New Zealand Journal of Agricultural Research abstracts

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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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