title: Decadal Changes in Soil Carbon and Nitrogen under a Range of Irrigation and Phosphorus Fertilizer Treatments

authors: Schipper, Louis A.

subjects: soil carbon

abstract: We determined decadal changes in soil carbon (C) and nitrogen (N) due to different irrigation regimes and phosphorus fertilization of pastures. Archived soil samples (0–75 mm) collected annually from two long-term trials in New Zealand were analyzed for %C and %N from three P input treatments (ranging from 0 to 376 kg superphosphate ha−1 yr−1, 1952–2009) and three irrigation treatments (unirrigated and irrigated when soil moisture content fell below either 10 or 20%, 1959–2002). In the fertilizer trial, soil C increased linearly from 2.7 to 4.2%, and there was no difference in rates of increase in C between treatments, despite much greater aboveground production when P was added. This lack of difference was attributed to higher stocking rates on treatments with higher production, and to the possibility that root inputs (which differed less between treatments) was a more important control of soil C accumulation. Nitrogen (%) was lower in the unfertilized than fertilized treatments due to lower clover N fixation, which was constrained by P availability. Soil C (%) was significantly greater in the unirrigated treatment than the irrigated treatments throughout the trial. Aboveground production was much greater in the irrigated than dryland treatment but root biomass was lower. Irrigation must have increased C and N losses, possibly via increased respiration rates during seasonally dry periods. Our study showed that P fertilizer application did not result in an increase in surface soil C and that flood irrigation resulted in a constrained increase in surface soil C content.

text: Decadal Changes in Soil Carbon and Nitrogen under a Range of Irrigation and Phosphorus Fertilizer Treatments We determined decadal changes in soil carbon (C) and nitrogen (N) due to different irrigation regimes and phosphorus fertilization of pastures. Archived soil samples (0–75 mm) collected annually from two long-term trials in New Zealand were analyzed for %C and %N from three P input treatments (ranging from 0 to 376 kg superphosphate ha−1 yr−1, 1952–2009) and three irrigation treatments (unirrigated and irrigated when soil moisture content fell below either 10 or 20%, 1959–2002). In the fertilizer trial, soil C increased linearly from 2.7 to 4.2%, and there was no difference in rates of increase in C between treatments, despite much greater aboveground production when P was added. This lack of difference was attributed to higher stocking rates on treatments with higher production, and to the possibility that root inputs (which differed less between treatments) was a more important control of soil C accumulation. Nitrogen (%) was lower in the unfertilized than fertilized treatments due to lower clover N fixation, which was constrained by P availability. Soil C (%) was significantly greater in the unirrigated treatment than the irrigated treatments throughout the trial. Aboveground production was much greater in the irrigated than dryland treatment but root biomass was lower. Irrigation must have increased C and N losses, possibly via increased respiration rates during seasonally dry periods. Our study showed that P fertilizer application did not result in an increase in surface soil C and that flood irrigation resulted in a constrained increase in surface soil C content.

year: 2012

title: Tephrochronology and its application: A review

authors: Lowe, David J.

subjects: tephras

abstract: Tephrochronology (from tephra, Gk ‘ashes’) is a unique stratigraphic method for linking, dating, and synchronizing geological, palaeoenvironmental, or archaeological sequences or events. As well as utilising the Law of Superposition, tephrochronology in practise requires tephra deposits to be characterized (or ‘fingerprinted’) using physical properties evident in the field together with those obtained from laboratory analyses. Such analyses include mineralogical examination (petrography) or geochemical analysis of glass shards or crystals using an electron microprobe or other analytical tools including laser-ablation-based mass spectrometry or the ion microprobe. The palaeoenvironmental or archaeological context in which a tephra occurs may also be useful for correlational purposes. Tephrochronology provides greatest utility when a numerical age obtained for a tephra or cryptotephra is transferrable from one site to another using stratigraphy and by comparing and matching inherent compositional features of the deposits with a high degree of likelihood. Used this way, tephrochronology is an age-equivalent dating method that provides an exceptionally precise volcanic-event stratigraphy. Such age transfers are valid because the primary tephra deposits from an eruption essentially have the same short-lived age everywhere they occur, forming isochrons very soon after the eruption (normally within a year). As well as providing isochrons for palaeoenvironmental and archaeological reconstructions, tephras through their geochemical analysis allow insight into volcanic and magmatic processes, and provide a comprehensive record of explosive volcanism and recurrence rates in the Quaternary (or earlier) that can be used to establish time-space relationships of relevance to volcanic hazard analysis.
The basis and application of tephrochronology as a central stratigraphic and geochronological tool for Quaternary studies are presented and discussed in this review. Topics covered include principles of tephrochronology, defining isochrons, tephra nomenclature, mapping and correlating tephras from proximal to distal locations at metre- through to sub-millimetre-scale, cryptotephras, mineralogical and geochemical fingerprinting methods, numerical and statistical correlation techniques, and developments and applications in dating including the use of flexible depositional age-modelling techniques based on Bayesian statistics. Along with reference to wide-ranging examples and the identification of important recent advances in tephrochronology, such as the development of new geoanalytical approaches that enable individual small glass shards to be analysed near-routinely for major, trace, and rare-earth elements, potential problems such as miscorrelation, erroneous-age transfer, and tephra reworking and taphonomy (especially relating to cryptotephras) are also examined. Some of the challenges for future tephrochronological studies include refining geochemical analytical methods further, improving understanding of cryptotephra distribution and preservation patterns, improving age modelling including via new or enhanced radiometric or incremental techniques and Bayesian-derived models, evaluating and quantifying uncertainty in tephrochronology to a greater degree than at present, constructing comprehensive regional databases, and integrating tephrochronology with spatially referenced environmental and archaeometric data into 3-D reconstructions using GIS and geostatistics.

text: Tephrochronology and its application: A review Tephrochronology (from tephra, Gk ‘ashes’) is a unique stratigraphic method for linking, dating, and synchronizing geological, palaeoenvironmental, or archaeological sequences or events. As well as utilising the Law of Superposition, tephrochronology in practise requires tephra deposits to be characterized (or ‘fingerprinted’) using physical properties evident in the field together with those obtained from laboratory analyses. Such analyses include mineralogical examination (petrography) or geochemical analysis of glass shards or crystals using an electron microprobe or other analytical tools including laser-ablation-based mass spectrometry or the ion microprobe. The palaeoenvironmental or archaeological context in which a tephra occurs may also be useful for correlational purposes. Tephrochronology provides greatest utility when a numerical age obtained for a tephra or cryptotephra is transferrable from one site to another using stratigraphy and by comparing and matching inherent compositional features of the deposits with a high degree of likelihood. Used this way, tephrochronology is an age-equivalent dating method that provides an exceptionally precise volcanic-event stratigraphy. Such age transfers are valid because the primary tephra deposits from an eruption essentially have the same short-lived age everywhere they occur, forming isochrons very soon after the eruption (normally within a year). As well as providing isochrons for palaeoenvironmental and archaeological reconstructions, tephras through their geochemical analysis allow insight into volcanic and magmatic processes, and provide a comprehensive record of explosive volcanism and recurrence rates in the Quaternary (or earlier) that can be used to establish time-space relationships of relevance to volcanic hazard analysis.
The basis and application of tephrochronology as a central stratigraphic and geochronological tool for Quaternary studies are presented and discussed in this review. Topics covered include principles of tephrochronology, defining isochrons, tephra nomenclature, mapping and correlating tephras from proximal to distal locations at metre- through to sub-millimetre-scale, cryptotephras, mineralogical and geochemical fingerprinting methods, numerical and statistical correlation techniques, and developments and applications in dating including the use of flexible depositional age-modelling techniques based on Bayesian statistics. Along with reference to wide-ranging examples and the identification of important recent advances in tephrochronology, such as the development of new geoanalytical approaches that enable individual small glass shards to be analysed near-routinely for major, trace, and rare-earth elements, potential problems such as miscorrelation, erroneous-age transfer, and tephra reworking and taphonomy (especially relating to cryptotephras) are also examined. Some of the challenges for future tephrochronological studies include refining geochemical analytical methods further, improving understanding of cryptotephra distribution and preservation patterns, improving age modelling including via new or enhanced radiometric or incremental techniques and Bayesian-derived models, evaluating and quantifying uncertainty in tephrochronology to a greater degree than at present, constructing comprehensive regional databases, and integrating tephrochronology with spatially referenced environmental and archaeometric data into 3-D reconstructions using GIS and geostatistics.

year: 2011

title: Tihei Mauri Ora: A Māori response to health disparities

authors: Waitoa, Alieta Jei

subjects: Maori

abstract: Māori bear a disproportionate burden of health problems which, in concert with other factors (e.g. poor housing, low socio-economic status and low education attainment), contribute to and maintain low health status. It is noted that there have been multiple attempts to reduce health inequities – however, such attempts have been largely unsuccessful. Barriers to success include government reticence, restrictions on Māori participation in determining health directions/solutions, current contract paradigms and a reluctance to engage in meaningful partnerships with Māori. Those barriers occur within a cultural framework which defines (and therefore prioritises) the health of an individual over the needs of the collective.

The hypothesis of this research is that Māori health disparities are best addressed via the development and delivery of Māori health models by services which are oriented to kaupapa Māori principles. Utilising a case study approach, this thesis looks at the outcomes generated when a kaupapa Māori service applies key Māori principles to health service delivery. The case study, in tandem with focus group interviews identifies the key elements necessary to developing services which are responsive to the needs of Māori.

This study identified the importance of promoting change (and ultimately improve Māori health status) that encompasses the formation of a framework which considers collective benefit over individualism, encompasses Māori values, acknowledges and accepts Māoricentric clinical interventions. In addition, the thesis asserts that Māori health status will improve once Māori are active participants rather than recipients of health services.

text: Tihei Mauri Ora: A Māori response to health disparities Māori bear a disproportionate burden of health problems which, in concert with other factors (e.g. poor housing, low socio-economic status and low education attainment), contribute to and maintain low health status. It is noted that there have been multiple attempts to reduce health inequities – however, such attempts have been largely unsuccessful. Barriers to success include government reticence, restrictions on Māori participation in determining health directions/solutions, current contract paradigms and a reluctance to engage in meaningful partnerships with Māori. Those barriers occur within a cultural framework which defines (and therefore prioritises) the health of an individual over the needs of the collective.

The hypothesis of this research is that Māori health disparities are best addressed via the development and delivery of Māori health models by services which are oriented to kaupapa Māori principles. Utilising a case study approach, this thesis looks at the outcomes generated when a kaupapa Māori service applies key Māori principles to health service delivery. The case study, in tandem with focus group interviews identifies the key elements necessary to developing services which are responsive to the needs of Māori.

This study identified the importance of promoting change (and ultimately improve Māori health status) that encompasses the formation of a framework which considers collective benefit over individualism, encompasses Māori values, acknowledges and accepts Māoricentric clinical interventions. In addition, the thesis asserts that Māori health status will improve once Māori are active participants rather than recipients of health services.

year: 2014