CHANGES IN SOIL pH AND CROP GROWTH FOLLOWING THE APPLICATION OF LIMEAMENDED BIOSOLIDS
Deborah Pritchard1, David Collins1, David Allen2and Nancy Penney3
1Curtin University of Technology, Muresk Institute, Northam, Western Australia,
2Chemistry Centre (WA), East Perth, Western Australia,
3Water Corporation of Western Australia, Leederville, Western Australia
(free)
Approximately half of all the agricultural soils in Australia are affected by soil acidity. Ground
limestone is a product used by farmers to better manage and neutralise soil acidity and to
improve plant productivity. The effect of lime-amended biosolids (LAB) as an alternative product
for neutralising soil acidity was applied at four rates (0, 5, 10 and 15 t DS/ha) and compared
with equivalent rates of lime (0, 2.3, 4.6 and 6.7 t/ha) and one rate of dewatered biosolids cake
(DBC) (7 t DS/ha) in a wheat/canola cropping rotation on an acidic red/brown sandy loam in the
wheatbelt of Western Australia. Soil pH (CaCl2) in the surface soil (0-10 cm) increased
significantly with increasing rates of either LAB or lime at the end of the first year, increasing
from 4.4 to 7.2, with similar values recorded between equivalent values of lime product. The
DBC treatment did not change soil pH. No further changes in soil pH had occurred by the end
of the second year. The increased yield of wheat with increasing rates of LAB in the first
season was attributed to improved nutrition rather than to the overall reduction in soil acidity.
The experiment is ongoing and has been sown to wheat in 2007 to further monitor the effects of
LAB over time.
KEY WORDS
Canola, dewatered biosolids cake, lime, lime-amended biosolids, soil acidity, wheat
