SPATIAL VARIATION OF SOIL TEST PHOSPHORUS AND POTASSIUM, OXALATE-EXTRACTABLE IRON AND ALUMINUM, PHOSPHORUS-RETENTION INDEX, AND ORGANIC-CARBON CONTENT IN SOILS OF WESTERN-AUSTRALIA
Mda. Bolland et Dg. Allen, SPATIAL VARIATION OF SOIL TEST PHOSPHORUS AND POTASSIUM, OXALATE-EXTRACTABLE IRON AND ALUMINUM, PHOSPHORUS-RETENTION INDEX, AND ORGANIC-CARBON CONTENT IN SOILS OF WESTERN-AUSTRALIA, Communications in soil science and plant analysis, 29(3-4), 1998, pp. 381-392
Spatial variation of bicarbonate soil test phosphorus (P) and bicarbon
ate soil test potassium (K) was studied by measuring soil test values
for 40 individual soil samples collected from random locations within
eight uniform 100 m by 100 m field sites in south-western Australia. I
n addition, for five of the sites, spatial variation of the three P so
rption indices (ammonium oxalate extractable iron, ammonium oxalate ex
tractable aluminum, and the P retention index) and of organic carbon (
C) was measured for 20 individual soils samples. Spatial variation was
found to be large, with coefficient of variation (CV) exceeding 20% i
n most cases, and 50% in some cases. It is therefore essential to coll
ect an adequate number of soil samples from uniform areas in paddocks
in order to provide a representative composite sample to measure the s
oil properties.