Location: Livestock and Range Research Laboratory
Project Number: 3030-21500-001-003-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Apr 7, 2022
End Date: Mar 30, 2027
Objective:
This study varies cool-season grass seed rates and uses herbicides indaziflam and glyphosate to increase success of revegetation efforts on coal mining lands.
Approach:
Study to Control Competition of Annual Bromes and Seeded Grasses
At 3 sites a year for 3 years, we will begin experiments (9 experiments total) that combine herbicide treatments to control annual bromes with cool-season grass seed rate treatments to limit seeded grass competition. Herbicide treatments will be the pre-emergence herbicide indaziflam applied alone or mixed with the non-selective post-emergence herbicide glyphosate. Cool-season grass seed rate treatments will be a subset of those used in the previous study (0.5, 1.0, and 6.0 lb PLS per acre). Specifically, the treatments will be:
1) Grasses seeded at 0.5 lb/acre
2) Grasses seeded at 1.0 lb/acre
3) Grasses seeded at 6.0 lb/acre
4) Grasses seeded at 0.5 lb/acre and indaziflam
5) Grasses seeded at 1.0 lb/acre and indaziflam
6) Grasses seeded at 6.0 lb/acre and indaziflam
7) Grasses seeded at 0.5 lb/acre and glyphosate plus indaziflam
8) Grasses seeded at 1.0 lb/acre and glyphosate plus indaziflam
9) Grasses seeded at 6.0 lb/acre and glyphosate plus indaziflam
Each of these 9 treatments will be replicated twice in each experiment, so there will be 18 plots (9 treatments × 2 replications) per experiment. Each plot will be three seeder passes wide and 100 feet long. As in the previous study, forb and shrub seed rates will be the same in every plot within an experiment. Seeding will occur in winter or spring, and herbicides will be applied in late summer or fall after the first growing season. The indaziflam alone treatment will be applied in August shortly before annual bromes germinate. Indaziflam kills plants only as they germinate, so it should cause little damage to native grasses, forbs and shrubs which will have mostly emerged prior to treatment. Because glyphosate risks damage to actively growing native grasses, forbs, and shrubs, the glyphosate plus indaziflam treatment will be applied in September or October when native plants are mostly dormant and annual bromes have emerged and are growing. The vegetation measurement protocol will resemble that used in the previous study. Ten frames (1.0 m × 1.0 m) will be positioned at fixed intervals along a transect in the center of each plot. The first growing season after seeding, we will measure density of all seeded species and cover of all unseeded species in each frame. In subsequent growing seasons until the end of a 5-year funding period, we will measure cover of each species as well as shrub density and volume (height × width in two perpendicular directions) by species.
Continued Monitoring of Previous Experiments
We will measure 7 existing experiments in summer 2022 and 2023 and all 18 experiments in summer 2024. The measurement protocol will be that used in previous study years. Seven frames (1.0 m × 1.0 m) will be positioned at fixed intervals along a transect in the center of each plot. Visual estimates of cover will be recorded for each species in each frame, as will shrub density and volume by species.
