title: Detection of differences in soil carbon and nitrogen stocks between paired dairy and drystock pastures

authors: Norris, Timothy

abstract: Soil is the largest terrestrial store of carbon (C) with some 2000 Pg to a depth of 1 m compared to 500 Pg in the atmosphere. Maximizing storage of C in soil is not only important for reducing atmospheric CO2 concentrations but also for maintaining soil quality. Recent research has shown that land use management is a key factor in determining the storage of C in pastoral systems. Barnett et al. (2014, AEE 185:34-40) used a paired pit approach to sample 25 adjacent dairy and drystock pastures to a fixed depth of 0.6 m and showed that soils under drystock sites had about 8.6 t.ha-1 more C in the top soil than adjacent dairy sites (P<0.05). However, there was no significant difference between land uses when C was accumulated to 0.6 m.

The main objective of this research was to test a potentially more accurate method for estimating differences in C stocks between sites sampled by Barnett et al. (2014), with a second objective being to better understand the effect of dairy and drystock grazed pastures on soil C and N stocks. A third objective was to investigate the effect of dairy and drystock managed pastures on earthworm abundance and biomass. 

A synthesis of recent literature showed that measuring differences in soil C stocks is difficult, given the high variability of soil C over small spatial scales. However, careful consideration to sampling methodology and statistical analysis can greatly improve the detection of differences in soil C stocks.   

Twenty three paired dairy and drystock sites were sampled to a depth of 0.6 m by taking 5 soil cores from each of two plots (5x5 m) within a paddock of each land use and soil C/N and soil mass were determined. Seventeen of the paired dairy and drystock farms were sampled from 3 points in each paddock between August and November 2013 for earthworms. Samples were sorted and earthworms were classified to species level.

To a depth of ~60 cm (C stocks adjusted for equivalent soil mass), drystock sites had 1.6 t ha-1 more C than dairy sites but this was not significant. However, when soil layers were analysed separately, drystock sites contained more C (4.1 ± 2.1 t C ha-1) in the top 10 cm (P=0.06) and dairy farms had significantly more C (3.7 ± 1.7 t C ha-1) in the 25-60 cm layer (P=0.04). The difference in the relative distribution of soil C in dairy and drystock sites may be due to the greater size and concentration of dairy urine patches which can solubilise C in the top-soil and redeposit dissolved C lower in the profile. 

When comparing whole-profile C stocks between dairy and drystock sites, the two-plot coring approach would have been able to detect a true difference of 9.3 t C ha-1, had it occurred, compared to 13.6 t C ha-1 for the pit approach (P<0.05). For the purpose of providing information for future sampling, power analysis was also conducted and revealed that with 23 paired sites, the pit approach could detect a significant difference (P<0.05) of 16 t C ha-1 with 66% certainty. In contrast, the coring approach could detect the same difference of 16 t C ha-1 with 90% certainty. These results supported the literature synthesis which demonstrated that sampling methodologies that include spatial variability of soil C can greatly improve the detection of differences. Furthermore, the coring approach reduced cost and increased efficiency compared to the single-pit approach.  

Earthworm abundance and biomass were not significantly different between dairy and drystock farms despite the significantly higher grazing intensity and top soil bulk density of dairy sites. Total earthworm abundance and biomass averaged 193 ± 30 ind m-2 and 77 ± 12 g m-2 for dairy farms compared to 188 ± 26 ind m-2 and 75 ± 13 g m-2 for drystock farms. These results suggested that for Allophanic Soils in the Waikato Region, the effects of varying grazing management on earthworm abundance and biomass is negligible.

text: Detection of differences in soil carbon and nitrogen stocks between paired dairy and drystock pastures Soil is the largest terrestrial store of carbon (C) with some 2000 Pg to a depth of 1 m compared to 500 Pg in the atmosphere. Maximizing storage of C in soil is not only important for reducing atmospheric CO2 concentrations but also for maintaining soil quality. Recent research has shown that land use management is a key factor in determining the storage of C in pastoral systems. Barnett et al. (2014, AEE 185:34-40) used a paired pit approach to sample 25 adjacent dairy and drystock pastures to a fixed depth of 0.6 m and showed that soils under drystock sites had about 8.6 t.ha-1 more C in the top soil than adjacent dairy sites (P<0.05). However, there was no significant difference between land uses when C was accumulated to 0.6 m.

The main objective of this research was to test a potentially more accurate method for estimating differences in C stocks between sites sampled by Barnett et al. (2014), with a second objective being to better understand the effect of dairy and drystock grazed pastures on soil C and N stocks. A third objective was to investigate the effect of dairy and drystock managed pastures on earthworm abundance and biomass. 

A synthesis of recent literature showed that measuring differences in soil C stocks is difficult, given the high variability of soil C over small spatial scales. However, careful consideration to sampling methodology and statistical analysis can greatly improve the detection of differences in soil C stocks.   

Twenty three paired dairy and drystock sites were sampled to a depth of 0.6 m by taking 5 soil cores from each of two plots (5x5 m) within a paddock of each land use and soil C/N and soil mass were determined. Seventeen of the paired dairy and drystock farms were sampled from 3 points in each paddock between August and November 2013 for earthworms. Samples were sorted and earthworms were classified to species level.

To a depth of ~60 cm (C stocks adjusted for equivalent soil mass), drystock sites had 1.6 t ha-1 more C than dairy sites but this was not significant. However, when soil layers were analysed separately, drystock sites contained more C (4.1 ± 2.1 t C ha-1) in the top 10 cm (P=0.06) and dairy farms had significantly more C (3.7 ± 1.7 t C ha-1) in the 25-60 cm layer (P=0.04). The difference in the relative distribution of soil C in dairy and drystock sites may be due to the greater size and concentration of dairy urine patches which can solubilise C in the top-soil and redeposit dissolved C lower in the profile. 

When comparing whole-profile C stocks between dairy and drystock sites, the two-plot coring approach would have been able to detect a true difference of 9.3 t C ha-1, had it occurred, compared to 13.6 t C ha-1 for the pit approach (P<0.05). For the purpose of providing information for future sampling, power analysis was also conducted and revealed that with 23 paired sites, the pit approach could detect a significant difference (P<0.05) of 16 t C ha-1 with 66% certainty. In contrast, the coring approach could detect the same difference of 16 t C ha-1 with 90% certainty. These results supported the literature synthesis which demonstrated that sampling methodologies that include spatial variability of soil C can greatly improve the detection of differences. Furthermore, the coring approach reduced cost and increased efficiency compared to the single-pit approach.  

Earthworm abundance and biomass were not significantly different between dairy and drystock farms despite the significantly higher grazing intensity and top soil bulk density of dairy sites. Total earthworm abundance and biomass averaged 193 ± 30 ind m-2 and 77 ± 12 g m-2 for dairy farms compared to 188 ± 26 ind m-2 and 75 ± 13 g m-2 for drystock farms. These results suggested that for Allophanic Soils in the Waikato Region, the effects of varying grazing management on earthworm abundance and biomass is negligible.

year: 2014

title: Assessment of the Potential of Waste Copper Chromium and Arsenic (CCA)-Treated Timber Fibre Reinforced Polypropylene Composites for Construction

authors: Nelson, Jacob

abstract: This paper investigates the potential of recycling waste copper chromium and arsenic (CCA)-treated timber for use as a reinforcement material in wood–plastic composites (WPCs) produced for use in construction, including an assessment of mechanical properties and the leaching of heavy metals. Wood flour was obtained through mechanical grinding, and fibres were obtained through alkaline digestion followed by bleaching. Composites produced with 40 wt.% bleached fibres showed increased tensile strength from 18.5 MPa for the polypropylene used as the matrix to 27.6 MPa. Likewise, the Young’s modulus was increased from 0.84 to 2.33 GPa. The treatment of fibres was found to reduce arsenic concentration by up to 99.9%. Furthermore, the arsenic in the leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing CCA-treated wood flour composites to bleached fibre composites. The composites’ material properties indicate that the use of end-of-life CCA-treated timber could be used to produce a composite material that could be used in New Zealand’s building sector to meet the requirements of semi-structural applications.

text: Assessment of the Potential of Waste Copper Chromium and Arsenic (CCA)-Treated Timber Fibre Reinforced Polypropylene Composites for Construction This paper investigates the potential of recycling waste copper chromium and arsenic (CCA)-treated timber for use as a reinforcement material in wood–plastic composites (WPCs) produced for use in construction, including an assessment of mechanical properties and the leaching of heavy metals. Wood flour was obtained through mechanical grinding, and fibres were obtained through alkaline digestion followed by bleaching. Composites produced with 40 wt.% bleached fibres showed increased tensile strength from 18.5 MPa for the polypropylene used as the matrix to 27.6 MPa. Likewise, the Young’s modulus was increased from 0.84 to 2.33 GPa. The treatment of fibres was found to reduce arsenic concentration by up to 99.9%. Furthermore, the arsenic in the leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing CCA-treated wood flour composites to bleached fibre composites. The composites’ material properties indicate that the use of end-of-life CCA-treated timber could be used to produce a composite material that could be used in New Zealand’s building sector to meet the requirements of semi-structural applications.

year: 2023

title: Words on walls: The linguistic landscape of Kirikiriroa primary school classrooms

authors: Burnette, Jessie

abstract: Language contact between te reo Māori and English has resulted in one of the central features of New Zealand English (NZE): the integration of loanwords from the Indigenous, donor language, te reo Māori, into a dominant Lingua Franca (Hay et al., 2008). Previous works have analysed the presence and presentation of these loanwords across a number of mediums. Our study, however, examines data directed at a previously unexamined demographic: primary school-aged children.

We aim to establish which loanwords children are regularly exposed to, and thus examine a most relevant domain: the classroom. Considering the linguistic landscape of classrooms (schoolscapes) offers insight into the language use that occurs within them. Further, the classroom is educational in the traditional sense, but also in the developmental sense, in the acquisition of broader social meaning. Previous schoolscapes research has highlighted not only their pedagogical importance, but their influence in the construction and transmission of language ideologies (Pzymus and Huddleston 2021; Brown 2012), making these particularly valuable spaces to study.

This study presents a schoolscape investigation of nine Waikato classrooms by analysing loanwords arising in educational artefacts directed at primary-aged children (7-11) in an English-medium school setting. We make the following contributions: (1) a systematic schoolscape method for analysing contact-induced language phenomena; (2) quantitative and qualitative analyses of loanwords identified in our data; (3) a detailed taxonomic expansion of te reo Māori loanword categories (semantic and syntactic) in present day NZE.

In this talk, we ask the following questions:

RQ1) What type of te reo Māori (loan)words are children regularly exposed to through schoolscapes in A/NZ?

RQ2) What is their distribution across schools/classrooms/years?

We find that, in the classes examined, children encounter both high levels of exposure to te reo Māori (loan)words and high levels of variation in the types of words present. On average, children encounter one te reo Māori token for every ten English tokens. As in previously identified trends (Macalister, 2006b), most loanwords found are nouns belonging to semantic categories pertaining to the environment, place names and social culture items. However, we also identify prominently occurring words and word types that have not previously been identified in corpora. We show that, within classrooms, children regularly encounter a landscape richer in te reo Māori (loan)words than previously seen, but also one characterised by substantial variation.

text: Words on walls: The linguistic landscape of Kirikiriroa primary school classrooms Language contact between te reo Māori and English has resulted in one of the central features of New Zealand English (NZE): the integration of loanwords from the Indigenous, donor language, te reo Māori, into a dominant Lingua Franca (Hay et al., 2008). Previous works have analysed the presence and presentation of these loanwords across a number of mediums. Our study, however, examines data directed at a previously unexamined demographic: primary school-aged children.

We aim to establish which loanwords children are regularly exposed to, and thus examine a most relevant domain: the classroom. Considering the linguistic landscape of classrooms (schoolscapes) offers insight into the language use that occurs within them. Further, the classroom is educational in the traditional sense, but also in the developmental sense, in the acquisition of broader social meaning. Previous schoolscapes research has highlighted not only their pedagogical importance, but their influence in the construction and transmission of language ideologies (Pzymus and Huddleston 2021; Brown 2012), making these particularly valuable spaces to study.

This study presents a schoolscape investigation of nine Waikato classrooms by analysing loanwords arising in educational artefacts directed at primary-aged children (7-11) in an English-medium school setting. We make the following contributions: (1) a systematic schoolscape method for analysing contact-induced language phenomena; (2) quantitative and qualitative analyses of loanwords identified in our data; (3) a detailed taxonomic expansion of te reo Māori loanword categories (semantic and syntactic) in present day NZE.

In this talk, we ask the following questions:

RQ1) What type of te reo Māori (loan)words are children regularly exposed to through schoolscapes in A/NZ?

RQ2) What is their distribution across schools/classrooms/years?

We find that, in the classes examined, children encounter both high levels of exposure to te reo Māori (loan)words and high levels of variation in the types of words present. On average, children encounter one te reo Māori token for every ten English tokens. As in previously identified trends (Macalister, 2006b), most loanwords found are nouns belonging to semantic categories pertaining to the environment, place names and social culture items. However, we also identify prominently occurring words and word types that have not previously been identified in corpora. We show that, within classrooms, children regularly encounter a landscape richer in te reo Māori (loan)words than previously seen, but also one characterised by substantial variation.

year: 2024