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Hydroseeding of forest road slopes for erosion control and resource protection

University of British Columbia

Soil erosion resulting from logging road construction is a serious problem affecting physical stream water quality and road stability in British Columbia. This study investigates slope re-vegetation by hydroseeding to alleviate this problem. Laboratory tests on the effect of fertilizer slurry contact on seed germination show a 30% loss in Trifolium repens germination after a 60-minute exposure to a solution of 90 kg 10-30-10 fertilizer per m³ of water (750 lbs fertilizer per 1000 gallons water). Although there was no significant effect of such exposure on Rhizobium inoculum, care must be taken to limit seed soaking time in the hydroseeder and to keep slurry fertilizer concentration as low as possible. Field hydroseeding tests show no significant advantage from separate applications of seed then fertilizer, nor from the use of a mulch in connection with slurry application. The effect of seed-fertilizer contact in the slurry did not appear to be operationally significant. Mulching did not have a significant effect on the composition of the vegetative cover established nor on the effectiveness of the plant cover in erosion control. All hydroseeding treatments yielded satisfactory vegetative cover (averaging 65%) and similar vegetative composition. Soil on untreated control plots eroded an average depth of 2.3 cm (0.9 in) from September 1976 to April 1977. This translates to 256 m³ of eroded soil material per km of logging road (540 cu yd per mile), assuming 1.5 ha of exposed side slope per km (6 acres per mile). The vegetation not only was successful in halting erosion from the vegetated areas, but it also acted as a catchment for soil particles brought into these areas from upslope by gravity and water erosion. The one-step slurry application of seed-fertilizer-soil binder and water was as effective in vegetation establishment and erosion control as the other hydroseeding treatments and much cheaper. Based on 1976 costs, it would take approximately $2000 to hydroseed a kilometer of logging road ($3000 per mile) by this method. This is a small investment for road-side revegetation that can protect the integrity of a forest road (which may initially cost upwards of $60,000/km), reduce road maintenance costs, and greatly benefit the adjacent aquatic environments.

Text

2010-02-16

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http://hdl.handle.net/2429/20295

Forestry

University of British Columbia

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