we start – an important note
This soil map has been quite a long time in the making. It was
begun when the New Zealand Genetic Soil Classification (Taylor 1948;
Taylor and Cox 1956; Taylor and Pohlen 1968) was operative. In this
system, soil series and types were typically gathered together into
genetic groups to which they belonged. Before the map was completed,
the New Zealand Soil Classification (Hewitt 1992; 1998) was introduced.
In this classification the higher order categories of Order, Group
and Subgroup are more rigorously defined than were the old genetic
groups. However, the new system has not as yet reached down to the
more local categories of soil series and type. Nevertheless the
new classification is acknowledged as having grown out of the old
(Hewitt 1992; 1998 P5). In this circumstance it has been judged
legitimate to gather the soil series and types identified in this
map under the umbrella of both the new Soil Orders (distinguished
by leading letter capitals) and the old genetic groups (all in lower
case letters). This should not be interpreted as a perfect fit with
the new system (sometimes the early series/type definitions were
too broad for this to be possible) but rather as a meaningful, workable
solution to bridge the gap between the two systems and enable the
lower categories of series and type to find their proper place in
the higher categories of Order and genetic group, which confers
on them a wider meaning than that of mere local categories.
Compilation of the Map
In the first instance, the original hand-drawn soil map was digitized
and compiled using Arc View software. The printed version of the
map was derived from this source.
Subsequently, the map was recompiled using public domain software,
for example Geotools, in order to make it accessible to a wider
audience. At the same time special code was written to enable images
of the soils corresponding to the soil units on the map to be portrayed
on the screen. This interactive computer version of the map is available
as a compact disc or alternatively may be accessed through the Massey
University Image Web Server.
When using the electronic version of the map it is important to
take full advantage of the “tool-bar” beneath the map,
in order to enlarge the particular area of interest, be it farm,
part of farm, river flat or terrace, and access the corresponding
soil profile images and descriptions.
The soil map may be read at three different levels. The first level
is that of the Soil Order (genetic group), the
second that of the soil series and the third that of the soil type.
The Soil Order (genetic group) is the broadest level. Here we are
recognising a major category of soil, the members of which share
certain defining properties that are dependent ultimately on a common
genesis. The map depicts four main Soil Orders or genetic groups,
- Recent Soils (recent soils)
- Recent Gley Soils (gley recent soils)
- Organic Soils (organic soils)
- Pallic Soils (yellow-grey earths)
each of which is distinguished by its own colour on the map, for
example, yellow for Recent Soils, green for Pallic Soils.
The intermediate level is that of the soil series.
The soil series is defined as an assemblage of soils with similar
soil profiles and similar soil temperature and soil moisture regimes,
that are derived from the same or similar parent material. Soil
series are given local geographic names, for example, Manawatu soil
series, Kairanga soil series. Soil series are distinguished on the
map by different shades of the colour of the Soil Order under whose
banner they are gathered. Thus the Ohakea soil series carries a
different shade of green from that of the Tokomaru soil series,
with green, as we have already noted, being the chosen basic colour
of the Soil Order of Pallic Soils.
The most detailed level is that of the soil type. Soil types are
distinguished within soil series chiefly on the basis of soil texture
(particle size), more particularly that of the topsoil, for example,
Rangitikei loamy sand, Rangitikei fine sandy loam. The soil types
are depicted on the map by symbols, thus Rkls for Rangitikei loamy
sand and Rkfsl for Rangitikei fine sandy loam.
In a detailed soil map such as this, various other subtleties may
be introduced at the soil type level and these
are discussed under the section on symbols below.
The high and intermediate terraces on the Massey property are delineated
by major terrace scarps. For convenience the soils on these are
shown on the map as belonging to either Halcombe Hill Soils (HaH)
or Halcombe Steepland Soils (HaS) depending on the steepness of
slope, with 25o constituting the break point between them. These
soils are highly variable but still fall under the umbrella of Pallic
Two legends accompany the soil map, a physiographic one and a pedological
The physiographic legend lists all the soils down
to the soil type level that are to be found on the different landscape
units of the area, for example, the soils that are located on the
high terrace or those that are found on the river flats. It is the
legend we can all feel familiar with. It helps us find our way around
The pedological legend links the soil classes
down to the soil series level with the wider Soil Orders, or genetic
groups, so that they may be placed accurately within the overall
context of New Zealand soils (the New Zealand Soil Classification)
or indeed the soils of the world. For example, the Tokomaru soil
series falls within the Order of Pallic Soils, while the Rangitikei
soil series fits nicely within the Order of Recent Soils. The pedological
legend widens our understanding of the soils.
Colours are used as an aid to distinguish the different classes
of soils down to the series level. Thus:
- different shades of yellow are used to differentiate those
soil series that fall within the Order of Recent Soils
- different shades of blue are used to distinguish soil series
that fall within the Order of Recent Gley Soils
- purple is used to designate the one soil series that falls within
the Order of Organic Soils
- different shades of green are used to distinguish those soil
series and close associates that belong to the Order of Pallic
There are too many soil types to be differentiated on the map solely
on the basis of colour. Therefore soil types are distinguished by
symbols. It will be recalled that soil types within series are chiefly
distinguished by textural differences, more particularly of the
topsoil. The symbol for the soil type thus carries two components,
the first two letters indicating the particular soil series followed
by letters indicative of the textural class, thus:
- Manawatu sandy loam: Mnsl
- Kairanga silt loam: Kasil
In a detailed soil map such as this we sometimes find it useful
to make further distinctions which are appended to the normal soil
type symbol. Thus the common soil type on the level tops of the
high terrace is the Tokomaru silt loam. We are aware, however, that
the level tops are dissected by a number of gullies and the soils
of these gullies are distinguished as a gully phase:
Tksil(G). We are also aware that there are areas where the flat
tops give way to gently sloping sides and the soils here are identified
as belonging to an undulating phase: Tksil (U).
These particular phase distinctions are essentially topographic.
A few soil types carry a single asterisk attached to them, thus
Rangitikei fine sandy loam* (Rkfsl*). The asterisk signifies a fuzzy
set. While in reality all soil classes are fuzzy, that
is, not entirely pure, some are more fuzzy than others! Thus Rkfsl*
is known to be highly variable in both texture and depth, but nevertheless,
for the greater part, it is distinguishable as a fine sandy loam
of reasonable depth.
A double asterisk indicates something different — a bisequal
soil. A good example is the Rangitikei fine sandy loam**(Rkfsl**).
In this soil only the upper part of the profile is a fine sandy
loam. A former soil of silt loam texture lies buried beneath. The
soil has experienced two separate stages of sediment deposition
and soil development.
Yet another distinction is conveyed by the presence of the letter
p prefixed to the soil type name. The letter p stands for
para, meaning a soil similar to but not identical with
the named soil type. A good example is the para Ohakea silt loam
(pOHsil). By and large we encounter the characteristic Ohakea silt
loam on reasonably extensive intermediate terraces. But there are
some more confined locations where small streams have entrenched
themselves in underlying terrace gravels producing local flats carrying
soils of essentially similar properties to the normal Ohakea silt
loam, but with subtle distinctions such as a thinner loess cover
or greater accumulation of sesquioxide concretions (iron pan). The
para prefix accommodates these broadly similar but not quite identical
soils. Other para soils have been distinguished because they have
been protected by stopbanks in relatively recent times and no longer
receive the deposition of flood sediments characteristic of the
These subtle distinctions are not meant to confuse! They simply
acknowledge the reality of the complexity that is present in the
The name that we give to a soil is important because is establishes
its identity and enables us to discuss it at will.
By picking up the symbol and colour for a particular soil depicted
on the map we are then able to go to the legends to obtain its proper
name. Thus Kasil translates readily to Kairanga silt loam, a Recent
Gley Soil (gley recent soil) found on the river flats, while Tksil
translates with equal facility to Tokomaru silt loam, a Pallic Soil
(yellow-grey earth) found on the high terrace. The soil names are
derived from two sources:
- the Soil Orders from Hewitt, A.E. 1998: New Zealand Soil Classification,
2nd Edition, Landcare Research Science Series No.1 (and the parallel
soil genetic groups from Taylor, N.H. 1948: Soil Map of New Zealand,
1:2,027,520 scale. DSIR, Wellington).
- the soil series and types, with one exception, from Cowie,
J.D. 1978: Soils and Agriculture of Kairanga County, North Island,
New Zealand. Soil Bureau Bulletin 33. DSIR, Wellington.
The one exception is the new soil type name of Turitea silt loam
(Tusil) used to replace the former name of Manawatu mottled silt
loam. As an important imperfectly drained soil on the river flats,
it was considered worthy of its own series/type name.
This soil map has been digitized so that each particular soil class
is contained within its own polygon or set of polygons. As a consequence
the boundaries between the different soil units are depicted as
solid lines. Sometimes the boundaries between soil classes are abrupt,
as when, for example, the Tokomaru silt loam drops over the terrace
edge onto the Halcombe Steepland Soil of the scarp. In this circumstance
the solid line fits the field reality. In other circumstances, however,
the boundaries between soil units may merge. This is most certainly
the case between adjacent fuzzy sets and also, for example, between
the Tokomaru silt loam proper and its undulating phase. In such
circumstances the solid boundary line is rather misleading, as it
tends to convey a precise separation of soil units when in fact
they actually grade into one another. Only with experience in the
field can one come to recognize soil boundaries that are sharp from
those that are merging.
Reference Soil Profiles
In the course of the survey a great many soil profile pits were
dug and the soils described in order to determine the soil pattern.
Fifty of these have been selected as reference soil profiles to
illustrate the properties of the different soil types. Thirty five
are illustrated in colour, three in black and white, with the remaining
twelve presented as straight text descriptions. In each case a simplified
soil profile description is given in terms by the colour and texture
of horizons, the soil is named and classified, and a brief comment
made on its overall properties.
It is important to note that these reference soil profile descriptions
relate to the soil as found at specific point locations on the ground.
In the printed map these locations are shown as red dots, with the
appropriate soil profile numbers alongside. However, in the electronic
version of the map that is available in the public domain, whenever
a particular polygon is flagged by clicking with the appropriate
icon from the “tool-bar” the image of the soil profile
corresponding to the soil type for that polygon appears on the screen.
This image is derived from the reference profile for the soil type,
although the position of the polygon pointed at may be a considerable
distance away from the spot location (geodetic reference point)
for the reference profile.
What we are relying on here is the consistency of the soil type
mapping unit. It cannot be claimed that the soil of the polygon
pointed at is identical with the reference profile portrayed. All
soil mapping units, of necessity, carry an element of variation,
some more so than others. None the less, with this understood, it
can be claimed that the soil of the polygon pointed at will resemble
in its essentials that of the image of the reference profile thrown
on the screen.
The areas for each of the soil units depicted on the map are shown
in Table 1. We can see at a glance that the most extensive soil
type is that of the Tokomaru silt loam and its associates occupying
the high terrace (554 ha).
Next come the various soil types found on the river flats of the
Manawatu River and the Turitea and Kahuterawa Streams (363 ha).
But be warned, this set of soils is far from uniform, including
as it does soils of many different textures and drainage classes.
The soils of the Ohakea Terrace, including those upon which the
University campus is built, come next (159 ha). Here we have to
deal with only a few soil types belonging to either the Ohakea or
Ashhurst series. But note that these two series, while grading into
one another, differ considerably in drainage and soil depth.
The soils of the major terrace scarps delineating the boundaries
of the high and intermediate terraces (102 ha) are not to be ignored.
Here slopes are hilly or steep and increasingly these have been
given over to plantings of either native or exotic shrubs and trees.
Much further information may be gleaned from Table 1. For example,
the individual soil types belonging to a particular soil series
may be summed to give an overall total for the series. Thus we see,
for example, that the well or moderately drained soils of the Rangitikei
series account for 150 ha, compared with those of the Manawatu series,
which occupy 113 ha.
With equal facility we may total up all the imperfectly or poorly
drained soils on the property. With respect to soils belonging to
these drainage classes, it is important to note that this is the
drainage condition of the soil in its natural state. The Tokomaru
silt loam, for example, carries the designation poorly drained.
Only extensive tile and mole underground drainage has made it possible
to conduct the modern dairy farming operation of Number Four Dairy
Unit on this particular soil type.
Lastly, cross reference to the Pedological Legend enables us to
calculate the areas of soils belonging to the different Soil Orders.
Final Cautionary Note
It is salutary to reflect that no soil map can be perfect. Consider
for a moment the problem of scale. Whereas the electronic map may
be zoomed into and out of at virtually any scale, the scale of the
hard-copy map covering the whole Massey property is limited by the
size of the paper it is printed on. For example, if AO (841 x 1189
mm) is the limiting paper size this restricts the scale at which
the map can be printed to 1:6000. This means that, linearly, 6000
cm or 60 metres on the ground has to be squeezed into 1 cm on the
map. Or, in terms of square measure, 60 m x 60 m = 3600 m2
= 0.36 ha on the ground has to be squeezed into 1 cm2 on the map
(equivalent area). A square cm on the map is not a large area on
which to depict the soil pattern over 0.36 ha (close to an acre)
on the ground.
Scale is not the only thing. Other important factors are soil variability
(always present), the state of knowledge at the time the map is
being constructed, the skill of the pedologist and the tools at
his or her disposal. With all that said we are lucky to have a soil
map at all!
Finally, we should note that the development of the Massey farms,
and the Turitea Campus in particular, has resulted in a number of
man-made modifications to the natural landscape and soil pattern.
Some examples are the construction of fresh water dams and effluent
ponds, the diversion of minor streams underground, the removal of
stones from the surface of playing fields, the development of the
all-weather athletic track on what was once the para Ashhurst soil,
the construction of landscaping mounds in the vicinity of buildings
and sports areas, the creation of car parks, and the formation of
spoil and waste-disposal dumps. Many, though not all, of these have
been noted on the map.
Cowie, J.D. 1978: Soils and Agriculture of Kairanga County, North
Island, New Zealand. Soil Bureau Bulletin 33. 92p., with 1:63360
scale soil map. DSIR, Wellington.
Hewitt, A.E. 1992: New Zealand Soil Classification. DSIR Land Resources
Scientific Report No. 19. 133p.
Hewitt, A.E. 1998: New Zealand Soil Classification, 2nd edition.
Landcare Research Science Series No.1. 133p.
Taylor, N.H. 1948: Soil Map of New Zealand, 1:2,027,520 scale.
Taylor, N.H.; Cox, J.E. 1956: The soil pattern of New Zealand.
New Zealand Institute of Agricultural Science Proceedings. 17p.
Taylor, N.H.; Pohlen, I. 1968: Classification of New Zealand Soils.
Pp. 15-33 in: Soils of New Zealand, Part 1. Soil Bureau Bulletin
26(1). 142p., with 1:1,000,000 scale soil map of New Zealand. DSIR,