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Papers by Siva Sivakumaran

Research paper thumbnail of Soil assessment of apple orchards under conventional and organic management

Australian Journal of Soil Research, 2006

ABSTRACT To determine the effect of wheel traffic and two different management practices on soil ... more ABSTRACT To determine the effect of wheel traffic and two different management practices on soil compaction and its consequences on physical and chemical soil properties, we measured penetration resistance, water infiltration, bulk density, macroporosity, chemical mobility, air permeability, and soil strength in a conventional orchard ( integrated fruit-production program) with bare ( sprayed with herbicides) rows and an organic apple orchard with grassed rows. Resistance measurements were taken both within the tree row and the wheel track, down to a depth of 0.35 to 0.40 m. The results indicate that compaction is greater in the wheel tracks under both management methods. Compaction in the wheel track was higher under organic than conventional management. Organic management resulted in a higher macroporosity in both the row and the wheel-track than conventional management. The 'close-to-saturation' infiltration rate was significantly greater within the row of the organic orchard (0.06 m/h) compared with the row of the conventional orchard (0.02 m/h), and compared with the wheel tracks (0.01 m/h). The precompression stress value in the top 100 mm, a measure of the soil strength, was low on all sites. The chemical mobilities were 57 and 50% in the organic orchard, and 86 and 93% in the conventional orchard, respectively, for wheel track and row. Apart from the compaction in the wheel track of the organic orchard, physical and chemical soil characteristics were in a better condition compared with the conventional orchard.

Research paper thumbnail of Carbon sequestration in urban landscapes: the example of a turfgrass system in New Zealand

Australian Journal of Soil Research, 2008

... 1993; Hummel 1993; Snow 1993; Taylor et al. 1997). ... The authors wish to thank those who co... more ... 1993; Hummel 1993; Snow 1993; Taylor et al. 1997). ... The authors wish to thank those who contributed to the project planning and collection of data, in particular Brendan Hannan (NZSTI) and David Smith (Manawatu Golf Club). ...

Research paper thumbnail of A New Method to Quantify the Impact of Soil Carbon Management on Biophysical Soil Properties: The Example of Two Apple Orchard Systems in New Zealand

Journal of Environment Quality, 2008

Abbreviations: C HWC , hot-water-extractable soil C; C t , total soil organic C.

Research paper thumbnail of Phytoremediation and long-term site management of soil contaminated with pentachlorophenol (PCP) and heavy metals

Journal of Environmental Management, 2006

Pentachlorophenol (PCP) is a persistent organic pollutant (POP) previously used as a timber treat... more Pentachlorophenol (PCP) is a persistent organic pollutant (POP) previously used as a timber treatment chemical to prevent sap stain and wood rot. Commonly used in wood treatment industries for the last 50 years, there are now many sites worldwide that are contaminated with PCP. Although persistent, PCP is a mobile contaminant and therefore has a propensity to leach and contaminate surrounding environments.

Research paper thumbnail of Screening of New Zealand Native White-Rot Isolates for PCP Degradation

Bioremediation Journal, 2003

... Monika Walter,1 Jenness M. Guthrie,1 Siva Sivakumaran,2 Emily Parker,3 Ann Slade,2 Don McNaug... more ... Monika Walter,1 Jenness M. Guthrie,1 Siva Sivakumaran,2 Emily Parker,3 Ann Slade,2 Don McNaughton,4 and Kirsty SH Boyd-Wilson1 ... has received particular atten-tion (Mileski et al., 1988;Lamar et al., 1990a, 1990b; Lamar and Dietrich, 1990, 1992; Lamar and Evans, ...

Research paper thumbnail of The impact of soil carbon management and environmental conditions on N mineralization

Biology and Fertility of Soils, 2011

Abstract Soil carbon (C) management is identified as a key element of sustainable agriculture, an... more Abstract Soil carbon (C) management is identified as a key element of sustainable agriculture, and an increase in nitrogen (N) mineralization rates is expected with an increase in soil C. However, any practical recommendation for using soil C management to ...

Research paper thumbnail of SOIL QUALITY IN PASTORAL HILL COUNTRY AS INFLUENCED BY THE PRESENCE OF WILLOW (SALIX MATSUDANA × ALBA) TREES

The benefits of conservation poplars and willows for the stabilization of soil on New Zealand hil... more The benefits of conservation poplars and willows for the stabilization of soil on New Zealand hill country are well recognised, but not so well understood is how these trees may influence soil quality. We tested the hypothesis that soil conservation trees growing on pastoral hill slopes would increase soil organic matter and change the physical properties that are influenced by organic matter (e.g., bulk density (BD)). The study was conducted in December 2010 on hill country sheep and beef farmland approximately 10 km SSW of Waipukurau in Central Hawke's Bay. Transects from three 13-year-old willow trees were marked out in an area where there were no other trees found within 10 m. Intact soil samples (0-15 and 15-30 cm layers) were taken at 1, 2, 3, 4, 5, 7 and 10 m from each tree. Total carbon (C) and nitrogen (N) determined by (LECO Truspec C/N analyser). Labile C and N: extracted using hot (80ºC) water; C and N in extracts determined using a Shimadzu total organic carbon (TOC...

Research paper thumbnail of Soil assessment of apple orchards under conventional and organic management

Australian Journal of Soil Research, 2006

ABSTRACT To determine the effect of wheel traffic and two different management practices on soil ... more ABSTRACT To determine the effect of wheel traffic and two different management practices on soil compaction and its consequences on physical and chemical soil properties, we measured penetration resistance, water infiltration, bulk density, macroporosity, chemical mobility, air permeability, and soil strength in a conventional orchard ( integrated fruit-production program) with bare ( sprayed with herbicides) rows and an organic apple orchard with grassed rows. Resistance measurements were taken both within the tree row and the wheel track, down to a depth of 0.35 to 0.40 m. The results indicate that compaction is greater in the wheel tracks under both management methods. Compaction in the wheel track was higher under organic than conventional management. Organic management resulted in a higher macroporosity in both the row and the wheel-track than conventional management. The 'close-to-saturation' infiltration rate was significantly greater within the row of the organic orchard (0.06 m/h) compared with the row of the conventional orchard (0.02 m/h), and compared with the wheel tracks (0.01 m/h). The precompression stress value in the top 100 mm, a measure of the soil strength, was low on all sites. The chemical mobilities were 57 and 50% in the organic orchard, and 86 and 93% in the conventional orchard, respectively, for wheel track and row. Apart from the compaction in the wheel track of the organic orchard, physical and chemical soil characteristics were in a better condition compared with the conventional orchard.

Research paper thumbnail of Carbon sequestration in urban landscapes: the example of a turfgrass system in New Zealand

Australian Journal of Soil Research, 2008

... 1993; Hummel 1993; Snow 1993; Taylor et al. 1997). ... The authors wish to thank those who co... more ... 1993; Hummel 1993; Snow 1993; Taylor et al. 1997). ... The authors wish to thank those who contributed to the project planning and collection of data, in particular Brendan Hannan (NZSTI) and David Smith (Manawatu Golf Club). ...

Research paper thumbnail of A New Method to Quantify the Impact of Soil Carbon Management on Biophysical Soil Properties: The Example of Two Apple Orchard Systems in New Zealand

Journal of Environment Quality, 2008

Abbreviations: C HWC , hot-water-extractable soil C; C t , total soil organic C.

Research paper thumbnail of Phytoremediation and long-term site management of soil contaminated with pentachlorophenol (PCP) and heavy metals

Journal of Environmental Management, 2006

Pentachlorophenol (PCP) is a persistent organic pollutant (POP) previously used as a timber treat... more Pentachlorophenol (PCP) is a persistent organic pollutant (POP) previously used as a timber treatment chemical to prevent sap stain and wood rot. Commonly used in wood treatment industries for the last 50 years, there are now many sites worldwide that are contaminated with PCP. Although persistent, PCP is a mobile contaminant and therefore has a propensity to leach and contaminate surrounding environments.

Research paper thumbnail of Screening of New Zealand Native White-Rot Isolates for PCP Degradation

Bioremediation Journal, 2003

... Monika Walter,1 Jenness M. Guthrie,1 Siva Sivakumaran,2 Emily Parker,3 Ann Slade,2 Don McNaug... more ... Monika Walter,1 Jenness M. Guthrie,1 Siva Sivakumaran,2 Emily Parker,3 Ann Slade,2 Don McNaughton,4 and Kirsty SH Boyd-Wilson1 ... has received particular atten-tion (Mileski et al., 1988;Lamar et al., 1990a, 1990b; Lamar and Dietrich, 1990, 1992; Lamar and Evans, ...

Research paper thumbnail of The impact of soil carbon management and environmental conditions on N mineralization

Biology and Fertility of Soils, 2011

Abstract Soil carbon (C) management is identified as a key element of sustainable agriculture, an... more Abstract Soil carbon (C) management is identified as a key element of sustainable agriculture, and an increase in nitrogen (N) mineralization rates is expected with an increase in soil C. However, any practical recommendation for using soil C management to ...

Research paper thumbnail of SOIL QUALITY IN PASTORAL HILL COUNTRY AS INFLUENCED BY THE PRESENCE OF WILLOW (SALIX MATSUDANA × ALBA) TREES

The benefits of conservation poplars and willows for the stabilization of soil on New Zealand hil... more The benefits of conservation poplars and willows for the stabilization of soil on New Zealand hill country are well recognised, but not so well understood is how these trees may influence soil quality. We tested the hypothesis that soil conservation trees growing on pastoral hill slopes would increase soil organic matter and change the physical properties that are influenced by organic matter (e.g., bulk density (BD)). The study was conducted in December 2010 on hill country sheep and beef farmland approximately 10 km SSW of Waipukurau in Central Hawke's Bay. Transects from three 13-year-old willow trees were marked out in an area where there were no other trees found within 10 m. Intact soil samples (0-15 and 15-30 cm layers) were taken at 1, 2, 3, 4, 5, 7 and 10 m from each tree. Total carbon (C) and nitrogen (N) determined by (LECO Truspec C/N analyser). Labile C and N: extracted using hot (80ºC) water; C and N in extracts determined using a Shimadzu total organic carbon (TOC...