EFFECTS OF SEEDBED TREATMENT ON GRASS ESTABLISHMENT 

 ON LOGGING ROADBEDS IN CENTRAL IDAHO 

 W. J. Kidd, Jr., and H. F. Haupt 



INTRODUCTION 



Soils derived from the granite of the Idaho Batholith of central Idaho erode 

 rapidly when disturbed or bared by man's activities. Thus, logging roads needed to 

 develop the timber resource necessarily expose a large area of unstable soil to damage 

 by erosion. As a remedial practice, the bared areas are sown with perennial grasses 

 that develop deep, fibrous root systems capable of binding and holding the soil, and 

 that also provide litter cover and protect the soil from raindrop splash. 



The seeding is usually done when logging roads are "put-to-bed" following timber 

 harvest operations. Either motorized or hand seeders are used to broadcast seed. 

 Usually no attempt is made to cover the seed or to precondition the hard-packed roadbed 

 before seeding. The accepted practice in this area is to broadcast a mixture of seeds 

 late in the fall. In the ponderosa pine areas east of the Cascades in Oregon and 

 Washington, fall seeding is also the practice, according to Gjertson (4). The seeds 

 lie dormant over winter and germinate as soon as snow disappears in the late winter or 

 early spring. Experience has shown that spring seeding generally results in failure 

 because the poorly developed seedling root systems cannot survive the hot, dry summers. 



Field results from broadcasting seed have varied because of the diverse site 

 conditions associated with roadbeds. Poor stands of perennial grasses have been as 

 common as good stands. Consequently a more reliable method of establishing a dense 

 grass cover on roadbeds is needed. 



j^^' ;,' : This paper presents the findings of a reseeding study designed to determine (a) 

 * whether scarifying a hard-packed roadbed, either before or after broadcasting seed, 

 ""leads to establishment of a better stand of grass than one grown on an untreated 

 s^roadbed, and (b) whether a wood-chip mulch, with or without fertilizer, further 

 '^encourages the growth of grass. A secondary objective was an evaluation of the 



-survival of five well-known perennial grass species growing on an extremely harsh 



.^5ite--the bare surface of a logging road. 



DESCRIPTION OF THE STUDY AREA 



'4«''The experimental area is 20 miles northeast of Idaho City on the Little Owl Creek 

 ^drainage of the Boise National Forest. The elevation ranges from 5,000 to 6,000 feet 

 and land slopes are moderately steep, averaging 46 percent (5). At this altitude 

 cnderosa pine and Douglas-fir grow in mixed stands. The soil, a coarse-textured 

 ^oany sand typical of the Idaho Batholith, h as a weak profile development, low humus 

 water-holding capacity, and is highly erodible. 



i< T - 



In the 3 years of study, annual precipitation as measured in gages within the. 

 Uidy area, averaged 37 inches; of this amount 10.0 inches was received in the period 

 ^4 1 ~^ ^^^°"gh September 30, which includes the growing season. Within the period, 

 ?ril and May rains accounted for 7.8 inches; the remaining 2.2 inches fell during the 

 l^nth dry period, June 1 through September 30, Compared with long-term U.S. Weather 

 ^^^^au records for the closest stations, growing-season rainfall on the Little Owl area 

 Slightly above normal for the three growing seasons following seeding. 



