By Erin Teichroew, Graduate Research Assistant, Montana State University, erin.teichroew@student.montana.edu

Introduction

Four whitish colored pellets on the ground with plant litter scattered around.

Intact seed pellets in the field. Photo: Erin Teichroew, MSU.

Rangelands across the western United States that are infested with invasive plants may need active restoration. Drill seeding native species can be successful but is not an option on steep or rocky terrain where the most accessible revegetation method is broadcasting seed. However, broadcast seeding with native species is often unsuccessful due to low precipitation and seed predation in these semi-arid environments. One restoration technology that may increase seeding success is seed pellets, grouping seeds into protective pellets to reduce seed predation and promote establishment. The pellets we tested contained native perennial grass seed, a binding material (clay), and a nutrient source (cattle manure). We conducted studies testing variations of these seed pellets, to improve restoration success in controlled and field environments.

Methods

Square black containers with grass seedlings growing in them. Containers are arranged side by side and sitting on a metal table in a greenhouse.

Seedlings growing from seed pellets in the greenhouse. Photo: Erin Teichroew, MSU.

In a greenhouse we tested the impacts of clay content, pellet size, and watering rate on seedling establishment and pellet disintegration. Understanding the influence of these factors helps us to make field recommendations. We compared different amounts of clay (55%, 35%, 20%, 10%), size of pellets (0.5-1.0-inch diameter), and watering rates (zero to high) to see which combinations performed best; the lower water rates most closely resembled our rangelands. The number of seeds per pellet varied by size and clay content but ranged from 10-60 seeds. In the field we tracked seedling establishment monthly over the spring and summer, seedling survival and disintegration of seed pellets (made with 10% and 55% clay at our different sizes). We compared these results to broadcast seed (the same rate as pellets; 8.25 pounds pure live seed (PLS)/acre) and non-seeded control plots.

Results and Management Implications

In the greenhouse, clay content did not impact seedling emergence, but the largest pellets were more likely to produce seedlings. In the field, clay content did impact seedling emergence; emergence was higher for both the 10% (1.4 seedlings/5.4 ft2) and 55% clay pellets (1.0 seedling/5.4 ft2) than the non-seeded control treatment (0.5 seedlings/5.4 ft2), and the 10% clay pellets were also higher than broadcast treatments (0.8 seedlings/5.4 ft2). Additionally, pellet disintegration did not affect seedling establishment. End-of-season survival was higher in 10% clay pellets (2.6 seedlings/5.4 ft2) than in 55% clay pellets (1.2 seedlings/5.4 ft2) and non-seeded control treatments (1.0 seedling/5.4 ft2). We also found that the largest pellets produced more seedlings than smaller sizes. Overall, our study suggests that using larger pellets with low levels of clay may be more successful for seedling survival in semi-arid environments. This study reinforces that seed pellets can be a useful technology to aid in restoring semi-arid and arid rangelands where drill seeding is not available. While not commercially available, seed pellets can easily be made by hand or with the use of a rotary drum.

See more results and read the entire article by Teichroew and Rew, Testing the effects of seed pellet composition to aid in semiarid restoration seeding.

Further Information

For more information about this month's weed post, contact Extension Invasive Plant Specialist Jane Mangold. Past posts are available in the Monthly Weed Post Directory.

This weed post is also available as a printable PDF (246 KB).