Adaptation of grasses for soil and water conservation at high altitudes

Eleven grass species, representing five use groups, were tested for adaptation to semiarid conditions at high altitude at the Tetonia Branch Station of the Idaho Agricultural Experiment Station. The trials were conducted on land that had been previously farmed with the wheat-fallow system for approximately 26 years. This system of farming had caused 50% reduction of the soil organic matter. Adaptation of the grasses used in the trial was measured by level and uniformity of total yield, volume weight of soil from each grass plot after the grasses had been established for 6 years, and the total soil organic matter content after the 6-year period. The results of this trial permit the following conclusions: 1. Big bluegrass, pubescent wheatgrass, smooth bromegrass, Fairway crested wheatgrass, and intermediate wheatgrass restored soil organic matter to levels that were not significantly different from the organic matter content of the virgin soil. 2. Soil from all grass plots was significantly higher in organic matter than soil from land that had continued to be farmed with the wheat-fallow system. 3. Sherman big bluegrass produced the highest total yield and resulted in the highest content of soil organic matter. 4. Fairway crested wheatgrass produced a significantly higher content of soil organic matter than the standard strain. 5. Grasses producing fine fibrous roots such as the fine-leaved fescues may not produce the highest amounts of soil organic matter content but there may be a favorable effect on soil structure as evidenced by volume weight of soil. 6. In the bunch-type wheatgrasses, bluebunch wheatgrass was better adapted than either standard or airway strains of crested wheatgrass. 7. Based on uniformity of data, intermediate wheatgrass showed better adaptation than all other species included in the large sod-forming grasses. 8. Hard fescue is better adapted to the site than Chewing's fescue. 9. Orchardgrass, a rapid developing long-lived grass, and a Columbia Basin strain of thickspike wheatgrass were out of their range of adaptation.