A little while back, John, Tara and Henry of the Erosion Control Training Facility conducted a pretty big Hydromulch study looking to answer the question:
”Does the application rate of 4,536 kg/ha (vs. 2,268 kg/ha) inhibit native grass seed from germination and growth?”
We've made the entire paper available for download here.
Here is the abstract...
Beginning in December of 2008, Shasta College’s Instructor John McCullah and his students from the watershed restoration class started hydro mulch test trials, at the Shasta College Erosion Control Training Facility, with the goal of answering the question”Does the application rate of 4,536 kg/ha (vs. 2,268 kg/ha) inhibit native grass seed from germination and growth?”
The study included 18 test plots (15ft x 10ft) on a 2:1 grade that had been track walked by a bulldozer. Using native California grass seed (Nasella pulchra), the plots were seeded before being hydro mulched and chosen plots were fertilized using Biosol and AM120 Mychorrizae. Six different products were applied, including Cotton Fiber Matrix, Flexterra, Soilguard, Terrawood, HydroStraw and Compost. Two control plots were established. One was track walked with no further treatment and the other was track walked, seeded and fertilized at the same rate as the other test plots.
The study included four test plots for each product. The application rate was set at 2,268 kg/ha and at 4,536 kg/ha. Students observed grass growth on each plot, each products’ ability to prevent erosion, and product retention on the soil surface in order to compare the effectiveness of the tested applications and to determine if 4,536 kg/ha application rates would inhibit seed germination and grass growth.
Student observations showed no indication that the application of any hydro mulch product tested in this study, at the rate of 4,536 kg/ha, inhibits seed germination or growth more than an application rate of 2,268 kg/ha. The application rate of 4,536 kg/ha appears to have performed better in terms of erosion control, soil stability and product retention through only one rain season.
Finally, the compost application of a 5cm (2”) blanket of medium screened, locally produced compost product performed significantly better in all criteria ( time to seed germination, quantity of seed germinated, growth , erosion control effectiveness, product retention on the plot) than any of the other hydro mulches tested.