New Zealand Journal of Agricultural Research abstracts
Comparison of six phosphate rocks and single superphosphate as phosphate
fertilisers for clover-based pasture
A. G. SINCLAIR*
P. D. JOHNSTONE+1
J. H. WATKINSON2
L. C. SMITH3
J. MORTON1
A. JUDGE2
1AgResearch
Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand
2AgResearch
Ruakura Agricultural Centre
Private Bag 3123
Hamilton, New Zealand
3AgResearch
Woodlands Research Station
Flemington Road
RD1
Invercargill, New Zealand
Abstract Six phosphate rocks (PRs), Sechura (SPR), North
Carolina (NCPR), Egypt (EPR), Arad (APR), Zin (ZPR), and Nauru (NPR), were
compared with single superphosphate (SSP) as annually applied P fertilisers for
mown ryegrass/white clover swards at two sites, in the central North Island (Te
Kuiti) and southern South Island (Woodlands) of New Zealand over a period of
three years. NPR was finely ground before application but the other PRs were
applied as received and so differed considerably in particle size distribution.
Measurements were made of annual dry matter (DM) production and % P in
harvested herbage, and Olsen P in the soil at the end of each year.
Overall, responses were in the order SSP>SPR~NCPR>APR~EPR~ZPR~NPR. There
were important differences in responsiveness to PRs at the two sites.
The agronomic performance of PRs was better related to their extractability by
formic acid than to extractability by citric acid. Replacement of the standard
citric acid test used in New Zealand by the formic acid test is recommended.
Keywords direct application; DM production;
fertiliser; herbage P concentration; Olsen P; pasture; phosphate; phosphate
rock; PR; RPR; reactive phosphate rock
New Zealand Journal of Agricultural Research, 1998, Vol. 41: 415-420
0028-8233/98/4103-0415 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (414K); (scanned from paper original: notes about this process)
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