The application of mulch products to disturbed soil is frequently used to decrease soil erosion. The addition of polyacrylamide (PAM) has been demonstrated to reduce erosion even further. We conducted rainfall-simulator and field tests on several types of mulch, hydromulch, and erosion control blankets with varying rates of PAM to determine the relative improvements in erosion control and vegetative establishment achieved by different groundcovers and PAM. We also compared applications of granular (37 and 74 kg ha-1) and aqueous (37 kg ha-1) PAM with straw. The tests were done on 2- x 1-m soil boxes tilted to 32% slope and three field locations with similar slopes. Under simulated rainfall, the addition of 37 kg ha-1 aqueous PAM to any mulch type tended to reduce runoff turbidity, TSS, and sediment loss, with reductions of 50% or more in some cases. In the absence of PAM, increasing hydromulch rate from 1971 kg ha-1 to 2957 kg ha-1 significantly reduced turbidity for an experimental cotton product but not for wood fiber. Granular PAM, when applied at a rate equal to that of aqueous PAM, had a significantly higher mean turbidity and TSS; total sediment loss was reduced by dry-PAM only at the higher rate. The lower rate of granular PAM apparently did not reduce erosion but did flocculate the sediment captured in the runoff collection bucket, reducing turbidity. In field experiments, bonded fiber matrix had significantly lower biomass and vegetative cover than all other treatments at one site but differences were not significant at other sites. In one instance where a cotton fiber matrix test product washed off the slope face, runoff turbidity and TSS was significantly higher than other treatments. There were no instances of straw with PAM significantly improving biomass or vegetative cover compared to straw alone.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-04252008-143910 |
| Date | 28 April 2008 |
| Creators | Babcock, Deanna |
| Contributors | Greg Jennings, R.A. McLaughlin, H.J. Kleiss |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-04252008-143910/ |
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