Disturbed Forest/Reclaimed Road Trial

Objective:

To assess the benefit of sludge for reclaiming a disturbed forest road.

Methods

  • 14 plots (5 m x 10 m) were established on a chip site haul road  in 1994.
  • The site was divided in half for winter and summer De-ink sludge application.
  • Summer application occurred on July 14, 1994. 
    • 3 plots received 60 t/h
    • 3 plots received 100 t/h
    • Sludge was incorporated with a caterpillar mounted ripper on July 15, 1994. 
  • Winter application occurred on November 24 and 25, 1994. 
    • 3 plots received 60 t/h
    • 3 plots received 100 t/h
    • Incorporation (ripping) was completed on December 21, 1994. 
  • Ten lodgepole pine (Pinus Contorta var. latifolia) seedlings were planted in each of the summer and winter application plots in August 1994.  
  • Pre and post application soil samples were collected for all treatments
  • Soil moisture and bulk density were measured until 1998. 
  • Tree heights and diameters were measured from 1994 to 2007 and again in 2010.  

Results

  • Differences between winter and summer application were confounded by slope and moisture conditions.
  • Tree height, diameter and stem volume data indicated that there was a slight enhancement in tree growth compared to controls, although the effect was not as significant as other trial areas.
  • Stem volume results for summer and winter applications of 0, 60, and 100 t/ha indicated there was very little treatment effect on the summer applied treatments.
  • One potential explanation for the limited effect of sludge application at this trial is the compaction that resulted from vehicle traffic on the road that was not properly scarified prior to treatment.
  • Age shift and growth mulitipiers for both winter and summer applications did not show significant increases in height or diameter compared to the control
    • It should be noted that the control was influenced by the location on the reclaimed road.
  • Elevated NO3-N values were observed when sampling soils to depths below 1 m after sludge application.

Conclusions

  • Site treatment prior to sludge application can have a major influence on the ability of sludge to have a positive impact on vegetative performance. 
  • There were no real differences in tree performance with summer or winter sludge application.
  • Additional research with respect to the benefits of sludge for reclamation was recommended.