Revegetation Guidelines for Western Montana - Global Restoration ...

Harrowing or raking is a secondary tillage operation that uses a spiked or toothed cultivating
implement to roughen the soil surface uniformly. Dragging small chains can also uniformly roughen
the soil surface. These methods are generally employed to break up crusts or to lightly cover seeds;
it is recommended these methods be used prior to, and following, broadcast seeding. Light packing
of the soil following broadcast seeding is beneficial.
Burned area revegetation typically does not require seedbed preparation if reseeding immediately
following a fire. A fall dormant broadcast seeding into the ash will cover and retain seeds. The wet /
dry / freeze / thaw action of the moisture during subsequent seasons will work the seeds into the soil
while also breaking down any hydrophobic soil layers. Frost heaving will also break down any ash
crust layers that may have formed from fall rains before or after reseeding. Harvesting fire-killed
trees is often implemented to prepare site for revegetation (if necessary), to reduce falling tree
hazards, reduce disease, and provide income to offset fire losses.
Soil amendments
Amendments are additions to soils prior to or shortly after seeding to provide a better medium for
plant growth. In many cases, the addition or reduction of nitrogen or soil microorganism additions
can greatly enhance seeded species establishment.
Nitrogen fertilizers should only be used when a soil test has revealed a gross deficiency or
in mesic sites when agronomic species, such as tall fescue (Festuca arundinacea), are seeded
when rapid growth and maximum production is desired. Smooth brome (Bromus inermis)
may require nitrogen fertilizer if the soil is not adequately
fertile (Smoliak et al. 1990). The high nitrogen requirements
of these non-native grasses make them well suited for use in
mixtures with nitrogen-fixing legumes such as alfalfa.
A healthy functioning
nitrogen cycle is
essential to long-term
revegetation success
Rarely is nitrogen needed for native species, especially lateseral
grasses like bluebunch wheatgrass (Pseudoroegneria spicata ssp. spicata). These
grasses have minimal nitrogen requirements, having evolved in low nutrient environments.
In many revegetation cases, reducing the amount of available nitrogen in the soil can
increase late seral grass establishment by reducing weed interference. For instance, when
seeding late-seral native grasses, such as bluebunch wheatgrass in moderate or high nitrogen
sites, consider seeding a sterile cover crop, such as Regreen or triticale that can quickly
sequester nitrogen. This nutrient reduction will hinder noxious weed growth while favoring
the late-seral seeded species. Cover crops further favor seeded species by:
• Providing quick protection to seeds and soil from erosion by wind and water;
• Conserving soil moisture from the effects of wind and sun; and
• Moderating soil temperatures.
The addition or reduction of nitrogen can have significant effects on noxious weed growth.
The reduction of soil nitrogen through cover crop sequestration can benefit native grasses
while addition of non-essential nitrogen reduces important mycorrhizal activity (St. John
1997) and encourages heavy weed growth that overwhelms slower growing natives. In a
southeastern Montana study, the main responses to nitrogen fertilization in a dryland
situation were increased annual grass or annual weed production and decreased diversity
(Hertzog 1983). Avoid nitrogen additions when seeding native grasses.
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