New Zealand Journal of Agricultural Research abstracts

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Available water capacities of key soil layers in the Gisborne-East Coast region, New Zealand

M. MCLEOD
W. C. RIJKSE

Landcare Research
Private Bag 3127
Hamilton, New Zealand

email: mcleodm@landcare.cri.nz

M. R. JESSEN

Landcare Research
Private Bag 11052
Palmerston North, New Zealand

Abstract  Soil water storage values are required in many climate-driven ecological models. Using targeted soil profile layers we have modified an existing "building block" method whereby available water capacities can be rapidly provided for soil classes. This building block approach allows available water capacity estimates to be generated inexpensively and rapidly on a regional scale. In the case of the Gisborne-East Coast region, regionalisation can be achieved via soil Subgroup polygons in the 1:50 000 scale second edition of the New Zealand Land Resource Inventory. Replicated undisturbed soil samples were taken from 45 key soil profile layers and analysed for available water capacity, % gravel, and bulk density. The analyses have been used as "building blocks" to determine the available water capacity of whole soil profiles by simple addition of the available water capacity of appropriate key layers and adjusting for % gravel. Soil layers containing tephra generally have high available water capacities, as do coastal dune sand and loamy alluvium. Bentonitic clay subsoil material had very high available water capacity, nearly double that of tephric material.

Keywords  soil; readily available water; total available water; tephra; Gisborne-East Coast; New Zealand Land Resource Inventory

New Zealand Journal of Agricultural Research, 1999, Vol. 42: 195-203

0028-8233/99/4202-0195 $7.00/0 (c) The Royal Society of New Zealand 1999

PDF file of entire paper: medium quality (726K); (scanned from paper original: notes about this process)

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