Influence of Amendments and Soil Depth on Available Nutrients and Microbial Dynamics in Contrasting Topsoil Materials Used for Oil Sands Reclamation
Howell, D. Mark. 2015. University of Alberta, M.Sc.
Abstract
As of December 2013, the cumulative area disturbed by oil sands mining in NE Alberta
was
896 km
2
out of an estimated final footprint of 4,800
km
2
all of which will require
reclamation.
Expensive handling costs and scarce soil resources necessitate judicious
management and application of salvaged topsoils and
soil
amendments
such that the post
-
mining
landscape
is re
-
established to
an %u201Cequivalent land capability%u201D of pre
-
disturbance conditions. Soil
microbial communities and microbially mediated nutrient a
vailability are largely overlooked in
reclamation analyses, despite their potential in providing a sensitive measurement of ecosystem
processes.
This
study measured nutrient availability and microbiological parameters in
directly
-
placed
forest floor mix (
FFM) and peat mix (PM)
, which were compared to natural reference
sites. The study was divided into two components: 1) assessing fertilizer and charcoal
amendments (reclamation to d ecosite); and 2) assessing topsoil application depths (reclamation
to a/b
ecosite).
1) The principal study on CNRL%u2019s Reclamation Area
-
1 (RA
-
1) compares a fertilizer
amendment on PM and FFM.
I
added a charcoal amendment to simulate natural additions
to soil
from wildfire; and compared reclaimed treatments to recently burned and unburned natural
reference sites. Microbial biomass
-
carbon was greatest in natural and reclaimed organic soils.
Burning and charcoal amendments tended to increase metabolic quotient, indicating potential
nutrient stress or decomposition inefficiency.
Nutrient profiles differed mostly between natural
and reclaimed sites, followed by sites receiving fertilizer. Fertilization increased
TIN
availability
by two orders of magnitude above unfertilized treatments, while P and K availability were below
natural variation.
2)
Syncrude Canada%u2019s Aurora
Soil
Capping Study
provided
Shallow and Deep
topsoil
application depths of
PM and FFM which
were compared to
a control
receiving no topsoil
and a
harvested analogue
(Harvest).
Soil respiration rates were greater in FFM and Harvest than in PM
treatments, with no difference attributable to subsoil type or placement depth.
Phospholipid fatty
acid analysis (PLFA) and community level physiological profiles (CLPP) measured microbial
community structure and function, respectively.
Non
-
metric multidimensional scaling
ordinations
revealed
the
greatest similarity between FFM and Harvest for available nutrients,
PLFA and CLPP analyses.
Deep FFM application shared greatest PLFA similarity to Harvest,
but Shallow FFM was more similar in CLPP.
Shallow PM was more similar than Deep for all
parameters measured.
PM indicated greater
TIN
and S availability, and deficiencies in P and K
compared to FFM and Harvest.
