The effect of seeding rate on the establishment of Great Basin Rangeland perennial grasses

Authors: Harmon, Daniel; Clements, Darin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/8/2025
Publication Date: 2/10/2026
Citation: Harmon, D.N., Clements, D.D. 2026. The effect of seeding rate on the establishment of Great Basin Rangeland perennial grasses. Meeting Abstract. 79:60.

Interpretive Summary:

Technical Abstract: Tens of millions of hectares in the western United States are invaded by exotic annual grasses. This invasion displaces native vegetation, alters ecosystem function and increases wildfire frequency and intensity. The economic impact from reduced forage and wildlife habitat can be significant and warrants active management efforts to reduce annual grass dominance. The most effective means for sustainable control of annual grasses is through competitive exclusion by established perennial grasses. Competitive grasses, like Siberian wheatgrass (Agropyron fragile), require about 4 plants/m2 minimum to utilize most soil resources and competitively exclude annual grasses such as cheatgrass (Bromus tectorum). In 2024 and 2025 we tested three seed rates at three sites in northern Nevada using six perennial grass species. We used a medium rate (standard single species rate), a low rate (50% less than standard), and a high rate (50% more than standard). Knowing the minimum amount of seed required to establish effective plant densities is very important to reduce the cost of seeding efforts. Overall, only Siberian wheatgrass and crested wheatgrass (Agropyron cristatum) established at the goal density of at least four plants/m2 and only for only drill seeding treatments (mean greatest density plants/m2, all sites both years: crested wheatgrass 5.3, Siberian wheatgrass 4.9, Sandberg bluegrass (Poa secunda) 2.6, bluebunch wheatgrass (Pseudoroegneria spicata) 2.0, thickspike wheatgrass (Elymus lanceolatus)1.5, and bottlebrush squirreltail (Elymus elymoides) 0.5). The low drill seeding rate (4lbs/acre) did not establish four plants /m2. Broadcast seeding at best established 1.2 plants/m2 (Siberian wheatgrass). We found one example of the medium rate being significantly greatest, which might indicate intraspecific competition at high seeding rates. Based on our results, we recommend using drill seeding whenever possible, avoiding low seeding rates, and using only those species that can establish at effective densities to competitively exclude annual grasses.