Factors contributing to the acid sulfate soil scalding process in the coastal floodplains of New South Wales, Australia

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 587 ◽  
Author(s):  
Mark A. Rosicky ◽  
Leigh A. Sullivan ◽  
Peter G. Slavich ◽  
Mike Hughes
Keyword(s):  
New South ◽  
New South Wales ◽  
Pyrite Oxidation ◽  
Soil Surface ◽  
Soil Parameters ◽  
Soil Core ◽  
Acid Sulfate Soil ◽  
Vegetative Cover ◽  
Acid Sulfate ◽  
South Wales

Acid sulfate soil (ASS) scalds are persistently bare areas of land, occurring in the coastal backswamps of New South Wales (NSW), Australia. This study aims to understand why particular areas become ASS scalds, while adjacent areas remain vegetated. Some important soil parameters are compared and field observations are summarised. Soil core sampling in both ASS-scalded land and surrounding areas of permanently vegetated paddocks has demonstrated similar pyrite concentrations and depth occurrence, soil salinity, and soil acidity (pH). As conditions are similar beneath both vegetated and non-vegetated land, there must be some additional factors influencing which areas become denuded. Several disparate (usually human-induced) events were found to cause initial loss of vegetative cover. Once the soil is bare, surface evaporation causes toxic solutes to build up quickly at the soil surface and ASS scalding is perpetuated. Some of the intervening events include fire, flood, flood-scouring, deliberate topsoil removal, surface pyrite oxidation, saltwater inundation of freshwater paddocks, saltwater exclusion from saltmarsh or mangroves, changes to the vegetation regimes, excessive vehicular traffic, and over-grazing. Backswamp management needs to ensure that land underlain by shallow pyritic layers (or with soil-water that is enriched with the toxic by-products of pyrite oxidation) is not laid bare by accident or design. Similar soil chemical conditions underlying both ASS scalds and the surrounding permanently vegetated paddocks suggest that much larger areas are potentially at risk of ASS scalding.

Surface and sub-surface salinity in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia

Soil Research ◽  
2006 ◽  
Vol 44 (1) ◽  
pp. 17 ◽  
Author(s):  
Mark A. Rosicky ◽  
Peter Slavich ◽  
Leigh A. Sullivan ◽  
Mike Hughes
Keyword(s):  
New South ◽  
New South Wales ◽  
Pyrite Oxidation ◽  
Soil Surface ◽  
Acid Sulfate Soil ◽  
Surface Salinity ◽  
Deep Soil ◽  
Acid Sulfate ◽  
South Wales ◽  
Land Denudation

Two-metre-deep soil profiles at 10 acid sulfate soil (ASS) scalds along the coast of New South Wales (NSW), Australia, were examined for salinity indicators. At 5 of the sites, permanently vegetated areas adjacent to the ASS-scalded land were also tested. Throughout the profiles, most sites had high soluble chloride (Cl−) concentrations (≤17 mg/g soil) and high soluble sulfate (SO42−) concentrations (≤17 mg/g soil). Very low Cl− : SO42− ratios (≤3) indicated active pyrite oxidation. Soil salinity (measured as electrical conductivity, EC) was extremely high in the top 2 m of most of the ASS scalds when related to the growth requirements of the typical introduced pasture species that were planted in these areas following drainage. This allows salinity, in addition to the extremely low pH of the surface soils, to contribute to land denudation, which can instigate or perpetuate pyrite oxidation and ASS-related land scalding. Although the sites had shallow watertables and soil-moisture content was high, the surface soil (top 0.10 m) of the scalds had consistently higher soluble Cl− and SO42− concentrations and EC than adjacent vegetated areas. All coastal ASS areas investigated, typically freshwater backswamps used for cattle grazing, were underlain by estuarine-derived sediments containing saline ground water. The results demonstrate that revegetation of ASS scalds must include investigation and management of salinity, in addition to acidity, within the soil profile and at the soil surface.

Techniques for revegetation of acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia: ridging, mulching and liming in the absence of stock grazing

2006 ◽  
Vol 46 (12) ◽  
pp. 1589 ◽  
Author(s):  
M. A. Rosicky ◽  
P. Slavich ◽  
L. A. Sullivan ◽  
M. Hughes
Keyword(s):  
Soil Moisture ◽  
Root Zone ◽  
New South ◽  
Combined Treatment ◽  
New South Wales ◽  
Soil Parameters ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
South Wales ◽  
Vegetation Species

Two revegetation field trials were undertaken on chronically bare acid sulfate soil scalds on grazing properties in the Hawkesbury and Macleay catchments of New South Wales, Australia. The aim was to test the effectiveness of various low cost and readily accessible techniques to encourage revegetation (via existing seedbank or surrounding vegetation) of the scalded sites. The trial at the more efficiently drained Hawkesbury site used a combined treatment of ridging (R), mulching (M) and liming (L) (i.e. R–M–L) compared with a control, within a fenced area. At the more waterlogged Macleay site, various elements of the combined treatment (i.e. R, M, R–M, R–L, R–M–L) were compared with a control, within a fenced area. Vegetation occurrence, biomass and species were tested, along with pertinent soil parameters (pH, salinity, soil moisture, soluble metals). Soil testing was undertaken at 2 depth levels to represent the seed germination zone (0–1 cm), and the potential root zone (1–10 cm). At the Hawkesbury site, the combined treatment (R–M–L) caused significantly greater vegetation occurrence and biomass, lower salinity, higher pH and increased soil moisture. At the Macleay site, results were more variable, but similar to the Hawkesbury trial as the site dried out. Mulching was the single most important treatment. All mulched sites had significantly more vegetation than the control, reaching 100% coverage in the R–M–L plots. Stock exclusion alone produced minimal results. Ridging alone was counterproductive. Liming without mulching caused proliferation of an insubstantial and transient vegetation species (Isolepis inundata). Most interesting was the different vegetation species encouraged by the different mulch treatments: treatment M was dominated by the sedge, Eleocharis acuta; treatment R–M was an even mix of Eleocharis acuta and native water-tolerant grasses (Paspalum distichum and Pseudoraphis paradoxa); treatment R–M–L was dominated by the aforementioned native grasses. These grasses are highly favoured for both economic (highly palatable to stock) and environmental (thick mulch cover, self seeding) objectives. The results demonstrate that revegetation of acid sulfate soil scalds is possible, and different treatments can influence vegetation species composition.

Some investigations into soil and vegetation relationships associated with alkaline-saline soil surfaces in the Walcha area, Northern Tablelands, New South Wales

1995 ◽  
Vol 46 (1) ◽  
pp. 209 ◽  
Author(s):  
KH Kreeb ◽  
RDB Whalley ◽  
JL Charley
Keyword(s):  
Cynodon Dactylon ◽  
New South ◽  
New South Wales ◽  
Soil Surface ◽  
Tree Planting ◽  
Soil Parameters ◽  
Alkali Cations ◽  
Grazing Land ◽  
South Wales ◽  
Wide Range

The characteristics of the soil, vegetation and groundwater at a dryland salinity site on Miramoona, a property near Walcha on the Northern Tablelands of New South Wales, were investigated. Soil parameters measured at 23 points along a 200 m transect were highly correlated with the pattern of vegetation. Of overriding significance was soil pH, which varied from a high of over 10 on bare areas delineated by Critesion marinum and Cynodon dactylon to a low of less than 5 on grazing land supporting the growth of a wide range of pasture species. The bare areas were characterized by alkalinity. While they were sodic at all depths measured, they were only marginally saline and then only at the soil surface. The chemical composition of the groundwater collected from three piezometer tubes varied quite markedly over the site. It is hypothesized that the presence of alkaline bare areas on the Northern Tablelands is not a new problem, but rather the natural result of alternating wet and dry periods which have induced accumulation of carbonates and bicarbonates of the alkali cations, notably sodium. Drainage of the original perched swamps by the early landholders, tree clearing and the grazing of domestic livestock would have accelerated the process since European settlement. However, tree planting would appear unlikely to have any impact on the reclamation process in the short term. A more viable option would be the recreation of the original swamps in suitable situations, although this solution would create problems for grazing management.

Soil properties in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia

Soil Research ◽  
2004 ◽  
Vol 42 (6) ◽  
pp. 595 ◽  
Author(s):  
Mark A. Rosicky ◽  
Leigh A. Sullivan ◽  
Peter G. Slavich ◽  
Mike Hughes
Keyword(s):  
Sulfur Content ◽  
Surface Soil ◽  
New South ◽  
New South Wales ◽  
Low Ph ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Soil Layers ◽  
Ph Values ◽  
South Wales

Soil profiles in 10 persistently bare areas (i.e. scalds), mainly located in coastal backswamps of New South Wales, Australia, were examined for chromium-reducible sulfur content and selected chemical properties. At 5 of the sites, the adjacent paddocks with vegetation cover were also examined. All of the tested sites had been affected by the extensive drainage of the surrounding acid sulfate soil (ASS) landscapes and the consequent oxidation of pyrite. All sites had low pH values in the surface soil layers and these low pH values extended for up to 150 cm into the underlying unoxidised blue/grey pyritic estuarine gels. This can be attributed to the downward diffusion of acidity, either produced in the overlying oxidised zones of these soils or transported laterally across the landscape to these low-lying areas. Acidified unoxidised pyritic zones 120 cm thick can evidently form within several decades after drainage disturbance. At the scalded sites the depth from the soil surface to the main pyritic zone varied from the surface to >200 cm depth, indicating that this variable is not critical to ASS scald formation. For most of the sites examined, the chromium-reducible sulfur contents in the surface soil layers were appreciably higher than those in the immediately underlying soil layers. In most of the vegetated sites the chromium-reducible sulfur content in the surface layers was considerably higher than for the adjacent scalded site. The conditions necessary for pyrite formation (i.e. adequate supplies of organic matter, soluble iron, sulfate, and waterlogging) were found to exist at all sites, and the pyrite accumulations in these surface soil layers are considered to be neo-formed. The vegetated soil-profile pyrite and pH results were very similar to their scalded counterparts except that they had an extra 20–40 cm layer of vegetation and mulch that was missing from the scalded profiles. This indicates that there is considerable potential for more extensive scalding in these ASS areas.

scholarly journals Acid sulfate soils and acid drainage, Lower Shoalhaven floodplain, New South Wales

2010 ◽  
Vol 16 (2) ◽  
pp. 56 ◽  
Author(s):  
M I Pease ◽  
A G Nethery ◽  
A R. M Young
Keyword(s):  
New South ◽  
New South Wales ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
Acid Drainage ◽  
South Wales ◽  
Sulfate Soils

Studies of soil seedbanks in native and sown pastures in northern New South Wales

2001 ◽  
Vol 23 (2) ◽  
pp. 204 ◽  
Author(s):  
G. M. Lodge
Keyword(s):  
New South ◽  
Perennial Grass ◽  
New South Wales ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Perennial Grasses ◽  
Soil Core ◽  
Phalaris Aquatica ◽  
South Wales ◽  
Native Pasture

Total and germinable soil seedbanks (litter and soil) were studied for a native pasture and three sown pastures (dominated by Phalaris aquatica L. cv. Sirosa) in northern New South Wales from 1993 to 1996. Soil core samples were taken from continuously grazed plots for both pasture types and two oversown treatments in the native pasture and from a spring-autumn rest treatment at the sown pasture sites. At each site above ground herbage mass was also estimated regularly as part of the Temperate Pasture Sustainability Key Program. For all sites and treatments, the proportion of germinable seeds as a percentage of the total (dormant and germinable) seedbank ranged from 1–26% for the native pasture and 1–39% for the sown pastures. Germinable seed numbers ranged from 280 to 26,110 seeds per m2, while total seedbank numbers were from 6700 to 178,360 seeds per m2. Native pasture herbage mass was dominated by native perennial grasses, but seeds of these species were less than 20% of the total seed bank in all treatments in 1994 and 1995. At the sown pasture sites, most of the germinable (51–92%) and total (65–97%) seedbanks were either barnyard grass (Echinochloa crus-galli (L.) Beauv, annual ryegrass (Lolium rigidum Gaudin), subterranean clover (Trifolium subterraneum L.) or wireweed (Polygonum aviculare L.). Since seeds of annuals and other forbs generally dominated both the total and germinable seedbanks of these perennial grass-based pastures, these species were likely to increase over time. Seeds of the sown perennial grass Phalaris aquatica L, cv. Sirosa were less than 1% of the total seedbanks in pastures sown in 1990 and less than 3% of those sown in 1979. With above average summer rainfall at the native pasture site in 1996 and prolific growth of redgrass, seeds of this species were 38–63% of the total and 11–29% of the germinable seedbank in May 1996. Except at this site and time, the species composition of the total and germinable seedbanks did not generally reflect the dominance of the above ground herbage mass of these pastures by perennial grasses.

Regeneration of annual winter legumes at Tamworth, New South Wales

1974 ◽  
Vol 14 (66) ◽  
pp. 57 ◽  
Author(s):  
MW Hagon
Keyword(s):  
Seed Production ◽  
New South ◽  
New South Wales ◽  
Soil Surface ◽  
Moisture Stress ◽  
Late Spring ◽  
South Wales ◽  
Hard Seeds ◽  
Improved Cultivars

The seed production and regeneration of a range of naturalized and introduced cultivars of annual clovers and medics was studied at Tamworth, New South Wales, between 1971 and 1973. Seed production was correlated with maturity grading within species only when moisture stress occurred in late spring. The proportion of seed lost as summer seedlings and the proportion of unrecovered seed were greater the lower the level of hardseededness. A greater proportion of unrecovered seed was recorded for those cultivars which bore their burrs at the soil surface. As a group the medics had a higher proportion of residual hard seeds than did the clovers. The results are discussed in relation to the likely persistence of improved cultivars compared to the successful persistence of the naturalized medics and clovers in the Tamworth district.

Movements of Feral Pigs (Sus Scrofa) at Sunny Corner, New South Wales.

1991 ◽  
Vol 18 (1) ◽  
pp. 49 ◽  
Author(s):  
G Saunders ◽  
B Kay
Keyword(s):  
Population Density ◽  
Home Range ◽  
Sus Scrofa ◽  
New South ◽  
New South Wales ◽  
Home Ranges ◽  
Peak Activity ◽  
Vegetative Cover ◽  
Feral Pigs ◽  
South Wales

This study describes the movements of feral pigs at Sunny Corner in eastern New South Wales. Population density at this site was 2 pigs km-2. Twenty-two pigs (12 males and 10 females) were captured and fitted with telemetry transmitters. Aggregate home range for males (10.7 � 6.9 km2) was significantly greater than for females (4.9 � 1.4 km2) as was 24 h home range (1.4� 1.1 km2, males and 0.8 � 0.4 km2, females). Seasonal home ranges were greatest in the winter and smallest in the autumn. These differences were attributed to variations in food availability. During all seasons there was a preference for creeklines that had vegetative cover. This was the result of thermoregulatory needs, refuge availability and food supply. Peak activity throughout the study occurred between 1900 and 2400 hours with little movement during the middle of the day. The implications of these results to management programs are discussed.

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