Soils of the Rai and Te Hoiere/Pelorus Catchment

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Soils of the Rai and Te Hoiere/Pelorus Catchment

Currently Council has detailed information for soils in the Wairau Plain and the lower Awatere Valley. For the rest of Marlborough we have very little or more often no soils information available. For example, in the Rai/Te Hoiere/Pelorus catchment there is no available information on important soil parameters such as water holding capacity, drainage, soil depth and permeability.

This kind of information is critical if we want to help landowners manage their soils for activities such as irrigation scheduling, effluent application, stock management etc. The aim of this study was therefore to describe and sample soils from representative sites in the Rai/Te Hoiere/Pelorus catchment and undertake a range of analysis for both topsoil and subsoils.

A series of soil auger observations were made across a range of sites in the Ronga, Tunakino, and Rai Valleys to identify soils which match the descriptions for the Ronga, Rai or Pelorus soil families previously mapped in this region. Seventeen soil profiles were described and soils analysed for a range of soil physical and chemical properties.

Three soil families were identified ie; Rai, Ronga and Te Hoiere/Pelorus soils which occupied different parts of the landscape. The Rai family of soils occurred on the higher terraces and fan surfaces above the floodplain. The Ronga family of soils occurred on the lower valley floodplain surface, while the Te Hoiere/Pelorus family of soils occurred on the strongly undulating or hilly land in the transition zone between the steeply sloping valley sides and valley floor. A report summarising the results has been compiled.