Author:
Burkitt L. L.,Gourley C. J. P.,Sale P. W. G.,Uren N. C.,Hannah M. C.
Abstract
Nine pasture soils from high rainfall zones of southern Victoria were analysed
for a range of chemical and physical properties before receiving a single
application of P fertiliser in the form of triple superphosphate (TSP), single
superphosphate (SSP), or TSP and lime (5 t/ha) at amounts ranging from 0
to 280 kg P/ha. Soils were analysed for bicarbonate-extractable P
concentration, using both the Olsen P and Colwell P methods, 6 and 12 months
after fertiliser application. A strong positive linear relationship existed at
all sites between the amount of P applied and both the Olsen P and Colwell P
concentrations. The slopes of these relationships measured the change in
extractable P concentration (Δ EP) per unit of P applied, whilst the
inverse of the ΔEP value indicated the amount of P fertiliser required
above maintenance to increase the extractable P concentration by 1 mg/kg.
These values ranged from 5 to 15 kg P/ha, depending on soil type. The
ΔEP measured by the Olsen (Δ EP Olsen )
method was closely related to selected soil properties and P sorption
measures, whilst the ΔEPColwell values were also
closely related to selected soil properties and P sorption measures, but only
when one particular site, an acidic sand, with a high organic carbon content
was excluded from the analysis. In general, simple, direct measures of soil P
sorption could allow the estimation of ΔEP values on different soil
types.
The application of P in the form of SSP resulted in a trend for higher
ΔEP values than occurred with TSP. This difference was significant on 3
sites (P < 0.05), but depended on the method of
extraction and the time after fertiliser application. The application of lime
significantly (P < 0.001) increased soil pH
(H2 O and CaCl 2 ) and decreased
the concentration of exchangeable Al, 6 months after treatments were applied,
but generally had little impact on ΔEP values.
Subject
Earth-Surface Processes,Soil Science,Environmental Science (miscellaneous)
Cited by
22 articles.
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