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Item Greenhouse gas mitigation in pasture-based dairy production systems in New Zealand: A review of mitigation options and their interactions(Elsevier B.V., 2025-08) Kalehe Kankanamge E; Ramilan T; Tozer PR; de Klein C; Romera A; Pieralli SReducing greenhouse gas (GHG) emissions from dairy farming is crucial for mitigating climate change and enhancing the environmental credentials of New Zealand's dairy exports. This paper aims to explore potential GHG mitigation measures and their interactive effects when combined within New Zealand context, emphasising the practicality of these combinations, particularly focusing on recent studies of pasture-based dairy systems. The review assesses various mitigation options across animal, manure management, feed-based, soil-related, and system-related interventions and identifies immediately applicable mitigation options based on specific criteria. It also discusses the implementation costs, implications on emissions, and the combined effects of these options when applied as bundles in pasture-based systems using a combination matrix. It is indicated that mitigation options on New Zealand's dairy farms can yield diverse outcomes and costs based on farming characteristics. By analysing different combinations of short-listed, it was found that although most mitigation options are compatible, some may have a lower overall reduction potential because of interaction effects. Integrating lower N fertiliser use, low-emission feed, and reduced stocking rates with high-performing animals provides a practical approach for GHG reductions and potential cost savings. However, implementing compatible mitigation bundles requires better quantification of their interactions, economic viability, and compatibility with existing farming systems which need further research.Item An evaluation of greenhouse gas emissions reduction potential of plantain (Plantago lanceolata L.) in pastoral dairy production systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Agriculture Systems Management at Massey University, Manawatu, New Zealand(Massey University, 2025-05-16) Sivanandarajah, KomahanThere is increasing interest in the ability of plantain (PL) to reduce nitrogen (N) leaching losses and mitigate nitrous oxide (N₂O) emissions, while maintaining milk and pasture production. While PL’s role in lowering urinary N concentration is well established, the results regarding the effect of PL on N₂O emissions have been inconsistent. Furthermore, evidence has shown that cows fed pure PL produce less methane (CH₄) emissions compared to those fed ryegrass. However, whether this CH₄ reduction can be achieved with PL in mixed pasture, along with a clear understanding of the mechanism(s) behind those reductions, are still to be determined. This thesis evaluates PL’s potential to mitigate CH₄ and N₂O emissions through a series of in vitro and a field experiment, focusing on mixed pastures with moderate PL levels. When pastures, either a conventional ryegrass-white clover (RWC) or an RWC mix containing ~40% of PL (PLM), were collected during different seasons and tested in an in vitro rumen batch culture system, differences in their chemical composition led to significant differences in CH₄ and rumen ammonia (NH₃) production. Compared to RWC, PLM had lower fibre (neutral detergent fibre and acid detergent fibre), higher lignin, more fermentable carbohydrates (non-structural carbohydrates), and plant secondary metabolites (PSM, acteoside and aucubin) detected only in PLM, while maintaining similar digestibility and crude protein (CP) levels. Consequently, PLM produced up to 27% less net NH₃ in spring, up to 19% less CH₄ in summer, and 17% less net NH₃ in autumn compared to RWC (p<0.05) in vitro. Plant secondary metabolites found in PL, have been associated with reducing N losses from grazed pastures. However, their influence on enteric CH₄ emissions remains unexplored. Additionally, the dose-response relationship between CH₄ and NH₃ production at different concentrations of PSM needs to be established. To address this, purified compounds (>99% purity) of acteoside and aucubin were incubated with perennial ryegrass (RG) as a basal substrate, and gas and CH₄ production were measured in vitro. The addition of acteoside to RG increased gas production (GP) by up to 12%, with a similar quantity of CH₄ production, but a 5–15% lower proportion of CH₄ in gas (%CH₄), compared to the control. Aucubin addition resulted in a longer lag phase for GP and CH₄ production. On addition of aucubin, it took up to 15% more time to reach the halftime (T1/2) GP and up to 20% longer to reach the T1/2 CH₄ production. The combined treatments of acteoside and aucubin produced up to 13% greater GP with similar CH₄ production and reduced %CH₄ by around 9%. These reductions are attributed to the modification of the hydrogen utilisation pathway (less hydrogen to produce CH₄) affected by acteoside. Aucubin reduced rumen net NH₃ production by up to 46%, with a similar reduction observed when acteoside was combined with aucubin. These reductions are attributed to the possible antimicrobial activity of aucubin. These results suggest that PL influences rumen fermentation in vitro, resulting in lower CH₄ and NH₃ production. Since higher rumen NH₃ correlates with greater urinary N excretion into the environment, reducing NH₃ levels in the rumen is advantageous. Previous studies have shown that N₂O emissions from PL pastures may be reduced due to smaller N concentrations in urine and/or biological nitrification inhibition (BNI) activity. In this study, urine collected from cows fed diets containing 0% PL, ~20% PL, and diluted urine from PL-fed cows, was applied to pastures containing 0% PL, 30% PL, and 40% PL during spring. The N₂O emissions were measured over 55 days. Results indicated a trend toward lower N₂O emissions as assessed using the emission factor (EF₃) metric, with increasing PL content (p<0.09), with an average reduction of around 28% for pastures containing 30–40% PL compared to RWC pastures (p=0.03). This reduction in N₂O emissions from PL pastures was attributed to BNI activity rather than differences in urine-N concentrations per se. These results enhance our understanding of PL’s role in mitigating environmental impacts from grazing ruminants in temperate systems. This thesis concludes that medium PL pastures (30–40% PL) exhibit significant environmental benefits compared to RWC pastures in vitro, with reductions in CH₄ and rumen NH₃ influenced by PSM in PL and the seasonal variability in chemical composition. Moreover, under conditions conducive to higher N₂O emissions (in spring), maintaining 30–40% PL in the pasture could reduce N₂O emissions more effectively than excluding PL.Item The role of land-use planning in reducing energy use and "greenhouse gas" emissions from urban transport : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Environmental and Resource Planning at Massey University(Massey University, 1997) de Joux, Alistair EdwardUrban transport has been one of the key environmental concerns of the last decades of the twentieth century. Private car use has become a particular focus for the contribution it makes to several key problems, including fossil fuel depletion, climatic change via the "greenhouse effect", air pollution and at more localised levels, severe traffic congestion. Land use planning has an important role to play in ameliorating the worst impacts of private car use, as different forms of urban development display quite different levels of transport needs. Twentieth century urbanisation patterns have made car ownership necessary in many cities, particularly where post-war development has resulted in the physical separation of various urban activities. Large areas of newly developed land were devoted to single land uses in many cities during the 1950s and '60s, and the private car became integral to moving between the dispersed locations of home, work and other activities. Many planners have identified reintegrating land-uses as a means of reducing this need for extensive intraurban travel. This thesis examined some of the assertions regarding urban land use by identifying several key factors which help to determine the energy performance of different areas of the city. The study was based on data from an extensive travel survey conducted in and around Wellington, New Zealand, late in 1988. Some 3000 households participated in the survey, with about 9000 people providing details of their daily travel for one weekday. This data was used to calculate transport energy performance and the levels of greenhouse gas emissions which resulted for 64 residential zones throughout the region. Mean daily household emissions were found to range from 3.3 to 19.6 kilograms carbon dioxide equivalent. (This includes the radiative warming potential of small quantities of other "greenhouse" gases). The "best performing areas" were mainly close to Wellington's CBD but also included zones around other centres in the region. Performance was then analysed further against urban form, transport use and socio-economic factors derived both from the survey data and other sources. Mean distance of the journey to work, car ownership levels and the proportion of all travel undertaken by walking emerged as the strongest influences on energy and emissions performance. Modal split for bus use, population and dwelling densities, and the distance to central Wellington were identified as moderate influences on these areas of interest, whereas modal split for rail and cycling had little influence on the relative performance of the different areas surveyed. It was concluded that strongly pedestrian oriented forms of development clustered in close proximity to existing public transport services, perhaps with some additional "fine coverage" minibus services, offered the best land-use pattern in terms of minimising energy use and greenhouse gas emissions.Item Emissions and removals of greenhouse gases at an institution level : a case study of Massey University Turitea campus : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Natural Resource Management, Institute of Natural Resources, Massey University, Palmerston North, New Zealand(Massey University, 2009) Butt, Zulfiqar HaiderThe first commitment period of the Kyoto Protocol (2008-2012) has started. Being a signatory to the protocol, New Zealand is committed to reduce its greenhouse gas (GHG) emissions down to 1990 levels by the end of the first commitment period, or to take responsibility for any emissions above this level if it cannot meet this target. Although the inventory of New Zealand's GHG emissions is made at a national level, the actual reductions in GHG emissions required under the Kyoto Protocol will need to be made by individuals and institutions in society. Little attempt has yet been made at an institution level, especially by the Universities in New Zealand, to determine their aggregated net emissions of the major GHGs: carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). In order to help Massey University to prepare its own emission budget, estimates of current emissions were made in four major sectors - energy, agriculture, waste and forestry - at the Turitea campus and the associated 2200 hectares of the University's farms. Greenhouse gas emissions from these sectors in 1990 were also estimated to compare the current emissions with the base year of the Kyoto protocol. An introduction to the major GHGs, their emissions, the effect of these emissions on climate change, and an overview of the approach to calculate these emissions is provided. Total emissions from the energy sector included emissions from the electricity, gas, coal, vehicles and aviation sub-sectors, that were calculated with the help of national and international emission factors. Greenhouse gas emissions from solid waste and wastewater were calculated using the Intergovernmental Panel on Climate Change (IPCC) tier 1 approach. Emissions from the agriculture sector were calculated using a combination of New Zealand national and IPCC default emission factors. This sector accounts for emissions resulting from enteric fermentation, animal manure management and agricultural soils. An overview of Massey University's forest estate has also been provided. At present, forestry is the only sector contributing toward the mitigation of GHGs at Massey University through Kyoto-defined plantation forests. The amounts of C sequestered by the native and exotic tree plantations, and the total amount of CO2 absorbed by these plantations are presented. Although an assessment of C sequestered by all Massey University's tree plantations was made, only plantations established in 1990 and after were considered for inventory purposes. In the conclusions, some suggestions to reduce GHG emissions from Massey University and to improve future inventories are given. The annual gross GHG emissions in terms of CO2 equivalents (CO2e) in 2004 were 26,696±2,674 Mg which were about 7.9% above the level of 1990 emissions. It was estimated that the forestry sector removed about 4,094±439 Mg of CO2e and therefore the overall net emissions in 2004 were 8.6% below the base-line GHG emissions of 1990. At present the major contributing sector to GHG emissions at Massey University's Turitea campus is the energy sector. This contributes 71.4% of the gross emissions, whereas the agriculture and waste sectors are producing 26.2% and 2.4% respectively of the total gross emissions. About 37% of the total GHG emissions from the energy sector were contributed by commuting traffic, whereas electricity and gas collectively produced 33% of the total 19,064±1,324 Mg CO2e energy emissions. The largest absolute uncertainties in emission estimates were in the energy sector and some suggestions have been made as to how Massey University might reduce these uncertainties and improve the overall accuracy of the estimates of GHG emissions.