1 Itinerary for Agricultural Heartlands fieldtrip Monday, 26 th July Sydney to Scone Time Location Activity 0730 Depart The University of Sydney – en route Sydney Basin geology Brief rest stop on F3 1030 Oakey Creek Rd, Pokolbin SBP1 – Brown Sodosol 1 1300 Pokolbin Community Hall Lunch, presentations 1430 Marrowbone Rd, Pokolbin Limestone/Marl cutting 1430 Marrowbone Rd, Pokolbin SBP2 – Shelly Calcarosol 1600 Drayton’s Family Wines Wine tasting 1900 Scone Motel & Dining Tuesday 27 th July Scone to Gunnedah Time Location Activity 0730 Depart Scone – en route Dairy & horse farming 0930 Nowley Farm, Spring Ridge Welcome/ morning tea 1015 Nowley Farm SBP3 – Red Chromosol 1230 Nowley Farm Lunch 1400 Nowley Farm SBP4 – Brown Sodosol 1830 Gunnedah Motel 1900 Wild Orchid Dinner 1 Will also include and refer to these in WRB and Soil Taxonomy in final documentation.
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Transcript
1
Itinerary for Agricultural Heartlands fieldtrip
Monday, 26th July Sydney to Scone
Time Location Activity
0730 Depart The University of Sydney –
en route Sydney Basin geology Brief rest stop on F3
1030 Oakey Creek Rd, Pokolbin SBP1 – Brown Sodosol1
Agricultural Heartland tourists at “Nowley”, July 27th, 2010
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Figure 2: Tour Route
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Figure 3: Day 1, July 26th
Figure 4: Day 2, July 27th
Day 1
Day 2
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Figure 5: Day 3, July 28th
Day 3
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Figure 6: Day 4, July 29th
Day 4
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Figure 7: Day 5, July 30th
Figure 8: Day 6, July 30th
Day 5
Day 6
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Figure 9: Profiles within and catchment features of the Liverpool Plains area.
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Figure 10: Hunter Valley profiles
Figure 11: Nowley profiles
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Figure 12: Pilliga profile
Figure 13: IA Watson profiles
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Figure 14: Terry Hie Hie profile
Figure 15: Goondiwindi Profile
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Figure 16: Wondalli profile
Figure 17: Yelarbon profile
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Figure 18: Gore (Traprock) profile
Figure 19: Karara profile
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Figure 20: Pampas profile
Figure 21: Profile 15‐ Toowoomba
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Figure 22: Toogoolawah profile
Figure 23: Wamuran profile
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Overview of the Geology of the Sydney‐Gunnedah Basins in NSW
New South Wales which lies in the east of the Australian Plate is bordered to the east by the adjacent oceanic lithosphere of the Tasman Sea. The nearest active margin passes through New Zealand, where the region between the coast and oceanic crust comprises a narrow continental shelf consisting mainly of continental sedimentary rocks. The coast and the inland region are dissected by the Eastern Highlands with the Great Dividing Range at the crest. These highlands are believed to have been uplifted due to the addition of igneous rocks from below (underplating). The lower part of the Sydney Basin is adjacent to the coast and forms the southern part of the Sydney‐Gunnedah‐Bowen Basins (Figure 1) which are bound by the New England and Lachlan Fold Orogen (Belts) as detailed below.
Figure 1. Map of the Tectonic units comprising New South Wales. The region west of the Eastern Highlands have subsided creating the Murray‐Darling Basin (Figure 2) resulting in river systems that commence in Queensland and flow to the west and south west meeting the ocean near Adelaide in South Australia. The eastern tectonic units that comprise the Murray‐Darling Basin include the; Bowen Basin, Clarence‐Morton Basin, Lachlan Fold Belt, New England Fold Belt, Gunnedah Basin, Upper Sydney Basin, and Surat Basin. Details of all tectonic units are given in (Figure 1) and the surface geology in (Figure 4).
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Figure 2: Map of the tectonic units housed by the Murray Darling Basin
The Sydney Basin
This is a major structural basin comprising a Permian to Triassic sedimentary sequence (290 Ma – 200 Ma) that has a maximum total thickness in the range of 5000 m. This forms the southern part of the Sydney‐Gunnedah‐Bowen basin system. The basin is surrounded to the south and west by the older, largely low‐grade metamorphic and granitic rocks of the Ordovician to Devonian Lachlan Fold Belt. The eastern part of the basin continues offshore to the edge of the continental shelf, while to the north, the basin is bound by the Devonian to Carboniferous New England Fold Belt and transitions into the contemporaneously developed Gunnedah basin to the north west.
The basin was initiated by crustal rifting in the Early Permian where the earliest depositions consisted of volcanogenic sands and silts deposited in a marine shelf. Along with basaltic island volcanoes in the lower Hunter this region forms the Dalwood and Lower Shoalhaven Groups (Table 1). Sediment shed from compression of the New England Fold belt was responsible for the deposition of the Greta Coal Measures in the north of the basin near Muswellbrook and Cessnock. Basement sagging led to increased marine conditions toward the top of the Greta Coal Measures, where in the west of the basin, sourced volcanogenics derived New England and quartz rich sand and silt derived from the Lachlan, forming the Maitland and upper Shoalhaven Groups. Faulting and folding of the New England Fold Belt resulted in the Hunter‐Bowen Orogeny which resulted in the delta plain and fluvial conditions forming the late Permian Tomago and Whittingham Coal Measures in the in the Muswellbrook‐Denman‐Singleton of the northern Hunter area, and the deposition of the lower Illawarra Coal Measures in the south of the basin (Table 1).
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Table 1: Simplified stratigraphic sequence of the Permo‐Triassic Sydney Basin. The lithology of the basin differs from north to south and is detailed in Figure 2.
Years (Ma)
Period Formation Lithology
WIANAMATTA GROUP Consists of three main formations called the Ashfield Shale (shale, siltstone, claystone), Minchinbury Sandstone (sandstone) and Bringelly Shale (shale, sandstone)
MITTAGONG FORMATION
Thin sandstone beds
HAWKESBURY SANDSTONE
Quartz rich sandstone with abundant cross‐bedding and inter‐bedded shale
205
TRIASSIC
NARRABEEN GROUP Lithic and quartz rich sandstones, siltstones
Siltstone, sandstone, shale, conglomerate; including the Gerringong Volcanics
GRETA COAL MEASURES Sandstone, shale, conglomerate , coal seams
251
298
PERMIAN
DALWOOD and LOWER SHOALHAVEN GROUPS
Calcareous sandstone, conglomerate, shale, limestone, lava flows and tuff
Coal measure development was terminated by a marine incursion forming the Dempsey and Denman formation in the north and Bargo claystone and Baal Bone formation in the south. The regression continued forming a meandering stream which dominated the alluvial plain, and in the north was responsible for the formation of the Newcastle and the Wollombi Coal Measures (completing the Singleton Supergroup). In the south it formed the upper Illawarra Coal Measures, effectively filling the basin.
Renewed uplift of the New England Fold belt in the early Triassic resulted in the deposition of the Narrabeen Group in an alluvial flood plain and estuarine environments, which can be found in the western regions of the Hunter Valley. During this period, sedimentation varied between the New England derived mixed load and quartz rich Lachlan. Uplift of the Lachlan Fold Belt or subsidence of the New England Fold Belt resulted in the deposition of the quartz rich Hawkesbury Sandstone, which is overlain by the Wianamatta Group (Table 1).
Jurassic age igneous activity resulted in the formation of the Prospect dolerite and diatremes over the eastern basin, while late Mesozoic activity resulted in the formation of numerous coastal dykes on the central coast and basaltic caps on Mount Banks, Wilson, and Tomah in the Blue Mountains. Only minor folding has occurred resulting in the Lapstone monocline in the east foothills, and further west, the Tomah Monocline in the Blue Mountains. Most of the unconsolidated material is Cainozoic or Quaternary in age, with significant thicknesses of up to 80 m being deposited in coastal depressions such as Botany Bay. The humid conditions of the Cainozoic resulted in the formation of well developed lateritic soils on the Hawkesbury Sandstone, Narrabeen and Wianamatta Groups.
Greater Sydney is developed on the Cumberland Plain, which is drained by the meandering creeks of the Hawkesbury and Parramatta Rivers. Much of the plain is covered by texture contrast or duplex acidic soils and uniformed textured alluvial derived soils of the river terraces. These soils are characteristic of much of the east coast of Australia and extend into the Great Dividing Range. The plateaus, such as the Blue Mountains and Hornsby that rise abruptly from the Cumberland Plain have coarse textured soils derived from the Hawkesbury sandstone, along with iron rich uniform clay soils derived from the isolated basalt occurrences. In this area, Hanging Swamps with organic rich soils can also be found. To the north in the Hunter Valley, the Broken Back Range is comprised of the
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Narrabeen capped by the Hawkesbury sandstone resulting in thin uniformly coarse textured soils. The areas around Cessnock and Singleton are underlain by the Dalwood and Maitland Group resulting in texture contrast acid soils. The presence of limestone in the area has resulted in the occurrence of uniform clays. Alluvial soils are common skirting the Hunter River and its tributaries.
The Gunnedah Basin (& Surat Basin)
This forms the central part of the Sydney‐Gunnedah‐Bowen Basin system and is unconformably overlain by the Surat Basin (Jurassic and Cretaceous Strata). The basin covers an area of over 15, 000 square kilometres and is comprised of rocks of Permian and Triassic in age. This basin is bound by the New England Fold Belt in the east and as with the Sydney basin, the west is bound by the Lachlan Fold Belt. The northern boundary with the Bowen Basin is believed to be marked by the highly eroded early Permian sediments north of Narrabri. The southern boundary with the Sydney basin is suspected to be either the Mount Coricudgy Anticline or Liverpool Range.
Deposition in the basin is marked by colluvial and alluvial material followed by an influx of vocanolithic sediments from the Boggabri Ridge. This forms the early Permian Bellata Group which is comprised of the Leard Formation and Maules Creek Formation, and is equivalent to the Greta Coal Measures of the Sydney Basin (Figure 3). They gave way to progressively marine conditions and the development of a marine shelf, the resulting deposition of the Porcupine and Watermark Formations outcropping on the eastern perimeter between Quirindi to Narrabri, and which are of similar age to the Maitland and lower Shoalhaven Groups of the Sydney Basin. The development of deltas in the late Permian resulted in the sediments of the Black Jack Group outcropping near Boggabri and Gunnedah (Table 2). The shallow marine facies of the Arkarula Formation gave way to delta environments resulting in widespread peat development forming the Hoskisson Coal. This was followed by increased alluvial development marking the upper part of the Black Jack Group and the end of the Permian sedimentation.
Techtonism of the New England Fold belt in the early Triassic resulted in the deposition of coarse clastic sediments forming the Digby Formation (Table 2), which is considered equivalent to the Narrabeen Group in the Sydney Basin. Outcrops can be found on the eastern perimeter between Quirindi to Narrabri. Howevver, the large deltas that were forming the Hawkesbury Sandstone in the Sydney basin did not occur further north but gave way to more moderate lacustrine and delta conditions and were responsible for the formation of the Napperby Formation in the Gunnedah Basin (Figure 3).
The Jurassic and Cretaceous sediments of the Surat Basin uncomfortably overlay the Gunnedah Basin in the north and west and form thick sequences in the northwest (Table 2). The course textured quartz sandstone of the Pilliga Sandstone outcropping between Baradine and Baan Ban , result in what is termed the Pilliga Scrub, and forms the main basement rocks for the region around and north of Narrabri. This is underlain by the clayey sands and mudstones of the Purlawaugh Formation and Garrawilla Volcanics (Table 2). The Pilliga Sandstone is overlain by the Orallo Group and Rolling Downs Group. The calcareous clays and marls of the Rolling Downs are found north of Narrabri, as are the Nandewar Volcanics. Much of the basin in the vicinity and north of Narrabri and west of Coonabarabran and Gilgandra are covered with undifferentiated post Jurassic sediments.
The Liverpool Plains forms an extensive physiographic unit covering the Lower Gunnedah Basin. The plain includes deep Quaternary alluvium of the Mooki River floodplain and is occasionally influenced by the Naomi river floodplain. The deep alluvium of the Goran Basin Plains can be found, and is associated with the lunettes and beaches forming the margins of Lake Goran.
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Table 2: Simplified stratigraphic sequence of the Permo‐Triassic Gunnedah Basin and the Jurassic Section of the Surat Basin.
Years (Ma)
Period Formation Lithology
LATE ORALLO FORMATION Clayey to quartzose sandstone, subordinate siltstone and conglomerate
PILLIGA SANDSTONE Fluvial, medium to coarse‐grained quartzose sandstones
MIDDLE PURLAWAUGH FORMATION
Carbonaceous claystone, siltstone, sandstone and subordinate coal.
141
159
184
205
JURASSIC
EARLY GARAWILLA VOLCANICS Alkali basalt, trachytes, hawaiite, pyroclastic and subordinate sediments
DERIAH FORMATION Green lithic sandstone rich in volcanic fragments and mud clasts
MIDDLE NAPPERBY FORMATION
Thinly bedded claystone, siltstones and sandstones, common bioturbation and burrows
230
241
TRIASSIC
EARLY DIGBY FORMATION Lithic and quartz conglomerates, sandstones and minor finer gained sediments
BLACK JACK GROUP
Dominantly fluvial and lacustrine sediments; lithic and quartz sandstones and conglomerates, siltstone and clay tuff and coal.
WATERMARK FORMATION
Regressive marine sediments; sandy siltstone, sandstone, common bioturbation sporadic erratics and secondary calcite “cone‐in‐cone” replacements
LATE
PORCUPINE FORMATION Marine shelf sediments; lithic sandstone and conglomerate and bioturbated mudstone
MAULES CREEK FORMATION
Fluvial; dominantly lithic and subordinate quartz‐rich sandstones and conglomerate
GOONBRI and LEARD FORMATIONS
Colluvial and lacustrine sediments; pelletoidal claystone and upward coarsening sequences of organic‐rich claystone to sandstones
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270
298
PERMIAN
EARLY
BOGGABRI VOLCANICS Mainly Rhyolite flows and pyroclastics
PRE‐PERMIAN
LACHLAN FOLD BELT Metavolcanics and Metasediments
Texture contrast soils are found between Curlewis and Lake Goran and are related to the Permian and early Triassic sediments. The texture contrast and sometimes sodic soils of Trinkey forest are derived from the Jurassic Purlewaugh Formation and Pilliga Sandstone. In and around Mullaley the Garawilla Volcanics provide material for the uniform cracking clay soils found. Some of the local mountains are capped with Tertiary basalts forming uniform clay soils in their footslopes. Further north the outcrop of the Pilliga Sandstone has provided uniform coarse profiles. In the areas north and west of Narrabri extensive alluvial plains representing the Quaternary history of the Darling River Basin are developed by meandering river systems, such as the Namoi River. The use of thermoluminescence has placed these sediments as between 5.6 ka to 56 ka. The weathering products of the basic volcanics capping the Nandewar Range and surrounding areas may have contributed to the clay sediments in the area. Selected outcrops of the Gunnedah and Surat rock formations at the base of the mountain ranges to the east of Narrabri have resulted in the development of texture contrast soils.
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Figure 3: Correlation of the lithostratigraphic units of the Gunnedah and Sydney Basin.
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Figure 4: Surface Geology of New South Wales
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Day 1 Sydney to Scone
Presenters:
Marcelo Stabile
PhD candidate, Faculty of Agriculture Food and Natural Resources,
Figure 2: Population and projections (Australian Bureau of Statistics 2009, Hunter Valley Research
Foundation 2009)
Our research aims at understanding the causes of this change and predicting the
landscape’s configuration in the future. For this, we have built a hybrid, Markov‐Cellular
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Automata model which utilises the neighbourhood configuration to dynamically change
transition probabilities for each pixel.
Currently the model can handle 4 or 8 neighbours and the user can specify the weight of
the CA component (1‐WTM), thus allowing the model to run exclusively on Markov mode
(solely on transition probabilities), on CA mode (transition only related to neighbourhood) or
any combination of both. The model was implemented in R, and thus complexity such as
areas of exclusion and suitability layers could easily be added.
An illustration of the model’s outcomes can be seen in Figure 3. Panel A illustrates the
landscape conditions in 2005 (Cessnock on the lower right). Panel B illustrates the simulated
landscape for 2020, when transition probabilities were driven from predicted climatic
patterns and the model run on CA mode (WTM 0). Panel C shows the outcome of empirically
derived transition probabilities and the model run with WTM=0.5. Panel D, finally, refers to
when the model was run with transition probabilities derived from projections of population
and in Markov mode (WTM=1).
Empirically derived transition probabilities suggested significant increase in the areas of
irrigated Agriculture and of intensive uses. Other transition probabilities, however, such as
the ones derived from population and climate, did not significantly alter the landscape’s
composition.
Further enhancement of the model would include: utilising more than 8 neighbours for
the CA component, implementation of other layers of information for modifying transition
probabilities and utilising a combination of spatial ancillary variables for modifying the
transition probabilities as well.
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Figure 3: Initial conditions and simulated outcomes form the Hybrid model
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Cited References:
AUSTRALIAN BUREAU OF STATISTICS, 2009, Census of population and housing (Canberra: ABS).
BUREAU OF RURAL SCIENCES, 2006, Guidelines for land use mapping in Australia: principles, procedures and definitions. 3rd edition, Bureau of Rural Sciences.
HUNTER VALLEY RESEARCH FOUNDATION, 2009, Newcastle and the Hunter region 2008‐2009, edited by R. McDonald, and M. Jonita (Maryville, NSW: HVRF).
MCMANUS, P., 2008, Mines, Wines and Thoroughbreds: Towards Regional Sustainability in the Upper Hunter, Australia. Regional Studies, 42, 1275 ‐ 1290.
O'NEILL, P., 2000, The gastronomic landscape. In Journeys: the making of the Hunter Region, edited by P. McManus, P. O'Neill, R. J. Loughran, and O. R. Lescure (St. Leonards, NSW: Allen & Unwin), pp. 158‐185.
STABILE, M. C. C., ODEH, I. O. A., and MCBRATNEY, A. B., 2008, Application of object‐oriented and knowledge‐based approach to multi‐temporal land use classification using Landsat images: 14ARSPC: Proceedings of the 14th Australasian Remote Sensing and Photogrammetry Conference.
TOURISM NEW SOUTH WALES, 2009, Hunter Valley tourism statistics, HVRF.
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An additional criterion for assessing the quality of digital soil attribute maps: The areal proportion of the map within a specified prediction interval.
Brendan P. Malone*A, Jaap J de GruijterB, Alex B. McBratneyA, Budiman MinasnyA
AFaculty of Agriculture Food & Natural Resources, The University of Sydney, NSW 2006, Australia. BWageningen University and Research Centre, Wageningen, The Netherlands. [email protected], [email protected], [email protected],
Overall these results show a moderate agreement between the observed and
fitted values where Lin’s Concordance Correlation Coefficient (CCC) ranged between
0.44 and 0.30, with the strongest predictions at the soil surface (0–5 cm). Similarly
the RMSE at 0–5 cm was 0.62 and gradually increased with depth to 0.7 (5–15 cm),
0.76 (15–30 cm), 1.01 (30–60 cm) and 1.14 (60–100 cm). It can be observed from
the plots that at higher pHs (>7) there is a systematic under prediction, particular at
15–30 cm, 30–60 cm and 60–100 cm (Fig. 5c-e). As a whole, by observing the
RMSEs found for each strata at each depth interval, predicted pHs deviate from their
corresponding observed measurements by between 0.5 and 1.2 pH units.
A further analysis performed was to gauge the level of bias and precision of
predictions within each stratum. Bias was calculated as the mean error (ME) between
observed and predicted values. Precision was assessed as the square root of the
difference between the mean square error (MSE) and ME2. These results are
summarised for each strata at the defined depth increments in Table 4.
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For all strata there was an observed decrease in the precision of prediction with
depth, with the worst observed for stratum D. The bias estimates were more varied
where for strata A, C and D there was a systematic under prediction (+bias) of pH.
This was particularly pronounced for stratum C where bias was consistently above
0.5 at all depth increments. For stratum B (high pH) bias estimates indicate a
predominant over prediction of pH particularly at the bottom two depth increments.
Table 4: Bias and precision estimates between observed and predicted values of pH at each
depth increment within each strata
Stratum A B C D A B C D
Depth
(cm)
Bias Precision
0–5 0.18 -0.19 0.54 0.04 0.47 0.50 0.57 0.62
5–15 0.46 0.05 0.57 0.22 0.50 0.51 0.72 0.57
15–30 0.26 -0.03 0.45 0.26 0.58 0.71 0.73 0.79
30–60 0.22 -0.41 0.54 0.12 0.88 0.90 0.90 1.13
60–100 0.09 -0.78 0.54 0.03 1.00 0.96 1.00 1.18
Conclusions
The prediction results indicate that bias exists between the observed aliquots and
their corresponding predictions. We have also identified an increasing level of
imprecision of pH predictions with depth. Rather than the method used to calculate
the prediction uncertainties, it is believed that a predominant factor for the lower than
ideal (95%) of correctly prescribed PIs is due to the quality of the predictions.
Nevertheless, we have presented a new criterion for which additional data are
used to determine the quality of a soil map which entailed some measure of the
known uncertainties attached to the predictions. The indicator of map quality in this
study is that 84% of the prediction area is correctly mapped based on a 95%
confidence level. Akin to mapping purities which are used to assess the quality of
polygon-based maps, our results are encouraging and indicate that the pH map used
in this study is of high quality. In such polygon-based maps, mapping purities of
between 70-80% are acceptable but can often be found as being much less than
70% (e.g. Burrough et al. 1971).
We recognise that this criterion is only one indicator of map quality and should be
used as we have done as a compliment to more conventional indicators.
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Nevertheless, the indicator of map quality we have presented simultaneously derives
measures of map quality based on both the predictions and their associated
uncertainties, for which conventional indicators are unable to do.
We also recognise that there are unknown sources of uncertainty which can not
be accounted for at this point in time. We are also mindful that these results reflect no
spatial component of quality for which further work will be needed to investigate. We
will also need to investigate the efficacy of transference of the same sample units to
validate maps of different soil properties in the same area. Nevertheless, we
envisage that in the future, such quality-based information as we have presented in
this study will accompany digital soil maps in the form of attached metadata.
References
Bishop, T.F.A., McBratney, A.B. and Whelan, B.M., 2001. Measuring the quality of digital soil
maps using information criteria. Geoderma, 103(1-2): 95-111.
Burrough, P.A., Beckett, P.H.T. and Jarvis, M.G., 1971. Relation between cost and utility in
soil survey. Journal of Soil Science, 22(3): 359–394.
Burrough, P.A., vanGaans, P.F.M. and Hootsmans, R., 1997. Continuous classification in soil
survey: Spatial correlation, confusion and boundaries. Geoderma, 77(2-4): 115-135.
de Gruijter, J.J., Brus, D.J., Bierkens, M.F.P. and Knotters, M., 2006. Sampling for Natural
Resource Monitoring. Springer-Verlag Berlin Heidelberg, The Netherlands.
Finke, P.A., 2006. Quality assessment of digital soil maps: producers and users
perspectives. In: P. Lagacherie, A.B. McBratney and M. Voltz (Editors), Digital soil
mapping: an introductory perspective. Elsevier, Amsterdam, pp. 523–541.
Lagacherie, P., 2008. Digital soil mapping: a state of the art. In: A.E. Hartemink, A.B.
McBratney and M.L. Mendonca-Santos (Editors), Digital Soil Mapping with Limited
Data. Springer Science, Australia, pp. 3–14.
Malone, B.P., McBratney, A.B., Minasny B. (in preparation) Empirical estimates of
uncertainty for mapping continuous depth functions of soil attributes.
Malone, B.P., McBratney, A.B., Minasny, B. and Laslett, G.M., 2009. Mapping continuous
depth functions of soil carbon storage and available water capacity. Geoderma,
154(1-2): 138-152.
Rayment, GE & Higginson, FR 1992, Australian Laboratory Handbook of Soil and Water
Chemical Methods. Inkata Press, Melbourne. (Australian Soil and Land Survey
Handbook, vol 3)
Shrestha, D.L. and Solomatine, D.P., 2006. Machine learning approaches for estimation of
prediction interval for the model output. Neural Networks, 19(2): 225-235.
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Hunter Valley Focus Maps
Figure 6: Sydney University Hunter Valley soil survey efforts
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Figure 7: Hunter Valley elevation (25m res)
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Figure 8: Hunter Valley Slope (25m res)
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Figure 9: Hunter Valley TWI (25m res)
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Figure 10: Hunter Valley soil classes (to ASC suborder)
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Figure 11: Soil classes to ASC sub‐order – zoomed
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1. Location and landscape
Landform This profile is situated mid‐slope on a low hill. In the Hunter Valley, undulating hills with slopes between 6‐12% are dominant.
Parent material or substrate
The most common soil parent materials within the region are shales and mudstones, but smaller amounts of sandstone and limestone are also present. Colluvium and alluvium are significant soil parent materials at lower elevations.
Drainage class Slowly drained, with a moderate run‐on rate and medium run‐off rate.
Surface condition
Soft surface which is currently stable. There is low soil erodibility around the site, which has a low erosion hazard. There is no salinity evident on the surface.
Site disturbance
Extensive clearing of the native vegetation occurred in the late 1800s to early 1900s to make way for pastures and viticulture. The region is now very well known for boutique wine production, with Semillon and Shiraz being the best performed grape varieties in the region. This site has been used for pasture production.
Native vegetation
The dominant vegetation consists of dry schlerophyll forests, with tall woodland stands and shrub/grass understory being most dominant. Two dominant Eucalyptus species present within the region are Eucalyptus fracta and Eucalyptus pumila (Pokolbin Mallee).
Climate The annual average rainfall for the district is 699 mm. The average minimum temperature in July is 3.8oC and the average maximum temperature in January is 30.0oC.
SB Profile 1: Oakey Creek Rd, Pokolbin, NSW
27
0 1 km
New South Wales
Queensland
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2. Description of soil profile A slow draining Sodosol, derived from shale and mudstone.
Very dark greyish brown‐ FSCL Weak Polyhedral 10‐20
<10% stones
A₂ E 0.18‐0.3 Clear Wavy 10YR 4/3 Brown
‐ SCL Massive ‐ ‐ <10% stones
B₂₁ Bt 0.3‐0.5 Abrupt Even 10YR 4/4
Dark yellowish brown ~3% RFP ~2% YPF
HC Strong ‐ ‐ <10% stones
B₂₂ Btn1 0.5‐0.9 Gradual Even 2.5YR 3/6 Dark red
~20% GPD HC Strong ‐ ‐ 10‐50% stones
B/C Btn2 0.9‐1.1 ‐ ‐ 7.5YR 4/2 Brown
~35% RDD HC Moderate ‐ ‐ ‐
A₁
B₂₁
B/C
B₂₂
A₂
A
E
Bt
Btn1
Btn2
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3. Soil mineralogy
X‐ray diffraction patterns of basally oriented clays show the presence of kaolinite, illite and
an interstratified swelling mineral. The proportion of the interstratified swelling mineral
increased with depth. In addition to the phyllosilicates, the random powder diffraction
patterns identified quartz, anatase, feldspar (plagioclase), lepidocrocite, goethite and
hematite in the soil clay fractions.
X‐ray diffraction patterns of the oriented clay fraction of B21 horizon soil after various pre‐
treatments; Mg saturated and air‐dried (‐‐‐‐‐‐), Mg saturated and ethylene glycolated (‐‐‐‐‐‐), K
saturated and air‐dried (‐‐‐‐‐‐) and K saturated and heated at 550°C (‐‐‐‐‐‐). I/S = interstratified
swelling mineral.
Thin sections
The left image (PPL) shows many small ferromanganiferous inclusions in the clayey matrix of the B21 horizon, while the right image (XPL) shows quite pronounced orientation of clay around grain edges and along pores, suggesting that illuviation has been an important process in this soil.
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4. Profile chemical characteristics
The pH values for this soil profile are strongly‐slightly acidic (5.29‐6.20) and the soil pH decreases with depth.
EC values range from very low to very high in this profile, with higher EC values towards the bottom of the profile.
Soil organic carbon content is high in the surface soil and declines down the profile.
CECs are very low to moderate for the profile, with the A₂ horizon exhibiting a particularly low value.
Nitrogen levels range from medium‐low and decline down the profile.
C/N ratio ranges from medium ‐ very low.
Chemical properties of soil profile
Cation exchange properties, available micronutrients and DCB and oxalate Fe and Al of soil profile
The particle size distribution for this profile shows a very high sand content in the topsoil and very high clay content in the B horizons.
Values of bulk density are moderate to very high and increase with depth. Penetration resistance decreases down the profile, being dense at the top of the profile
and very dense in the underlying horizons.
The water content at permanent wilting point is low in the top 2 horizons but increases in the subsoil horizons.
Soil physical characteristics
Particle size analysis (%) Moisture ()
Horizon Clay
(<2 µm) Silt
(2‐20 µm) Fine sand (20‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
A₁ 20.1 8.2 63.6 8.1 1.43 0.21 0.06 0.39 1.7
A₂ 22.5 3.3 64.3 9.9 1.53 0.17 0.05 0.34 2.4
B₂₁ 54.8 3.2 28.3 12.0 1.69 0.31 0.24 0.34 2.3
B₂₂ 71.3 3.4 21.3 4 1.92 0.25 0.19 0.27 2.4
B/C 58.3 3.4 33.1 5.2 1.98 0.24 0.19 0.27 ‐
Estimated USDA PSA (%)
Horizon Silt
(2‐50 µm) Sand (50‐2000 µm)
A₁ 21 58.9
A₂ 11.4 66.1
B₂₁ 7.3 37.8
B₂₂ 2.5 26.2
B/C 7.2 34.5
A1 A1 A1 A1
A2 A2 A2
A2
B22
B21 B21 B21
B22
B22 B22
B21
B/C B/C B/C
A1
A2
B21
B22
32
2. Location and landscape
Landform This profile is situated on the upper slope of a steeply sloping hill in the Hunter Valley. A north‐south running ridgeline extends from the mid‐slope of this hill.
Parent material or substrate
The soil parent material at this site is limestone, with many fossilised shells present. The north‐south running ridgeline extending from this site is also comprised of limestone parent material.
Drainage class Well drained, with a low run‐on rate and low‐medium run‐off rate.
Surface condition
Soft surface which is currently stable. Despite the moderately steep slope of this site, the soil erodibility is low and the erosion hazard is low, due to the vegetative cover.
Site disturbance
Like the Oakey Creek site, this site would have been cleared of native vegetation in the 1800s or 1900s, and has been used as grazing land.
Native vegetation
Similar to the Oakey Creek site (Profile 1).
Climate Similar to the Oakey Creek site (Profile 1).
Profile 2: Marrowbone Rd, Pokolbin, NSW
33
0 1 km
New South Wales
Queensland
54
2. Description of soil profile A well drained Shelly Calcarosol, located on an extensively cleared hillslope.
Clay and silt are present in moderate amounts within this profile. Both fine and coarse sand are present in low amounts.
The bulk density is very low‐low, which not much variation within the profile.
The water content at permanent wilting point is about the same throughout the profile
Penetration resistance increases down the profile (1.3‐2.5 MPa), indicating a medium‐dense degree of soil consolidation.
Soil physical characteristics
Particle Size Analysis (%) Moisture ()
Horizon Clay
(<2 µm) Silt
(2‐20 µm) Fine sand (20‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
A 46.1 24.4 20.3 9.2 0.88 0.47 0.25 0.56 1.3
AB 38.7 25.8 26.2 9.3 1.25 0.42 0.25 0.49 2.9
B 39.5 30.2 23.2 7.1 1.25 0.43 0.26 0.50 2.5
C 35.2 35.2 24.1 5.5 1.24 0.43 0.25 0.50 2.5
Estimated USDA PSA (%)
Horizon Silt
(2‐50 µm) Sand (50‐2000 µm)
A 39.9 14.0
AB 44.0 17.3
B 47.9 12.6
C 53.4 11.4
A A A A
ABAB ABAB
C
B B B
C C
B
C
A
AB
B
C
58
Day 2
Scone to Gunnedah
Presenters:
Noel Ticehurst
Manager
E J Holtsbaum Agricultural Research Institute (Nowley Farm), Spring Ridge
59
Nowley Focus Maps
Figure 12: Nowley elevation (100 m resolution)
Figure 13: Nowley slope (10 m resolution)
60
Figure 14: Nowley RGB ternary radiometric image (100 m resolution)
Figure 15: Nowley radiometrics‐ K (%) (100 m resolution)
61
Figure 16: Nowley radiometrics‐ eTh (ppm) (100 m resolution)
Figure 17: Nowley soil classifications
62
3. Location and landscape
Landform This site is situated on the Liverpool Plains. The region consists of alluvial channels and extensive floodplains, with some undulating hills and sloping plains. Profile 3 is located on a sloping plain.
Parent material or substrate
The bioregion comprises mainly of horizontally‐bedded Jurassic and Triassic quartz sandstones and shales with limited areas of conglomerate and basalts. Nowley itself comprises mainly of Quaternary alluvial plains and outwash fans derived from Tertiary basalts.
Drainage class Moderately drained, with a moderate low‐on rate and slow run‐off rate.
Surface condition
Hard surface which is currently stable. The topsoil is moderately erodible, leading to a moderate wind and water erosion hazard when the vegetative cover is poor.
Site disturbance Extensive clearing of native vegetation for agricultural practices has occurred over the last 150 years. Landuses include sheep and cattle grazing, along with dryland cropping of winter cereals and various summer crops.
Native vegetation
Plains grass, windmill grass and blue grass can be found as well as white box (Eucalyptus albens), yellow box (Eucalyptus melliodora), rough‐barked apple (Angophora floribunda) and hill red gums (Eucalyptus camaldulensis).
Climate This area falls into a summer dominant rainfall system, and has an average annual rainfall of 686 mm. The mean maximum temperature in January is 32.2oC, whilst the mean minimum temperature in July is 1.6oC.
Profile 3: Nowley Farm 1, Spring Ridge, NSW
63
0 1 km
Queensland
New South Wales
64
2. Description of soil profile A non‐sodic, red, texture‐contrast soil with a hypercalcic horizon (>20% of soft, finely divided
carbonate) occurring in the transition from lower B to C horizons. These soils are commonly found in
the wheat‐sheep belt of south‐eastern Australia and are valued as a good cropping soil.
Soil morphology
CL= clay loam; LMC= Light medium clay; MC= Medium clay
Australian Soil Classification: Red Chromosol (CH AA)
World Reference Base: Luvic Vertic Calcisol (Ruptic, Clayic, Rhodic)
The particle size data show that the moderate‐high clay content increases with depth, sand content shows an opposite trend to clay content, while silt content does not vary much throughout the profile.
Bulk density increases down the profile, and ranges from low to moderate.
Penetration resistance increases down the profile and suggests an extreme degree of soil consolidation in the B21 horizon (11.2 MPa).
Soil physical characteristics
Particle Size Analysis (%) Moisture ()
Horizon Clay
(<2 µm) Silt
(2‐20 µm) Fine sand (20‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
A 33.2 22.5 36.9 7.4 1.04 0.43 0.21 0.53 3.3
B21 46.7 24.4 23.7 5.2 1.16 0.45 0.28 0.52 8.9
B22 49.2 23.5 23.2 4.1 1.58 0.37 0.29 0.40 11.2
B23 63.5 12.1 19.8 4.6 1.6 0.35 0.28 0.38 ‐
Estimated USDA PSA (%)
Horizon Silt
(2‐50 µm) Sand (50‐2000 µm)
A 41.8 25.0
B21 39.7 13.6
B22 37.8 13.0
B23 18.4 18.0
A A A A
B21B21 B21
B23
B22 B22 B22
B23
B23 B23
B22
A1
B21
B22
B21
68
4. Location and landscape
Landform Similar to that of Profile 3, but located further downslope on the sloping plain.
Parent material or substrate
Similar regional parent materials to those of Profile 3. Profile 4 is derived from Quaternary alluvium sourced from Jurassic sandstones.
Drainage class Rapidly draining topsoil and slowly draining subsoil. Slow run‐on and run‐off rate.
Surface condition
Sandy and loose. Erodibility and erosion hazard are relatively low due to the coarse sandy texture of the topsoil and the small slope of the land.
Site disturbance Similar to Profile 3, although this site has generally been used for grazing rather than cropping.
Native vegetation
Similar to that of Profile 3.
Climate Similar to that of Profile 3.
Profile 4: Nowley Farm 2, Spring Ridge, NSW
69
0 1 km
Queensland
New South Wales
70
2. Description of soil profile A strongly duplex profile with a sodic upper B horizon. This soil has been used for improved
pasture production and dryland cropping.
Soil morphology
S= sand; LC= Light clay; MC= Medium clay
Australian Soil Classification: Eutrophic, Mottled‐Mesonatric, Brown Sodosol
Sand content decreases down the profile, ranging from very high to low, whilst clay content shows an opposite trend, ranging from very low to very high.
Moderate to high bulk densities are observed throughout the entire profile. Penetration resistance increases down the profile, suggesting a dense to extremely dense
Michael Nelson, & Inakwu Odeh, The University of Sydney
In Australia, a move towards catchment‐based management, under the auspices of various
Catchment Management Authorities (CMAs), has led to increased demand for catchment‐
scale information. To meet this demand, some CMAs have initiated projects to integrate
disparate soil data into soil spatial information systems, or, more broadly, land resource
information systems useful for natural resource management.
We collated soils data for the Namoi catchment from various sources and used the soil
profile information to create catcment‐scale digital soil class maps of the Namoi catchment
(Nelson & Odeh, 2009).
The Namoi Catchment is an area of ~42 000 km2, in north‐western NSW. The geology of the eastern section of the catchment is dominated by Tertiary volcanics, with basalt rocks forming the south, south‐western, and north‐eastern boundaries (Donaldson and Heath 1997). The central section of the catchment is dominated by sedimentary geology, including shales, sandstones, and conglomerate rocks, with the alluvial plains consisting of Quaternary sedments (Zhang et al. 1999). A large alluvial plain stretching from Narrabri west to Walgett is dominated by Quaternary sediments (Zhang et al. 1999). The soils on the alluvial plains, especially where sediment is predominately sourced from the basaltic ranges, are generally moderately fertile, deep cracking clays (Donaldson and Heath 1997; Young et al. 2002) or Vertosol (Isbell 1996). In some places, these Vertosols are found in association with duplex soils termed as Chromosols, Sodosols, and Kurosols, and Dermosols and Ferrosols (Isbell 1996; Donaldson and Heath 1997). In the eastern part, which is characterised by rough or steep terrain, the soil associations are predominantly made up of duplex soils as well as Kandosols, Tenosols, and Dermosols (Isbell 1996; Donaldson and Heath 1997) Soils formed on Pilliga sandstone, which are located in the southern central section of the catchment, are coarse‐textured Kandosols, Tenosols, and some Sodosols (Donaldson and Heath 1997) Below are maps created for the Namoi catchment using Classification Trees (Figure 18) .
76
Figure 18: Digital soil class map of the Namoi catchment developed using a classification tree algorithm
Enlarged sections of the whole catchment maps around Nowley (Figure 19) and the I. A. Watson
Research Station (Figure 20) are shown below.
Figure 19: Section of the Namoi Catchment soil class map for the area around Nowley
Figure 20: Section of Namoi catchment soil class map for the area surrounding the IA Watson research station
Data mining algorithms such as Classification trees are useful in producing maps of soil
classes, but do not quantify the uncertainty surrounding any predictions. Model—based
77
approaches provide an alternative whereby predictions and prediction error variances can
be quantified.
Digital soil mapping using generalized linear spatial models
Michael Nelson, Inakwu Odeh, Thomas Bishop & Neville Weber
The University of Sydney
Our research examines the use of model—based geostatistics (Diggle & Ribiero, 2007) to
produce digital soil class maps. We have developed a generalized linear spatial model for
digital soil class mapping (Nelson et al 2009) and are now considering the quantifying the
various sources of error and effects on the error in the final map.
Below is a simple example using binomial data, a digital soil map predicting the presence or
absence of Vertosols for a section of the Upper Namoi catchment. A map of the study area
is presented in Figure 21, with the predicted probability in Figure 22 and prediction error
variance in Figure 23. The use of the generalized linear spatial model avoids the problems
associated with indicator kriging (Papritz, 2009) , providing a theoretically sound approach
for mapping Bernoulli data.
Figure 21: Location of the Upper Namoi study area and soil survey locations
78
Figure 22: Predicted probability of Vertosol occurrence for the Upper Namoi using a generalized linear spatial model for binomial data
Figure 23: Prediction error variance for predicted probability of Vertosol occurrence for the Upper Namoi
References
Diggle PJ, Ribiero Jr PJ (2007) Model—based geostatistics. Springer Series in Statistics, New York.
Donaldson S, Heath T (1997) Namoi river catchment report on land degradation and Proposals for
integrated management for its treatment and prevention' NSW Department of Land and Water
Conservation.
Nelson, MA, Odeh IOA (2009) Digital soil class mapping using legacy soil profile data: a comparison of a genetic algorithm and classification tree approach. Australian Journal of Soil Research, 47, 1—18.
79
Nelson MA, Bishop TFA, Odeh IOA, Weber, N (2009) A generalized linear spatial model for digital soil
class mapping [Digital soil class mapping using model‐based geostatistics] in Proceedings of
Pedometrics 2009 conference, Beijing.
Papritz, A (2009) Why indicator kriging should be abandoned. Pedometron 26
Zhang L, Beavis SG, Gray SD (1999) Development of a spatial database for large‐scale catchment
management: geology, soils and landuse in the Namo Basin, Australia. Environment International 25,
853‐860.
80
High resolution soil carbon mapping
Budiman Minasny, The University of Sydney
A new methodology was developed and applied to make an assessment of the distribution
of total, organic and inorganic carbon at a grains research and grazing property compared
with an adjacent permanent pasture stock‐route, in the IA Watson farm. The I.A. Watson
Grains Research Institute (30°16´12.35˝S, 149°48´13.14˝E) is a 460 hectare (320 ha of
cropping and 120 ha of pastoral land) property in Narrabri, north‐west New South Wales.
The property has been breeding cereals (wheat, rye and triticale) under traditionally
managed irrigated cropping operations for half a century. Repeated cultivation of the soil
with limited SOM inputs has caused a decline of carbon levels. An adjacent strip of crown
land used as a travelling stock route was incorporated into the survey area, to allow for
comparisons of soil carbon content between these two different land use regimes. There
was also variation in the soil types between Vertosols and Dermosols of the cropping area
compared with the Calcarosols of the pasture area
A baseline survey was carried out to identify map areas of soil variation across the farm with
data from a Multi‐ Sensor Platform (M‐SP). The M‐SP consisted of 3 proximal soil sensors
including a Geonics Electromagnetic Induction (EM) 38 and EM 31 ECa sensors (Geonics Ltd,
Mississauga, Ontario, Canada) and a GR320 Gamma radiometric spectrometer (Exploranium
Radiation Detection Systems, Acworth, Georgia, USA). The vehicle was driven across the field
at a speed of approximately 10km/h and the sensor measurements were logged at a rate of
1 Hz and georeferenced with an OmniSTAR HP, single frequency, Differential Global
Positioning System (D‐GPS) (OmniSTAR Inc, Houston, Texas, USA) which simultaneously
acquired elevation data. The swath width across the field ranged in distance from 20‐30
metres. All geo‐referenced continuous data layers were interpolated with Vesper software
using block kriging onto a standard 5m grid for analysis.
81
Figure 24: Electromagnetic induction (EM) 38
ECa data interpolated onto a 5 metre grid
Figure 25: Electromagnetic induction (EM) 31 ECa
data interpolated onto a 5 metre grid
82
Figure 26: Gamma spectrometer data inPotassium (K) region of interest
Figure 27: Gamma spectrometer data in Thorium (Th) region of interest
83
Figure 28: Digital elevation model in metres above sea level (ASL)
Coupled with a digital elevation model and secondary terrain attributes all of the data layers
were combined by k‐means clustering to develop a stratified random soil sampling scheme
for the survey area. Soil samples were scanned at 15cm increments to a depth of 1m with a
mid‐infrared (MIR) diffuse reflectance spectrometer, which was calibrated using a
proportion of the samples that were analysed in a laboratory for total carbon and inorganic
carbon content.
The values from the observed soil profiles were then interpolated throughout the farm at a
resolution of 5 m x 5 m grid using regression model based on the covariate/ ancillary
information derived from the soil survey. A regression rule program CUBIST was used to
derive models that could estimate carbon across the entire property and stock‐route.
The combination of new methodologies and technologies have the potential to provide large
volumes of reliable, fine resolution and timely data required to make baseline assessments,
mapping, monitoring and verification possible.
84
References
Miklos, M., Short, M.G., McBratney, A.B., Minasny, B., 2010. Mapping and comparing the distribution
of soil carbon under cropping and grazing management practices in Narrabri, NW NSW. Australian
Journal of Soil Research 48, 248–257.
Table 5: Mean soil total, organic and inorganic carbon stock, based on landuse
Land use No. of
Samples
Total Carbon
(kg/m2)
Organic Carbon
(kg/m2)
Inorganic Carbon
(kg/m2)
Cropping 30 12.41 5.04 7.37
Pasture 18 16.25 6.79 9.46
Stock‐route 11 13.89 8.21 5.68
Figure 29: Organic carbon stock to one metre Figure 30. Inorganic carbon stock to one metre
85
EDGEROI FOCUS MAPS
Figure 31: The Edgeroi study area
86
Figure 32: The Edgeroi Data set (McGarry et al. 1989) point locations (yellow triangles)
87
Figure 33: Maps of organic carbon and available water capacity to 1m in the Edgeroi area.
88
1. Location and landscape
Landform
Pilliga Scrub is part of the Pilliga Nature Reserve, which covers a total area of 80,000 ha. It consists of low, undulating, sandy country with occasional outcrops of rocky sandstone and low cliffs. Landforms in the southern area tend to be more steep and rugged with the presence of small gorges.
Parent material or substrate
The bedrock of the area consists of the Jurassic‐aged Pilliga Sandstone, underlain by silty sandstones, claystones and shales. The Pilliga Sandstone dips in a north‐west direction with an angle of 5‐10° when not disrupted by igneous intrusions. In the north, extensive sediments were deposited by dendritic streams
Drainage class Irregular drainage, with a moderate low‐on rate and a very slow run‐off rate.
Surface condition
Loose and sandy. The soil erodibility is low, as is the erosion hazard.
Site disturbance Very low site disturbance as it is classed as a nature reserve, although there is a main road situated about 50 m away from the profile. Land surrounding the reserve is used for timber production.
Native vegetation
The dominant canopy species of vegetation are Eucalyptus spp and Callitris endlicheri. The shrub and groundcover includes species such as Acacia spp, Allocasuarina spp, Brachycome spp, Styphelia triflora and Swainsona spp.
Climate The area has a warm, sub‐humid climate, with an annual average rainfall of approximately 625 mm. The mean maximum temperature in January is 33.5oC, whilst the mean minimum temperature in July is 2.2oC.
Profile 5: Pilliga Scrub, Pilliga, NSW
89
Queensland
New South Wales
0 1 km
90
2. Description of soil profile This is an apedal sandy soil, with an extremely low CEC throughout the entire profile. Krotovinas are
present in the upper B horizon.
Soil morphology
LS= Loamy sand; CS= Clayey sand
Australian Soil Classification: Orthic Tenosol (TE DS)
World Reference Base: Cutanic Lixisol (Humic, Chromic)
Very high sand content throughout the entire profile ranging from 68‐71%.
Low to moderate bulk density for all horizons in the profile.
The water content at permanent wilting point is low and does not vary much within the profile.
Hydraulic conductivity increases down the profile.
The penetration resistance ranges from medium to dense. Soil physical characteristics
Particle Size Analysis (%) Moisture ()
Horizon Clay
(<2 µm) Silt
(2‐20 µm) Fine sand (20‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
A 10.8 7.5 10.4 71.3 1.46 0.23 0.07 0.38 0.9
B1 14.3 5.1 12.3 68.3 1.46 0.23 0.08 0.37 1.6
B21 13.2 5.1 11.8 70.0 1.28 0.24 0.09 0.43 1.2
B22 13.5 5.2 11.7 69.6 1.39 0.23 0.08 0.40 ‐
Estimated USDA PSA (%)
Horizon Silt
(2‐50 µm) Sand (50‐2000 µm)
A 19.0 70.2
B1 14.4 71.2
B21 14.2 72.6
B22 14.5 72.0
A A A A
B1 B1 B1 B1
B22
B21 B21 B21
B22 B22 B22
B21
A1
B1
B21
94
5. Location and landscape
Landform This site is located on an alluvial fan of the Namoi River.
Parent material or substrate
Basaltic alluvium. The basalt shield volcano to the east has been extensively eroded, leaving its highest peak, Mt Kaputar, at 1508 m. The basalt flows overlie Tertiary alluvial sandstone and conglomerate. Calcareous clays and marls of the Rolling Downs Group form gentle slopes on the properties such as IA Watson.
Drainage class Slow drainage, with a low run‐on and run‐off rate.
Surface condition
Epipedal and cracked when dry. The soil has a low erodibility and is regarded as being a low erosion hazard. There is no salinity evident on the surface.
Site disturbance The surround region land has been extensively cleared for agricultural production including the growth of cotton, wheat, barley and oilseeds. Livestock production includes cattle and pigs.
Native vegetation
Native vegetation is sparse on the floodplain, but where it occurs it consists of open grasslands (mainly Austrostipa aristiglumis and Dichanthium sericeum) with scattered trees (e.g. Eucalyptus spp. and Angophora floribunda) and shrubs (e.g. Acacia pendula and Rumex spp.)
Climate The area has a warm, sub‐humid climate, with an annual average rainfall of 643 mm. The mean maximum temperature in January is 35.3oC, whilst the mean minimum temperature in July is 3.4oC.
Profile 6: I.A. Watson Research Institute, Narrabri, NSW
95
0 1 km
Queensland
New South Wales
96
2. Description of soil profile A grey Vertosol used for dryland wheat production and/or irrigated cotton and wheat production. Mechanical compaction has degraded the subsurface structure of this profile.
Soil morphology
GPD= Grey, pale, distinct; LC= Light clay; LMC= Light medium clay; MC= Medium clay
Australian Soil Classification: Grey Vertosol
World Reference Base: Calcic‐Mollic Vertisol (Pallic) OR Calcic Vertisol
Soil Taxonomy: Sodic Calciustert
Boundary Colour Structure Horizon Depth (m)
Distinctness Shape Moist Dry
MottlesTexture grade
Grade Shape Size (mm)
Coarse fragments
Ap1 Ap1 0‐0.08 Clear Even 7.5YR 3/2 Dark brown
‐ ‐ LC Weak ‐ ‐ ‐
Ap2 Ap2 0.08‐0.30 Clear Even 5YR 4/1 Dark grey
10YR 4/2 Dark greyish
brown ‐ LC Massive ‐ ‐ ‐
B1 Bw 0.30‐0.45 Gradual Wavy 5YR 2.5/1 Black
7.5YR 4/1 ‐ LMC Moderate Angular‐blocky
50‐100 ‐
B21 Bssk1 0.45‐0.90 Diffuse Even 10YR 4/2
Dark greyish brown
10YR 5/2 Greyish brown
‐ LMC Strong Lenticular 50‐100<10 % stones
B22 Bssk2 0.90‐1.65 ‐ ‐ 10YR 5/2
Greyish brown10YR 5/2
Greyish brown~30% G, P, D
MC Strong Angular‐ blocky
50‐100
A1
B1
B22
B21
A₂
Ap1
Ap2
Bw
Bssk1
Bssk2
97
3. Soil mineralogy
X‐ray diffraction patterns of basally oriented clays show the presence of smectite, kaolinite
and minor amounts of illite. Smectite content is very high in B21 and B22 horizons. Quartz,
anatase and feldspar (microcline) are also identified in the random powder diffraction
patterns of the soil clay fractions.
X‐ray diffraction patterns of the oriented clay fraction of B21 horizon soil after various pre‐
treatments; Mg saturated and air‐dried (‐‐‐‐‐‐), Mg saturated and ethylene glycolated (‐‐‐‐‐‐), K
saturated and air‐dried (‐‐‐‐‐‐) and K saturated and heated at 550°C (‐‐‐‐‐‐).
98
4. Profile chemical characteristics
The pH values for this soil profile range from slightly acidic in the topsoil to very strongly alkaline in the subsoil (6.48‐9.53).
Very low EC values are found in the A horizons and upper B horizon, while medium EC values are found in the lower B horizons.
The organic carbon levels are considered to be moderate in the surface horizon and vary from low‐very low in the underlying horizons.
The cation exchange capacity (CEC) is low to moderate for the profile.
Exchangeable sodium percentage (up to 20%) is very high in the subsoil.
Chemical properties of soil profile
Cation exchange properties, available micronutrients and DCB Fe and Al of soil profile
High to very high clay contents are found in this profile, with the B22 horizon having the highest clay content.
The profile has a moderate to high bulk density throughout. The penetration resistance ranges from 0.9 to 2.9 MPa, indicating a medium to very dense degree
of consolidation.
Soil physical characteristics
s
Particle Size Analysis (%) Moisture ()
Horizon Clay
(<2 µm) Silt
(2‐20 µm) Fine sand (20‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
Ap1 41.9 23.7 28.5 5.9 1.64 0.35 0.26 0.38 0.9
Ap2 46.4 22.1 27.8 3.7 1.59 0.37 0.28 0.40 1.9
B1 44.7 19.6 31.2 4.5 1.65 0.35 0.26 0.38 1.7
B21 42.3 24.6 26.2 6.9 1.73 0.32 0.25 0.35 2.9
B22 67.6 16.1 15.1 1.2 ‐ ‐ ‐ ‐ ‐
International system PSA (%)
Horizon Silt
(2‐50 µm) Sand (50‐2000 µm)
Ap1 40.7 17.4
Ap2 37.3 16.2
B1 35.0 20.2
B21 41.5 16.2
B22 21.3 11.0
Ap1 Ap1
Ap1 Ap1
Ap2 Ap2 Ap2 Ap2
B21
B1 B1 B1
B21 B21 B21
B1
B22
Ap1
Ap2
B1
B21
100
6. Location and landscape
Landform It is located in a low energy environment as a result of the site being positioned on a flat, upper alluvial floodplain.
Parent material or substrate
The profile overlies a basalt shield volcano which has eroded leaving its highest peak at Mt Kaputar at 1508 m. This shield overlies tertiary alluvial sandstone and conglomerate. At the site mudstone and basalt are recognised as the dominate parent material.
Drainage class Slow drainage, with a low‐on rate and a ponded run‐off rate.
Surface condition
Firm surface which is very stable. There is low soil erodibility around the site, which is also regarded as having a low erosion hazard. There is no salinity evident on the surface.
Site disturbance Similar to that of Profile 6.
Native vegetation
Similar to that of Profile 6.
Climate Similar to that of Profile 6.
Profile 7: Cooyong, Narrabri, NSW
101
102
2. Description of soil profile A polygenetic profile with a strongly structured Red Chromosol overlying a calcic Brown Vertosol. A stone line separates the two profiles.
Soil morphology
GPD= Grey, pale, distinct; LC= Light clay; LMC= Light medium clay; MC= Medium clay
Australian Soil Classification: Red Chromosol over a Brown Vertosol
World Reference Base: Calcic Stagnic Vertisol (Chromic, Mollinovic)
Figure 52: Locations of APSRU reference sites across Australian continent
Figure 53: APSRU reference site plant available water data (WA wheatbelt)
109
Figure 54: APSRU reference site plant available water data (SE Australia)
Figure 55: APSRU reference site plant available water data (Liverpool Plains)
110
Figure 53: APSRU reference sites within the Liverpool plains area with reference to tour profile locations.
111
7. Location and landscape
Landform Romaka is situated in the Gwydir River valley, which is located in the Murray Darling Basin. It lies between the Masterman Range to the north, and the Nandewar Ranges to the south. The site is located on a slight rise in a broad floodplain.
Parent material or substrate
The parent material at the profile site is likely to be quartz sandstone and alluvium from Jurassic and Carboniferous sediments in the surrounding ranges. The field also includes soil derived from Tertiary basaltic alluvium.
Drainage class Moderate drainage and low run on and run off rate due to the flat terrain.
Surface condition:
The profile has a weakly pedal and friable topsoil. Due to the flatness of the surrounding terrain and lack of frequent flood events, the site has a low erosion hazard.
Site disturbance
The site has been under cultivation for an extended period of time. Cereal and sorghum crops have been the most recent crops used in rotation on the property. Sorghum roots can still be seen in the profile.
Native vegetation
Closed grasslands with scattered woodlands dominate. Main tree species are Eucalyptus albens (white box), Eucalyptus melliodora (yellow box), Acacia Pendula (myall), Heterodendron oleifolium (rosewood) and Casurina cristata (belah). The main grass species are Stipa aristiglumis (plains grass) with many Aristida spp.(wire grass), Stipa spp. (spear grass) and Danthonia spp. (wallaby grasses).
Climate Nearby Moree is situated in a semi‐arid climate with hot summers and frosty winters. Annual rainfall is approximately 580 mm. Average maximum temperature is 27.6°C and average minimum temperature is 11.7°C.
Profile 8: Romaka, Terry Hie Hie, NSW
112
0 1 km
Queensland
New South Wales
113
2. Description of soil profile A red, clayey soil formed on very old alluvium. This reddish soil occurs on slightly elevated
areas of land, whilst the surrounding soils consist mainly of greyish Vertosols.
Soil morphology
RDD= Red, dark, distinct; SCL= Sandy clay loam; LMC= Light medium clay; MC= Medium clay
Australian Soil Classification: Red Dermosol (DE AA)
World Reference Base: Calcic Cutanic Luvisol (Endo‐clayic, Chromic)
Landform Wide, alluvial plains of the lower Macintyre River. Local relief is <9 m and most slopes are <1% conferring a complex drainage system in the area.
Parent material or substrate
Quaternary alluvium. Clay alluvia have been deposited on the back plains of major streams.
Drainage class Imperfectly drained, with a low run‐on rate and a ponded run‐off rate. Very slow internal drainage.
Surface condition:
Periodic cracking, with loose fragments. The soil has low erodibility and the site a low erosion hazard.
Site disturbance
Very minor disturbance by grazing animals, as the site is a stock route. The dominant landuse in the region is broadacre cropping; the stockroute is bordered by irrigated and dryland cropping paddocks.
Native vegetation
Open woodland of coolabah (Eucalyptus coolabah), belah (Casuarina cristata) and myall (Acacia melvillei), with tussock grassland of curly Mitchell grass (Astrebla lappacea) and Queensland bluegrass (Dichanthium sericeum).
Microrelief Normal gilgai with 0.15 m vertical intervals and approximately 6 m horizontal intervals.
Climate This area has unreliable, summer dominant rainfall, causing periods of drought and flood events. The average annual rainfall is 592 mm. The mean January maximum temperature is 34.1°C, while the mean July minimum temperature is 4.5°C.
Profile 9: South Callandoon, Goondiwindi, Queensland
118
0 1 km
Queensland
New South Wales
119
2. Description of soil profile A black, shrink‐swell, cracking clay soil that formed as a result of different alluvial events on the flood
plain of the lower Macintyre River.
Soil morphology
MC= medium clay
Australian Soil Classification: Black Vertosol (VE AE)
The particle size analysis reflects a low coarse sand content, low silt content and high to very high clay content throughout all the horizons to a depth of 2.2 m.
The bulk density of the soil profile increases going down the profile for the first three horizons, ranging from 1.31 to 1.53 g/cm3. All horizons have moderate bulk density levels.
Penetration resistance reflects a medium to very dense degree of soil consolidation. Soil physical characteristics
Particle Size Analysis (%) Moisture () Horizon
Clay (<2 µm)
Silt (2‐20 µm)
Fine sand (20‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/ cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
1A 46 32 14 8 1.31 0.43 0.29 0.48 1.03
1B1 61 24 9 6 1.42 0.41 0.29 0.45 2.49
1B2 67 18 9 6 1.53 0.38 0.28 0.42 2.9
2B21 81 4 11 5 1.47 0.4 0.29 0.44 ‐
2B22 69 15 11 4 1.41 0.41 0.29 0.46 ‐
2B23 68 15 13 4 1.60 0.36 0.27 0.39 ‐
Estimated USDA PSA (%)
Horizon Silt
(2‐5 µm) Sand (50‐2000 µm)
1A 47 7
1B1 33 6
1B2 24 9
2B21 4 15
2B22 19 12
2B23 20 12
1B1
1B1 1B1 1B1 1B1
1B2 1B1 1B1
1A
1B1
1B2
1A 1A 1A 1A
2B22 2B22 2B22 2B22
2B21 2B21 2B21
2B21
2B23 2B23 2B23
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Day 5
Goondiwindi to Toowoomba
Presenters:
Andrew Biggs
QLD Department of Environment and Resource Management
The tour organisers and the Congress Committee would like to acknowledge the Traditional Owners
and Custodians of this land (the Bigambul people) and pay respect to the Elders both past and
present, for they hold the memories, the traditions, the culture and hopes of Aboriginal Australia.
124
125
Itinerary 8:00 Depart Goondiwindi 8:20 Site 1 Wondalli Gilgaied Grey Vertosol 9:35 Site 2a Yelarbon Extremely alkaline soils with unique vegetation 10:00 Site 2b Yelarbon Cultural heritage site (eat smoko) 10:25 Depart Yelarbon site Have option of going back thru town if people need to use toilet Gore (Site 3) Brief toilet stop, gravelly soils 1:15 Site 4 Bulloak Sodosol 2:45 Site 5 Pampas Black Vertosol, lysimeters, geophysics 5:00 Site 6 Toowoomba Red Ferrosol pit (drinks & nibblies)
Regional geology From Goondiwindi to Toowoomba, we will be transiting two major geological provinces – the Great
Artesian Basin (GAB) and the New England Fold Belt. The GAB is an intra‐cratonic basin that extends
from far north Queensland to South Australia. It is the largest artesian basin in the world. In
southern inland Queensland, it is comprised primarily of Cretaceous argillaceous sediments overlying
(and capping) quartzose sandstones. Water quality in the capping sequences is generally poor, while
that in the sandstones is generally good. In some areas, e.g the Carnarvon Ranges, the quartzose
elements outcrop in an inclined manner, leading to “GAB recharge zones”. In general however,
recharge rates are very slow (thousands of years). In discharge zones e.g where the sandstones lap
up onto hard rock outcrop or faults occur, GAB springs may be present.
Overprinting the Cretaceous landscape are extensive areas of deep weathering (mostly during the
Tertiary), and extensive fluvial systems, some of which also date back to the Tertiary. Weathering
zones are often lateritic and may be more than 30 m thick. Residuals often possess ferricrete and
other forms of induration/silicification, particularly in the west. Tertiary rounded gravels were
126
deposited in some areas, and are present as both outcrop and subcrop. The fluvial systems vary in
age, but most of the larger rivers have occupied their valleys since pre‐Holocene, and maximum
alluvial thickness is generally 100‐110 m. In the Balonne River floodplain to the west, current
exposures of Tertiary gravels are more than 100 m above the bottom of the alluvial fill. The palaeo‐
valley is about 200 m below current land surface in one area, and there is some evidence to suggest
the oldest alluvia may be Miocene (the oldest dated alluvia is Early Pliocene). Some folding and
faulting has occurred in the region post Tertiary.
Figure 4 Basins within the eastern GAB
In the east, the GAB laps onto the hard rocks of the Texas Block (the Traprock and the Granite Belt) –
part of the New England Fold Belt (Figure 2). The Texas Block is comprised primarily of Carboniferous
metasediments (the Traprock), with some limestone, volcanics and re‐worked Permian sediments.
The various granitoids of the Granite Belt are primarily Triassic to late Permian. Both landscapes are
steep, with shallow soils, and incised drainage lines, although in parts of the Granite Belt there are
areas of gently undulating, more weathered landscapes.
The Kumbarilla Ridge represents the boundary between two sub‐basins within the GAB – the Surat to
the west and the Clarence‐Moreton to the east. The latter wraps around, and laps onto the Texas
Block and Granite Belt rocks on the western and northern sides i.e in both the Border Rivers and
Condamine catchments (Figure 3). Jurassic sandstones are uppermost in the Clarence‐Moreton sub‐
basin, primarily coal measures and labile feldspathic sandstones.
127
Figure 5 Schematic cross-section of geological units
Abutting the northern end of the Granite Belt and the Texas Block are the olivine basalts of the Main
Range Volcanics. These extend northwards, and form the eastern edge of the Condamine
catchment. At this point, they also form the Great Escarpment. The volcanics both intrude through,
and overly the Jurassic sandstones of the area. In areas such as Toowoomba, there is a deeply
weathered surface (The Toowoomba Plateau). The Condamine valley is comprised of erosional
landscapes of basalt and Jurassic sandstones in the uplands, with an extensive valley floor of
colluvial/fluvial material.
Figure 6 Regional geology
Geomorphology Sites 1 and 2
Goondiwindi lies on the Macintyre River floodplain. This is comprised of Quaternary alluvia,
overlying labile Jurassic to Cretaceous sediments, which slope into NSW. Running north‐south
through the town is the Goondiwindi Fault. The floodplain has been fed by Macintyre Brook and the
Dumaresq River in Queensland, and the Macintyre River from NSW. These rivers all have different
source materials, which combined with the lengthy evolution of the floodplain, has led to a wide
128
variety of alluvial soils. To the north and east, the lower uplands are comprised of fresh argillaceous
sediments, giving rise to clay soils that are extensively cropped. The higher uplands are more
quartzose, and in parts lateritised. Soils are sandier, and used for grazing and forestry.
Driving from Goondiwindi to Site 1, we quickly leave the younger alluvia, and cross onto contrasting
relict flow paths of the Macintyre‐Dumaresq system (Figure 4). The better soils, which are
extensively cultivated, are typically Grey Vertosols with varying amounts of microrelief (gilgai),
originally covered in brigalow/belah (Acacia harpophylla/Casuarina cristata) communities. At the
other end of the spectrum are strongly alkaline, sodic, texture contrast soils (Sodosols), generally
vegetated with poplar box/pilliga box (Eucalyptus populnea/E. pilligaiensis) communities.
Figure 7 Tour route from Goondiwindi to Inglewood
129
Site 10a Wondalli This site lies on the older alluvia of the Macintyre River Floodplain. The site is a gilgaied Grey
Vertosol, typical of landscapes known locally as “brigalow claysheet”. These are generally
older/relict alluvia, and the soils have accumulated salt and developed gilgai. It is common for
brigalow (Acacia harpophylla) to only grow on the mounds, and in this case, belah (Casuarina
cristata) which is more tolerant of waterlogging,
is growing in the depressions. These soils are
used extensively for grain cropping, unless the
gilgai are too large. Laser levelling of paddocks is
common. Mounds of gilgai are typically crusting,
have less ground cover, are slightly lighter
textured and more sodic than the depressions,
which are often (but not always) heavier textured,
darker, more fertile and exhibit a more
cracking/self‐mulching surface. No one knows
how the gilgai form.
This site displays many of the typical features,
although it lacks the gypsum frequently found in
similar soils to the west. Gypseous horizons
invariably occur below the carbonate horizon, and
mark the EC and Cl bulge i.e they are present at
the long‐term wetting front. Manganese laminae
are also a common feature in the mid to lower profile. Large slickensides are common, as is large
prismatic structure in the subsoil. Deep coring of these soils indicates that below the wetting front,
both general morphology and chemistry remain constant unless there is a substantial change in
texture. Zones of weak structure are not uncommon, although the reasons for this are not clear.
While brigalow/belah clays are extensively cropped, the presence of high Cl, high EC and low pH
leads to “subsoil constraints” to production of more sensitive crops such as chickpea. These subsoil
constraints have been studied extensively in recent years by agronomists (although pedologists have
known about them for decades!).
Deep drainage in Grey Vertosols has been studied in recent years using the chloride balance method.
It has revealed that under native vegetation, long‐term annual average deep drainage is <1 mm/yr.
When cleared it can increase to as much as 2 mm/yr and when cropped (long‐fallow wheat), it can be
as much as 15 mm/yr. While these are average figures, deep drainage is in fact very episodic.
Neither of these things are surprising, given evaporation is >> rainfall, and rainfall is highly variable.
Site 11a Yelarbon Lying at the junction of Macintyre Brook and the Dumaresq River, just north of the Queensland‐New
South Wales border (Figure 11), the area around Yelarbon consists of landscapes unique in southern
Queensland. Because of its barren appearance, the area is commonly referred to as the Yelarbon
‘desert’. The slightly to severely degraded landscapes have also been referred to as the Yelarbon
‘salinity scald’ (Knight et al. 1989). Until recently, detailed laboratory analysis existed for only one
soil profile in the ~70 km2 area.
Yelarbon soil
Figure 11 Yelarbon area The Yelarbon area. Results for Sites A, B & C are illustrated in Figures 3 & 4. Site D was described by Thwaites & Macnish (1991)
The Yelarbon ‘desert’ is mapped as spinifex grassland with scattered low trees and shrubs (DERM
2009). It is home to some locally unique species, in particular the spinifex (Triodia scariosa) and tea
tree (Melaleuca densispicata). It is the most easterly occurrence of spinifex in southern Queensland,
while the Melaleuca is limited to small isolated communities scattered across southern inland
Queensland. Bull oak (Allocasuarina luehmannii), also present on the scalded areas, has a more
widespread distribution. The vegetation of the area is highly disturbed and degraded, with weeds
such as mother of millions (Bryophyllum spp.)
common. Fensham et al. (2007) recently
surveyed the floristics of the scalded and non‐
scalded areas, and investigated relationships to
factors such as drainage lines and soil pH. They
refined the mapping of the ‘desert’ area and
found gradients in floristic patterns were
related primarily to drainage lines, and
secondarily to soil pH. In areas marginal to the
‘desert’, emergent species such as Pilliga box
(Eucalyptus pilligaensis), poplar box (Eucalyptus
populnea) and belah (Casurina cristata) are
common, while spinifex is absent. Figure 12 Degraded land at Yelarbon
A1
A21
A22e
B2k
135
Site 11b - Yelarbon General description: Groundwater influenced extremely sodic, alkaline texture contrast soils
Distribution: Unique to the Yelarbon area
Parent material: Altered alluvia from Jurassic sediments and Devonian/Carboniferous
Harris, P. S., A. J. W. Biggs, et al., Eds. (1999). Central Darling Downs Land Management Manual,
Department of Natural Resources, Queensland.
Knight MJ, Saunders BJ, Williams RM, Hillier J (1989) Geologically induced salinity at Yelarbon,
Border Rivers area, New South Wales, Queensland. Journal of Australian Geology and Geophysics 11,
355‐361.
Maher, J. M., Ed. (1996). Understanding and managing soils in the Stanthorpe‐Rosenthal Region.
Brisbane, Queensland Department of Natural Resources.
Macnish, S.E., Koppi, A.J., Little, I.P and Schafer, B.M. (1987). The distribution, nature and origin of
some red sesquioxidic materials in south‐eastern Queensland, Australia. Geoderma 41, 1–27
Ross, D. J. and A. J. Crane (1994). Land resource assessment of the Goodar area, Queensland.,
Department of Primary Industries, Queensland.
Thwaites, R. N. and S. E. Macnish, Eds. (1991). Land management manual, Waggamba
Shire. Brisbane, Queensland Department of Primary Industries.
153
Resistivity imaging across native vegetation and irrigated Vertosols of the Condamine catchment—a snapshot of changing regolith water storage
Jenny FoleyA, Mark SilburnB and Anna GreveC
ADepartment of Environment and Resource Management, Toowoomba, QLD, Australia, Email [email protected] BDepartment of Environment and Resource Management, Toowoomba, QLD, Australia, Email [email protected] CWater Research Laboratory, UNSW, Manly Vale, NSW, Australia, Email anna‐[email protected]
Abstract Over use of one of Queensland’s most productive groundwater systems, the Condamine River
alluvium, has led to substantial depletion in groundwater levels. Most use is for irrigation (mainly
furrow), which is known to increase deep drainage below the root zone. Thus irrigation should
create greater groundwater recharge, but this is not generally detected in groundwater levels. The
enhanced deep drainage may be filling a moisture deficit in the unsaturated zone and is therefore
not yet causing greater recharge. Geophysical 2D resistivity imaging and soil coring was used to look
at changes in stored regolith water in the alluvium. Transects were imaged across naturally
vegetated landscapes (as a reference) into irrigated paddocks. All soils under native vegetation were
found to be very dry (low conductivity) even when only sparsely populated by trees. In contrast,
significant long‐term migration of water has occurred to deep within the regolith (up to 15 m) in
most irrigated paddocks. A wet (close to saturated) zone was found in the upper 6 m of soil in the
irrigated paddocks. Deeper regolith (20‐60 m) was resistive, both above and below the water table,
due to low salinities in the groundwater and coarser textures.
Key words Deep drainage, groundwater, geophysical survey, recharge, unsaturated zone
Introduction The Condamine River Alluvium and its tributaries is one of the most productive and utilized
groundwater resources in Queensland. The main system is over 150 km long, up to 30 km wide, and
over 120 m deep in places, with multiple sand and gravel aquifers in a matrix of clayey sediments. An
estimated 95 000 ML/yr are used for agriculture (90%) on Vertosols, and some urban purposes.
Groundwater levels have fallen substantially because of over use, particularly in the Central
Condamine where ~70% of all usage occurs (Murphy 2008). This decline has been particularly
evident over the last decade as the system has been in a virtual ‘recharge drought’. There is also
increasing evidence of water quality deterioration, both in shallow groundwater as a result of
increased salt leaching, and in deep systems as a result of the migration of poor quality groundwater
from adjacent areas and from bedrocks (Murphy 2008).
Irrigation alters the surface water balance. Water not used for plant growth or lost to evaporation,
drains below the root zone (deep drainage). Deep drainage of 100‐200 mm/yr has typically been
measured under furrow irrigation in a large number of sites on Vertosols and Sodosols in Australia
(Silburn and Montgomery 2004; Smith et al. 2005; Gunawardena et al. 2008). There is some
evidence, from bore monitoring, of rises in groundwater level in shallower aquifers in the alluvium
(DERM groundwater database), likely due to recharge from deep drainage, but many shallower bores
have been dry for many years. Diffuse recharge (i.e. through the soil) in the alluvium is considered to
154
be small, with the aquifers mainly recharged by river leakage (Lane 1979). Thus there is a disparity—
deep drainage below the root zone is seen to be high but recharge from this source is thought to be
low. This would be explained, in part, if deep drainage was being stored in an unsaturated zone left
dry by the previous native vegetation, creating a time lag between deep drainage and recharge.
Little is known about the moisture capacity and status of the regolith (unsaturated zone) or how this
has changed as a result of changes in the soil water balance. To examine the moisture status of the
regolith, electrical resistivity tomography and soil coring was applied to transects in the central
alluvium. Soil resistivity is related to soil water content, salinity and clay (content and type). Data
can be interpreted qualitatively with the aid of lithology from bore logs and measures of salt and clay
content. Contrasts in regolith under native vegetation and under irrigated agriculture were
examined, to assess the impacts from land use changes.
Methods Two dimensional resistivity images were taken using an ABEM SAS4000 Terrameter and LUND ES464,
across transects (200–600 m long and 60 or 21.5 m deep) in the Central Condamine alluvia, in SE
Queensland. Where possible, transects running through native vegetation and adjoining irrigated
paddocks were imaged to look at differences in water and salt due to the irrigation. Sites imaged
were:
1. Dalby, Black Vertosol—a) 400 m transect down an irrigation furrow with 2.5 m wide spacing of electrodes, measuring to 60 m depth, b) 600 m transect through native vegetation (Acacia harpophylla, A. homalophylla, Casuarina cristata, Eucalyptus populnea) into irrigated sorghum (stubble present) to 60 m
2. Pampas, Black Vertosol—480 m transect running down a furrow in irrigated paddock to 21.5 m depth
3. Brookstead, Black Vertosol—400 m transect from one irrigated field (sorghum stubble) through native vegetation (Eucalyptus camaldulensis) and into another irrigated paddock (fallow) to 60 m depth.
Soil volumetric water content was sampled with a soil coring rig. Soil samples were collected and
analysed for electrical conductivity (EC), chloride (Cl) and dispersed particle sizes, along the transects
to assess the influence of salt and clay content on resistivity. Two dimensional resistivity images were
inverted using the RES2DINV software. Data was converted to conductivity (reciprocal of resistivity)
with high conductivity generally indicating high water contents.
Results and discussion All the images are deeper than—or close to, in the case of Pampas—groundwater levels. The
saturated zone and the deeper unsaturated zone are generally resistive, due to the low salinity of the
groundwater (Pampas and Brookstead 400, Dalby 1200 μS/cm) and sands and sometimes gravels
interbedded in the clays. Thus the less resistive deeper material at the Dalby site (Fig. 1) is consistent
with the higher groundwater salinity.
155
Figure 1. Dalby transect L to R, furrow irrigated paddock, head ditch (L) to past mid point in paddock.
Figure 2. Pampas transect: L to R, furrow irrigated paddock, head ditch (L) to past mid point in paddock.
The first two transects were measured down typical irrigation furrows at Dalby and Pampas. Images
show highly conductive zones of soil (very wet, with medium salinity typical of soils in the region),
along the entire length of the transects in the upper 6 m of the profile (Figures 1, 2). Soil volumetric
water sampling revealed, on average, these areas had >550 mm of water above that stored under
native vegetation and up to 250 mm above drained upper limit in the top 6 m of soil. This is ‘new’
water added by irrigation.
Water in this near‐saturated layer is not static. It is draining into the deeper regolith at a rate
proportional to the hydraulic conductivity of the deeper clay and sand layers. The soil profile changes
at around 5–6 m, with increasing sandy, sandy clay and occasionally gravel layers. These often create
confining zones. Once saturated clay layers become interspersed with sand layers, the soil will
remain saturated in the clay but not in the sand, due to hydraulic relationships. Water will continue
to move deeper in the regolith, but these zones will not show up on the image as having a high
conductivity due to the increasing presence of unsaturated sand. Also, salinity will be a mixture of
that in the leachate (i.e. higher, due to salt from the soil) and the lower salinity in groundwater
discussed above. Groundwater levels were at 10–20 m before 1965, so some of the current
unsaturated zone once held groundwater of low salinity.
156
Native veg Sorghum stubble Fallow - irrigated
Figure 3. Dalby transect: L to R, native vegetation into sorghum stubble (irrigated).
0
1
2
3
4
5
6
0.20 0.40 0.60 0.8Soil moisture (v/v)
Dep
th (
m)
Native veIrr-130mIrr-260mIrr-550mTP
a)
0
1
2
3
4
5
6
0.0 0.4 0.8 1.2EC dS/m
Dep
th (
m)
Native vegIrr-130mIrr-260mIrr-550m
b)
0
1
2
3
4
5
6
20 40 60 80Clay %
Dep
th (
m)
Native vegIrr-130mIrr-260m Irr-260m
c)
Figure 4. Dalby transect a) soil volumetric water contents, b) EC and c) clay contents, taken in native
vegetation and at 130, 260 and 550 m (refers to distances along transect in Figure 3).
The image at Dalby (Figure 3) shows a clear increase in conductivity in the upper layers at 120 m,
where native vegetation ends and the irrigated paddock starts. Soil under native vegetation had
lower conductivity, half that in the irrigated paddock, and was dry (Figure 4a). Soil was extremely wet
under irrigation to the depth measured (Figure 4a). Water contents were close to total porosity (TP);
the soil was near‐saturated and had little air content. EC profiles show a salt bulge higher in the
irrigated paddock, consistent with salt added in irrigation water (Figure 4b). However by 3 m depth,
EC was reasonably uniform along the entire transect. Similarly, % clay was consistent along the
transect to 4 m (Figure 4c). Deeper that this, some sandy layers begin to emerge, creating variability
in particle size analysis. Overall, these results indicate changes in conductivity in the upper profile are
predominately due to differences in soil water. The depth of the highly conductive zone is shallower
at the tail drain (near the native vegetation) than towards the head ditch, consistent with less
drainage occurring along furrow irrigated fields (Gunawardena et al. 2008).
As with the Dalby transect, a clear delineation is seen when moving from irrigation to native
vegetation at Brookstead (Figure 5). The wet zone extends considerably further down (to 15 m),
under irrigation. Soil EC and clay contents are very uniform along the transect (Figures 6b, 6c), and so
it can be assumed that conductivity changes along the transect (at shallow depths) are due to
changes in soil water.
Conclusion 2‐D resistivity imaging and soil coring showed that irrigated fields in the Condamine alluvium were
consistently near‐saturated in the upper regolith to depths of about 10 m, whereas under native
157
vegetation the regolith was dry. Thus considerable deep drainage from irrigation has been stored in
regolith previously kept dry by native vegetation, preventing it from contributing to recharge. It is
not possible to determine from resistivity imaging whether deeper layers (e.g. >15m) are also wet
because they are resistive in the unsaturated zone and below the water table, due to low salinity of
the groundwater. Deeper coring is required to determine the moisture status and confirm the
salinity of these deeper materials.
Native veg
Sorghum stubble - irrigated Fallow - irrigated
Figure 5. Brookstead transect: L to R, sorghum stubble (irrigated) into native vegetation, into fallow irrigated.
0
1
2
3
4
0.20 0.40 0.60 0.8Soil moisture (v/v)
Dep
th (
m)
Nat veg206 m223 m243 mTPDUL
a)
0
1
2
3
4
0 0.2 0.4 0.6 0.8 1EC dS/m
Dep
th (
m)
Native vegGrassFurrows
b)
0
1
2
3
4
20 40 60 80Clay %
Dep
th (
m)
Native vegGrassFurrows
c)
Figure 6. Brookstead transect a) soil volumetric water contents, b) EC and c) clay contents taken at 196 m (native veg), 203 m (grassed) 206 m (furrow start), and 223 and 243 m (refers to distances along transect in Figure 5).
Acknowledgments Water Research Laboratory (UNSW) for use of resistivity imaging equipment, technical expertise and
image analysis. Funds were provided by Cotton Catchment Communities CRC Project 2.1.02 and
Condamine Alliance. Kind thanks to Denis Orange, Maria Harris, Ralph de Voil and Tony King for field
and laboratory assistance; and to farm owners and managers for access to farm sites.
References Lane WB (1979) Progress report on Condamine underground investigation to December 1978. QWRC
Groundwater Branch Report, June 1979. (Queensland Water Resources Commission). Gunawardena TA, McGarry D, Gardner EA, Stirzaker R (2008) Managing Deep Drainage for Improved
WUE: Solute Monitoring and Ground Water Response in the Irrigated Landscape. In “Proceedings of the 14th Australian Cotton Conference.” 12 – 14 August 2008, Broadbeach, Australia.
Murphy G (2008) Management of Groundwater – Condamine River and tributary alluvium: Information paper for groundwater licensees and users (Central Condamine River Alluvium). (Department of Natural Resources and Water: Brisbane).
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Silburn DM, Montgomery J (2004) Deep drainage under irrigated cotton in Australia – A review. WATERpak a guide for irrigation management in cotton. Section 2.4. pp. 29–40. (Cotton Research and Development Corporation/Australian Cotton Cooperative Research Centre: Narrabri).
Smith RJ, Raine SR, Minkevich J (2005) Irrigation application efficiency and deep drainage potential under surface irrigated cotton. Agricultural Water Management 71, 117–130.
Extract from a report by T. Gunawardena and D. McGarry (2007).
The Pampas site is part of the “Deep Drainage under Furrow Irrigation – Surface and Groundwater
Implications” project (Project: 1.02.04 of the CCC‐CRC and CRDC).
‐ Three drainage lysimeters were installed (13‐15 July, 2004) and an automated weather station in
October 2004. The lysimeters were spaced equidistant along the length of the field and 50 metres
into the field (perpendicular to the edge).
‐ One irrigated crop (cotton 2004‐5) and one rainfed crop (sorghum 2005‐6) have been grown on this site with bare fallow between.
A maximum deep drainage (DD) of just under 1 ML/ha was measured with the lysimeters during the 2004‐5 cotton season at the head ditch end of the field, 0.5 ML/ha of DD at the mid, and almost zero DD at the tail.
Zero DD was measured at all other times, i.e. during the dryland sorghum crop and the bare fallow periods, despite up to 400 mm of rain during those times.
Water balance analysis (the SIRMOD/ET model) indicated the same trend in DD at the site; that DD was greatest at the head location and decreased almost 25% at the mid and was zero at the tail. The SIRMOD ET analysis predicted approximately x2 the amount of DD at both the head and mid locations, relative to the lysimeter data. (2.1 ML vs 1 ML at the head, and 1.6 ML vs 0.4 ML at the mid, for SIRMOD / ET vs lysimeter, respectively).
SaLF analysis (based on inherent soil properties, rainfall and irrigation amounts) also predicted more DD at the head ditch location, and equal amounts at both mid and tail. However, the values were more than 10‐fold the value of the lysimeter data. SaLF analysis predicts these soils are prone to DD, particularly at the head ditch end where there is less clay, more sand and lower CEC levels. SaLF takes no account of ET and temperatures during season, or crop growth (or type); all of which will have marked impact on DD amounts and in‐field variability.
The very low soil EC values at the site may show historic, large flushing episodes (through‐water movement). This seems to correspond well with the SaLF results but not the lysimeter data collected to date.
The EC and chloride values of the DD leachate waters are not regarded as “of concern”. The EC values are marginal in terms of what is considered “optimum” for cotton growth and are far lower than many of the other lysimeter sites.
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The lysimeters should be maintained to measure DD in future irrigated irrigation seasons, with more “typical” (non drought) during season weather patterns and irrigation events / volumes.
Figure 14 Lysimeter installation design
The lysimeters are buried at 150 cm from the soil surface, 50 metres rectangularly into the field from
the lysimeter trap, at each the head, mid and tail locations.
09/0
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1/0
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2/0
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01/0
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02/0
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03/0
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Dee
p dr
aina
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)
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40
60
80
100
120
140
160R
ainf
all (
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100
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300
400
500
600HeadMidTailCum RF
Figure 15 Cumulative deep drainage recorded (electronic tips) from the Pampas site during the 2004‐5 cotton season. The actual volumes of water collected for each of the head, mid and tail locations were 71, 106 and 62 mm, respectively. Arrows show irrigations. The cumulative rainfall is plotted as a dashed line.
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9. Location and landscape
Landform Toowoomba is located on the escarpment of the Great Dividing Range. The slope of the landscape is about 5°.
Parent material or substrate
The geology of the area is dominated by basalt flows and associated rocks from the late Tertiary. Subsequent denudation in the Quaternary resulted in westward migration of the Great Dividing Range and the development of an east-facing escarpment.
Drainage class Well drained, with a low run‐on rate and run‐off rate.
Surface condition:
A stable, granular, organic‐rich surface. The soil has low erodibility and is regarded as a slight erosion hazard.
Site disturbance
Completely cleared and currently under pasture, though has been cultivated in the past. Surrounding areas are sealed and urbanised.
Native vegetation
Eucalyptus spp.
Climate The area has a temperate climate with no dry season. The annual average rainfall is 954 mm. Toowoomba experiences distinctly cool winters with warm, wet summers. The mean January maximum temperature is 27.6°C and the mean July minimum temperature is 5.3°C.
SB Profile 15: Toowoomba, Queensland
161
Queensland
New South Wales
162
2. Description of soil profile A red clay soil that has formed as a result of the weathering of basalt from the Main Range Volcanics. Although it is not texturally evident, due to the mid‐slope position of the site it is likely that upslope colluvium has contributed to the development of the soil.
Soil morphology
LC= light clay, LMC= light medium clay, MC= medium clay
Australian Soil Classification: Red Ferrosol (FE AA)
World Reference Base: Lixic Nitisol (Manganiferric, Humic, Rhodic) OR Ferrallic Lixic Nitisol (Manganiferric, Humic, Rhodic)
Landform Situated in the Upper Brisbane River catchment. Parts of the region lay in the foothills of the Great Dividing Range and the Conondale Range. Undulating hills are the dominant landscape form within the region, exhibiting slopes of 4‐15%.
Parent material or substrate
Located on the Esk formation, which is derived from sediments formed by uplifting Palaeozoic mountainous areas. Granite is the most dominant parent material in the region, causing soils to be generally nutrient poor.
Drainage class Rapidly drained, with a high run‐on rate and medium run‐off rate.
Surface condition
Sandy and gritty. The soil is moderately erodible, and there is a significant erosion hazard at the site due to past quarrying activities.
Site disturbance
The region is dominated by livestock grazing, intensive agriculture and native bushland. Rural residential use and other activities such as quarrying also take place within the region. This profile has been highly disturbed by quarrying activities.
Native vegetation
The dominant vegetation consists of mostly native woodland with grass understorey. The woodland is comprised of mid‐high to tall Eucalyptus tereticornis, Eucalyptus crebra, Corymbia tesselaris, Angophora floribunda and Angophora leiocarpa.
Climate
Sub‐tropical climate with intense storms mostly during the summer. The annual average rainfall is 860 mm. Hot summer days and warm summer nights are characteristic of the area, with an average daily maximum temperature (in summer) of 30.4°C. Winter days are warm with cold nights. The average daily maximum temperature in winter is 19.3°C.
Profile 16: Toogoolawah, Queensland
168
0 1 km
Queensland
New South Wales
169
2. Description of soil profile A free‐draining Tenosol of coarse sandy nature that is derived from granite parent material.
Soil morphology
CS= Clayey sand, LS= Loamy sand
Australian Soil Classification: Paralithic Orthic Tenosol (TE DS)
World Reference Base: Cutanic Lixisol (Manganiferric?, Hypereutric?, Arenic, Chromic)
X‐ray diffraction patterns of basally oriented clays show the presence of kaolinite, small
amounts of illite and an interstratified swelling mineral. The proportion of the interstratified
swelling mineral increases with depth. In addition to the phyllosilicates, the random powder
diffraction patterns identified quartz and feldspar (plagioclase) in the soil clay fractions.
X‐ray diffraction patterns of the oriented clay fraction of B21 horizon soil after various pre‐
treatments; Mg saturated and air‐dried (‐‐‐‐‐‐), Mg saturated and ethylene glycolated (‐‐‐‐‐‐), K
saturated and air‐dried (‐‐‐‐‐‐) and K saturated and heated at 550°C (‐‐‐‐‐‐). I/S = interstratified
swelling mineral.
Thin sections
The left image (PPL) shows a degree of clay bridging between sand‐sized grains of the B23 horizon,
along with some fine‐grained iron oxide. The right image, showing the same view in XPL, reinforces
the patchiness of the clay bridging.
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4. Profile chemical characteristics
The pH values for this soil profile range from neutral to mildly alkaline (6.9‐7.7).
There are low EC values in all horizons of the profile.
Nitrogen levels are high in the A1 horizon and then decline dramatically in the underlying horizons, which are classed as very low for N.
The organic carbon contents are considered low to moderate in the surface horizon and extremely low in all other horizons.
The cation exchange capacity (CEC) is very low throughout the entire profile. Chemical properties of soil profile
Cation exchange properties of soil profile
Horizon pH
(1:5 H2O) EC
(dS/m) Organic C (%)
Total N (%)
C:N ratio
NO₃‐N (mg/kg)
Colwell P (mg/kg)
PBI‐Colwell
SO4 (mg/kg)
Avail. K (mg/kg)
Cl (mg/kg)
A₁ 6.88 0.09 1.10 0.31 3.54 49 10 23 4.10 130 10
A3 7.67 0.02 0.32 0.07 4.57 2 6 ‐ ‐ 35 10
B₂₁ 7.26 0.02 0.15 0.04 3.75 1 5 ‐ ‐ 46 10
B₂₂ 6.71 0.06 0.15 0.02 7.50 1 5 ‐ ‐ 50 50
B₂₃ 7.08 0.03 0.15 0.02 7.50 1 10 ‐ ‐ 43 22
Cation exchange properties mmolc/kg DTPA extractable micronutrient status
(mg/kg) DCB (%)
Horizon
CEC Ca Mg K Na Al Zn Cu Fe Mn Fe Al
A₁ 34 24 6 1 4 1 0.63 0.24 20 39 0.4 0.03
A3 24 14 5 2 2 1 ‐ ‐ ‐ ‐ 0.3 0.02
B₂₁ 22 7 6 2 3 1 ‐ ‐ ‐ ‐ 0.4 0.03
B₂₂ 22 5 7 3 3 2 ‐ ‐ ‐ ‐ 0.4 0.02
B₂₃ 23 8 9 2 3 ‐ ‐ ‐ ‐ ‐ 0.4 0.02
A1 A1 A1
A3 A3 A3 A3
B21 B21 B21 B21
B22 B22 B22 B22
B23 B23 B23 B23
A1
CEC (mmolc/kg)
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5. Profile physical characteristics
The PSA for the profile reflects a very high sand content and low silt and clay content. There is not much variation throughout the profile.
The bulk density slightly increases down the profile, being rated as low to moderate. The penetration resistance is very low in the upper 2 horizons, whilst it is considered to be
moderate in horizon B21 and high in the bottom 2 horizons.
Soil physical characteristics
Particle Size Analysis (%) Moisture ()
Horizon Clay
(<2 µm) Silt
(2‐50 µm) Fine sand (50‐200 µm)
Coarse sand (200‐ 2000 µm)
Bulk density (g/cm
3) 10 kPa
1500 kPa (PWP)
0 kPa (FC)
Penetration resistance (MPa)
A₁ 7.9 18.3 13.8 60.1 1.20 0.33 0.11 0.40 0.08
A3 6.8 14.8 12.8 65.6 1.27 0.29 0.09 0.42 0.07
B₂₁ 9.9 17.3 16.6 56.3 1.28 0.32 0.11 0.40 1.6
B₂₂ 7.3 16.7 15.7 60.3 1.32 ‐ ‐ ‐ 1.5
B₂₃ 9.1 15.9 13.4 61.6 1.37 ‐ ‐ ‐ 1.5
Estimated USDA PSA (%)
Horizon Silt
(2‐50 µm) Sand (50‐2000 µm)
A₁ 38.3 53.8
A3 32.3 61.0
B₂₁ 36.7 53.4
B₂₂ 35.6 57.1
B₂₃ 34.3 56.6
A1 A1 A1 A1
A3 A3 A3 A3
B22
B21 B21 B21
B22 B22 B22
B21
B23 B23 B23 B23
A1 A1
A3 A3
B21 B21
B22 B22
B23 B23
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1. Location and landscape
Landform The landform of the immediate area is gently undulating hills to plains (0-5% slope), with
imperfectly or moderately drained soils.
Parent material or substrate
Wamuran is situated on Jurassic Landsborough Sandstone, on the North D'Aguilar Block. Sand and clay sediments, with some basaltic lava flows of the coastline have been folded and crumpled into the North D'Aguilar Block. The North D'Aguilar Block has also been intruded by granite-type rocks in the late Permian to mid-Triassic.
Drainage class Moderately drained, with a low run‐on rate and medium run‐off rate.
Surface condition:
Soft and friable. The soil has low erodibility and as the area has only a slight erosion hazard.
Site disturbance
After the First World War, returned soldiers were permitted to settle this land for agricultural use, although it was not understood that the soils were of low fertility. Today, the Wamuran area specialises in dryland horticulture, predominantly growing strawberries, pineapples, and bananas.
Native vegetation
Land has been cleared, although there are some native dry sclerophyll forests present in the surrounding areas. Vegetation species include Scribbly Gum, Spotted Gum, Ironbark (Eucalyptus spp.), Bloodwood (Corymbia spp.) and Paperbarks (Melaleuca spp.)
Climate This area has a subtropical climate with cool winters and warm wet summers. Annual average rainfall is approximately 1380 mm. Summer temperatures have an average maximum of 30.5°C, while the average winter maximum temperature is 20.2°C.
Profile 17: Wamuran, Queensland
174
Queensland
New South Wales
0 1 km
175
2. Description of soil profile A moderately drained Yellow Chromosol, with slightly acidic pH levels.
X‐ray diffraction patterns of basally oriented clays show the presence of kaolinite, inhibited
vermiculite and traces of illite in the clay fraction of the soil. In addition to the phyllosilicates,
the random powder diffraction patterns show quartz (trace amounts in B22 horizon),
anatase, goethite and hematite in the soil clay fractions.
X‐ray diffraction patterns of the oriented clay fraction of A1 horizon soil after various pre‐
treatments; Mg saturated and air‐dried (‐‐‐‐‐‐), Mg saturated and ethylene glycolated (‐‐‐‐‐‐), K
saturated and air‐dried (‐‐‐‐‐‐) and K saturated and heated at 550°C (‐‐‐‐‐‐).
Thin sections
The left image (PPL) shows some very prominent argillans in the B22 horizon, while the right image
(XPL) shows oriented clay coating grains and occupying long, continuous pores in the B22 horizon.
These features attest to the importance of illuviation in this profile.
177
4. Profile chemical characteristics
The pH values for this profile are strongly acidic to slightly acidic (5.38‐6.24) and there is no consistent pattern in the soil pH values within the profile.
Very low EC values throughout the soil profile.
Organic carbon and total nitrogen contents are high in the top two horizons and low in rest of the horizons.
The cation exchange capacity (CEC) ranges from very low to low through the profile. There is a significant amount of free iron in the B horizons.
Chemical properties of soil profile
Cation exchange properties, available micronutrients and DCB and oxalate Fe and Al of soil profile