Land-use and historical management effects on soil organic carbon in grazing systems on the Northern Tablelands of New South Wales

Soil Research ◽  
2013 ◽  
Vol 51 (8) ◽  
pp. 668 ◽  
Author(s):  
Brian R. Wilson ◽  
Vanessa E. Lonergan
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Surface Soil ◽  
Soil Depth ◽  
New South ◽  
New South Wales ◽  
Soil Layers ◽  
South Wales ◽  
Native Pasture ◽  
Historical Management

We examined soil organic carbon (SOC) concentration (mg g–1) and total organic carbon (TOC) stock (Mg ha–1 to 30 cm soil depth) in three pasture systems in northern New South Wales: improved pasture, native pasture, and lightly wooded pasture, at two sampling times (2009 and 2011). No significant difference was found in SOC or TOC between sample times, suggesting that under the conditions we examined, neither 2 years nor an intervening significant rainfall event was sufficient to change the quantity or our capacity to detect SOC, and neither represented a barrier to soil carbon accounting. Low fertility, lightly wooded pastures had a slightly but significantly lower SOC concentration, particularly in the surface soil layers. However, no significant differences in TOC were detected between the three pasture systems studied, and from a carbon estimation perspective, they represent one, single dataset. A wide range in TOC values existed within the dataset that could not be explained by environmental factors. The TOC was weakly but significantly correlated with soil nitrogen and phosphorus, but a more significant pattern seemed to be the association of high TOC with proportionally larger subsoil (0.1–0.3 m) organic carbon storage. This we attribute to historical, long-term rather than contemporary management. Of the SOC fractions, particulate organic carbon (POC) dominated in the surface layers but diminished with depth, whereas the proportion of humic carbon (HUM) and resistant organic carbon (ROC) increased with soil depth. The POC did not differ between the pasture systems but native pasture had larger quantities of HUM and ROC, particularly in the surface soil layers, suggesting that this pasture system tends to accumulate organic carbon in more resistant forms, presumably because of litter input quality and historical management.

Surface soil acidity and fertility in the central-western wheatbelt of New South Wales

2007 ◽  
Vol 47 (2) ◽  
pp. 184 ◽  
Author(s):  
C. M. Evans ◽  
B. J. Scott
Keyword(s):  
Organic Carbon ◽  
Soil Acidity ◽  
Surface Soil ◽  
Soil Depth ◽  
New South ◽  
New South Wales ◽  
Sodic Soils ◽  
Surface Soils ◽  
Pasture Production ◽  
South Wales

Documentation of the chemical fertility status of the soils is sparse for the western and central-western wheatbelt of New South Wales, Australia. We examined properties of the surface soils (0–10 cm) from central-western NSW by collating two published and nine unpublished datasets of soil analyses representing about 2800 soil samples. The emphasis was on the red soils used extensively for cropping. The surface soils of central-western NSW have low phosphorus (47% of soils) and sulfur (70% of soils <5 mg S/kg using KCl-40 analysis) status and commonly have organic carbon contents of about 1%. Surface soil acidity was a substantial problem with 56% of soils (0–10 cm) having a pHCa <5.0. Sodic and dispersive soils are also of concern in this area and these soils have received little attention or research. Approximately 5% of surface (0–10 cm) soils had an exchangeable sodium percentage of ≥6% (sodic). Salinity of surface soils was of minor significance compared with other soil problems in the area, although isolated areas occur. These results indicated that lime applications in this area are likely to benefit crop and pasture production. Additional use of phosphorus and sulfur fertilisers and agricultural practices which increase or maintain organic carbon will also need to be adopted to improve pasture and crop production. The use of gypsum and/or lime on sodic soils may also need to be addressed. As a priority, we suggest that the benefits of lime application to crop yield be examined. The application of lime to the 0–10 cm soil depth should ultimately arrest acidification of the subsurface soil (10–20 cm depth) through downward movement of the lime effect. Further examination of gypsum applications to dispersive sodic soils and the evaluation of sulfur deficiency in the field for pastures and canola are also priority areas of likely agricultural relevance.

Removing Grazing Pressure from a Native Pasture Decreases Soil Organic Carbon in Southern New South Wales, Australia

2016 ◽  
Vol 29 (2) ◽  
pp. 274-283 ◽  
Author(s):  
Susan Elizabeth Orgill ◽  
Jason Robert Condon ◽  
Mark Kenneth Conyers ◽  
Stephen Grant Morris ◽  
Douglas John Alcock ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
New South ◽  
New South Wales ◽  
Grazing Pressure ◽  
South Wales ◽  
Native Pasture

Driving factors of soil organic carbon fractions over New South Wales, Australia

Geoderma ◽  
2019 ◽  
Vol 353 ◽  
pp. 213-226 ◽  
Author(s):  
Jonathan Gray ◽  
Senani Karunaratne ◽  
Thomas Bishop ◽  
Brian Wilson ◽  
Manoharan Veeragathipillai
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
New South ◽  
New South Wales ◽  
Driving Factors ◽  
Carbon Fractions ◽  
South Wales ◽  
Organic Carbon Fractions ◽  
Soil Organic Carbon Fractions

Spatial variation in soil organic carbon and nitrogen at two field sites under crop and pasture rotations in southern New South Wales, Australia

Soil Research ◽  
2018 ◽  
Vol 56 (8) ◽  
pp. 780 ◽  
Author(s):  
Mark Conyers ◽  
Beverley Orchard ◽  
Susan Orgill ◽  
Albert Oates ◽  
Graeme Poile ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Spatial Variation ◽  
New South ◽  
New South Wales ◽  
Wagga Wagga ◽  
Soil Cores ◽  
South Wales ◽  
Sampling Protocols ◽  
The Mean

Estimating the likely variance in soil organic carbon (OC) at the scale of farm fields or smaller monitoring areas is necessary for developing sampling protocols that allow temporal change to be detected. Given the relatively low anticipated soil OC sequestration rates (&lt;0.5 Mg/ha.0.30 m/year) for dryland agriculture it is important that sampling strategies are designed to reduce any cumulative errors associated with measuring soil OC. The first purpose of this study was to evaluate the spatial variation in soil OC and nitrogen (N), in soil layers to 1.50 m depth at two monitoring sites (Wagga Wagga and Yerong Creek, 0.5 ha each) in southern New South Wales, Australia, where crop and pasture rotations are practiced. Four variogram models were tested (linear, spherical, Gaussian and exponential); however, no single model dominated across sites or depths for OC or N. At both sites, the range was smallest in surface soil, and on a scale suggesting that sowing rows (stubble) may dominate the pattern of spatial dependence, whereas the longer ranges appeared to be associated with horizon boundaries. The second purpose of the study was to obtain an estimate of the population mean with 1%, 5% and 10% levels of precision using the calculated variance. The number of soil cores required for a 1% precision in estimation of the mean soil OC or N was impractical at most depths (&gt;500 per ha). About 30 soil cores per composite sample to 1.50 m depth, each core being at least 10 m apart, would ensure at least an average of 10% precision in the estimation of the mean soil OC at these two sites, which represent the agriculture of the region.

scholarly journals Mathematical Functions to Model the Depth Distribution of Soil Organic Carbon in a Range of Soils from New South Wales, Australia under Different Land Uses

Soil Systems ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 46 ◽  
Author(s):  
Brian W. Murphy ◽  
Brian R. Wilson ◽  
Terry Koen
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Exponential Function ◽  
Depth Distribution ◽  
Soil Depth ◽  
New South ◽  
Exponential Functions ◽  
Two Phase ◽  
Mathematical Functions ◽  
South Wales

The nature of depth distribution of soil organic carbon (SOC) was examined in 85 soils across New South Wales with the working hypothesis that the depth distribution of SOC is controlled by processes that vary with depth in the profile. Mathematical functions were fitted to 85 profiles of SOC with SOC values at depth intervals typically of 0–5, 5–10, 10–20, 20–30, 30–40, 40–50, 50–60, 60–70, 70–80, 80–90 and 90–100 cm. The functions fitted included exponential functions of the form SOC = A exp (Bz); SOC = A + B exp (Cz) as well as two phase exponential functions of the form SOC = A + B exp (Cz) + D exp (Ez). Other functions fitted included functions where the depth was a power exponent or an inverse term in a function. The universally best-fitting function was the exponential function SOC = A + B exp (Cz). When fitted, the most successful function was the two-phase exponential, but in several cases this function could not be fitted because of the large number of terms in the function. Semi-log plots of log values of the SOC against soil depth were also fitted to detect changes in the mathematical relationships between SOC and soil depth. These were hypothesized to represent changes in dominant soil processes at various depths. The success of the exponential function with an added constant, the two-phase exponential functions, and the demonstration of different phases within the semi-log plots confirmed our hypothesis that different processes were operating at different depths to control the depth distributions of SOC, there being a surface component, and deeper soil component. Several SOC profiles demonstrated specific features that are potentially important for the management of SOC profiles in soils. Woodland and to lesser extent pasture soils had a definite near surface zone within the SOC profile, indicating the addition of surface materials and high rates of fine root turnover. This zone was much less evident under cropping.

Should we manage soil organic carbon in Vertosols in the northern grains region of Australia?

2003 ◽  
Vol 43 (3) ◽  
pp. 261 ◽  
Author(s):  
R. J. Farquharson ◽  
G. D. Schwenke ◽  
J. D. Mullen
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
New South ◽  
New South Wales ◽  
Soil Health ◽  
Organic Carbon Content ◽  
Continuous Cropping ◽  
South Wales ◽  
On Farm ◽  
Carbon Concentrations

Two issues prompted this paper. The first was the measured soil organic carbon decline in fertile northern Australian soils under continual cropping using traditional management practices. We wanted to see whether it was theoretically possible to maintain or improve soil organic carbon concentrations with modern management recommendations. The second was the debate about use of sustainability indicators for on-farm management, so we looked at soil organic carbon as a potential indicator of soil health and investigated whether it was useful in making on-farm crop decisions. The analytical results indicated first that theoretically the observed decline in soil organic carbon concentrations in some northern cracking clay soils can be halted and reversed under continuous cropping sequences by using best practice management. Second, the results and associated discussion give some support to the use of soil organic carbon as a sustainability indicator for soil health. There was a consistent correlation between crop input decisions (fertilisation, stubble management, tillage), outputs (yield and profits) and outcomes (change in soil organic carbon content) in the short and longer term. And this relationship depended to some extent on whether the existing soil organic carbon status was low, medium or high. A stock dynamics relationship is one where the change in a stock (such as soil organic carbon) through time is related not only to the management decisions made and other random influences (such as climatic effects), but also to the concentration or level of the stock itself in a previous time period. Against such a requirement, soil organic carbon was found to be a reasonable measure. However, the inaccuracy in measuring soil organic carbon in the paddock mitigates the potential benefit shown in this analysis of using soil organic carbon as a sustainability indicator.These results are based on a simulation model (APSIM) calibrated for a cracking clay (Vertosol) soil typical of much of the intensively-cropped slopes and plains region of northern New South Wales and southern Queensland, and need to be interpreted in this light. There are large areas of such soils in north-western New South Wales; however, many of these experience lower rainfalls and plant-available soil water capacities than in this case, and the importance of these characteristics must also be considered.

Variations in soil organic carbon for two soil types and six land uses in the Murray Catchment, New South Wales, Australia

Soil Research ◽  
2013 ◽  
Vol 51 (8) ◽  
pp. 631 ◽  
Author(s):  
M. C. Davy ◽  
T. B. Koen
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
New South ◽  
New South Wales ◽  
Agricultural Landscapes ◽  
Soil Types ◽  
Land Uses ◽  
South Wales ◽  
Physico Chemical ◽  
Soc Stocks

The aim of this study was to investigate variations in soil organic carbon (SOC) for two soil types and six common land uses in the New South Wales Murray Catchment and to explore the factors influencing those variations. Samples were collected from 100 sites on duplex soils (Ustalfs) of the Slopes region, and 100 sites on red-brown earths (Xeralfs) of the Plains region. Stocks of SOC (0–30 cm) across the study area ranged between 22.3 and 86.0 t ha–1, with means (± s.e.) of 42.0 ± 1.3 and 37.9 ± 0.8 t ha–1 for the Slopes and Plains regions, respectively. Higher SOC stocks were present in pasture-dominated land uses compared with mixed cropping in the Slopes region, with particularly high stocks found in pastures at positions on a slope of 7–10%. No significant differences in SOC stocks were identified between land-use groups (pastures or cropping) in the Plains region (<500-mm rainfall zone). Significant correlations were found between SOC and a range of climatic, topographical, and soil physico-chemical variables at both the catchment and sub-regional scale. Soil physico-chemical and topographical factors play an important role in explaining SOC variation and should be incorporated into models that aim to predict SOC sequestration across agricultural landscapes.

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.

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