The Phosphate Status of the Soils of Riverhead Forest in Relation to Growth of Radiata Pine

Authors: R. Ballard
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1970, Issue N.Z.J.For. 15(1) 1970, pp 88-99, May 1970
Publisher: New Zealand Institute of Forestry

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Abstract: An investigation of the relationships between soil phosphorus (P) levels, and foliar P levels and productivity of 40-year-old radiata pine stands at Riverhead Forest showed that:
(a)   Productivity throughout the forest is limited by inadequate available soil P.
(b)   Soil P extracted by some chemical soil tests is as closely related to productivity as is foliar P.
(c)   Soil chemical tests which remove readily exchangeable phosphate from the soil (Olsen, Bray No. 2 exchange resin) provide the best reflection of the soil P status for radiata pine. Tests for total P were suitable only when considered within groups of soils having similar properties.

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