Spread Without Incorporation on a Slope Trial 


To evaluate the impact of sludge application without incorporation on non-frozen soils with nearly level to rolling topography


The spread without incorporation on a slope trial was established in 1997 at 3 different locations in a cut-block located in 19-58-18-W5. The trial included:

  • 21 plots each measuring 10 m x 25 m
  • 3 sludge application rates - 0, 50 or 80 t/ha of ANC sludge
  • 80 lodgepole pine seedlings were planted in each plot in July 1998
  • Tree height measurements were completed immediately after planting
  • Annual height and diameter measurements were taken from 1999 to 2007, and 2010
  • Baseline soil samples were collected in 1997 in 15 cm depth intervals to 50 cm in 15 of the plots. 
  • Post-application samples were collected to various depths from 1998 to 2002
  • Initially surface water samples were obtained in various locations to evaluate runoff water quality, however it was deemed unnecessary to sample surface water subsequent to 1999

Results and Conclusions

  • Although results indicated that sludge application increased tree heights, diameters and volume for each of the areas assessed, tree survival for each of the areas was not equivalent. 
  • The initial vegetative cover in each of the areas prior to sludge application was different. 
  • The center area was lower, wetter and dominated by marsh reedgrass
  • The north and south areas were located in the mid to upper slope positions, thus were drier and less dominated by grasses.  
  • The grass flourished with the application of sludge and impacted the survival and performance of the planted seedlings.
  • Seedlings that were planted in more dense grass covers demonstrated less vigor than those in open areas.
  • Sludge is less effective as an amendment for tree growth in areas where grasses are a dominant component of the ground cover or where moisture availability is not a limiting factor.
  • There was no significant difference in terms of tree growth between the 50 and 80 t/ha applications, however the 50 t/ha application showed less dense competing vegetative cover and had less potential for NO3-N leaching indicating that the 50 t/ha application rate is more suitable for application in forest cut-blocks prior to planting.
Area Application Rate (t/ha) Age Shift Growth Multiplier
 Height Diam Height  Diam 
ANC Spread w/out
Incorporation on a Slope
 50 2.9 8 1.12 1.35
80 4.5 12.7 1.19 1.55

Tree stem volume and projection

Pine survival at the spread without incorporation on a slope trial in 2007

  • The south plot area was located on a slope ranging from 14 to 17% above a poorly drained organic soil area. 
  • The centre plot area was located adjacent to a pond and has a slope ranging from 0 to 2%
  • The north plot area was located approximately 35 m from a stream and has slopes ranging from 11% to 14%.