Gd. Schwenke et al., Soil stripping and replacement for the rehabilitation of bauxite-mined land at Weipa. III. Simulated long-term soil organic matter development, AUST J SOIL, 38(2), 2000, pp. 395-410
Long-term trends in soil organic carbon (C) and nitrogen (N) under current
and alternative rehabilitation practices at Weipa were simulated using the
CENTURY model. After 100 years, predicted organic C in the surface soils (0
-20 cm) of each treatment had risen to new dynamic equiliPbria. Since the '
passive' pool of recalcitrant organic C, which occupied 47% of organic C, c
hanged little over the simulation period, the new equilibria differed accor
ding to initial organic C content. Most organic matter recovery occurred in
the 'slow' fraction, although the greatest rate of change occurred in the
'active' C pool, which stabilised within 50 years at levels similar to the
native forest. Similarly, 'slow' C accumulated in all treatments to new equ
ilibria which were similar to that in undisturbed forest soil. The main dif
ference between treatments was in the predicted time until a stable equilib
rium in the 'slow' pool was reached: between 90 and 160 years depending on
the soil stripping and replacement operation used. Successful development o
f new equilibria was highly sensitive to the amount of legume N-2 fixation
in the system and also to the severity of C and N losses during fire events
. Reasonable agreement was found between simulated organic C accumulation a
nd that observed in surveyed rehabilitation of up to 15 years of age (r(2)
= 0.67 for freshly replaced soils, r(2) = 0.72 for soils stockpiled before
respreading).