utilised by cereal cropping in South Canterbury. Dense
subsoils and winter perched water tables make many of the
Fragic, Duric, and Perch-gley Pallic Soils less suited to such
uses as orchard crops and intensive vegetable production.
The Tokomaru soil in Manawatu and the Poporangi soil in
Hawke’s Bay are both widely used for pastoral agriculture
and seasonal fodder crops such as maize.
Fragic Pallic Soils are extensive in the New Zealand
sub-humid lowlands. Apart from a few reserves under
remnants of the original native forest, the soils are predominantly in pastoral use, and have been for over a century.
Peter McIntosh and collaborators compared Fragic Pallic
Soils under native forest reserves with those at adjacent sites
that had been under pasture for 80–100 years. The results
showed that the native forest soils were different from the
pasture soils. One important difference was that the soils
under forest had more subsoil carbon than similar soils under
pasture. It could be argued that Fragic Pallic Soils under
forest are a truly endangered soil, and that we should protect
remnants of these with reserve status.
The Immature Pallic Soils have high versatility, because
of their deep rooting potential, which enables exploitation of
the high available water capacity. Intermittent wetness may
occur where there is a permeability restriction, or where
groundwater is periodically high in topographically low
positions in the landscape. Immature Pallic Soils are highly
productive where they occur on flat to gently undulating land
in deep loamy alluvium, recent loess, and on colluvium in hill
country. The Templeton soils of the Canterbury Plains are
versatile with productive Immature Pallic Soils that support a
wide variety of cropping and intensive pastoral uses.
The Argillic Pallic Soils are also versatile with deep
rooting potential, typified by the Pahau soils of Canterbury.
The Laminar Pallic Soils are also productive versatile soils,
again due to deep rooting potential and satisfactory permeability. They are exemplified by the Ngapara soil of North
Otago, and the Otama soils of northern Southland.
10.7.2 Soil Water Management
All Pallic Soils are subject to summer drought in most years,
and unless there is irrigation, animal farming will require
summer feed strategies that involve reduced stock numbers
or grazing off-farm. The soils are suited to crops that require
summer senescence for ripening, for example, significant
areas of cereals have been cropped on Pallic Soils in the
loess downs near Timaru. Depending on water availability
and crop needs, summer irrigation may be appropriate for all
Pallic Soils. Irrigation is likely to be most efficiently used on
the Immature Pallic, Argillic Pallic, and Laminar Pallic soil
groups where there is enough available soil water holding
capacity in the rooting zone for efficient water storage and
access by roots.
The Perch-gley soil groups have a water table that forms
above a slowly permeable layer. Most often the slowly
permeable layer is a fragipan or other another poorly structured, dense, horizon such as an iron pan or a well-developed
argillic horizon. The perched-gleying causes topsoil wetting
in winter and commonly into spring, and heavy grazing can
develop pugging and promote runoff of sediment including
faecal matter into water bodies. Mottled subgroups normally
have a shorter, intermittent, period of wetness. The periodic
high water table in mottled subgroups may result either from
perching on a slowly permeable layer, or from high
groundwater on relatively low-lying sites.
Tile and mole drains (formed by dragging a ‘mole’
through the soil to leave a small open cavity) are widely used
to improve winter soil conditions on perch-gley and mottled
Pallic Soils. The mole drains have been known to remain
effective for decades at some sites where maintenance of
outfall drains is undertaken. However, it is generally recommended that mole drains be regularly replaced.
The hard pans in the Fragic and Duric Pallic Soil groups
severely restrict potential root depth. Deep ripping has been
trialled in soils with hard pans and benefits have been documented. However, in Pallic Soils from loess, the benefits
are likely to be limited because the original high soil density
may recover following ripping.
Topsoil structures may break down under prolonged
impact by heavy stock trampling, machinery use, or continuous tillage. Structural decline is attributed to the low
contents of stabilising iron, aluminium oxides, and organic
matter. Lack of strong structure renders the soils susceptible
to erosion, especially when exposed to water runoff.
10.7.3 Soil Erosion
Both the silt and fine sand loess materials are dispersive.
Some coastal Pallic Soils also have a high sodium level
which also contributes to clay dispersion when soils are
saturated. Thus Pallic Soils on slopes are susceptible to
tunnel gully erosion. Tunnel gulley erosion is initiated in
slopes by entry of water into soil that is, to some degree,
dispersive. Once the downward pathway is established
through the soil (for example, a crack between structural
prisms in a fragipan), the path steadily widens as saturated
flow disperses and removes soil material and the flow is able
to accelerate. Initially the only sign of the process will be a
‘swallow hole’ in the soil surface as a downslope tunnel
forms. A sequence of events follows involving the discharge
of soil-coloured water at lower points on the slope, surface
soil collapse above the tunnel, and formation of a gully,
10.7 Use and Management of Pallic Soils
159
subsoils and winter perched water tables make many of the
Fragic, Duric, and Perch-gley Pallic Soils less suited to such
uses as orchard crops and intensive vegetable production.
The Tokomaru soil in Manawatu and the Poporangi soil in
Hawke’s Bay are both widely used for pastoral agriculture
and seasonal fodder crops such as maize.
Fragic Pallic Soils are extensive in the New Zealand
sub-humid lowlands. Apart from a few reserves under
remnants of the original native forest, the soils are predominantly in pastoral use, and have been for over a century.
Peter McIntosh and collaborators compared Fragic Pallic
Soils under native forest reserves with those at adjacent sites
that had been under pasture for 80–100 years. The results
showed that the native forest soils were different from the
pasture soils. One important difference was that the soils
under forest had more subsoil carbon than similar soils under
pasture. It could be argued that Fragic Pallic Soils under
forest are a truly endangered soil, and that we should protect
remnants of these with reserve status.
The Immature Pallic Soils have high versatility, because
of their deep rooting potential, which enables exploitation of
the high available water capacity. Intermittent wetness may
occur where there is a permeability restriction, or where
groundwater is periodically high in topographically low
positions in the landscape. Immature Pallic Soils are highly
productive where they occur on flat to gently undulating land
in deep loamy alluvium, recent loess, and on colluvium in hill
country. The Templeton soils of the Canterbury Plains are
versatile with productive Immature Pallic Soils that support a
wide variety of cropping and intensive pastoral uses.
The Argillic Pallic Soils are also versatile with deep
rooting potential, typified by the Pahau soils of Canterbury.
The Laminar Pallic Soils are also productive versatile soils,
again due to deep rooting potential and satisfactory permeability. They are exemplified by the Ngapara soil of North
Otago, and the Otama soils of northern Southland.
10.7.2 Soil Water Management
All Pallic Soils are subject to summer drought in most years,
and unless there is irrigation, animal farming will require
summer feed strategies that involve reduced stock numbers
or grazing off-farm. The soils are suited to crops that require
summer senescence for ripening, for example, significant
areas of cereals have been cropped on Pallic Soils in the
loess downs near Timaru. Depending on water availability
and crop needs, summer irrigation may be appropriate for all
Pallic Soils. Irrigation is likely to be most efficiently used on
the Immature Pallic, Argillic Pallic, and Laminar Pallic soil
groups where there is enough available soil water holding
capacity in the rooting zone for efficient water storage and
access by roots.
The Perch-gley soil groups have a water table that forms
above a slowly permeable layer. Most often the slowly
permeable layer is a fragipan or other another poorly structured, dense, horizon such as an iron pan or a well-developed
argillic horizon. The perched-gleying causes topsoil wetting
in winter and commonly into spring, and heavy grazing can
develop pugging and promote runoff of sediment including
faecal matter into water bodies. Mottled subgroups normally
have a shorter, intermittent, period of wetness. The periodic
high water table in mottled subgroups may result either from
perching on a slowly permeable layer, or from high
groundwater on relatively low-lying sites.
Tile and mole drains (formed by dragging a ‘mole’
through the soil to leave a small open cavity) are widely used
to improve winter soil conditions on perch-gley and mottled
Pallic Soils. The mole drains have been known to remain
effective for decades at some sites where maintenance of
outfall drains is undertaken. However, it is generally recommended that mole drains be regularly replaced.
The hard pans in the Fragic and Duric Pallic Soil groups
severely restrict potential root depth. Deep ripping has been
trialled in soils with hard pans and benefits have been documented. However, in Pallic Soils from loess, the benefits
are likely to be limited because the original high soil density
may recover following ripping.
Topsoil structures may break down under prolonged
impact by heavy stock trampling, machinery use, or continuous tillage. Structural decline is attributed to the low
contents of stabilising iron, aluminium oxides, and organic
matter. Lack of strong structure renders the soils susceptible
to erosion, especially when exposed to water runoff.
10.7.3 Soil Erosion
Both the silt and fine sand loess materials are dispersive.
Some coastal Pallic Soils also have a high sodium level
which also contributes to clay dispersion when soils are
saturated. Thus Pallic Soils on slopes are susceptible to
tunnel gully erosion. Tunnel gulley erosion is initiated in
slopes by entry of water into soil that is, to some degree,
dispersive. Once the downward pathway is established
through the soil (for example, a crack between structural
prisms in a fragipan), the path steadily widens as saturated
flow disperses and removes soil material and the flow is able
to accelerate. Initially the only sign of the process will be a
‘swallow hole’ in the soil surface as a downslope tunnel
forms. A sequence of events follows involving the discharge
of soil-coloured water at lower points on the slope, surface
soil collapse above the tunnel, and formation of a gully,
10.7 Use and Management of Pallic Soils
159