditions. The reasons for these discrepancies between greenhouse tests and field performance under saline conditions may be related to salinity effects on early seedling growth. Additional studies on saline soil effects on early growth are therefore warranted.

Technical Abstract: Increasing salinity of formerly productive soil in the James River valley in east central South Dakota is an increasing concern for crop producers. This problem arises when water evaporates from poorly drained and subirrigated soils and leaves salts on the soil surface. Replacing evaporation from the soil surface with transpiration through deep-rooted salt-tolerant perennial plant species may help remediate soil salinity by utilizing excess soil moisture which, in turn, will help leach salts through the soil profile. The first step needed to accomplish this goal is to identify plant species that germinate under saline conditions. A laboratory assay was developed and used to evaluate germination of 16 perennial grass species in a soil with an electrical conductivity ranging from non-saline (2 dS/m) to very strongly saline (14 dS/m). Russian wildrye and tall wheat grass germinated at 14 dS/m while streambank wheatgrass, Nutall alkaligrass, slender wheatgrass, and switchgrass (‘Sunburst’) germinated at 11 dS/m. The laboratory assay correctly identified the 3 species that grew under saline conditions in the field as well as several other species that merit further field evaluation.