Publication Date
1993
Description
North Carolina phosphate rock (NCPR) was compared with triple superphosphate (TSP) as a phosphorus (P) fertiliser for permanent grass-clover pastures over a period of 6 years at 12 sites located throughout New Zealand. Pasture production was measured by mowing, and herbage P concentrations were measured on all harvests at 2 sites. In year 1, averaged over all sites, 1 unit of P in NCPR produced the same DM response as 0.24 units of Pin TSP (substitution value=0.24). In year 6 the mean substitution value was 0.80, and over the 6-year period it was 0.60. The site with highest pH (6.3) and lowest rainfall (712 mm annually) had the lowest 6-year substitution value (0.19). No clear relationships of substitution values with edapbic and climatic conditions could be detected among other sites, possibly because of large standard errors in calculated substitution values. Si1'•year mean herbage P concentrations at the two sites where they were measured gave substitution values very similar to those derived from DM production. The change in substitution values with time fitted a cubic dissolution model for NCPR.
Citation
Sinclair, A G.; Johnstone, P D.; Smith, L C.; Shannon, P W.; O'Connor, M B.; Nguyen, L; and Risk, W H., "Evaluation of North Carolina Reactive Phosphate Rock as a Phosphorus Fertilizer for Permanent Pastures" (2024). IGC Proceedings (1993-2023). 7.
https://uknowledge.uky.edu/igc/1993/session40/7
Included in
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Evaluation of North Carolina Reactive Phosphate Rock as a Phosphorus Fertilizer for Permanent Pastures
North Carolina phosphate rock (NCPR) was compared with triple superphosphate (TSP) as a phosphorus (P) fertiliser for permanent grass-clover pastures over a period of 6 years at 12 sites located throughout New Zealand. Pasture production was measured by mowing, and herbage P concentrations were measured on all harvests at 2 sites. In year 1, averaged over all sites, 1 unit of P in NCPR produced the same DM response as 0.24 units of Pin TSP (substitution value=0.24). In year 6 the mean substitution value was 0.80, and over the 6-year period it was 0.60. The site with highest pH (6.3) and lowest rainfall (712 mm annually) had the lowest 6-year substitution value (0.19). No clear relationships of substitution values with edapbic and climatic conditions could be detected among other sites, possibly because of large standard errors in calculated substitution values. Si1'•year mean herbage P concentrations at the two sites where they were measured gave substitution values very similar to those derived from DM production. The change in substitution values with time fitted a cubic dissolution model for NCPR.
