Long term effects of withholding phosphate application on North Island hill country: Whatawhata Research Centre
| Autor: | J. Riley, I. L. Power, A. G. Gillingham, S.C. Richardson |
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| Rok vydání: | 1990 |
| Předmět: | |
| Zdroj: | Proceedings of the New Zealand Grassland Association. :11-16 |
| ISSN: | 1179-4577 0369-3902 |
| DOI: | 10.33584/jnzg.1990.51.1908 |
| Popis: | From June 1984 to May 1988 a large-scale grazing trial at Whatawhata Research Centre evaluated the effects of a halt to previous superphosphate fertiliser application on hill country production. Over the 4-years pasture production, pasture species composition, stock grazing days or Olsen P soil fertility status were little affected as a result of halting topdressing. Pasture production declined most on 'easy' ( lo-20° slope) slopes after a halt to fertiliser application. The decline was greatest (lo- 13 %) where previous rates of fertiliser had been high. Total production on 'steep' (30~40° slope) slopes did not decline significantly. However, at soil test (Olsen P) levels of less than 10 the pasture moss and dead matter content increased, indicating a deterioration in pasture quality. Legume content did not decline. Within the range of normal topdressing rates to hill country (O-30 kg P/ha/yr) Olsen P tests did not reflect topdressing differences or any effects of a halt to fertiliser application. At higher topdressing rates (50-100 kg Plhalyr) the effect of continued or discontinued topdressing was reflected predominantly in the O-3 cm soil depth. A halt to previous topdressing significantly reduced available grazing over the final 3 years. This decline reflected the decline in measured pasture production. Keywords Phosphate, fertiliser, hill country, residual effects |
| Databáze: | OpenAIRE |
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