Guide to the Soils of Kaihiku-Hokonui Land Region

Manaaki Whenua Landcare R esearch NZ PRESS

1111 11 111 111 11 111 11 111 11 111 11 111 11 111 1111 111111 1111111 111 111 L000004842 NDCARE RESEARCH ~CIENCE SERIES NO. 4 Guide to the Soils of Kaihiku-Hokonui Land Region

Peter D. Mcintosh

Manaaki Whenua - Landcare Research Private Bag 7930, Dunedin

Landcare Research Science Series No. 4

Manaaki Whenua P R E S S

Lincoln, Canterbury, New Zealand 1994 © Landcare Research New Zealand Ltd 1994

No part of this work covered by copyright may be reproduced or copied in any form or by any means (graphic, electronic or mechanical, including photocopying, recording, taping, information retrieval systems, or otherwise) without the written permission of the publisher.

CATALOGUING IN PUBLICATION

MCINTOSH, P.O. (Peter Douglas), 1950- Guide to the soils of Kaihiku-Hokonui Land Region I Peter D. Mcintosh. - Lincoln, Canterbury, N.Z. : Manaaki Whenua Press, 1994.

(Landcare Research science series, ISSN 11 72-269X ; 4) ISBN 0-478-04530-1.

I. Title. II. Series.

UDC 631.44(931.334.7 + 931.353.3)

Cover: A typical landscape in the Hokonui land system: the central valley of the Hokonui Hills is dominated by Kaiwera soils, formed in tuffaceous sandstone and mudstone, on both the hilly land and rolling land. The deep, moisture-retentive soils are well suited to forestry plantations. Similar soils occur over large parts of the Kahiku-Hokonui Land Region described in this report. Photograph by Peter Mcintosh.

Desktop publishing by John McNeil, Page Plus Ltd, PO Box 28-058, Christchurch 2.

Printed by Toltec Print, 373 Wilsons Road, Christchurch.

Printed on Ambassador Gloss recycled paper.

Published by Manaaki Whenua Press, Landcare Research, PO Box 40, Lincoln 8152, New Zealand 3

Contents

Summary 5

1. Introduction 6 1.1 Purpose 7 1.2 Area, physiography, geology and parent rocks 7 1.3 Climate 8 1.4 Vegetation 9

2. The land region and its soils 10 2.1 Definition 10 2.2 Previous research 10 2.3 Soil parent material 11 2.4 Soils 15

3. Land systems 20 3.1 Soil-landscape models 20 3.2 The Kaiwera land system 22 3.3 The Hokonui land system 25 3.4 The Owaka land system 27 3.5 The Pukepahi land system 29 3.6 The Tautuku land system 31

4. Soils and land use 33 4.1 Pastoral farming and element deficiencies 33 4.2 Horticulture 35 4.3 Forestry 38

Acknowledgements 41

References 42

Appendix 1: Brief soil profile descriptions 46

Appendix 2: Glossary 57

SUMMARY 5 Summary

The Kaihiku-Hokonui land region covers about 410 OOO hectares of land underlain by predominantly tuffaceous sandstone and mudstone rocks in central and eastern Southland and south Otago, New Zealand. Previous studies have established the parent material and soil variation within the region. This report collates this research, updates the soil classification, provides keys and models for the soil distribution pattern, extrapolates the information of detailed surveys to the wider area and assesses advantages and disadvantages of land for pastoral, horticultural and forestry use.

The land region is divided into the Kaiwera, Hokonui, Owaka, Pukepahi and Tautuku land systems. Within each land system there is a complex interaction of rainfall, altitude, parent material, degree of weathering and aspect. Pictorial models of soil distribution in the landscape help explain the soil pattern.

Soils in the region have previously been mapped in twenty soil sets. The Kaiwera, Kaiwera hill, Kaihiku hill and Waimahaka hill sets were the most extensive. More recent detailed mapping has resulted in the identification of new soil units, most of which are classified as Brown Soils in the New Zealand Soil Classification. Allophanic Soils, Melanie Soils, Gley Soils, Recent Soils and Podzols also occur. Keys based on pedological, chemical and slope criteria enable soils to be identified.

Phosphorus and sulphur deficiencies are the major nutrient limitations for improved pastures. However, sulphur may be adequate in soils near the coast. Deficiencies of cobalt and copper affect stock health, and are most severe on strongly leached upland soils.

Otaraia, Owaka, Titiroa and Tuturau soils, formed in loess, are suitable for horticulture. Cool temperatures limit the range of crops that can be grown but arable crops such as vegetables are possibilities. Titiroa soils contain the least clay and most sand and after drainage are highly suitable for cultivation.

A four-class system for rating soils for forestry suitability is presented. Most soils are suitable for forestry, being deep and well drained and on rolling or hilly land. Only a few soils on uplands are classed as marginally suitable or unsuitable for forestry because of steep slopes, or sites that are too exposed or too cold, or soils that are peaty or fragmental.

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Land Land Kaihiku-Hokonui Kaihiku-Hokonui INTRODUCTION 7

1. Introduction

1.1 Purpose TIUs guide to the soils of the Kaihiku-Hokonui land region collates and summarises the soil information available for the region, and indicates the main limitations and potential of the region for pastoral, horticultural and forestry land uses. Many of the subjects covered in the guide (e.g. parent material origins and cause and extent of trace element deficiencies) have been dealt with in detail elsewhere. Tills guide presents the main findings of these investigations, with references to the original research, so that readers can follow up any subjects of special interest. One of the aims of the guide is to enable land users to extrapolate information from detailed surveys to the wider area. A glossary is included (p. 53) to explain technical terms.

1.2 Area, physiography, geology and parent rocks Soils developed mainly in tuffaceous (andesitic) sandstone and mudstone in the Kaihiku Hokonui land region cover approximately 410 OOO hectares of the southeast part of the South Island New Zealand (N.Z. Soil Bureau 1968) (Figs 1 and 2). The sandstone and mudstone originated as sandy and muddy sediments on the sea floor in the Triassic and Jurassic periods, 135 to 230 million years ago. While these sediments were accumulating volcanoes were active so that the sediments incorporated volcanic (tuffaceous) material. (Stevens (1980) gives a reconstruction of Triassic and Jurassic geography). The sediments later became hardened and were folded to form the Southland syncline which has its axis running through the region in a WNW-ESE direction (Wood 1956, 1966; McKellar 1966, 1969; McKellar and Speden 1978).

Fig. 2 A typical landscape in the Kaihiku-Hokonui land region. Long ridges form where the underlying strata is resistant tuffaceous sandstone, while the valleys are underlain by less resistant tuffaceous mudstone. Loess, derived mainly from outside the region, mantles lower altitude undulating and rolling slopes. 8 INTRODUCTION

The rocks have subsequently been uplifted and eroded. The tuffaceous sandstone rocks have resisted erosion, so that the landscape in the region is dominated by ridges of tuffaceous sandstone separated by valleys underlain by less resistant, tuffaceous mud stone. Altitudes range from sea level to 720 m on Mt Pye (3 km north of Ajax Hill (Fig. 1)), but most areas are below 600 m altitude and occur on slopes that mostly vary between rolling (8-15°) and hilly (16-25°).

The tuffaceous sandstone and mudstone parent rocks contain more iron, manganese, titanium, potassium, aluminium and magnesium than the schist and greywacke typically occurring on much of the South Island hill country (Table 1), because of the andesitic ash component of the parent rocks. Although most soils are formed in parent material derived from tuffaceous sandstone and mudstone rocks, some soils of the region are formed partly in loess derived from schist and greywacke rocks occurring outside the region.

Table 1. Analysis of three soil materials occurring in South Island hill country. Analyses are of deepest horizons of soils developed on these parent materials.

Element Greywacke Schist Tuffaceous sandstone (%) colluvium1 colluvium2 and mudstone colluvium3

Fe 3.2 3.9 5.5 Mn 0.06 0.09 0.14 Ti 0.42 0.52 0.60 Ca 2.04 2.43 0.92 K 1.70 1.35 2.34 p 0.04 0.07 0.05 Si 32.1 29.1 26.6 Al 7.4 8.78 10.1 Mg 0.83 0.96 1.38 Na 2.09 2.34 1.84

1Profile SB10074, Benmore Range 2Profile SB09912, Hector Mountains 3Profile SB09867, Kaiwera (SB numbers refer to laboratory samples held by Landcare Research).

1.3 Climate Mean annual rainfall ranges from 800 to 1600 mm (N.Z. Meteorological Service 1973), the wetter areas being at higher altitude and near the south coast (Fig. 1). Mean annual air temperature is 9.7°C at Gore at 123 m altitude and is estimated to fall below 8°C at 560 m altitude. Most soils have a mesic soil temperature regime (mean annual soil temperature 8°C or higher) but a cryic temperature regime (mean annual soil temperature less than 8°C) may occur at altitudes above 600 m on sunny aspects and above 170 m on shady slopes (Mcintosh 1988). Further details of climate in the Kaiwera district east of Gore are given by Mcintosh (1992a). INTRODUCTION 9 1.4 Vegetation Vegetation before the arrival of humans was probably largely broadleaf-podocarp forest over all areas except for exposed and/ or poorly drained uplands such as Ajax Hill (27 km west of Owaka), and for large areas of beech forest in the east, shown by Allen (1985). The forest on the northern limb of the Southland syncline was probably burnt by Polynesians, and red tussock (Chionochloa rubra) subsequently predominated. The red tussock grassland has been progressively replaced by grass and clover species introduced by European farmers. Isolated pockets of forest remain in the northern (drier) area, for example at Glenure Hill near Balfour. In the southern (moister) area forest is still extensive. 10 LAND REGION AND SOILS

2. The land region and its soils

2.1 Definition The Kaihiku-Hokonui land region is the region identified by the tuffaceous sandstone and mudstone terrain of the Southland syncline, having soils formed predominantly in tuffaceous sandstone and mudstone parent material. It extends from the North Range (near Dipton) to Nugget Point (Fig. 1).

2.2 Previous research The region comprises soils previously mapped in twenty soil sets (Table 2).

Table 2. Areas of soil sets in the Kaihiku-Hokonui land region (N.Z. Soil Bureau 1968).

Soil set and number Hilly land (ha) Flat to rolling land (ha)

Tuturau 35 - 6500 Kaihiku hill 35aH 56300 - Owaka 36 - 19600

Owaka hill 36H 21300 - Chaslands 36a - 11500 Chaslands hill 36aH 2600 - Titiroa 36b - 6000 Kaiwera 36c - 73600 Kaiwera hill 37cH 67700 - Tawanui hill 37fH 12000 - Waimahaka 39 - 8200 Waimahaka hill 39H 47400 - Tautuku 61 - 6400 Tautuku hill 61 H 33900 - Toetoes 63b - c.1 OOO Pukepahi hill 64dH 21100 - Riverton 70a - c. 1000 Otanomomo 87 - c. 1 OOO Kaherekoau 88 - c. 6000 Makarewa 90f - c. 6500

262300 147300

Total area (ha) 409600

The broad relationship of soil fertility to climate was noted in the reconnaissance scale 1:253 440 soil map of the South Island (N.Z. Soil Bureau 1968). In the drier parts of the region base rich soils of near-neutral pH, mapped in the Kaihiku hill set, predominate. In the wetter parts of the region greater leaching has occurred and many of these less fertile soils have been mapped in the Kaiwera and Kaiwera hill sets. The most leached soils are podzolised and have .:::::::::::::::::::::::::::::::.:;:::::·::::: :;:::::::::·:::·:·:::::<:::·.::::::::::::;:::::;·.:::::::;:::::::::::::::::::::;::::~::~ :;:;:;·:;:;:::::::::::::::::::::.:::::::::::::;:;:::::::::::::::::::::::::::::::::::::::;:::;:::;:;:;:~;:::::::;::;:;:::::::::::;::::::::::: :::::::::::::.:·::·::::·:·::::::::::.:::::~>:·. •• • • ...... ·.·.·.·... :;:::::::::::::::::;:;::::::.;::~ :::;:;:;;::;:::;:;:;:;:;:::::::;:::::::;:::;:;:;::~::: ::::::;:::::;:::::::::;:;:::::::::::::::::::::::;:::;:;:;:::;:::;:;:;~:::;r;:~::::;:;;::;~::. ::::::;:;:;:::::::;:;:;:;:;:;:;:::::::::::;:;:;:;:::::::::;::;::~;~:;::::::::::;· LAND REGION AND SOILS 11

an iron pan. Criteria for distinguishing sets were not always made clear by N.Z. Soil Bureau (1968), and some sets were distinguished on vegetation rather than soil characteristics. For example, the Pukepahi and Tautuku sets included soils both with and without iron pans and soils of the Tawanui and Waimahaka sets were largely distinguished on the basis of vegetation cover (beech forest and podocarp forest cover respectively). Although Tuturau, Owaka and Titiroa sets were restricted to loess parent material, the Kaiwera set included both soils developed on thick loess and thin soils on rock. The Makarewa set covered all soils in alluvium.

To clarify the soil pattern, soil surveys at 1:25 OOO and 1:30 OOO scale in areas east and west of Gore (Bruce 1984; Mcintosh 1992a, b) were undertaken. The detailed mapping and description of soil properties allowed land to be assessed for forestry, pastoral and horticultural use on a more scientific basis than was formerly possible. For example Mcintosh (1992c) assessed soils for horticultural uses and Sherrell et al. (1989) evaluated trace element deficiencies in pastures.

2.3 Soil parent material There are six types of parent material present, four of which are subdivided into subclasses as follows: 1. In-situ rock a. Slightly to moderately weathered b. Highly weathered 2. Hillslope colluvium a. Stony colluvium (>35% stones by volume) b. Colluvium with stones (<35% stones by volume) c. Colluvium from frittered mudstone 3. Loess a. > 70% derived from greywacke and schist . b. >30% derived from tuffaceous sandstone and mudstone 4. Alluvium 5. Peat a. Moderately decomposed (mesic) b. Strongly decomposed (humic) 6. Dune sand

Most of the in-situ rock is slightly to moderately weathered. Highly weathered rock occurs extensively around Ferndale, where the undulating landform indicates that it may be the substrate of an ancient terrace.

The stony colluvium predominates below scarps of tuffaceous sandstone whereas the less stony tuffaceous mudstone colluvium predominates on dip slopes (Fig. 3). Consequently, stony colluvium is more common on north-facing slopes on the northern limb of the Southland syncline and on south-facing slopes on the southern 1imb. The stony colluvium commonly overlies less stony colluvium and Mcintosh et al. (1990) concluded that the stony upper layer was a result of erosion in a cold and wet period that followed a drier period in which the less stony lower layer accumulated.

Colluvium from frittered mudstone (Fig. 4) is an important parent material on uplands, where it is up to 4 m thick. The colluvium appears to have formed under very dry conditions. A date 12 LAND REGION AND SOILS

<35o/o stones >35% stones

Fig. 3 Parent materials on hill soils are related to outcrop of tuffaceous sandstone and mudstone. On the dip slope the colluvium contains less than 35% stones, and tuffaceous mudstone is the predominant parent rock. On the scarp slopes below the ridge the colluvium contains more than 35% stones, and tuffaceous sandstone is the dominant parent rock. LAND REGION AND SOILS 1 3

Fig . 4 Frittered mudstone (Lynn and Crippen 1991) is an important parent rock on uplands. The upper photograph shows soil developed in colluvium from frittered mudstone. Note the low proportion of stones. The centre photograph shows the mudstone from which the parent material forms by fragmentation along joints. (Photographed rock is 150 mm wide.) The lower photograph shows recent colluvium of frittered mudstone in a road cutting. 14 LAND REGION AND SOILS

of 29140 yr B.P. for one deposit indicates that the deposits formed during the last glacial period (Mcintosh et al. 1990). The deposits probably accumulated as fine screes under sparse vegetation.

Loess mantles most of the lowland valleys and upland basins east of Gore. The loess has variable mineralogy (Eden et al. 1987) which is related to its distance from the primary source, the Mataura River floodplain (Fig. 5). Deposits within 7 km of the floodplain are 70% derived from greywacke and schist of Mataura River origin. More distant loess deposits and those at higher altitude contain more minerals of volcanic origin like hornblende, derived from local rocks (tuffaceous sandstone and mudstone). By measuring ratios of minerals in loess deposits in the Kaiwera district, Eden et al. (1987) showed that local rocks contribute l~ss than half the parent material of the loess. Parent material compositions of loess deposits near Owaka and at Titiroa near Fortrose are also consistent with a predominantly schist and greywacke origin (Landcare Research, unpublished data).

Alluvium is confined to the valley floors of the numerous small streams and rivers. Gravelly deposits are rare, the alluvium mostly being silty or loamy. Peat occurs as raised bogs on the margins oflowland floodplains and on poorly drained uplands, notably on Bleak Hill and Ajax Hill (Johnson et al. 1977). Dunesand occurs in narrow bands behind beaches, but the coastline is predominantly rocky.

West East 4 Q) "'O c Q) 3 .0 c..... 0 .c 2 Q) ...... 0 "'O 0.. 1 Q) 0 :+J ctS...... O> 0 0 _J R

5 10 15 Distance from Mataura River (km)

Fig. 5 With increasing distance from the Mataura River the mineral composition of loess in the Kaiwera district changes from a composition close to that of Mataura River sediments (S) to one closer to that of tuffaceous rocks (R).The graph plots the epidote/hornblende ratio of silt in loess.The ratio is high near the Mataura River (because epidote is common in Mataura River sediments) and low further east (where local rocks that are richer in hornblende have contributed to loess composition). LAND REGION AND SOILS 15 2.4 Soils During mapping soils are classified on the basis of measured or observed soil profile criteria, e.g. drainage, texture, stoniness, soil acidity. The class limits used to separate soil map units are predefined and arranged in the form of keys (Hewitt 1992; Clayden and Webb 1994). The classes relevant to the soils of the Kaihiku-Hokonui land region are used in the abbreviated key shown in Table 3, which enables all soils to be identified by soil name. A brief description of each soil is given in Appendix 1.

Since the publication of the detailed surveys of Bruce (1984) and Mcintosh (1992a, b), the soil classification system for New Zealand has been revised (Hewitt 1992; Clayden and Webb 1994), and the concept of soil series (the named taxonomic unit in old surveys) has been superseded by that of the soilform (Clayden and Webb 1994). To avoid confusion, and to provide a link with previous work, published soil names have been used in this report.

As soil symbol conventions varied between surveys, soil symbols have been rationalised as shown in Table 4. -..l :::;:· Table 3. Key for identification of soils in the Kaihiku-Hokonui land region based on Hewitt (1992) and additional pedological criteria.

iioi; ::0 ii SOILS OF H SOILS IN H PLANT I UNDULATING IANDREWS KAIHIKU- >90cm FRAGMENTS · · AeU HOKONUI PEAT IDENTIFIABLE 8HI rn LAND o REGION PLANT UNDULATING KAHEREKOAU FRAGMENTS NOT KeU IDENTIFIABLE ~I >2% GREY >50% GREY I UNDULATING IMAKAREWA MOTTLES MOTTLES MkU GIJ ABOVE 60 cm IN HORIZON DEPTH, NO BELOW IRON PAN A HORIZON <50% GREY GREY I I NO CLAY I UNDULATING IOTARAIA MOTTLED MOTTLES MOTTLES t----i SKINS Orum IN HORIZON RANDOM BELOW

A HORIZON 11 CLAY I HILLY ISTONYCREEK SKINS StH PRESENT

GREY UNDULATING MOTTLES RELATED TO WEATHERED ROLLING I STRATA

<2% GREY IN HIGHLY MOTTLES WEATHERED ABOVE 60 cm - TUFFACEOUS DEPTH ROCKS i IN SLIGHTLY I THIN IRON pH IN PAN SHALLOW ROLLING TO MOD. j-- PAN <5.5 SOIL ON WEATHERED I PRESENT ROCK TUFFACEOUS ROCKS ~r~z~~1g~ ROLLING I B HORIZON PEDS '------iHILLY

NO ORGANiel ROLLING I~UKEPAHI ~STAINS ON j PpR SOIL FORMED LITHOSOL IN BOULDERS LH (FRAGMENT AL)

SOIL NOT FRAGMENTAL (Go to page 17) SOIL NOT HORIZON WITH BULK DENSITY LITHIC ROLLING IPUKERAU FRAGMENTAL P RETENTION <0.9 kg/m3 CONTACT PuR >85% PRESENT IN PART OF AT45cmOR BHORIZON SHALLOWER NO LITHIC >35% HILLY lvENLAW I CONTACT STONES+-~~~~~~~~~~~~~--4 VeH AT45cmOR SHALLOWER STEEP IVENLAW VeS

<35% ROLLING I WAIARIKIKI STONES+-~~~~~~...-~~~~~~--; WrR HILLY I WAIARIKIKI I WrH

BULK DENSITY SILTY <90cm ROLLING I ROSEMARKIE >0.9 kg/m3 PARTICLE DEEP RoR1 IN PART OF SIZE BHORIZON CLASS >90cm ROLLING I ROSEMARKIE DEEP Ro RO I HILLY I ROSEMARKIE RoH i CLAYEY ROLLING IKAIWERA PARTICLE KwR SIZE CLASS ! f NO HORIZON HORIZON CLAY ROLLING I KAIHIKU f: WITH P RETN. WITH>35% SKINS KhR >85% STONES PRESENT --- PRESENT ~u H STEEP I KAIHIKU KhS

NO BwpH ROLLING I MANDEVILLE CLAY 5.70R MORE MeR SKINS

BwpH ROLLING IKAIWERA <5.7 KwRt

HILLY IKAIWERA KwHt ~I

STEEP IKAIWERA KwSt I z:''': ~~·· <35%STONES BwpH ROLLING ITAWANUI T090cm 4.8 OR LESS 1------~------TwR DEPTH I (Go to page 18) HILLY ITAWANUI I e1 TwH ~ [;f '-I }

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OWAKA OWAKA

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ITUTURAU ITUTURAU

INITHDALE INITHDALE

IRIVERTON IRIVERTON

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ROLLING ROLLING ROLLING ROLLING

UNDULATING UNDULATING

ROLLING ROLLING

HILLY HILLY

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1992c), 1992c),

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moderate moderate moderate moderate

rapid rapid moderate moderate

moderate moderate moderate moderate

rapid rapid

moderate moderate

moderate moderate moderate moderate

rapid rapid moderate moderate moderate moderate

moderate moderate

moderate moderate moderate moderate

moderate moderate

moderate moderate moderate moderate

moderate moderate

Profile Profile slow slow

moderate moderate

permeability permeability

(Mcintosh (Mcintosh

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Guide Guide

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1994) 1994)

Bureau Bureau

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silty silty

loamy loamy

silty silty silty

silty silty

silty silty silty silty

clayey clayey

silty silty

silty silty sandy sandy Particle Particle clayey clayey

clayey clayey

silty silty

silty silty clayey clayey

clayey clayey

silty silty

clayey clayey silty silty

clayey clayey clayey clayey

clayey clayey

size size

clayey clayey

tuffaceous tuffaceous

Landuser Landuser

= =

Webb Webb

Soil Soil

= =

Ts Ts

(Tm) (Tm)

and and

LG1 LG1

(Ts) (Ts)

steep; steep;

Zealand Zealand

deep(Tm) deep(Tm)

deep deep

deep(Tm) deep(Tm)

deep deep

(Ts) (Ts)

= =

(1) (1)

S S

Clayden Clayden

(1977), (1977),

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(Ts) (Ts)

=New =New

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al. al.

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et et

1992; 1992;

= =

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lithic lithic lithic(Ts) lithic(Ts)

Humic Humic

moderately moderately

Fibriform Fibriform

deep deep

deep deep deep deep

moderately moderately

with with deep deep

deep deep

angular-stony(Ts) angular-stony(Ts)

moderately moderately

deep deep with with

angular-stony angular-stony

angular-stony(Ts) angular-stony(Ts)

deep deep Parent Parent angular-stony angular-stony

with with

angular-stony angular-stony

deep deep

with with

angular-stony(Ts) angular-stony(Ts)

deep deep with with

angular-stony angular-stony

with with

fragmental fragmental

with with

deep deep with with

material material with with deep deep

with with

H H

NZSB NZSB

(Hewitt (Hewitt

Johnson Johnson

rolling; rolling;

(1985), (1985),

= =

R R

al. al.

Recent Recent

Podzol Podzol

Brown Brown

Podzol Podzol

Brown Brown Brown Brown Brown Brown

Brown Brown

Brown Brown Brown Brown

Brown Brown

Melanie Melanie Brown Brown Allophanic Allophanic Brown Brown

Allophanic Allophanic Brown Brown Brown Brown Brown Brown

Brown Brown

Brown Brown Brown Brown Podzol Podzol Melanie Melanie

Melanie Melanie

Allophanic Allophanic Gley Gley Brown Brown

Allophanic Allophanic

Brown Brown

Allophanic Allophanic

Brown Brown

Brown Brown Order Order

Organic Organic

JOH= JOH=

et et

Classification Classification

1992b), 1992b),

=Smith =Smith

fie fie

hie hie

=undulating; =undulating;

SMI SMI

U U

Perch-gley Perch-gley

Ma Ma

Pan Pan

Firm Firm

Humic Humic

Firm Firm

Orthic Orthic

Firm Firm Orthic Orthic

Pan Pan Orthic Orthic

Sandy Sandy

Orthic Orthic Orthic Orthic

Firm Firm

Acid Acid

Orthic Orthic Orthic Orthic Orthic Orthic

Sandy Sandy

Orthic Orthic

Allophanic Allophanic

Orthic Orthic

Allophanic Allophanic Mesic Mesic

Allophanic Allophanic

Orthic Orthic

Allophanic Allophanic

Group Group Ort Ort

Acid Acid

Allophanic Allophanic

Orthic Orthic Allophanic Allophanic

Acid Acid

Allophanic Allophanic

Orthic Orthic

), ),

(Mcintosh (Mcintosh

(1981 (1981

symbol: symbol:

al. al.

survey survey

soil soil

Humose Humose

Acidic Acidic

Acidic Acidic Acidic Acidic Argillic Argillic

Acidic Acidic

Acidic Acidic Typic Typic Acidic Acidic Acidic Acidic

Mottled Mottled

Acidic Acidic Typic Typic

Acidic Acidic Acidic Acidic

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Land systems divide a land region into units with similar landform-soil associations, and similar potential for land use. Within the Kaihiku-Hokonui land region, five land systems have been described (Fig. 6; Table 5). Land systems are broadly related to the distribution of soil sets as mapped by N.Z. Soil Bureau (1968). In the Kaihiku-Hokonui land region the Kaiwera land system occurs on the inland rolling and hilly lowlands east of Gore. The Hokonui land system occurs in the hilly land west of Gore. The Owaka land system occurs on the drier rolling land and associated ridges near the coast. The Pukepahi land system occurs on inland hilly and steep uplands and their associated basins and rolling land. The Tautuku land system occurs on rolling and hilly land in the wetter coastal belt.

Table 5. Brief description of land systems occurring in the Kaihiku-Hokonui land region.

Land system Dominant Landforms Altitude Rainfall (m) (mm) Kaiwera (1) Rolling downlands 110-400 1000-1400 (2) Hilly slopes following strike ridges Hokonui (1) Hilly slopes following strike ridges 100-500 800-1200 (2) Steep slopes following strike ridges Owaka (1) Rolling downlands of broad valleys 0-400 800-1300 (2) Hilly slopes following strike ridges Pukepahi (1) Rolling uplands 300-600 1200-1600 (2) Hilly slopes following strike ridges Tautuku (1) Rolling downlands 0-300 c. 1200 (2) Hilly slopes

3.1 Soil-landscape models

It is impractical to undertake detailed soil mapping over the total area of a land region. Soil patterns in areas not covered by detailed survey can be predicted using soil-landscape models showing the relationships of soils to landscape units. When only two or three landscape variables determine the soil pattern (e.g. aspect, slope and parent material), the model can be relatively simple. Where several variables (e.g. rainfall, altitude, parent material, degree of weathering, slope, drainage, aspect) determine the soil pattern, as in this region, the predictive model becomes more complicated and single soil classes can seldom be confidently predicted from landscape criteria alone. However, within individual land systems, variability of soil forming factors is less, and soil-landscape models are more useful.

Soil variation is described in three ways. Firstly, Table 3 presents a means of identifying a soil anywhere in the Kaihiku-Hokonui land region; to use this table a soil description and some basic pedological knowledge is required. Secondly, soil-landscape relationships within the five land systems are shown diagrammatically in Figs. 7, 10, 11, 12 and 13. Thirdly, soil-landscape relationships are tabulated in Tables 6-15. These figures and tables predict the soil most likely to occur at a particular site, but for definitive soil identification soil description from road cuttings or pits is recommended.

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3.2 The Kaiwera land system The Kaiwera land system is dominated by the characteristic parallel ridges and valleys of the Southland syncline (Fig. 7; Table 6).

Table 6. Definition of Kaiwera land system.

Location: Eastern Southland and south Otago Altitude: 11 0-400 m Rainfall: 1000-1400 mm Geology: Tuffaceous sandstone and mudstone forming northern and southern limbs of the South land syncline (Wood 1956, 1966; McKellar 1966; McKellar and Speden 1978) Physiography*: (a) Rolling downlands and uplands; (b) hilly slopes following strike ridges; (c) steep slopes following strike ridges; (d) flat to undulating floodplains and low terraces Soil parent material*: (a) stony colluvium (chiefly from tuffaceous sandstone); (b) colluvium with stones (chiefly from tuffaceous mudstone); (c) loess (chiefly from schist and greywacke); (d) alluvium from tuffaceous sandstone and siltstone; (e) peat. Soil Information: N.Z. Soil Bureau (1968); Bruce (1984); Mcintosh (l 992a).

*Physiographic and parent material components are listed in order of area covered (first component is most common).

MkU AeU In clayey alluvium In deep peat in river valleys

MjU, MjR <' NtU KwH in highly weathered n ("" In loamy alluvium KwRt In clayey colluvium tuffaceous rocks ("" ("" with stones, on shady on low terraces In stony clayey colluvium hilly slopes <'<"' <' / in rolling basins (associated ('\<' / with rock outcrops) KhH <'<' In stony colluvium on sunny hilly slopes / / /

In clayey colluvium in rolling basins

Or RO In deep loess (silty) >7 km from Mataura River OrR1 TuR In 45 - 90 cm loess (silty) >7 km from Mataura River In deep loess (silty) within ~ stony clayey highly weathered 7 km of Mataura River ~ colluvium greywacke OrUm TiU In depressions in clayey coHuvium I"n~ I rock outcrops In deep loess (loamy) deeploess with stones n" within 1O km of Mataura River, near coast loess II alluvium

Fig. 7 The Kaiwera land system: soil-landscape relationships on lowlands east of Gore. From Mcintosh (1992a). LAND SYSTEMS 23

Table 7. Soils of the Kaiwera land system.

Land Components Slopes Soil Map Unit Soil Series Symbol* Name Loess downlands Convex rolling TuR Tuturau <7 km from Mataura River Undulating TiU Titiroa Loess downlands Or RO Otaraia >7 km from Convex rolling Mataura River OrRl Hollows Orum Highly weathered Undulating MjU McNab tuffaceous sandstone on downlands Convex rolling MjR Downlands with KwR Kaiwera rocky outcrops Convex rolling KwRt Sunny slopes, Hilly KhH Kaihiku low altitude, low rainfall Sunny slopes, Hilly KwHt Kaiwera high altitude, high rainfall Shady slopes KwH Kaiwera Hilly KwHt Low terraces Undulating NtU Nithdale Raised bogs Undulating AeU Andrews Floodplains Undulating MkU Makarewa

*First two letters identify soil series. U, R, H, and S identify undulating, rolling, hilly and steep phases respectively. Additional phases are identified as follows: 0 =deep phase; 1 =moderately deep phase; m = mottled phase; t = stony phase (refer to Mcintosh l 992a).

The nine soil series present are related to landforms and parent material (Fig. 7; Table 7). The soil pattern is a complex mosaic ofloessial soils of differing origin (Tuturau, Titiroa and Otaraia soils), soils derived from tuffaceous sandstone and mudstone (McNab, Kaiwera and Kaihiku soils), soils formed in alluvium (Nithdale and Makarewa soils) and soils formed in peat (Andrews soils).

Soil chemical criteria were used to help define soils and to plot trends relevant to land use (Mcintosh 1986; Mcintosh and Whitton 1988). Kaihiku hill soils have higher pH and lower P retention in their uppermost Bw horizon than the more leached and weathered Kaiwera hill soils (Fig. 8). Similarly, Otaraia soils are separated from the higher altitude Rosemarkie soils (of the Pukepahi land system) by the P retention value in the uppermost Bw horizon (Fig. 9): Rosemarkie soils all have Bw P retention values exceeding 75% and improved pastures are likely to have higher P requirements than those on dtaraia soils. 24 LAND SYSTEMS

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pH • .• ••- 6.0 •-·- • •• 0

• 0 cx::o 0 00 0 co 0 0 0 0 CX)CO co OOO 0 0 5.0 00 00 0 0 0

0 50 100 P retention (o/o)

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30 • 100 200 300 400 Altitude ( m)

Fig. 9 P retention values of the Bw horizons of • Otaraia soils (of the Kaiwera land system) and II Rosemarkie soils (of the Pukepahi land system), two soils formed in loess. With increasing altitude P retention values rise indicating greater weathering and greater P requirement for pastures on the upland soils. From Mcintosh and Whitton (1988). LAND SYSTEMS 25 3.3 The Hokonui land system The Hokonui land system, like the Kaiwera land system previously described, is dominated by the parallel ridges and valleys of the Southland syncline, but hilly rather than rolling slopes predominate (Fig. 10; Table 8). The six soil series present are related to landforms and parent material (Table 9; Fig. 10).

Table 8. Definition of Hokonui land system

Location: Central and eastern Southland Altitude: 100-500 m. (Small areas at higher altitude contain soils of the Pukepahi land system.) Rainfall: 800-1200 mm Geology: Tuffaceous sandstone and mudstone forming northern and southern limbs of the Southland syncline f'Nood 1956, 1966; McKellar 1966; McKellar and Speden 1978). Physiography*: (a) Hilly slopes following strike ridges; (b) steep slopes following strike ridges; (c) rolling downlands (d) flat to undulating floodplains and low terraces (e) rolling uplands. Soil parent material*: (a) stony colluvium (chiefly from tuffaceous sandstone); (b) colluvium with stones (chiefly from tuffaceous mudstone); (c) alluvium from tuffaceous sandstone and siltstone. Soil Information: N.Z. Soil Bureau (1968); Mcintosh (l 989a, b; l 992b).

*Physiographic and parent material components are listed in order of area covered (first component is w N PuR S-----11~> In thin stony clayey KwHt colluvium on rolling In stony clayey colluvium E ridges on uplands on hilly slopes above 400m altitude VeH MeR In thick stony clayey In thin stony clayey colluvium above 400m colluvium on rolling LH altitude, on sbady ridges below 400m altitude In fragmental screes hilly slopes KhH In stony clayey colluvium KwH on sunny hilly slopes In clayey colluvium StH with stones below 400m altitude,on hilly slopes

NtU In loamy alluvium in valley floors

In clayey colluvium Dip of rocks in rolling basins In stony clayey colluvium in rolling basins In clayey colluvium with stones, on In stony clayey colluvium In stony clayey colluvium hilly ~ stony clayey slopes on sunny steep slopes on northern low-altitude fragipan ~ colluvium rn rolling slopes r:::'.::::8 clayey colluvium ~ with stones I,.,,..,'"''"' ,..,.-. I rock outcrops ii alluvium

Fig. 10 The Hokonui land system: soil-landscape relationships in the Hokonui Hills. Note that Venlaw soils, hilly phase (VeH) and Pukerau soils, rolling phase (PuR), both upland soils more commonly found in the Pukepahi land system, occur at higher altitudes. 26 LAND SYSTEMS

Table 9. Soils of the Hokonui land system.

Land Component Slopes Soil Map Unit Soil Series Symbol* Name

Sunny slopes, Hilly KhH Kaihiku low altitude ( <400 m) Steep KhS Sunny slopes, Hilly KwHt Kaiwera high altitude (>400 m)

Steep KwSt Shady slopes, Hilly VeH Ven law high altitude (>400 m)

Sunny scree slopes Hilly LH Unnamed Lithasol Shady slopes Hilly KwHt Kaiwera KwH Ridges with rock Rolling KhR Kaihiku outcrops; low altitude, in north ( <400 m)

Ridges on uplands, >400 m Rolling PuR Pukerau altitude

Basins with Rolling KwRt Kaiwera rock outcrops, in south KwR Sunny toeslopes Hilly StH Stonycreek Ridges with rock outcrops, in Rolling MeR Mandeville north

Valley floors Undulating NtU Nithdale

*First two letters identify soil series. U, R, H, and S identify undulating, rolling, hilly and steep phases respectively. Additional phases are identified as follows: 0 = deep phase; 1 = moderately deep phase; m = mottled phase; t = stony phase (refer to Mcintosh 1992a).

Many of the soils have been described by Mcintosh (1989 a,b; 1992b). Kaihiku and Kaiwera soils predominate. Kaihiku soils occur mainly on sunny slopes in the northern (drier) part of the land system. As altitude and rainfall increase southwards, the more leached and more acid Kaiwera soils predominate. Kaiwera soils also occur on shady slopes throughout the land system. Small areas of rolling phases of these soils occur on in-situ rock.

Other soils include unnamed Lithosols formed in screes on hilly slopes, Stonycreek soils on imperfectly drained toeslopes, Mandeville soils in shallow colluvium around rock outcrops and Nithdale soils in alluvium on low terraces.

Within the land system, soils typical of the Pukepahi land system (Venlaw and Pukerau soils) occur at higher altitudes on ridges, and are likely to be more common in southern, wetter areas. LAND SYSTEMS 27 3.4 The Owaka land system The Owaka land system is dominated by rolling downlands in broad valleys (Table 10; Fig. 11).

Table 10. Provisional definition of the Owaka land system

Location: South Otago Altitude: 0-400 m. Rainfall: 800-1 300mm Geology: Tuffaceous sandstone and mudstone forming northern limb of the Southland syncline (Wood 1966; McKellar 1966; McKellar and Speden 1978). Physiography*: (a) Rolling downlands of broad valleys; (b) hilly slopes following strike ridges; (c) flat to undulating floodplain. Soil parent material*: (a) loess (chiefly from schist and greywacke; (b) stony colluvium (chiefly from tuffaceous standstone); (c) colluvium with stones (chiefly from tuffaceous mudstone): Soil Information: N.Z. Soil Bureau (1968); Mcintosh (1992d).

*Physiographic and parent material components are listed in order of area covered (first component is most common).

OwH KhH In loess on hilly slopes KwR In stony colluvium In clayey colluvium in rolling basins on sunny hilly slopes ~ OwR in loess on rolling land MkU ~ In clayey alluvium in river valleys

Dip of rocks ~ stony clayey ----r'-----'> N ~ colluvium KwRt In stony clayey colluvium t.:i.:1.:1.:1.:11 cl~yey colluvium , ,.,...,.., I rock outcrops ~. loess in rolling basins (associated with stones ,,...,,., ~ Ill alluvium with rock outcrops)

Fig. 11 The Owaka land system: soil-landscape relationships. 28 LAND SYSTEMS

Table 11. Soils of the Owaka land system

Land Component Slopes Soil Map Unit Soil Series Symbol* Name Loess-covered downlands Convex rolling OwR Owaka and valley floors Valley floors KwRt Kaiwera with rocky Convex rolling outcrops KwR Slopes at Hilly OwH Owaka margins of downlands Sunny slopes Hilly KhH Kaihiku

Shady slopes Hilly KwH Kaiwera Floodplains Undulating MkU Makarewa

*First two letters identify soil series. U, R, H, and S identify undulating, rolling, hilly and steep phases respectively. Additional phases are identified as follows: 0 = deep phase; 1 = moderately deep phase; m = mottled phase; t = stony phase (refer to Mcintosh 1992a).

The limits of the Owaka land system are the coast to the east, the lower Clutha plains to the north, the margins of the Owaka and Puerua catchments to the west and terrain above about 300 m or with more than 1300 mm annual rainfall to the south.

Reconnaissance observations and the N.Z. Soil Bureau (1968) map indicate the relationship of the soil pattern to land components (Table 11). As in the Kaiwera land system, loess is present on rolling valley floors, and colluvium mantles most hill slopes. Owaka soils described by Mcintosh (1992d) occur in loess on rolling land and adjacent hills. Kaiwera and Kaihiku soils occur on hilly slopes. Kaiwera soils also occur around rock outcrops on rolling land. Makarewa soils occur on floodplains. LAND SYSTEMS 29 3.5 The Pukepahi land system

The Pukepahi land system occurs mainly on rolling and hilly uplands above 300 m altitude (Table 12; Fig. 12).

Table 12. Definition of Pukepahi land system.

Location: East and south Otago Altitude: Mostly 300-600 m; few areas to 720 m Rainfall: 1200-1600 mm Geology: Tuffaceous sandstone and mudstone forming northern and southern limbs of Southland syncline 01'/ood 1956; 1966; McKellar 1966; McKellar and Speden 1978). Physiography*: (a) Rolling uplands; (b) hilly slopes following strike ridges; ( c) steep slopes following strike ridges. Soil parent material*: (a) Colluvium with gravels (chiefly from tuffaceous mudstone); (b) stony colluvium (chiefly from tuffaceous sandstone): ( c) loess (from schist and greywacke and tuffaceous sandstone and mudstone): (d) peat. Soil information: N.Z. Soil Bureau (1968); Mcintosh (1992a).

*Physiographic and parent material components are listed in order of area covered (first component is most common).

stony clayey rock outcrops KeU ~A colluvium IRRI In deep peat on undulating uplands . silty colluvium iron pan MoR [ill with gravels B In thin colluvium on ~ rock; iron pan present loess VeH,VeS ~ PuR In thin stony PpR clayey colluvium In silty colluvium with on rolling ridges gravels on rolling slopes; A I I WrH iron pan present I

Ro RO RoR1 WrR In deep loess (silty) In 45 - 90cm loess (silty) In silty colluvium with on rolling slopes on rolling slopes gravels on rolling slopes RoH In deep loess (silty) and silty colluvium on hilly slopes

Fig. 12 The Pukepahi land system: soil-landscape relationships on uplands east of Gore. From Mcintosh (1992a). 30 LAND SYSTEMS

Table 13. Soils of the Pukepahi land system

Land Component Slopes Soil Map Unit Soil Series Name Symbol*

Loess covered basins Convex rolling Ro RO Rosemarkie RoR1

Margins of basins and Convex rolling WrR Waiarikiki dissected uplands Gully sides WrH

Broad ridges Convex rolling PpR Pukepahi Slopes at margins of basins Hilly RoH Rosemarkie WrH Waiarikiki Shady Slopes Hilly VeH Ven law Steep VeS

Exposed ridge tops (rainfall Rolling PuR Pukerau <1400 mm)

Exposed ridge tops (rainfall Rolling MoR Mokoreta >1400 mm)

Moist upland peats Undulating KeU Kaherekoau *First two letters identify soil series. U, R, H, and S identify undulating, rolling, hilly and steep phases respectively. Additional phases are identified as follows: 0 = deep phase; 1 = moderately deep phase; m = mottled phase; t = stony phase (refer to Mcintosh 1992a).

Soils are upland soils and six of the seven series present (Table 13) have been defined and described by Mcintosh (1992a). Upland basins contain Rosemarkie soils formed in loess. More exposed sites without loess cover have Waiarikiki or Pukepahi soils developed in colluvium derived from frittered mudstone. Hilly and steep slopes have Venlaw soils. Pukerau and Mokoreta soils (in thin colluvium) and Kaherekoau soils (in peat) occur on upland ridges and plateaux respectively.

The moist climate, generally good soil drainage and tuffaceous sandstone and mudstone parent material has produced several soils having allophanic properties (i.e. low bulk density, high P retention). Pukerau, Waiarikiki and Venlaw soils are examples (see Appendix 1). These soils characteristically have a pH of 5.0 to 5.2 in subsoils. In some Venlaw soil profiles P retention can be as high as 100%. Mokoreta soil is the most leached soil as it occurs on ridges at highest altitudes, and is classified as a Podzol (Appendix 1). LAND SYSTEMS 31 3.6 The Tautuku land system

The Tautuku land system occurs predominantly on rolling and hilly slopes near the coast (Table 14; Fig. 13). It includes soils previously mapped in the Chaslands (36a, 36aH), Tawanui (37fH), Waimahaka (39, 39H), Tautuku (61, 61H), Toetoes (63b), Riverton (70a) and Makarewa (90f) sets (N.Z. Soil Bureau 1968). As mentioned in section 2.2, the criteria for distinguishing these sets were not clear, and in this report only five soil series are at present identified within the land system (Table 15). Analyses are limited to a Tautuku profile described by Bruce et al. (1981) and to a coastal dune sequence described by Smith et al. (1985).

Table 14. Provisional definition of the Tautuku land system

Location: South Otago Altitude: 0-300 m Rainfall: c. 1200 mm Geology: Tuffaceous sandstone and mudstone forming the axis and northern and southern limbs of the Southland syncline 0Nood 1966; McKellar 1966; McKellar and Speden 1978); Physiography*: (a) Rolling downlands; (b) hilly slopes; (c) undulating floodplains; (d) dunes. Soil parent material*: (a) Stonycolluvium (chiefly from tuffaceous sandstone; (b) loess; ( c) alluvium from tuffaceous standstone and mudstone; (d) coastal dune sand. Soil Information: N.Z. Soil Bureau (1968); Bruce et al. (1981 ); Smith et al. (1985).

*Physiographic and parent material components are listed in order of area covered (first component is most common).

TwH In stony clayey colluvium on hill slopes. TwR In stony clayey colluvium on ridges. TtR In clayey loess; pan present. TeR RvR Soils in old dunes. Soils in young dunes.

Unnamed Organic soils in peat.

TtHt

Fig. 13 The Tautuku land system: soil-landscape relationships. 32 LAND SYSTEMS

Table 15. Soils of the Tautuku land system

Land Component Slopes Soil Map Unit Soil Series Symbol* Name Downlands Rolling TtR Tautuku Hills TtHt Tautuku Hilly TwH Tawanui Floodplain Undulating MkU Makarewa Old dunes Rolling TeR Toetoes Young dunes Rolling RvR Riverton Peaty depressions Hollows Not named

*First two letters identify soil series. U, R, H, and S identify undulating, rolling, hilly and steep phases respectively. Additional phases are identified as follows: 0 = deep phase; 1 = moderately deep phase; m = mottled phase; t = stony phase (refer to Mcintosh l 992a).

The soil-landscape relationships shown in Fig. 13 will require modification after the pedological concepts behind the set names listed above can be established by detailed mapping. Table 15 shows the relationships of soils to land components.

High rainfall has caused leaching of nutrients and induced podzolisation and iron pan formation in the predominant Tautuku soils. Consequently Tautuku soils are extremely acid (A horizon pH = 4.3). The Tautuku soil name is also applied at present to soils with an iron pan that occur in stony colluvium on rolling and hilly slopes. Tawanui soils occur in stony colluvium but do not have an iron pan (N.Z. Soil Bureau 1968). Soils in dune sands range from Riverton soils (Recent Soils) in the youngest dunes to Toetoes soils (Brown Soils) in the older dunes. Unnamed organic soils occur between dunes. The soils in dune sands and their associated organic soils are not used for agriculture or commercial forestry and are estimated to cover only 2000 ha. SOILS AND.,, LAND USE 33 4. Soils and land use

4.1 Pastoral farming and element deficiencies The soils of the Kaihiku-Hokonui land region have been used for pastoral farming and cropping since the arrival of the Europeans in the 1860's. They are naturally deficient in phosphorus, and with the exception of areas near the coast (During 1972; Boswell et al. 1992), sulphur is also deficient for improved pastures. The current fertiliser recommendation for pasture is to apply about 200 kg/ha superphosphate per year. Although During (1972) noted a positive relationship between pasture vigour and potassium topdressing, potassium appli cation is no longer recommended except for pastures being cut regularly for hay, indicating that in the past potassium requirements may have been overestimated. A horizon pH values on lowland soils are typically in the range 5.0-5.8 (Appendix 1) and lime is necessary to maintain high levels of production. An application rate of 1 tonne per hectare every four years is standard practice on intensively grazed lowland pastures. Upland soils tend to be more acid and these soils tend to be limed less frequently, at lower rates. The financial returns from liming of hill soils are marginal and aerial lime application is seldom practised on these soils. Molybdenum deficiency (During 1972) can be overcome by application of 10 g/ha of sodium molybdate per year (W. Catto, personal communication).

Deficiencies of cobalt and copper may affect stock health, and are soil-related (Mcintosh et al. 1986; Sherrell and Mcintosh 1987; Sherrell et al. 1987; Metherell 1989). Soils of the Pukepahi land system, because they are more leached than those in lowland land systems, are most affected (Table 16). The leaching process has depleted upper horizons of copper and cobalt, and enriched lower horizons in these elements. In soils with an iron pan (e.g. Pukepahi and Mokoreta soils), cobalt is concentrated in the pan, together with iron and manganese (Fig. 14).

Table 16. Mean copper and cobalt concentrations in pastures on lowland and upland soils. From Sherrell and Mcintosh (1987).

Spring Pastures Summer pastures Lowland Upland SEO Lowland Upland SEO Soils Soils Soils Soils Cu (ppm) 10.2 8.8 0.5** 9.6 8.6 0.4** Co (ppm) 0.16 0.09 0.01 ** 0.07 0.05 0.007**

SED = Standard error of the difference; ** = P<0.01

The cobalt concentration in pasture varies seasonally (Fig. 15). On upland soils pastures may be deficient in cobalt throughout the year, except .briefly in spring, but the deficiency period on lowlands is confined to summer and early autumn. Consequently sheep grazing upland pastures become deficient or marginally deficient in vitamin B12, whereas sheep grazing lowland pastures have adequate vitamin B12 levels (Fig.16). Rosemarkie, Waiarikiki, Pukerau and Pukepahi soils and the strongly leached lowland Tautuku soil are likely to support pastures deficient in copper and cobalt for stock. Deficiencies of copper and cobalt can be avoided by circulating stock onto pastures on different soils (including lowland soils with pastures containing more cobalt and copper). For cobalt-deficient sheep vitamin B12 injection is an effective remedy.

Because of the expense of applying lime to upland soils and hill soils long-term pastoral use of these soils may be uneconomic, and forestry may be a more viable land use. ::::::::::::::::;~m:~;:;:;::: :::::::::::::::::~~;::~:::::~:::::::::::~;::;:;:3;:::;:*:::::;:;:..::;:::,::;~~::::·· .. ,~::·.········ • -:·:-:-:':-:-:-:--.-:·.: ... ·::.··:·:···:·:·:·:::·:·:::::·::::::=:=:::::;:::::::;:;::::::~:::::::::~~::;:;:::::::=:::=::::::::::;:.=:=.=:=:=::·:::::: :::::::::::::::::::::::::::::::::::~~:::::: ::::::::::§.:&::. ·:::::::::::: :::=:=::~:::::::=:=::::::::::::::::::~::;:;::'ir~:::::::: :::::::::: ::::;:::;::::::::::::::::::::::::::::::::::::=::::: .·:::·:::::::~:::::::~::·=·:;:-:-:-:·:·········· .... 34 SOILS AND LAN~o USE

Cobalt Copper 0 10 20 (ug/g) 40 o~-1~0~_-.2o__ (u0 gl_g)_4,o~__,so

Ah I Ah Ah/Bw Ah/Bw Bw1 I Bw1 Bw2 0 Bw2 ::J I ~ :.c: 2Bt1 cm 2Bt1 "iii ::..:: 50 2Bt2 2Bt2

100

I a> Ah2 I ~ Ah/BwAh1g m Bw M11 E BC1 A~~ Q) Ul ~ BC2 BC2

I ·-Bms8; ~ BC1_Ah~ I fil" BC2 1------'- Bm:!\ ~ -----'--, if_ BC3 BC3 --~

Fig. 14 Total cobalt and copper in a lowland soil (Kaihiku series), a non-podzolised upland soil (Rosemarkie series) and a podzolised upland soil (Pukepahi series). From Mcintosh et al. (1986). Note the low values of cobalt and copper i'.n upper horizons of upland soils, and the accumulation of cobalt in subsoils and in the iron pan of Pukepahi soil. Upland soils like Rosemarkie and Pukepahi soils have pastures that are more cobalt and copper deficient than lowland soils.

Ill October D February (}2

Pasture Co cone. (ppm) ···sheep···

•• · · · · · ··· · ·· ·· ·· · · · ·· · ·· ··· ··· · · · · · · · ·· · ···· • · · cattle • • • • • • • ...... " ... · · ·· ·· ·

0 Lowland soils Upland soils

Fig. 15 Decline in pasture cobalt concentrations from spring (October) (total histogram heights) to summer (February) (unshaded portion of histograms) on lowland and upland soils, in relation to requirements of sheep and cattle. From Sherrell et al. (1987). SOILS AND LAND USE 35

-::::::: 0 E -3: 2000 c: 0 ro -"- 1500 c: -CJ) (..) c:. r=and 0 (..) 1000 ....N CD c: E 500 ro ·s:- E :J 0 "- CJ) DS 0 N J F M A M J J A S (j) 1985 1986

Fig. 16 Seasonal variation in serum vitamin Bl 2 of sheep grazing upland and lowland pastures of the Pukepahi and Kaiwera land systems respectively. A= ewes; o = lambs. Shaded area indicates threshold deficiency level of serum vitamin Bl 2 for sheep. From Sherrell et al. (1987).

4.2 Horticulture

The cool moist conditions in the Kaihiku-Hokonui land region limit the options for horticul tural crops. No commercial orchard crops can be grown in the land region, but the deep Otaraia, Owaka, Titiroa and Tuturau soils (all formed inloess) are suitable for cool temperature arable crops such as vegetables. These soils have the advantage of good drainage, total available water (TAW) exceeding 100 mm to 60 cm depth and only slight development of subsoil pans (Tables 17-20). Although macroporosity is less than 5% in Tuturau and Otaraia subsoil horizons there is no evidence that the low values restrict roots or impede drainage.

Clay percentage in these soils is variable, and affects land-use options. Titiroa soils contain the least clay and most sand and are highly suitable for cultivation. In some areas of Titiroa soils deep subsoils may be water-saturated and these soils require drainage. Tuturau soils are next most suitable, but their frequent occurrence on rolling land dissected by deep gullies is a disadvantage. Otaraia and Owaka soils do not have this disadvantage, but contain up to 35% clay in topsoils, so that cultivation can be difficult from late autumn to spring. Natural aggre gates (peds) in the A horizon of all four soils are only moderately developed, so that cropping must be done with care to avoid compaction and topsoil loss by rill erosion. Cultivation out of pasture and rotation of horticultural crops with periods of pasture is probably advisable. None of the soils are naturally fertile, which is to be expected from their classification as Brown Soils (Table 4).

Other soils have major limitations for horticultural use,_ including high clay content, stoniness, acidity, exposure or occurrence on hilly or steep slopes. 36 SOILS AND LAND USE

Table 17. Properties of Otaraia silt loam (from Mcintosh 1992c).

Chemical properties A horizon Subsoil to 60 cm pH 5.2 5.2 P retn. (%) 59 64

Physical properties A horizon Subsoil to 60 cm Pedality Moderate Weak %Sand 7 6 %Silt 58 60 %Clay 35 34 Water 0-30 cm 0-60 cm 0-100 cm RAW(mm) 15 30 40 TAW(mm) 65 120 180 Overall Drainage Well drained Lowest Macroporosity 3% at 35-65 cm depth Highest Bulk Density 1 .4 t/m3 at 35-65 cm depth

Table 18. Properties of Owaka silt loam (from Mcintosh 1992c).

Chemical properties

A horizon Subsoil to 60 cm pH 5.8 5.7 P retn. (%) 37 45

Physical properties

A horizon Subsoil to 60 cm

Pedality Moderate Moderate %Sand 4 3 %Silt 64 61 %Clay 32 36

Water

0-30 cm 0-60 cm 0-100 cm

RAW(mm) 20 35 50 TAW(mm) 65 105 145

Overall Drainage Well drained Lowest Macroporosity 5% at 60-100 cm depth Highest Bulk Density 1 .5 t/m3 at 60-100 cm depth SOILS AND LAND USE 37

Table 19. Properties of Titiroa sandy loam (from Mcintosh l 992c).

Chemical properties

A horizon Subsoil to 60 cm pH 5.8 5.8 P retn. (%) 43 45 Physical properties

A horizon Subsoil to 60 cm

Pedality Moderate Weak %Sand 44 51 %Silt 39 35 %Clay 17 14 Water

0-30 cm 0-60 cm 0-100 cm RAW(mm) 25 50 85 TAW(mm) 70 115 165

Overall Drainage Moderately well drained Lowest Macroporosity 11 % at 0-14 cm depth Highest Bulk Density 1 .5 t/m3 at 60-100 cm depth

Table 20. Properties of Tuturau silt loam (from Mcintosh l 992c).

Chemical properties

A horizon Subsoil to 60 cm

pH 5.8 5.3 P retn. (%) 47 52 Physical properties

A horizon Subsoil to 60 cm

Pedality Moderate Weak to moderate %Sand 5 5 %Silt 63 65 %Clay 32 30 Water

0-30 cm 0-60 cm 0-100 cm

RAW(mm) 15 30 40 TAW(mm) 65 110 105

Overall Drainage Well drained Lowest Macroporosity 4% at 50-70 cm depth Highest Bulk Density 1 .5 t/m3 at 70-100 cm depth 38 SOILS AND LAND USE 4.3 Forestry

Earlier assessments of soil suitability for forestry have been based on Cutler's (1968) system of five classes and subclasses based on various combinations of slope, drainage, occurrence of pans, nutrient deficiencies, altitude and moisture. Assignment of soils to classes was subjective as class limits for some properties were not defined.

A new system has been devised using four classes with defined limits (Table 21), based on principles used in regional land use assessments (e.g. Mcintosh and Burgham 1993).

Table 21. Preliminary classification and key for rating soils for forestry suitability, based on limitations. Soils not having a// the attributes of class 1 soils are considered for class 2, then class 3, then class 4, until the classification is made.

Code Attribute

Class 1. Highly suitable for commercial forestry.

S Slopes <26° T Mean annual soil temperature >8°C F Frosts no more severe than -12°C E Not exposed* G No very gravelly layer (>35% stones by volume) within 45 cm depth P Not fragmental or peaty D Well drained or moderately well drained X No pans or rock at 0-90 cm depth, or thin pan present that can be ripped W More than 100 mm Total Available Water (max. 100 cm depth) H Minimum pH 4.9 or greater at 20-60 cm depth R Phosphate retention <60% in A horizon

Class 2. Very suitable for commercial forestry

S Slopes <26° T Mean annual soil temperature >8°C F Frosts no more severe than -12°C E Not exposed* P Not fragmental or peaty D Well drained or moderately well drained, or poorly drained but readily improved X Pans or rock at >60 cm depth or thin pan present, that can be ripped W More than 100 mm Total Available Water (max. 100 cm depth) H Minimum pH 4.9 or greater at 20-60 cm depth

Class 3. Suitable for commercial forestry, with slight to moderate limitations

T Mean annual soil temperature >8°C E Not exposed* P Not fragmental or peaty

Class 4. Marginally suitable or unsuitable for commercial forestry

Soils not meeting criteria for class 3

*No simple measure of exposure is proposed in this report. Exposed sites are those sites on uplands or near the coast where gales and/or salts damage trees and produce poor form as well as low growth rates. SOILS AND LAND USE 39

Values of two climate attributes (mean annual soil temperature and frost severity and exposure) for different soils were estimated from Southland lapse rates (Sansom 1984) and four years of recording of minimum air temperatures on lowland hill slopes (Landcare Research, unpublished data). Only Venlaw soil, steep phase (on shady slopes) and Mokoreta soil, rolling phase, have mean annual soil temperature less than 8°C. Minimum air temperatures recorded over four years on eastern Southland hill slopes at less than 300 m altitude on Nithdale station, Otaraia have never exceeded-10°C and-12°C frosts only appear to be likely to occur on the cooler upland soils above 400 m altitude. Exposure is considered to be a problem only on rolling upland soils on convex ridge tops (i.e. on Pukerau, Pukepahi and Mokoreta soils in the Pukepahi land system) and on soils near the coast (Riverton and Toetoes soils in the Tautuku land system).

Other information was obtained from field descriptions and laboratory analyses (see list of laboratory numbers in Table 4) or estimated.

Class 1 soils are considered to have no soil limitations for forestry, and should suit most species tolerant of cool-temperate climates (e.g. Eucalyptus nitens, Pin us radiata, Cupressus macrocarpa). Class 2 soils (e.g. Kaihiku soils, hilly phase, Fig. 17) have a few limitations that may affect growth rates or site suitability for some species such as Cupressus macrocarpa. Class 3 soils require more careful assessment before planting: steep slopes, soil acidity, droughtiness and pans may limit production and/ or site suitability but these soils are suitable for Pinus radiata. Class 4 soils have quite severe limitations and plantation forests may be uneconomic. These classes require calibrating against actual growth rates of plantation trees. It should be noted

Fig. 17 Kaihiku soils, hilly phase, are class 2 soils for forestry (very suitable). Deep well drained soils, high fertility and occurrence on sunny slopes of 16-24° are all advantages. 40 SOILS AND LAND USE

Table 22. Suitability of soils for forestry.

Symbol Soil Name Limitation*

Class 1. Highly suitable

KwH Kaiwera, hilly phase Or RO Otaraia, rolling, deep phase OrRI Otaraia, rolling, moderately deep phase Orum Otaraia, undulating, mottled phase OwR Owaka, rolling phase TuR Tuturau, rolling phase TiU Titiroa, undulating phase

Class 2. Very suitable KhH Kaihiku, hilly phase G KhR Kaihiku, rolling pase G KwR Kaiwera, rolling phase G KwRt Kaiwera, rolling, stony phase G,X KwHt Kaiwera, hilly, stony phase G,X MjR McNab, rolling phase x MjU McNab, undulating phase x NtU Nithdale, undulating R Ro RO Rosemarkie, rolling, deep phase R RoRl Rosemarkie, rolling, moderately deep phase R RoH Rosemarkie, hilly phase R StH Stonycreek, hilly phase x WrR Waiarikiki, rolling phase R WrH Waiarikiki, hilly phase R Class 3. Suitable, with slight to moderate limitations KhS I Kaihiku, steep phase s KwSt Kaiwera, steep, stony phase s MeR Mandeville, rolling phase w MkU Makarewa, undulating phase D PpR I Pukepahi, rolling phase F TtR Tautuku, rolling phase H TtHt Tautuku, hilly, stony phase H TwR Tawanui rolling phase H TwHI Tawanui hilly phase H VeH I Venlaw, hilly phase F,H

Class 4. Marginally suitable or unsuitable

AeU Andrews, undulating p KeU Kaherekoau, undulating P,T LH Unnamed Lithosol, hilly phase p MoR Mokoreta, rolling phase E,T PuR Pukerau, rolling phase E RvR Riverton, rolling phase E TeR Toetoes, rolling phase E VeS Venlaw, steep phase T

* Limitations listed are the primary limitations, i.e., those that prevent classification in the next higher class. ACKNOWLEDGEMENTS 41

that management limitations, such as the difficulty of weed control on hilly slopes, are not taken into account in this classification, except that all soils on steep slopes are class 3 or 4, regardless of other favourable properties.

Most soils of the Kaihiku-Hokonui land region fall into classes 1 to 3 for forestsuitability (Table 22). Most lowland soils formed in loess, and Kaiwera soils, hilly phase are highly suitable for forestry (class 1).

Acknowledgements

The information presented is based on the research of many persons including Dr. C.G. Sherrell, Messrs. P. Brunsden, J.G. Bruce, P.G. Prema, J.S. Whitton and Dr. D.N. Eden; I would like to thank these persons for cooperation over several years. I am grateful to Dr. A.E. Hewitt, Mr. G.G. Hunter and Mr. I. H. Lynn for constructive comments on drafts of the report, to Ms M. Rolston and Mr J. Arand for editing the final draft, and to Ms J. Grindell, Mr B. Ellison and Mr G. Comfort for layout advice. Funds for this research were provided by the Foundation for Research, Science and Technology under Contract C09223. 42 REFERENCES References

Allen, R.B. 1985: The ecology of Nothofagus menziesii in the Catlins ecological region, Southeast Otago, New Zealand. Unpublished Ph.D. thesis, University of Otago.

Bates, R.L.; Jackson, J.A. 1987: Glossary of geology (third edition). American Geological Institute, Alexandra, Virginia, USA. 788 pp.

Boswell,C.C.;Risk,W.H.;Gray,G.M.;Swanney,B.;Parmenter,G.A.;Smith,L.C.1992:Sulphur in rainfall in Southland, New Zealand. Invermay technical report 30. New Zealand Pastoral Agriculture Research Institute.

Bruce, J.G. 1973: Loessial deposits in southern South Island, with a definition of Stewarts Claim Formation. New Zealand journal of geology and geophysics 16: 533-538.

Bruce, J.G. 1984: Soils of the Gore-Waikaka district, South Island, New Zealand. New Zealand soil survey report 74.

Bruce,J.G.; Childs, C.W.; Furkert, R.J. (compilers) 1981: Soils with variable charge conference, Palmerston North, February 1981. Guide book for tour 2: pre-conference South Island, New Zealand. Pp. 120-124.

Clayden, B; Hewitt, A.E. 1989: Horizon notation for New Zealand soils. Division of Land and Soil Sciences scientific report 1. Department of Scientific and Industrial Research. 30 pp.

Clayden, B.; Webb, T.H. 1994: Criteria for defining the soilform - the fourth category of the New Zealand Soil Classification. Landcare Research science series 3. Manaaki Whenua - Landcare Research New Zealand Ltd, Lincoln. 36 pp.

Cutler, E.J.B. 1968: Soils of the Otago region. In: National Resources Survey part V - Otago region. Town and Country Planning Branch, Ministry of Works, Wellington. Pp. 35- 51.

During, C. 1972: Fertilisers and soils in New Zealand farming. Government Printer, Wellington. 312 pp.

Eden, D.N.; Mcintosh, P.D.; Reynolds, J. 1987: Sources of loess in the Kaiwera-Mimihau District, Southland, New Zealand. New Zealand journal of geology and geophysics 30: 307- 316.

Griffiths, E. 1985: Interpretation of soil morphology for assessing moisture movement and storage. New Zealand Soil Bureau scientific report 74. Department of Scientific and Industrial Research.

Hewitt, A.E. 1988: Key to hydromorphic soils. Unpublished New Zealand Soil Bureau report. Department of Scientific and Industrial Research.

Hewitt, A.E. 1992: New Zealand Soil Classification. Land care Research science series 1. Manaaki Whenua - Landcare Research New Zealand Ltd, Lincoln. 133 pp. REFERENCES 4 3

Johnson, P.N.; MarkA.F.; Baylis,G.T.S. 1977: VegetationatAjaxHill,south-eastOtago,New Zealand. New Zealand journal of botany 15: 209-220.

Lynn, I.H.; Crippen, T.F. 1991: Rock type classification for the New Zealand Land Resource Survey. DSIR Land Resources scientific report 10. Department of Scientific andindustrial Research.

Milne, J.D.G.; Clayden, B; Singleton, P.L. and Wilson, A.D. 1991: Soil description handbook. DSIR Land Resources, Department of Scientific and Industrial Research, Lower Hutt. 133 pp.

Mcintosh, P.D. 1986: Chemical criteria as an aid to soil mapping in hill country: an example from the Hokonui Hills, Southland, New Zealand. Soil survey and land evaluation 6: 73- 82.

Mcintosh, P.D.; Sherrell, C.G.; Prema, P.G. 1986: Distribution of cobalt, copper and zinc in upland and lowland soils of the Kaiwera District, eastern Southland, New Zealand. New Zealand Soil Bureau scientific report 78. Department of Scientific and Industrial Research.

Mcintosh, P .D.; Sherrell, C.G. 1987: Cobalt and copper leaching causes ill-thrift in south. New Zealand journal of agriculture 152: 22-23.

Mcintosh, P.D. 1988: Soil taxonomic unit descriptions for Kaiwera district, eastern Southland, New Zealand. New Zealand Soil Bureau soil taxonomic unit descriptions 24. Department of Scientific and Industrial Research.

Mcintosh, P.D.; Whitton, J .S. 1988: Use of chemical criteria to distinguish soils formed in loess in eastern Southland, New Zealand. New Zealand journal ofgeology and geophysics 31: 363- 373.

Mcintosh, P.D. 1989a: Soil series descriptions for soils of the Mandeville District, Southland, New Zealand. Division of Land and Soil Sciences file report 1. Department of Scientific and Industrial Research.

Mcintosh, P.D. 1989b: Soil map unit descriptions for soils of the Mandeville District, Southland, New Zealand. Division of Land and Soil Sciences file report 2. Department of Scientific and Industrial Research.

Mcintosh, P.D. 1992a: Soils of the Kaiwera District, eastern Southland, New Zealand. DSIR Land Resources scientific report 32. Department of Scientific and Industrial Research.

Mcintosh, P.D. 1992b: Soil map of Mandeville District, South Island, New Zealand. 1:25000. DSIR Land Resources map417 (2 sheets). Department of Scientific and Industrial Research.

Mcintosh, P .D. 1992c: Soils for horticulture in Southland. Land user guide 1. Landcare Research New Zealand Ltd, Lincoln and RavensdownFertiliser Cooperative Ltd, Dunedin. 83 pp.

Mcintosh, P.D. 1992d: Soils for horticulture in Coastal Otago. Landuser guide 3. Landcare Research New Zealand Ltd, Lincoln and Ravensdown Fertiliser Cooperative Ltd, Dunedin. 83 pp. ::::;:;;::::,;::~::::~:::::m:::::~::::s~:rn:r::::::::·:::::::: ;:::::::<·:::·::::::::=:::::::::::;:;::::::::::::~:::~::::::: ::::::=.:::::::-.::;;:::·:::;:;:::::;:::::::::::::::=::::::::::::::::::::::::::~ :···=-:·.~·.:~-:·:·:-:;.;.;.;.·.:·:·"····· ·Z·:·-·.:-:-:-:··::··:···:·:·:.:-=·:·::-:·:.:··-=·:·:·:·:·.:::::::::::::::::=::::::.::::::::::=::.;;::~:::::::::::::::::::~::::::::::::::::::::::~:::::~::::::::::~:::::: :::::::::::::~::::::::: ::::::>:;::~:; :::::::·:::::::::::::::::::::::::::::::::::::.:::::::::::::::}::::::::::r::::::::.·:·:::·:.;:::·:::·~' 44 REFERENCES

Mcintosh, P .D.; Burgham, S.J. 1993: Classification of land for horticulture, forestry and urban use in the Gore District. Unpublished Landcare Research con tract report LC9293 /2 7. Manaaki Whenua - Landcare Research, Dunedin.

Mcintosh, P.D.; Eden, D.N.; Burgham, S.J. 1990: Quaternary deposits and landscape evolution in northeast Southland, New Zealand. Palaeogeography, palaeoclimatology, palaeoecology 81: 95-113.

McKellar, I.C. 1966: Sheet 25- Dunedin (lst edition). Geological map of New Zealand, 1: 250 000. New Zealand Geological Survey, Deparhnent of Scientific and Industrial Research, Wellington.

McKellar, I.C. 1969: Sheet S169-Winton. Geological map of New Zealand, 1: 63 360. New Zealand Geological Survey, Deparhnent of Scientific and Industrial Research, Lower Hutt.

McKellar, I.C.; Speden, LG. 1978: Jurassic stratigraphy, Southland and southeast Otago. In: The geology of New Zealand -volume 1. Government Printer, Wellington. 343 pp. Pp. 241-252.

Metherell, A.K. 1989: The cobalt enigma - some observations and strategies for Otago and Southland. Proceedings of the New Zealand Grassland Association 50: 101-108.

New Zealand Soil Bureau 1968: General survey of soils of South Island, New Zealand. New Zealand Soil Bureau bulletin 27. Department of Scientific and Industrial Research.

New Zealand Meteorological Service 1973: Rainfall normals for New Zealand 1941to1970. New Zealand Meteorological Service miscellaneous publication 145. 34 pp.

Sansom, J. 1984: The climate and weather of Southland. New Zealand Meteorological Service miscellaneous publication 115.

Sherrell, C.G.; Mcintosh, P.D. 1987: Nutrient status of soils and pastures of the Kaiwera district, eastern Southland, New Zealand. New Zealand journal of agricultural research 30: 261-268.

Sherrell, C.G.; Brunsden, P.; Mcintosh, P.D. 1987: Pasture cobalt concentration and its effect on vitamin B12 status of sheep grazing upland and lowland pastures in the Kaiwera District, eastern Southland, New Zealand. New Zealand journal of agricultural research 30: 325-331.

Sherrell, C.G.; Mcintosh, P.D.; Brunsden, P. 1989: Cobalt deficiency in the Kaiwera District, eastern Southland. In: Proceedings of the New Zealand Grassland Association Conference, Balclutha, 1988. Pp. 109-115.

Smith, S.M.; Allen, R.B.; Daly, B.K. 1985: Soil-vegetation relationships on a sequence of sand dunes, Tautuku Beach, southeast Otago, New Zealand. Journal of the Royal Society New Zealand 15: 295-312.

Soil Survey Staff 1992: Keys to soil taxonomy. SMSS technical monograph 19 (5th edition). Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA. 541 pp. REFERENCES 45

Stevens, G.R. 1980: New Zealand adrift. Reed, Wellington. 442 pp.

Wood, B.L. 1956: The geology of the Gore Subdivision. New Zealand Geological Survey bulletin 53. Deparhnent of Scientific and Industrial Research.

Wood, B.L. 1966: Sheet 24- Invercargill (lst edition). Geological map of New Zealand, 1: 250 000. New Zealand Geological Survey, Deparhnent of Scientific and Industrial Research, Wellington. 46 BRIEF PROFILES Appendix 1: Brief soil profile descriptions

The descriptions below expand on the soil classification information given in Table 4. Full profile descriptions and analytical data can be found in the references listed. Horizon notation is according to Clayden and Hewitt (1989). Explanations of terms used in soil classification are given by Hewitt (1992).

AeU Andrews soil Acid Mesic Organic Soil, Ff The soil consists of moderately decomposed (mesic) organic matter and has a pH less than 4.5 in most horizons. The organic matter is Fibriform (Ff) meaning it is derived from fibrous material like sedges. Horizon Depth (cm) P retention (%) pH Oml 0-19 4.7 Om2 19-85 3.9 Om3 85-140 3.9 Reference: Mcintosh (1992a).

KeU Kaherekoau soil Acid Humic Organic Soil, Hu The soil contains strongly decomposed (humic) organic matter and pH is less than 4.5. Hu indicates the organic matter is undifferentiated and amorphous. Horizon Depth (cm) P retention(%) pH

Orn 4-12 4.0 Reference: Johnson et al. (1977).

KhH Kaihiku soil, hilly phase Argillic Orthic Melanie Soil, Ms, C/K, m Melanie indicates the soil has high base saturation (i.e. is rich in calcium, magnesium and potassium), is well structured, has a dark A horizon, and is weakly acid. The parent material is rich in calcium and/ or magnesium. Ms indicates the soil is stony but contains on average less than 35% stones by volume. C/K indicates the soil matrix is clayey and overlies a horizon which is skeletal (i.e. contains more than35% stones by volume). Permeability is moderate (m). Horizon Depth (cm) P retention(%) pH Ah 0-24 38 5.8 Ah/Bw 24-35 41 5.9 Bwl 35-66 40 5.8 Bw2 66-92 36 6.1 2Btl 92-150 32 6.3 2Bt2 150-200 31 6.4 Reference: Mcintosh (1992a). BRIEF PROFILES 47

KhR Kaihiku soil, rolling phase

The soil is similar to Kaihiku soil, hilly phase, except that it occurs on rolling slopes.

KhS Kaihiku soil, steep phase The soil is similar to Kaihiku soil, hilly phase, except that it occurs on steep slopes.

KwH Kaiwera soil, hilly phase Acidic Orthic Brown Soil, Ms, C, m

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Orthic indicates the soil is structured in subsurface horizons or has weak soil strength. Acidic indicates that the soil has a pH of less than 5.5 in some part of the Bw horizon to 60 cm depth. Ms indicates that the soil contains less than 35% by volume of stones. The soil matrix is clayey (C). Permeability is moderate (m). Horizon Depth (cm) P retention (%) pH Ah 0-18 60 5.6 Ah/Bw 18-30 67 5.5 Bw 30-62 71 5.3 BCl 62-90 68 5.4 BC2 90-100 58 5.4 Reference: Mcintosh (l 992a)

KwHt Kaiwera soil, hilly and stony phase Acidic Allophonic Brown Soil, Mo(Ts), C, m

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a char~cteristic brown colour. The soil is Allophanic because it has P retention of 85% or more in the Bw horizon. Acidic indicates that the soil has a pH of less than 5.5 in some part of the Bw horizon to 60 cm depth. Ma(Ts) indicates the soil has more than 35% by volume of stones which are tuffaceous sandstone (Ts). The soil matrix is clayey (C). Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH Ah 0-26 71 5.5 Ah/Bw 26-37 81 5.5 Bwl 37-60 86 5.3 Bw2 60-73 92 5.1 c 73-86 63 5.2 Reference: Mcintosh (l 992a).

KwR Kaiwera soil, rolling phase Acidic Allophonic Brown Soil, Mm(Tm), C/K, m Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. The soil is Allophanic because it has P retention of 85% or more in the Bw horizon. Acidic indicates that the soil has a pH of less than 5.5 in some part of the Bw horizon to 60 cm depth. The soil has a rock contact between 45 cm and 90 cm depth so has the code Mm (moderately deep). Tm indicates the underlying rock is tuffaceous mudstone. Particle-size class is clayey (C) over skeletal (K) (more than 35% stones by volume). Permeability is moderate (m). 48 BRIEF PROFILES

Horizon Depth (cm) P retention (%) pH

Ap 0-19 73 6.2 Ah/Bw 19-33 87 6.1 Bw 33-58 95 5.3 BC 58-84 94 5.3

Reference: Mcintosh (l 992a).

KwRt Kaiwera soil, rolling and stony phase Acidic Allophonic Brown Soil, Mo(Ts), C, m Except for occurrence on rolling slopes this soil is similar in all respects to Kaiwera soil, hilly and stony phase (see KwHt).

Horizon Depth (cm) P retention(%) pH

Ah 0-25 64 6.1 Ah/Bw 25-35 80 5.8 Bw 35--46 87 5.7 BC 46--60 88 5.4

Reference: Landcare Research, unpublished data.

KwSt Kaiwera soil, steep and stony phase Acidic Allophonic Brown Soil, Mo(Ts), C, m Except for occurrence on steep slopes this soil is similar in all respects to Kaiwera soil, hilly and stony phase (see KwHt).

Horizon Depth (cm) P retention(%) pH

Ah 0-17 63 4.8 Ah/Bw 17-33 81 4.9 Bw 33-67 87 5.1

Reference: Landcare Research, unpublished data.

LH Unnnamed Lithosol Typic Orthic Recent Soil, Mf(Ts), r The subgroup Orthic Recent Soils occur on land that has been eroded or has received sediment that has been deposited mainly as the result of slope processes. Typic indicates the soil is typical of the subgroup. Mf(Ts) indicates that the parent material is fragmental, that is, it is composed of rock fragments with insufficient fine earth to fill interstices (the soil is in fact formed in scree) and that the rock fragments are tuffaceous sandstone (Ts). Permeability is rapid (r).

Reference: Mcintosh (l 989a).

MeR Mandeville soil, rolling phase Typic Mofic Brown Soil, Ml(Ts), C, m Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Mafic Brown Soils contain more dark magnesium-and iron-rich minerals than other Brown Soils. Typic indicates the soil is typical of the subgroup. Ml(Ts) indicates the soil is formed on tuffaceous sandstone rock (Ts) at less than 45 cm depth. Particle-size class is clayey (C). Permeability is moderate (m). BRIEF PROFILES 49

Horizon Depth (cm) P retention (%) pH Ahl 0-14 26 5.3 Ah2 14-32 31 5.5 Ah/Bw 32-45 34 5.9 Reference: Mcintosh (1989a).

MjR McNab soil, rolling phase Typic Acid Brown Soil, Mm(Tm), Z, m.

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron mineralsgive them a characteristic brown colour. Acid Brown Soils have pH of 4.8 or less between 20 and 60 cm depth. Typic Acid Brown Soils are the typical soils of the subgroup. Mm indicates the soil is moderately deep (45-90 cm on rock). The underlying rock is tuffaceous mudstone (Tm). Particle size is silty (Z). Permeability is moderate (m). Horizon Depth (cm) P retention (%) pH Ah 0-17 43 5.3 Ah/Bw 17-25 56 5.2 Bw 25-39 59 5.2 BC(g)l 39-52 56 5.0 BC(g)2 52-64 54 4.8 C(g) 64-84 39 4.9 Reference: Mcintosh (1992a).

MjU McNab soil, undulating phase These soils have the same classification and properties as McNab soil, rolling phase.

MkU Makarewa soil, undulating phase Typic Orthic Gley Soil, Ms, C, s

Gley soils are waterlogged in their natural state. If the soil is flooded, little sediment is deposited. Ms indicates that the soil contains stones, but less than 35% by volume. Particle size class is clayey (C).Permeability is slow (s).

Horizon Depth (cm) P retention(%) pH

Ah 0-21 68 5.4 Ahg 21-31 71 5.5 BCgl 31-51 69 5.6 BCg2 51-71 73 5.7 Reference: Mcintosh (1992a).

MoR Mokoreta soil, rolling phase Ortstein Perch-gley Podzol, Ml(Ts), Z, m/s

Podzols are acid soils and are leached of most nutrients. Ortstein indicates an iron pan is present. Perch-gley indicates that the soil is periodically saturated with water above the pan. Ml(Ts) indicates that a rock contact with tuffaceous sandstone (Ts) occurs within 45 cm depth. Particle-size class is silty (Z). Permeability is moderate (m) but becomes slow (s) with increasing depth, i.e., at the pan. 50 BRIEF PROFILES

Horizon Depth (cm) P retention (%) pH

Ah 0-24 81 4.6 Ah/Bg 24-36 80 4.9 Bgl 36-48 85 5.0 Bms 48-49 (pan) 95 5.1 BC 49-75 82 5.2

Reference: Mcintosh (l 992a).

NtU Nithdale soil, undulating phase Acidic Orthic Brown Soil, Md, Z, m

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Orthic Brown soils have structured B horizons or have weak soil strength in subsurface horizons. Acidic indicates the soil has pH of less than 5.5 in some part of the B horizon to 60 cm depth. Md indicates the soil is 45-90 cm deep. Particle size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH

Ah 0-17 71 5.3 Ah/Bw 17-27 72 5.3 Bw 27-50 71 5.4 BCl 50-77 59 5.3 BC2 77-91 52 5.4

Reference: Mcintosh (1992a)

OrRO Otaraia soil, rolling and deep phase Acidic Firm Brown Soil, Md, Z, m

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Firm Brown soils have a slightly firm subsurface horizon which has some of the characteristics of a fragipan. Acidic indicates the soil has pH of less than 5.5 in some part of the B horizon to 60 cm depth. Md indicates that the soil is more than 90 cm deep. Particle-size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention (%) pH

Ah 0-25 59 5.2 Ah/Bw 25-37 62 5.1 Bw 37-66 65 5.3 BC 66-100 59 5.3

Reference: Mcintosh (l 992a)

OrRl Otaraia soil, rolling and moderately deep phase Acidic Firm Brown Soil, Mm(Tm), Z, m

The soil is similar to Otaraia soils, rolling and deep phase, except that the parent material is moderately deep (Mm) and overlies tuffaceous mudstone rock (Tm) at 45-90 cm depth. BRIEF PROFILES 51

OrUm Otaraia soil, undulating and mottled phase Mottled Firm Brown Soil, Md, Z, m/s Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Firm Brown soils have a slightly firm subsurface horizon which has some of the characteristics of a fragipan. The pan perches water causing mottling in the profile. Md indicates the soil is more than 90 cm deep. Particle-size class is silty (Z). Permeability is moderate (m) but becomes slow (s) with increasing depth, i.e., in the Bw(g) horizon.

Horizon Depth (cm) P retention (%) pH

Ap 0-20 54 5.8 Ah/Bw 20-31 66 5.3 Bw 31-53 70 5.1 Bw(g) 53-81 48 5.0 BCg 81-94 58 5.1 Reference: Mcintosh (l 992a).

OwR Owaka soil, rolling phase Typic Firm Brown Soil, Md, z, m Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Firm Brown soils have a slightly firm subsurface horizon which has some of the characteristics of a fragipan. Typic indicates the soil is typical of the Firm Brown subgroup. Md indicates the soils are deep. Particle-size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH Ahl 0-9 34 5.9 Ah2 9-29 38 5.8 Bwl 29-39 44 6.0 Bw2 39-60 45 5.5 BC 60-100 42 5.1 Reference: Mcintosh (l 992d).

PpR Pukepahi soil, rolling phase Cemented Firm Brown Soil, Ms, Z, m/s Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Firm Brown soils have a firm layer that in Pukepahi soil takes the form of a cemented iron pan (placic horizon). Ms indicates that the soil is stony but stones occupy less that 35% of the soil by volume. Particle size is silty (Z). Permeability is moderate (m) but becomes slow (s) with increasing depth, i.e., at the iron pan.

Horizon Depth (cm) P retention (%) pH

Ah 0-14 64 5.0 E 14-20 73 5.0 Bms 20-20.6 96 5.1 Bw 20.6-27 87 5.1 BCl 27-53 67 5.1 BC2 53-78 48 5.2 BC3 78-100 41 5.3 Reference: Mcintosh (l 992a). 52 BRIEF PROFILES

PuR Pukerau soil, rolling phase Acidic Orthic Allophonic Soil, Ml(Tm), Z, m Allophanic soils have low bulk density (in the non-stony matrix). They mostly occur in volcanic ash but also in tuffaceous parent material. Orthic Allophanic Soils are permeable soils without barriers to penetration of roots. Acidic indicates the soil has pH ofless than 5.5 in some part of the B horizon to 60 cm depth. Ml(Tm) indicates that a contact with tuffaceous muds tone rock (Tm) occurs at less than 45 cm depth. Particle-size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH

Ahl 0-13 80 5.5 Ah2 13-27 82 5.4 Bw 27-48 92 5.2

Reference: Mcintosh (1992a).

RvR Riverton soil, rolling phase Typic Sandy Recent Soil, Md, S, r Recent soils have a distinct topsoil but no distinctive horizons in subsoils (although buried A horizons may be present). Sandy Recent Soils have a sandy (S) particle-size class. Typic Sandy Recent Soils are the typical soils of the subgroup. Md indicates the soil is >90 cm deep. Permeability is rapid (r).

Horizon Depth (cm) P retention(%) pH

Ah 0-17 4 7.3 c 17-65 3 8.0 bAh 65-92 6 7.6 bC 92-100 6 7.5

Reference: Smith et al. (1985).

RoH Rosemarkie soil, hilly phase Classification and properties are the same as for Rosemarkie soils, rolling and deep phase.

RoRO Rosemarkie soil, rolling and deep phase Acidic Allophonic Brown Soil, Md, Z, m Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Allophanic Brown Soils have horizons with very high P retention and/ or low bulk density. Acidic indicates the soil has pH of less than 5.5 in some part of the B horizon to 60 cm depth. Md indicates the soil is deep. Particle-size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention (%) pH

Ahl 0-12 80 4.8 Ah2 12-23 83 4.9 Ah/Bw 23-34 85 5.0 Bw 34-44 87 5.0 BCl 44-77 81 5.2 BC2 77-100 76 5.2

Reference: Mcintosh (1992a). BRIEF PROFILES 53

RoRl Rosemarkie soil, rolling and moderately deep phase Acidic Allophonic Brown Soil, Mm(Tm), Z, m

Classification and properties are the same as for Rosemarkie soil, rolling and deep phase except that the soil is moderately deep (Mm) and has a contact with tuffaceous mudstone rock (Tm) at 45-90 cm depth.

StH Stonycreek soil, hilly phase Mottled Orthic Melanie Soil, Ms, C/K, m/s

Melanie indicates the soil has high base saturation (i.e. is rich in calcium, magnesium and potassium), is well structured, has a dark A horizon and is weakly acid. Orthic refers to the high calcium content. Mottled indicates periodic saturation with water in subsurface horizons. Ms indicates the soil is stony but that the stones occupy less than 35% of the total soil volume. Particle-size class is clayey (C) but overlies a skeletal horizon (K) with more than 35% stones. Permeability is moderate (m) but becomes slow (s) with increasing depth.

Horizon Depth (cm) P retention (%) pH

Ah 0-15 33 6.1 Ah/Bw 15-26 38 6.2 Bw 26--47 30 6.2 Btg 47-78 23 6.3 2Btg1 78-92 22 6.5 2Btg2 92-100 23 6.5

Reference: Mcintosh (1992b).

TeR Toetoes soil, rolling phase Typic Sandy Brown Soil, Md, S, r

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Sandy Brown soils have a sandy (S) particle-size class. Typic Sandy Brown Soils are typical of the subgroup and have a pH of 5.5 or more in subsoils. Md indicates the soil is more than 90 cm deep. Permeability is rapid (r).

Horizon Depth (cm) P retention (%) pH

F 0-3 16 5.2 Ah 3-15 17 5.3 Bwl 15-40 15 5.7 Bw2 40-59 15 5.7 c 59-100 13 5.9

Reference: Smith et al. (1 985).

TiU Titiroa soil, undulating phase Typic Orthic Brown Soil, Md, L, m

Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Orthic Brown soils have structured B horizons or have weak soil strength in subsurface horizons. Typic soils are typical of the Orthic Brown subgroup. Md indicates the soil is more than 90 cm deep. Particle-size class is loamy (L). Permeability is moderate (m). Note that the soil may be poorly drained below 60 cm depth and this fact is not indicated by the soil classification. 54 BRIEF PROFILES

Horizon Depth (cm) P retention (%) pH Ap 0-14 43 5.8 Ap/Bw 14-25 43 5.8 Bwl 25-38 45 5.8 Bw2 38-60 45 5.7 Cr 60-100 28 5.6 Reference: Mcintosh (1992c).

TuR Tuturau soil, rolling phase Acidic Orthic Brown Soil, Md, Z, m Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Orthic Brown soils have structured B horizons or have weak soil strength in subsurface horizons. Acidic indicates that the soil has a pH of less than 5.5 in some part of the B horizon to 60 cm depth. Md indicates that the soil is deep. Particle size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH Ap 0-20 47 5.8 Ap/Bw 20-37 50 5.4 Bwl 37-50 55 5.3 Bw2 50-70 52 5.3 BC 70-100 42 5.4 Reference: Mcintosh (1992a).

TtHt Tautuku soils, hilly and stony phase Humose Pan Podzol, Ms, C, m/s Classification and properties are similar to those of Tautuku soils, rolling phase, except that profiles contain stones (<35%), so that particle size is Ms rather than Md.

TtR Tautuku soils, rolling phase Humose Pan Podzol, Md, C, m/s Podzols are acid soils and are leached of most nutrients. Pan Podzols have a firm or indurated layer that restricts the penetration of roots and reduces permeability. In these soils the pan is a thin iron pan. Humose refers to accumulation of organic matter in subsurface horizons. Md indicates that the soil is more than 90 cm deep. Particle-size class is silty (Z). Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH Ah 0-7 38 4.3 E 7-20 70 4.3 Bms 20-20.5 91 Bhl 20.5-26 89 4.7 Bh2 26-43 92 5.0 BC1 43-78 83 5.1 BC2 78-100 78 5.1 Reference: Bruce et al. (1981) BRIEF PROFILES 55

TwH Tawanui soil, hilly phase Typic Acid Brown Soil, Mo(Ts), C, m Classification and properties are the same as for Tawanui soil, rolling phase

TwR Tawanui soil, rolling phase Typic Acid Brown Soil, Mo(Ts), C, m Brown soils tend to be leached of nutrients and to be moderately weathered. Iron minerals give them a characteristic brown colour. Acid Brown Soils have pH of 4.8 or less between 20 and 60 cm depth. Typic Acid Brown Soils are the typical soils of the subgroup. Ma(Ts) indicates that the soils contain more than 35% by volume of stones that consist predominantly of tuffaceous sandstone. Particle-size class is clayey (C) above the skeletal horizons. Permeability is moderate (m). No chemical information is available. Classification is based on limited morphological information and likely leaching status. The soil requires further study.

Reference: N.Z. Soil Bureau (1968)

VeH Venlaw soil, hilly phase Classification and properties are the same as for Venlaw soil, steep phase.

VeS Venlaw soil, steep phase Acidic Orthic Allophonic Soil, Mo(Ts), C, m Allophanic soils have low bulk density and P retention of 85% or more in the non-stony matrix. They mostly occur in volcanic ash but also occur in tuffaceous parent materials. Orthic Allophanic Soils are permeable soils without barriers to penetration of roots. Acidic indicates the soil has pH of less than 5.5 in some part of the B horizon to 60 cm depth. Ma(Ts) indicates that the soils contain more than 35% by volume .of stones that consist predominantly of tuffaceous sandstone. Particle-size class is clayey (C) above the skeletal horizons. Permeability is moderate (m).

Horizon Depth (cm) P retention(%) pH

Aul 0-18 91 4.7 Au2 18-28 95 5.0 Bw 28-47 97 5.2 BC 47-64 97 5.4

Reference: Mcintosh (l 992a).

WrH Waiarikiki soil, hilly phase Classification and properties are the same as for Waiarikiki soil, rolling phase.

WrR Waiarikiki soil, rolling phase Acidic Orthic Allophonic Soil, Ms, Z, m Allophanic soils have low bulk density and P retention of 85% or more in the non-stony matrix. They mostly occur in volcanic ash but also in tuffaceous parent material. Orthic Allophanic Soils are permeable soils without barriers to penetration of roots. Acidic indicates the soil has pH of less than 5.5 in some part of the B horizon to 60 cm depth. Ms indicates the soil is stony but that the stones occupy less than 35% of the soil volume. Particle-size class is silty (Z). Permeability is moderate (m). 56 BRIEF PROFILES

Horizon Depth (cm) P retention(%) pH

Ahl 0-10 79 5.5 Ah2 10-20 86 5.4 Ah/Bw 20-27 89 5.2 Bw 27-38 87 5.2 BCl 38-60 86 5.3 BC2 60-100 80 5.4

Reference: Mcintosh (l 992a). GLOSSARY 57 Appendix 2: Glossary

The terms below have been defined in several publications. For comprehensive definitions of many geological terms the Glossary of Geology (Bates and Jackson 1987) was used and for soil terms used in a New Zealand context the Soil Description Handbook (Milne et al. 1991) was a useful guide.

Andesite: a dark coloured fine grained volcanic rock containing feldspars and dark minerals such as hornblende, biotite or pyroxene. Intermediate in composition between rhyolite and basalt.

Alluvium: unconsolidated sediment laid down by streams or rivers.

Bulk density (BD): the bulk density of a soil is the mass of oven-dry soil contained in a sample of known volume. Soils with low bulk density generally have fewer problems of root penetration and water permeability than soils with high bulk density. A horizon with a bulk density of 1.5 t/m3 or more may present a barrier to roots or be slowly permeable to water.

Clay: clay particles are soil particles which have a diameter of less than 0.002 mm. A soil or soil horizon is described as a clay if it contains more than 60% clay in the size fraction that is less than 2 mm diameter. Soils or horizons with more than 35% clay but less than 60% clay are loamy clays or silty clays, depending on their content of silt and sand. Soils with more than 35% clay in some horizon may have permeability problems and topsoils with more than 35% clay may be difficult to cultivate when wet.

Colluvium: a heterogeneous mass of soil material or rock fragments deposited chiefly by mass movement. Colluvium occurs mostly on hilly and steep slopes, and in the areas considered in this report, was probably deposited at a time when erosion was more general, for example, during the last glacial period.

Cryic: a term to describe soil temperature. Soils which have a difference of 5°C or more between mean summer and mean winter soil temperature, measured at 50 cm depth, have a cryic soil temperature class if mean annual soil temperature is less than 8°C (Soil Survey Staff 1992).

Dip slope: in hilly or steep terrain, the slope that is approximately parallel to the dip of the underlying strata (see Fig.3).

Drainage: four drainage categories are used: well drained, moderately well drained, imper fectly drained and poorly drained (Hewitt 1988). The terms are an indication of how quickly a soil can rid itself of excess water. In practice, drainage is measured by the amount of grey coloured mottling present in a soil, and its nearness to the surface. For example, poorly drained soils have a higher proportion of grey mottles close to the surface than well drained soils.

Floodplain: a strip of land adjacent to a river that is regularly flooded by river water.

Frittered mudstone: jointed mudstone that on exposure subdivides into angular fragments mostly a few millimetres in diameter. Described by Lynn and Crippen (1991). In the Kaihiku Hokonui land region the mudstone is interbedded with sandstones, and erosion features as described by Lynn and Crippen are not characteristic.

Greywacke: a dark grey indurated coarse-grained sandstone consisting of poorly sorted angular to subangular grains of quartz and feldspar and including fragments of fine material such as siltstones and mudstones. Often interbedded with siltstones and mudstones. 58 GLOSSARY

Highly weathered: more than half the rock mass is changed to a soil. The rock material can be cut with a spade.

Horizon: a soil layer that has a texture, colour or other property that distinguishes it from other layers in the soil profile.

Lithic contact: the contact of the soil with underlying rock that is hard or very hard and is impractical to dig with a spade.

Loess: a fine-grained blanket deposit consisting predominantly of silt and subordinate clay and fine sand, deposited from airborne suspension by wind. Most loess in Otago and Southland was deposited during cold glacial periods (Bruce 1973).

Macroporosity: the volume of soil occupied by pores larger than 0.06 mm. These large pores are important for the movement of air and water. A macroporosity of over 10% ensures good oxygen supply to roots and assists drainage. Problems with drainage and aeration may occur if the macroporosity is between 5 and 10%, and a macroporosity of less than 5% may lead to restricted drainage, poor aeration, and reducing conditions.

Mesic: a term used to describe soil temperature. Soils which have a difference of 5°C or more between mean summer and mean winter soil temperature, measured at 50 cm depth, have a mesic soil temperature class if mean annual soil temperature is 8°C to 15°C (Soil Survey Staff 1992).

Moderately weathered: the rock material is significantly weaker than fresh rock material.

Mudstone: a fine-grained sedimentary rock formed from sediments containing a large proportion of clay.

Ped, Pedality: aped is a natural aggregation of particles in a soil. Pedality refers to the extent to which soil material is organised into peds. In fopsoils peds are commonly spheroidal or polyhedral, and in subsoils they are commonly blocky or prismatic. Soils having well developed pedality, and peds of moderate or high strength, are relatively resilient to manage ment impacts such as cultivation or stock treading. Soils having weakly developed pedality are more prone to physical damage under inappropriate management.

Permeability: the rate at which water flows through a soil. A permeability of <4 mm/hr is classified as slow or very slow (Griffiths 1985).

pH: a measure of the acidity or alkalinity of a soil. It is measured using a glass electrode in a suspension of soil in water. The pH of a soil is a measure of the acid groups associated with clay or organic matter, and the extent to which they are neutralised by bases. Strong leaching, or the accumulation or large amounts of organic matter, causes pH to decrease (i.e. makes the soil more acid) as the proportion of acid groups rises. The pH of a soil controls the availability of plant nutrients, particularly the availability of trace elements, and aluminium toxicity. It also affects the biological activity of the soil and hence the release of nutrients from organic matter. The optimum pH level for most plants is about 6.0. .

Phosphate retention (P retn.): an empirical measure of the ability of the soil to rapidly remove phosphorus from solution. This is a more rapid process than, and probably a precursor to, the process of fixation, which renders phosphorus unavailable to plants. In acid soils the phospho rus is retained by reactive aluminium and iron minerals. High values of P retention indicate that a soil will give a lower response to the same amount of phosphate fertiliser than a soil with low P retention. GLOSSARY 59

Readily Available Water (RAW): the volume of water extracted between field capacity (10 kPa) and a suction of 100 kPa. Above 100 kPa, water is no longer considered to be readily extractable by plant roots, and plant growth will slow down and plants may show signs of stress.

Sand: sand particles are soil particles which have a diameter of between 0.06 mm and 2 mm. A soil or soil horizon may be described as a sand if it contains 80% or more sand and 8% or less clay. The broader class of sandy soils contains 8% or less clay and up to 40% silt. Sandy soils are generally rapidly permeable and easily cultivated but tend to be droughty.

Scarp slope: in hilly or steep terrain, the slope that is approximately at right angles to the dip of the underlying strata (see Fig. 3).

Set: a reconnaisance soil map unit used in the 1:253 440 soil map of South Island (N.Z. Soil Bureau 1968). Soil sets are variable units, useful for obtaining a general idea of the soil characteristics of a region, but less useful for detailed land-use planning.

Silt: silt particles are soil particles which have a diameter between 0.002 and 0.06 mm. A soil or soil horizon may be described as silty if it contains 40% or more silt and up to 35% clay. Silty soils are divided into silt loams containing 18-35% clay, loamy silts containing less than 18% clay, and silts containing more than 82% silt.

Slightly weathered: rocks that are not significantly weaker than fresh rocks.

Soilform: a soilform is identified by the name of the appropriate soil subgroup (Hewitt 1992) followed by the specifications of three further criteria: parent material class, particle-size group and permeability class for mineral soils, and nature of the substrate, kind of organic material, and the textural attributes of the material forming the control section, for organic soils (Clayden and Webb 1994).

Soil Set: see Set.

Strike ridge: a ridge following the strike of the geological strata i.e., a ridge following the bedding plane of the geological strata, as they intersect the horizontal.

Terrace: terraces referred to in this guide have been formed by rivers. Terraces are flat or gently inclined surfaces formed by the action of water, that are now higher than the river and lie parallel to it. They are old floodplains, now too high to be flooded. River terraces are commonly formed predominantly from gravelly alluvium, but may be covered with loess, or loamy, silty or sandy sediments.

Toeslope: the lowest part of a slope.

Total Available Water (TAW): the volume of water extracted between field capacity and wilting point, measured in the laboratory at water suctions of lOkPa and 1500 kPa respectively. It is usually expressed as millimetres (mm) of water.

Tuffaceous: an adjective applied to sediments containing up to 50% tuff (volcanic ash and particles formed by aerial expulsion from a volcano).