Recovery 1
Recovery 1 Tacoma, WA bullet (800) 949.5852
Recovery 1 is a Resource Recovery, Recycling & Research Facility Dedicated to Developing Sustainable Waste Management Systems
Waste is a Resource Out of Place

Recovery 1 wood chip mulch

    Wood chips made from recycled wood from Recovery 1 inc. and arborist chips tested for their effects on annual weed suppression and the health and growth of transplanted Douglas fir (Pseudotsuga menziesii) and snowberry (Symphoricarpos albus). Both types of wood chips were applied in coarse (1.09 to 7.62 cm) and fine (≤1.09 cm) particle sizes, at depths of 10, 20, or 30 cm.

    Annual weed biomass was not significantly affected by wood chip type or particle size.  Weed biomass was significanlty affected by depth; the average annual weed biomass collected was 59.4 g/m2 from 10, 20, and 30 cm mulch depth, respectively.

    Plant health was rated on a 1-5 scale, with 5 being the healthiest. Douglas fir health, height, and caliper were not significantly affected by depth. Douglas fir health, height, and caliper were significantly affected by particle size. Trees showed poor health and growth in fine particles of either type of wood chips and grew much better in course chips of either type. When in coarse particles, trees showed no difference in health and growth between arborist wood chips and Recovery 1 wood chips. However, when in fine chips, where the trees were showing poor health and less growth than in coarse chips, there was a difference between the wood types with trees in arborist chips doing better than trees in Recovery 1 chips.

    Snowberry plants were not affected by any treatment and showed healthy growth in any depth, at any particle size, and in either type of wood.

    From this research, Recovery 1 wood chip mulch was shown to be just as good at suppressing weeds as arborist wood chip mulch, maintained at a depth of at least 20 cm (though 30 cm is would be better). In general, coarse particle Recovery 1 wood chip mulch performs just as well as arborist wood chip mulch. The use of fine particle mulch in thick layers is not recommended, as it can have a negative impact on plant health as demonstrated with the Douglas fir trees.


Dr. Eric Owl Eulenberg




 Centimeters  = Inches 
 1  =  0.39
 10  =  3.94
 20  =  7.87
 30  =  11.81