Using the EM38 to measure the effect of soil salinity on Eucalyptus globulus in south-western Australia

Bennett, D. L.; George, R.J.

doi:10.1016/0378-3774(95)91232-v

Cited by 49 publications

(24 citation statements)

References 8 publications

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“…The mean of the vertical and horizontal readings provides a more effective integration of soil profile EC a than either measurement alone (Slavich 1990). A number of studies have successfully used EM38 measurements to determine rootzone salinity in areas with shallow saline water tables (Slavich and Peterson 1990;Bennett and George 1995).…”

Section: Em38 Surveymentioning

confidence: 99%

Alteration of groundwater and sediment geochemistry in a sulfidic backswamp due to Melaleuca quinquenervia encroachment

Johnston¹,

Slavich²,

Hirst³

2003

Soil Res.

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Extensive encroachment of the native tree species Melaleuca quinquenervia (Cav.) Blake has occurred on a coastal floodplain sulfidic backswamp in eastern Australia. Almost 50% of the open swamp area c. 1870 is now monospecific M. quinquenervia forest. Encroachment has been associated with shortened hydroperiods and land management changes following drainage for agriculture. Large differences to shallow groundwater and sediment geochemistry were observed beneath both individual M. quinquenervia trees and encroaching forests compared to open swamp. Groundwater beneath M. quinquenervia had enhanced titratable acidity and acidic metal cations, increased concentrations of other ionic species (Cl–, SO42–), altered ionic ratios, and increased dissolved organic carbon. Soil beneath M. quinquenervia displayed enhanced accumulation of acidity and soluble ions, with concentration profiles suggesting vertical redistribution towards the surface. Deepening of the sulfide oxidation front in the soil beneath encroached M. quinquenervia suggests that enhanced sulfide oxidation may be occurring. Changes in soil pH, redox potential, and Fe mineral precipitation/dissolution were also evident. These changes appear to be the result of interactions between M. quinquenervia physiology and the unique groundwater and sediment geochemistry of the surrounding sulfidic/sulfuric horizons. Mechanisms to explain the observed changes are discussed along with potential management implications.

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Section: Em38 Surveymentioning

confidence: 99%

Alteration of groundwater and sediment geochemistry in a sulfidic backswamp due to Melaleuca quinquenervia encroachment

Johnston¹,

Slavich²,

Hirst³

2003

Soil Res.

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“…In this study, published calibration curves for the EM38 developed for soils of this region (Bennett & George, 1995) were used to produce estimates of soil salinity. Based on the EM38 values, the soil salinity was in excess of 10 dS m…”

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confidence: 99%

Bio‐mitigation of carbon following afforestation of abandoned salinized farmland

2011

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As the global demand for food continues to increase, the displacement of food production by using agricultural land for carbon mitigation, via either carbon sequestration, bioenergy or biofuel is a concern. An alternative approach is to target abandoned salinized farmland for mitigation purposes. Australia, for example, has 17 million ha of farmland that is already or could become saline. At a representative, salinized, low rainfall (350 mm yr À1 ) site at Wickepin, Western Australia, we demonstrate that afforestation can mitigate carbon emissions through either providing a feedstock for bioenergy or second generation biofuel production and produce salt-tolerant fodder for livestock. A range of factors markedly affect this mitigation. These include hydrological conditions such as salinity, site factors such as slope position and soil properties and a range of silvicultural factors such as species, planting density and age of the planting. High density (2000 stems ha À1 ) plantings of Eucalyptus occidentalis Endl. produced a mean total biomass of 4.6 t ha À1 yr À1 (8.5 t CO 2 -e ha À1 yr À1 ) averaged over 8 years. Atriplex nummularia Lindl. produced a mean total biomass of 3.8 t ha À1 yr À1 (6.9 t CO 2 -e ha À1 yr À1 ) averaged over 4 years and approximately 1.9 t ha À1 yr À1 of edible dry matter annually to 8 years of age. With differences in salt tolerance between E. occidentalis and A. nummularia, we propose an integrated approach to treating salinized sites that takes salinity gradients into account, replicates natural wetland ecosystems and produces both fodder and biomass. Continued mitigation is expected as the stands mature, assuming that growth is not affected by the accumulation of salt in the soil profile. Such carbon mitigation could potentially be applied to salinized farmland globally, and this could thus represent a major contribution to global carbon mitigation without competing with food production.

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“…Planting perennial vegetation such as trees in the lower hillslope positions may have little eect on the piezometric heads related to the deep subsurface¯ow system. Any vegetation growing in the saline area would have a fairly low rate of ET because of the salinity (Bennett and George, 1995). If the rate of extraction by this vegetation was no higher than that which would occur by seepage through the modi®ed B horizon, there would be little impact on the¯ow system.…”

Section: The Impact Of Perennial Vegetationmentioning

confidence: 96%

Modelling subsurface flow conditions in a salinized catchment in south-western Australia, with a view to improving management practices

Stolte

George²,

McFarlane³

1999

Hydrol. Process.

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Abstract:Finite element modelling of the saturated±unsaturated surface±subsurface¯ow mechanisms operative in a small salinized catchment in south-western Australia was used to help de®ne the¯ow system and explain the causes of waterlogging and salinization there. Data available at the site from a previous study were used to obtain a ®rst approximation to the¯ow system. Altering the properties of some of the strata gave a closer calibration. It was found that the modelled saturated hydraulic conductivity of the B horizon in the duplex soil zone needed to be at least an order of magnitude lower than that measured in order to reproduce the perching conditions observed in the ®eld. Also, the model indicated the in¯uence of a doleritic dyke, whose presence was con®rmed by ®eld measurement.Our analysis showed that there were two main¯ow systems operating in the hillslope. The ®rst, and most dominant, was the recharge occurring through the upslope gradational soil zone and percolating down to both the deeply weathered regolith and the basal aquifer. The second¯ow system is an unsaturated¯ow system operating in the high permeability A horizon in the downslope duplex soil zone. The ®rst system is primarily responsible for the saline seepage zone in the valley bottom. The second contributes to the waterlogging and perching occurring upslope of the seepage zone.Vertical¯ow through the higher permeability B horizon in the gradational soil zone in the upper slopes is a major contributor of recharge. Recharge by¯ow through macropores occurs where, but only where, perched aquifers develop and allow the macropores to be activated. Areas with perched aquifers occurred in downslope locations and near a doleritic dyke located upslope. Thus, the area where macropore recharge occurred was not large.The recharge rate required to maintain the piezometric levels at present values is only about 30 mm/yr (about 5% of the annual rainfall). The piezometric levels under the upper part of the catchment varied greatly with only small changes in recharge rate. A 50% reduction in recharge rate had the eect of reducing the length of the seepage zone at the end of winter by 40%. Changes in recharge rate had little eect on the extent of the perched aquifer at the end of winter. Deep-rooted perennial forages, shrubs or trees on the gradational soil zone in the upper part of the catchment and on the zones upslope of geological barriers to¯ow would be required to reduce the recharge and to allow for rehabilitation of the saline valley¯oor. Waterlogging associated with the perched water table in the bottom part of the catchment would be best addressed by tree plantations located just upslope of the salinized zone in the valley¯oor.

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Using the EM38 to measure the effect of soil salinity on Eucalyptus globulus in south-western Australia

Cited by 49 publications

References 8 publications

Alteration of groundwater and sediment geochemistry in a sulfidic backswamp due to Melaleuca quinquenervia encroachment

Alteration of groundwater and sediment geochemistry in a sulfidic backswamp due to Melaleuca quinquenervia encroachment

Bio‐mitigation of carbon following afforestation of abandoned salinized farmland

Modelling subsurface flow conditions in a salinized catchment in south-western Australia, with a view to improving management practices

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