New Zealand Journal of Agricultural Research abstracts
A quick field test for evaluating phosphorus movement in sandy soils
R. D. Rhue
V. D Nair
W. G. Harris
Soil and Water Science Department
University of Florida
Gainesville, FL 32611-0510, USA
Abstract Assessing the risk of phosphorus (P)
leaching in sandy soils requires a valid and practical indicator of the
depth to which applied P has moved in soil. This paper describes a
rapid field test for soil P called the Phosphorus Quick Test (PQT) that
is based on the phosphomolybdate blue procedure. One gram samples of
soil taken from known depths within a soil profile were saturated with
0.10 M HCl on a porcelain spot plate and a few drops of the
solution were treated with phosphomolybdate reagent to form a blue
colour. The depth to which P has moved into the soil can be determined
visually after only a few minutes. A comparison of the PQT results with
soil (Mehlich-1 P) and water-soluble P tests showed that the PQT could
accurately determine the depth of P movement in sandy soils. Results of
the PQT at a field site that had received a single, heavy application
of dairy lagoon effluent showed that considerable downward movement of
P occurred in some areas of the field as a result of the effluent
application.
Keywords effluent application; water-soluble P;
soil test P; P leaching; phosphomolybdate reagent
A04076; Received 14 July 2004; accepted 28 April 2005; Online
publication date 8 August 2005
New Zealand Journal of Agricultural Research, 2005, Vol. 48:
367–375
0028–8233/05/4803–0367 © The Royal Society of New Zealand 2005
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