title: Online Thermal Analysis of Batch Roasted Coffee Beans

authors: Kelly, Cameron Brian Desmond

subjects: coffee roasting

abstract: We constructed and instrumented a fluidised-bed coffee roaster. This work has been carried out as part of a search for the “ideal point”, which is the point in time when an expert roaster would terminate the roast in order to yield beans that produce the optimal brew. We roasted Costa Rican Arabica beans whilst controlling the roasting temperature to follow a linear ramp. We measured and recorded the input, output, and coffee bean surface temperatures. We introduce the idea of “bean load”, an uncalibrated measure of the heat load presented by the material being roasted. The bean load under constantly-ramping bean surface temperature shows the roast is increasingly endothermic. Toward the end of the roast the endothermic phenomena decrease, or are assisted by exothermic activity. The bean load also has a repeatable dip around first crack. Due to limitations with the roaster we were not able to make reliable measurements at and beyond second crack. We observed no waypoints or events that might be used to pinpoint the “ideal point” to end the roast.

text: Online Thermal Analysis of Batch Roasted Coffee Beans We constructed and instrumented a fluidised-bed coffee roaster. This work has been carried out as part of a search for the “ideal point”, which is the point in time when an expert roaster would terminate the roast in order to yield beans that produce the optimal brew. We roasted Costa Rican Arabica beans whilst controlling the roasting temperature to follow a linear ramp. We measured and recorded the input, output, and coffee bean surface temperatures. We introduce the idea of “bean load”, an uncalibrated measure of the heat load presented by the material being roasted. The bean load under constantly-ramping bean surface temperature shows the roast is increasingly endothermic. Toward the end of the roast the endothermic phenomena decrease, or are assisted by exothermic activity. The bean load also has a repeatable dip around first crack. Due to limitations with the roaster we were not able to make reliable measurements at and beyond second crack. We observed no waypoints or events that might be used to pinpoint the “ideal point” to end the roast.

year: 2014

title: The impact of maize silage production and supplementary feed use on the carbon balance of New Zealand dairy farms

authors: Wall, Aaron M.

subjects: Eddy covariance

abstract: Globally, agriculture contributes 10-12% to anthropogenic greenhouse gas (GHG) emissions. Consequently, mitigation of agricultural GHGs has taken on increased importance, particularly in countries like New Zealand where agriculture accounts for almost half of national emissions. Sequestration of atmospheric CO₂ in the soil by altering land management practices has been identified as a potential mitigation option for anthropogenic GHG emissions. However, implementing management practices as a mitigation option first requires an understanding of their effect on soil C stocks. Often the effects of cropping and grassland management on soil C stocks are studied individually, but these practices are linked when the resulting crop is supplied to grazing animals as supplemental feed. This is important for the New Zealand dairy industry, which has been traditionally pasture-based, but increasingly is supported by supplemental feed to compensate for periods of low pasture growth and to boost productivity. To understand the impact of supplemental feed use on soil C stocks and, therefore, on any mitigation potential, both the production of the feed and its use need to be considered together. The overarching aim of this thesis was to experimentally determine the impacts of supplemental feed production and use on soil C by using the net ecosystem carbon balance (NECB) methodology to quantify changes in ecosystem carbon (C) stocks (assumed synonymous to the change in soil C). A secondary aim of this thesis was to advance NECB methodology in complex grazed pasture systems, primarily through examination of the scale at which measurements were made. Improved methodology and understanding are needed to allow a greater number of management practices to be tested.
Conceptually, importation of supplemental feed and its embodied C can lead to an increase in ecosystem C because consumption of supplemental feed C by the animals results in additional excreta deposition on the pasture during grazing that can be stored as soil C. This hypothesis was tested by determining the NECB for three years on a dairy farm where imported supplemental feed accounted for >40% of the cows’ diet. A positive NECB (indicating a gain of ecosystem C) was calculated for all three years, but consideration of uncertainties resulted in only one year having a definitive gain of C. The three-year average NECB was 71 ± 77 g C m⁻² y⁻¹ (mean ± uncertainty) and was not considered different from zero. Theoretical calculations based on the imported quantity of supplemental feed C (average 526 g C m⁻² y⁻¹) coupled with the digestibility of the feed and manure retention rates suggest gains of around 25 g C m⁻² y⁻¹ could be expected. The results of this study were of the same order of magnitude to what was expected from modelling and manure C retention literature, and although experimentally a gain in C associated with a large import of supplemental feed could not be definitively concluded, the results confirmed that large gains of ecosystem C are unlikely.
A broad range of supplemental feed is used within the New Zealand dairy industry including grazed and harvested feeds, with maize harvested for silage being one of the more common. Internationally, sites where maize cropping with full biomass harvest occurs have been identified as a large source of C, but these studies tend to be from long-term cropping systems. Within New Zealand dairy farm systems, maize silage is often grown as part of the pasture renewal process and, consequently, findings from studies within long-term cropping systems may not apply. In this study, NECBs were calculated for a system where a long-term pasture site was converted to maize silage cropping for two years before a return to permanent pasture. To isolate the C balance of the maize crop alone, NECBs were calculated for the period of maize crop establishment through to seedling emergence of the subsequent sward (~190 days). The Year 1 maize crop NECB was –850 g C m⁻² (a loss of C), while the Year 2 maize crop lost a further –415 g C m⁻². Concurrent grazed pasture NECBs from the same farm were 11 g C m⁻² and –115 g C m⁻² over the same two periods. Above-ground biomass production was around three times greater from the maize crop than adjacent pastures, with more than 90% of this production exported from the site, compared to around 60% net export of the pasture biomass after accounting for returned excreta. The hypothesis that a large loss of ecosystem C could be expected from maize silage cropping for supplement feed was supported. Future research to determine whether the return to permanent pasture results in recovery of previously lost C are required to understand the long-term impacts of periodic cropping for supplemental feed production.
Consideration of the effect that all types of supplemental feed production have on ecosystem C stocks was beyond the scope of this thesis, but conclusions can be drawn on systems which use maize silage. Dairy farms which import supplemental feed (maize silage or other) are likely to see small increases (<50 g C m⁻² y⁻¹) in the ecosystem C stocks regardless of the quantity imported, while the production site would be expected to have large losses when producing maize silage. Results from this thesis suggest that where production and use occur within the same dairy farm system a net loss would be expected, and if averaged across the entire farm would be in the order of –40 g C m⁻² y⁻¹. Losses during maize silage production may be reduced by minimising the time that soil is bare during establishment, and although not tested, possibly by decreasing tillage intensity. Moreover, if ecosystem C losses during production are recovered longer-term when returned to grazed pasture (i.e. in the several years following cropping), on-farm production of periodically cropped maize silage may lead to small, but consistent gains in soil C and provide the potential for GHG mitigation. A key unresolved question is the rate of C recovery following a return to permanent pasture relative to the cropping return period. 
While determining the effect of supplemental feed on ecosystem C, the opportunity also arose to investigate two aspects of NECB measurement scale. Firstly, NECBs were compared when calculated with an ecosystem boundary equivalent to (i) the paddocks included within the eddy covariance (EC) flux footprint (NECBFootprint), and (ii) the farm boundary (NECBFarm). Both calculated NECBs were similar (NECBFootprint was 56 ± 77 g C m⁻² y⁻¹ and NECBFarm was 71 ± 77 g C m⁻² y⁻¹) and the selection of the best boundary definition was dependent on the quality of the available data with NECBFarm considered best in this study. Furthermore, components contributing to the NECB differ with system boundary location and, therefore, can influence interpretation. When choosing a system boundary, the assumption that the measured CO₂ exchange is representative of the entire area within the defined boundary needs to be cautiously considered. The second methodology investigation calculated paddock-specific NECBs for two adjacent paddocks with a single EC system located between them. Provided regular EC data are available from both paddocks (i.e. due to regularly changing wind directions), paddock-specific NECBs can be calculated. Advantages of this approach include eliminating inherent management heterogeneity (e.g. asynchronous grazing), and the ability to allow for treatment comparisons or provide replication while minimising spatial variability and potentially reducing equipment requirements. Key disadvantages were a reduction in data coverage (from 49.1% for the full footprint to 25.9% and 15.7% for each paddock), an increase in uncertainty (by about 25%), and the need for prior assessment of site suitability (i.e. the need for regular wind from both paddocks). Comparisons of NECBs from adjacent rotationally grazed paddocks identified large inter-annual and between-paddock variability, with the latter often due to subtle management differences despite the same overall management regimes. Finally, due to the spatial and temporal variability, several measurement years would be needed to (i) determine the true trajectory of ecosystem C balances and (ii) determine similarity or differences between the two paddocks.

text: The impact of maize silage production and supplementary feed use on the carbon balance of New Zealand dairy farms Globally, agriculture contributes 10-12% to anthropogenic greenhouse gas (GHG) emissions. Consequently, mitigation of agricultural GHGs has taken on increased importance, particularly in countries like New Zealand where agriculture accounts for almost half of national emissions. Sequestration of atmospheric CO₂ in the soil by altering land management practices has been identified as a potential mitigation option for anthropogenic GHG emissions. However, implementing management practices as a mitigation option first requires an understanding of their effect on soil C stocks. Often the effects of cropping and grassland management on soil C stocks are studied individually, but these practices are linked when the resulting crop is supplied to grazing animals as supplemental feed. This is important for the New Zealand dairy industry, which has been traditionally pasture-based, but increasingly is supported by supplemental feed to compensate for periods of low pasture growth and to boost productivity. To understand the impact of supplemental feed use on soil C stocks and, therefore, on any mitigation potential, both the production of the feed and its use need to be considered together. The overarching aim of this thesis was to experimentally determine the impacts of supplemental feed production and use on soil C by using the net ecosystem carbon balance (NECB) methodology to quantify changes in ecosystem carbon (C) stocks (assumed synonymous to the change in soil C). A secondary aim of this thesis was to advance NECB methodology in complex grazed pasture systems, primarily through examination of the scale at which measurements were made. Improved methodology and understanding are needed to allow a greater number of management practices to be tested.
Conceptually, importation of supplemental feed and its embodied C can lead to an increase in ecosystem C because consumption of supplemental feed C by the animals results in additional excreta deposition on the pasture during grazing that can be stored as soil C. This hypothesis was tested by determining the NECB for three years on a dairy farm where imported supplemental feed accounted for >40% of the cows’ diet. A positive NECB (indicating a gain of ecosystem C) was calculated for all three years, but consideration of uncertainties resulted in only one year having a definitive gain of C. The three-year average NECB was 71 ± 77 g C m⁻² y⁻¹ (mean ± uncertainty) and was not considered different from zero. Theoretical calculations based on the imported quantity of supplemental feed C (average 526 g C m⁻² y⁻¹) coupled with the digestibility of the feed and manure retention rates suggest gains of around 25 g C m⁻² y⁻¹ could be expected. The results of this study were of the same order of magnitude to what was expected from modelling and manure C retention literature, and although experimentally a gain in C associated with a large import of supplemental feed could not be definitively concluded, the results confirmed that large gains of ecosystem C are unlikely.
A broad range of supplemental feed is used within the New Zealand dairy industry including grazed and harvested feeds, with maize harvested for silage being one of the more common. Internationally, sites where maize cropping with full biomass harvest occurs have been identified as a large source of C, but these studies tend to be from long-term cropping systems. Within New Zealand dairy farm systems, maize silage is often grown as part of the pasture renewal process and, consequently, findings from studies within long-term cropping systems may not apply. In this study, NECBs were calculated for a system where a long-term pasture site was converted to maize silage cropping for two years before a return to permanent pasture. To isolate the C balance of the maize crop alone, NECBs were calculated for the period of maize crop establishment through to seedling emergence of the subsequent sward (~190 days). The Year 1 maize crop NECB was –850 g C m⁻² (a loss of C), while the Year 2 maize crop lost a further –415 g C m⁻². Concurrent grazed pasture NECBs from the same farm were 11 g C m⁻² and –115 g C m⁻² over the same two periods. Above-ground biomass production was around three times greater from the maize crop than adjacent pastures, with more than 90% of this production exported from the site, compared to around 60% net export of the pasture biomass after accounting for returned excreta. The hypothesis that a large loss of ecosystem C could be expected from maize silage cropping for supplement feed was supported. Future research to determine whether the return to permanent pasture results in recovery of previously lost C are required to understand the long-term impacts of periodic cropping for supplemental feed production.
Consideration of the effect that all types of supplemental feed production have on ecosystem C stocks was beyond the scope of this thesis, but conclusions can be drawn on systems which use maize silage. Dairy farms which import supplemental feed (maize silage or other) are likely to see small increases (<50 g C m⁻² y⁻¹) in the ecosystem C stocks regardless of the quantity imported, while the production site would be expected to have large losses when producing maize silage. Results from this thesis suggest that where production and use occur within the same dairy farm system a net loss would be expected, and if averaged across the entire farm would be in the order of –40 g C m⁻² y⁻¹. Losses during maize silage production may be reduced by minimising the time that soil is bare during establishment, and although not tested, possibly by decreasing tillage intensity. Moreover, if ecosystem C losses during production are recovered longer-term when returned to grazed pasture (i.e. in the several years following cropping), on-farm production of periodically cropped maize silage may lead to small, but consistent gains in soil C and provide the potential for GHG mitigation. A key unresolved question is the rate of C recovery following a return to permanent pasture relative to the cropping return period. 
While determining the effect of supplemental feed on ecosystem C, the opportunity also arose to investigate two aspects of NECB measurement scale. Firstly, NECBs were compared when calculated with an ecosystem boundary equivalent to (i) the paddocks included within the eddy covariance (EC) flux footprint (NECBFootprint), and (ii) the farm boundary (NECBFarm). Both calculated NECBs were similar (NECBFootprint was 56 ± 77 g C m⁻² y⁻¹ and NECBFarm was 71 ± 77 g C m⁻² y⁻¹) and the selection of the best boundary definition was dependent on the quality of the available data with NECBFarm considered best in this study. Furthermore, components contributing to the NECB differ with system boundary location and, therefore, can influence interpretation. When choosing a system boundary, the assumption that the measured CO₂ exchange is representative of the entire area within the defined boundary needs to be cautiously considered. The second methodology investigation calculated paddock-specific NECBs for two adjacent paddocks with a single EC system located between them. Provided regular EC data are available from both paddocks (i.e. due to regularly changing wind directions), paddock-specific NECBs can be calculated. Advantages of this approach include eliminating inherent management heterogeneity (e.g. asynchronous grazing), and the ability to allow for treatment comparisons or provide replication while minimising spatial variability and potentially reducing equipment requirements. Key disadvantages were a reduction in data coverage (from 49.1% for the full footprint to 25.9% and 15.7% for each paddock), an increase in uncertainty (by about 25%), and the need for prior assessment of site suitability (i.e. the need for regular wind from both paddocks). Comparisons of NECBs from adjacent rotationally grazed paddocks identified large inter-annual and between-paddock variability, with the latter often due to subtle management differences despite the same overall management regimes. Finally, due to the spatial and temporal variability, several measurement years would be needed to (i) determine the true trajectory of ecosystem C balances and (ii) determine similarity or differences between the two paddocks.

year: 2021

title: Ko te reo i Te Rarawa: Pēhea rainī te tūāhua reo o ngā mātua tūpuna i Pukepoto

authors: McGrath, Daniel

abstract: Ko te reo Māori, ko te reo ā-iwi, ko te mita o te reo; ko tēhea te mea nui? Mai anō tēnei tohe, ko tēhea ko runga, ko tēhea ko raro. He tinitini nei anō ngā rangahau mō te reo Māori, mō ngā rautaki whakaora i te reo Māori. Erangi pēhea mai ana te reo ā-iwi? I te mahi nui whakaharahara ki te whakaora i te reo Māori e noho ana tērā kaupapa hei aronga matua. E kite mārika ana i ngā hua o aua mahi, hoi anō te reo ā-iwi, te hanga nei, i paria ki rāhaki. Nā, i ngā tau tata nei anō, kua kitea rawatia te wheinu o ngā uri whakaheke, o ngā mokopuna o ngā iwi ki te ako i ō rātou mita, otirā i te reo ā-iwi.
Hoi anō tēnei kaupapa rangahau he mea whakapiripiri ki ngā rangahau mō te reo Māori, waihoki mō te reo ā-iwi. E āta mātai atu ana te titiro ki te reo ake anō o Te Rarawa, otirā ki te reo o ngā kaumātua i noho ai i Pukepoto. Ko ngā whāinga matua o te rangahau kia kitea pēnā rainī he patanga wō te reo i te kāinga ki te mana, ki te ahurea o te tangata, ka tahi. Ka rua, kia huraina mai ai ngā āhuatanga motuhake o te reo o Te Rarawa, otirā, o te reo i Pukepoto. I runga i tērā, ko te pātai matua o te rangahau nei, ko tēnei;
Pēhea hoki nei te tūāhua reo Māori i kōrerohia ai e ngā mātua tūpuna, e ngā wheinga i Pukepoto?
Nā, e tutuki ngā whāinga rangahau, i arohia wētahi rīpene kei te pātaka kōrero o Te Reo Irirangi Māori o Te Hiku o Te Ika e mau nei ngā reo o ngā kaumātua o te kāinga e kōrero ana mō ngā tini āhuatanga e hāngai ana ki ō rātou nā ao. E tāwharautia ana tēnei kaupapa e te Rangahau Kaupapa Māori, ā, ko ngā tikanga, ko ngā kōrero i ahua mai i Te Rarawa i Pukepoto e noho mai ana hei tāhuhu tikanga mōku. Ko ngā taupānga hou kua oti kē nei i a Te Reo Irirangi Māori o Te Hiku o Te Ika hei taputapu e nanao atu ai a hau ki te pātaka kōrero o Te Hiku o Te Ika, e pai ai taku āta wānanga i ngā kupu, i ngā kōrero kei ngā rīpene e mau ana.
Tokowhitu katoa ngā kaumātua i āta arohia e ahau i tēnei rangahau nei, katoa i noho ai i Pukepoto. Ko tāku, he āta whakataringa atu ki wā rātou kōrero, ka āta arotake ai i wētahi kupu, i wētahi kīwaha, i wētahi whakatakotoranga rerenga kōrero i kaha whakahuangia e rātou mā. Kei te puke tuaono te roanga o ngā kōrero mō ngā kitenga o te rangahau; i mārama te kite atu he tini ngā momo kupu, ngā kīwaha me ngā rerenga kōrero he tikanga kē atu wō rātou, he whakamahinga kē anō, ka mutu, arā wētahi kāhore e tino rangona ana i wēnei wā nei. Nō reira, ko tā tēnei rangahau e whai ana kia whakahokia wēnei āhuatanga o te reo ki ngā arero o ngā uri whakaheke o Pukepoto, o Te Rarawa, otirā o Te Hiku o te Ika.

text: Ko te reo i Te Rarawa: Pēhea rainī te tūāhua reo o ngā mātua tūpuna i Pukepoto Ko te reo Māori, ko te reo ā-iwi, ko te mita o te reo; ko tēhea te mea nui? Mai anō tēnei tohe, ko tēhea ko runga, ko tēhea ko raro. He tinitini nei anō ngā rangahau mō te reo Māori, mō ngā rautaki whakaora i te reo Māori. Erangi pēhea mai ana te reo ā-iwi? I te mahi nui whakaharahara ki te whakaora i te reo Māori e noho ana tērā kaupapa hei aronga matua. E kite mārika ana i ngā hua o aua mahi, hoi anō te reo ā-iwi, te hanga nei, i paria ki rāhaki. Nā, i ngā tau tata nei anō, kua kitea rawatia te wheinu o ngā uri whakaheke, o ngā mokopuna o ngā iwi ki te ako i ō rātou mita, otirā i te reo ā-iwi.
Hoi anō tēnei kaupapa rangahau he mea whakapiripiri ki ngā rangahau mō te reo Māori, waihoki mō te reo ā-iwi. E āta mātai atu ana te titiro ki te reo ake anō o Te Rarawa, otirā ki te reo o ngā kaumātua i noho ai i Pukepoto. Ko ngā whāinga matua o te rangahau kia kitea pēnā rainī he patanga wō te reo i te kāinga ki te mana, ki te ahurea o te tangata, ka tahi. Ka rua, kia huraina mai ai ngā āhuatanga motuhake o te reo o Te Rarawa, otirā, o te reo i Pukepoto. I runga i tērā, ko te pātai matua o te rangahau nei, ko tēnei;
Pēhea hoki nei te tūāhua reo Māori i kōrerohia ai e ngā mātua tūpuna, e ngā wheinga i Pukepoto?
Nā, e tutuki ngā whāinga rangahau, i arohia wētahi rīpene kei te pātaka kōrero o Te Reo Irirangi Māori o Te Hiku o Te Ika e mau nei ngā reo o ngā kaumātua o te kāinga e kōrero ana mō ngā tini āhuatanga e hāngai ana ki ō rātou nā ao. E tāwharautia ana tēnei kaupapa e te Rangahau Kaupapa Māori, ā, ko ngā tikanga, ko ngā kōrero i ahua mai i Te Rarawa i Pukepoto e noho mai ana hei tāhuhu tikanga mōku. Ko ngā taupānga hou kua oti kē nei i a Te Reo Irirangi Māori o Te Hiku o Te Ika hei taputapu e nanao atu ai a hau ki te pātaka kōrero o Te Hiku o Te Ika, e pai ai taku āta wānanga i ngā kupu, i ngā kōrero kei ngā rīpene e mau ana.
Tokowhitu katoa ngā kaumātua i āta arohia e ahau i tēnei rangahau nei, katoa i noho ai i Pukepoto. Ko tāku, he āta whakataringa atu ki wā rātou kōrero, ka āta arotake ai i wētahi kupu, i wētahi kīwaha, i wētahi whakatakotoranga rerenga kōrero i kaha whakahuangia e rātou mā. Kei te puke tuaono te roanga o ngā kōrero mō ngā kitenga o te rangahau; i mārama te kite atu he tini ngā momo kupu, ngā kīwaha me ngā rerenga kōrero he tikanga kē atu wō rātou, he whakamahinga kē anō, ka mutu, arā wētahi kāhore e tino rangona ana i wēnei wā nei. Nō reira, ko tā tēnei rangahau e whai ana kia whakahokia wēnei āhuatanga o te reo ki ngā arero o ngā uri whakaheke o Pukepoto, o Te Rarawa, otirā o Te Hiku o te Ika.

year: 2021