Jm. Reichert et Ld. Norton, FLUIDIZED-BED BOTTOM-ASH EFFECTS ON INFILTRATION AND EROSION OF SWELLING SOILS, Soil Science Society of America journal, 58(5), 1994, pp. 1483-1488
Fluidized bed combustion (FBC) bottom ash, rather than being used as f
ill at dumping sites, can be utilized to amend certain soils for erosi
on control. Because FBC bottom ash is a source of both electrolytes an
d alkalinity, its effectiveness in controlling runoff and erosion shou
ld be greater on soils with a predominance of permanent charges. Five
soils, with and without addition of 5 Mg ha(-1) surface-applied FBC bo
ttom ash, were prewetted and subjected to 110 mm h(-1) rain for 90 min
. The critical flocculation concentration (CFC) varied from 0.5 mmol(c
) L(-1) for the smectitic-kaolinitic soil to 3.5 mmol(c) L(-1) for the
illitic soil. Steady-state infiltration rates (I,) for the control we
re very low, ranging from 1.8 to 5.8 mm h(-1). These rates were increa
sed 3.6- to 5.0-fold with the application of FBC bottom ash, with a le
sser increase for the highly smectitic and illitic soils. For the cont
rol, total soil loss ranged from 220 to 1998 g m(-2), and total water
loss from 78 to 112 mn, with the greatest losses for soils with a larg
e cation-exchange capacity/clay ratio. The FBC bottom ash reduced tota
l water loss by 1.1- to 2.0-fold and total soil loss by 1.5- to 3.9-fo
ld. The CFC of the soil was correlated with I,, while aggregate stabil
ity was correlated with erosion and total runoff. The FBC bottom ash e
ffectiveness in increasing infiltration and controlling erosion on the
se soils is attributed to an increase in electrolytes in the runoff, t
hus decreasing soil swelling and the dispersion of clay platelets and
preventing surface sealing.