Browsing by Author "Davies C"
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- ItemASSESSMENT OF NITROGEN FERTILIZERS UNDER CONTROLLED ENVIRONMENT – A LYSIMETER DESIGN(12/04/2019) Gnaratnam A; McCurdy M; Grafton M; Jeyakumar P; Bishop P; Davies C; Currie, L; Christensen, CThis paper introduces a closed system lysimeter design to measure fertilizer performance on ryegrass. The lysimeter will measure plant mass growth, gas emissions and leachate in a controlled climate environment based on a long term 90 day spring climate from the Taranaki. A range of commercial fertilizers will be compared to bespoke fertilizers manufactured under this project. This work, although undertaken in laboratory conditions will help quantify the impacts of nitrogenous fertilizers on the environment by mimicking actual conditions in a controlled setting. The study should provide data on the effectiveness of novel fertilizers manufactured within the programme; and other slow and controlled fertilizers, in reducing nitrogen leaching and greenhouse gas (GHG) emissions on pasture. Nitrogenous fertilizers readily leach as nitrates are highly soluble and GHG are emitted through volatilisation of ammonia and nitrous oxide. Reduced leaching and volatilisation increases fertilizer efficiency as less is wasted and more is attenuated in the plant. The aims of the research are to increase the effectiveness and efficiency of nitrogen fertilizer use in New Zealand. This should benefit farmers by reducing the amount of fertilizer applied, ideally reducing fertilizer cost, or at no extra cost by improved plant attenuation. This would also have an environmental benefit through reduced leaching and GHG emissions.
- ItemCOMPARATIVE EVALUATION OF CONTROLLED RELEASE FERTILISERS FOR NITRATE LEACHINGRaveendrakumaran B; Grafton M; Jeyakumar P; Bishop P; Davies C; Christensen, C; Horne, D; Singh, RA lysimetric study was carried out with an objective of evaluating the leaching behaviour of different fertilisers on spinach growth on Manawatu sandy soil. The fertiliser treatments applied were urea, two controlled release fertilisers called ‘g’and ‘SmartN’ at the rates of 50 kg N/ha (50N), 100 kg N/ha (100N) and 200 kg N/ha (200N). The 200 kg N/ha urea application was made in 10 split doses at a rate of 20 kg N/ha in 7-day intervals, whereas 200N application of ‘g’ and ‘SmartN’ were made twice at a rate of 100 kg N/ha at the time of planting and six weeks after planting. The control treatment did not receive any fertiliser application (0N). The application of Urea and ‘g’ at all rates except ‘g’-50N produced significantly higher nitrate leaching losses (19.8 to 27.7 kgN/ha) compared to the control (9.1 kgN/ha), while SmartN at all rates produced no significant increase in nitrate leaching. The total nitrate leached per ton of dry matter production was significantly reduced by the application of N fertilisers compared to the control (135.1 kgNO3 - -N/MgDM). On an average, 16.4 kg NO3 - -N/MgDM was leached from the fertilised treatments. Dry matter production increased at 200N application rates with all three fertilisers, but urea-200N produced the highest dry matter yield of 2377 kg/ha. In conclusion, frequent split applications of urea (urea - 200N) increased dry matter yield thereby significantly reduced nitrate leaching.
- ItemFood, nutrition and cancer: perspectives and experiences of New Zealand cancer survivors(New Zealand Medical Association, 2021-11-12) Peniamina R; Davies C; Moata'ane L; Signal L; Tavite H; Te Morenga L; McLean RAIM: This research sought to understand and describe cancer survivors' perspectives and post-diagnosis experiences of food and nutrition, with a particular focus on barriers to healthy eating, health equity, and Māori and Pacific perspectives. METHOD: Data were collected using semi-structured interviews with cancer survivors from three different ethnic groups (Māori, Pacific Peoples, and New Zealand European). Thematic analysis was undertaken to identify both similar and contrasting experiences and perspectives in relation to topics of interest. Data analysis also sought to identify any trends indicating differences between ethnic groups. RESULTS: Limited awareness of the role nutrition has in cancer recovery or prevention, combined with little or no access to nutrition advice/support, meant that healthy dietary change was not a focus for some cancer survivors in this study, whereas others invested considerable time and money accessing nutrition information and support outside of cancer care services. Financial limitations (eg, cost of healthy food and low income) and lack of practical support were also important barriers to post-diagnosis healthy eating. CONCLUSION: There is a need for more widely available cancer-specific nutrition advice and support in New Zealand. Interventions to address financial barriers and increase access to cancer-related nutrition advice and support have the potential to improve cancer outcomes and reduce inequities in cancer outcomes.
- ItemHe Kāinga Oranga: reflections on 25 years of measuring the improved health, wellbeing and sustainability of healthier housing(Taylor and Francis, on behalf of Te Aparangi, The Royal Society of New Zealand, 2023-02-06) Howden-Chapman P; Crane J; Keall M; Pierse N; Baker MG; Cunningham C; Amore K; Aspinall C; Bennett J; Bierre S; Boulic M; Chapman R; Chisholm E; Davies C; Fougere G; Fraser B; Fyfe C; Grant L; Grimes A; Halley C; Logan-Riley A; Nathan K; Olin C; Ombler J; O’Sullivan K; Pehi T; Penny G; Phipps R; Plagman M; Randal E; Riggs L; Robson B; Ruru J; Shaw C; Schrader B; Teariki MA; Telfar Barnard L; Tiatia R; Toy-Cronin B; Tupara H; Viggers H; Wall T; Wilkie M; Woodward A; Zhang WThis paper reflects on the influences and outcomes of He Kāinga Oranga/Housing and Health Research Programme over 25 years, and their impact on housing and health policy in Aotearoa and internationally. Working in partnership particularly with Māori and Pasifika communities, we have conducted randomised control trials which have shown the health and broad co-benefits of retrofitted insulation, heating and remediation of home hazards, which have underpinned government policy in the Warm Up NZ-Heat Smart programme and the Healthy Homes Standards for rental housing. These trials have been included as evidence in the WHO Housing and Health Guidelines and led to our designation as a WHO Collaborating Centre on Housing and Wellbeing. We are increasingly explicitly weaving Māori frameworks, values and processes with traditional Western science.
- ItemIron-rich sand promoted nitrate reduction in a study for testing of lignite based new slow-release fertilisers(Elsevier, 20/12/2022) Abhiram G; Grafton M; Jeyakumar P; Bishop P; Davies C; McCurdy MMThe N losses and agronomic performances of newly developed slow-releasing fertilisers (SRFs; Epox5 and Poly5) were tested against conventional N fertilisers, urea and diammonium phosphate (DAP), in a climate-controlled lysimeter system. The dry matter (DM) yield and N losses of SRFs were not significantly different from urea and DAP. However, nitrate leaching and nitrous oxide (N2O) losses were unexpectedly low and therefore, it was inferred that nitrate underwent a chemical transformation. It was observed that a thick fibreglass wick interrupted drainage and created an anaerobic condition in the soil. The subsoil was found to have a high extractable total iron and it was postulated that iron played a role in the observed low level of N losses. An investigation was carried out with a factorial design using sand types and rates of N application as the main factors. Two types of sand; with high and low iron concentration and four levels of N applications; 0 (control), 50, 100 and 200 kg N ha-1 were employed in a leaching column and nitrate and N2O losses were measured. The nitrate leaching was significantly (P < 0.05) affected by sand types wherein a lower nitrate level was recorded for high‑iron concentration sand than for low-iron concentration sand at all N application levels. The N2O emission was significantly (P < 0.05) lower for high-iron sand than for low-iron sand for the 200 N treatment, but not significantly different between sand types for other treatments. These observations provide evidence for the involvement of iron in nitrate transformation under anaerobic conditions and it was hypothesised path was dissimilar nitrate reduction (DNR). Further studies are recommended, to identify the underlying mechanism responsible for nitrate reduction with iron-rich sand.
- ItemSTUDY THE INFLUENCE OF SOIL MOISTURE AND PACKING INCREMENTAL LEVEL ON SOIL PHYSICAL AND HYDRAULIC PROPERTIES(14/07/2020) Gunaratnam A; Grafton M; Jeyakumar P; Bishop P; Davies C; McCurdy M; Christensen, C; Horne, D; Singh, RReconstructed soil packing is an alternative for monolithic soil columns in lysimeter studies. The excavated soil is packed in uniform layers to represent the natural soil conditions. Reconstructed soil packing alters the physical properties, including bulk density and porosity, thus can distort the hydraulic properties of the soil, so consistency of the method used is critical. Therefore, the selection of a suitable packing method is imperative. This preliminary study comes under the broad research programme: “developing and testing new fertilizer formulations in lysimeters”. This work was aimed to study the effect of incremental packing methods on the hydraulic properties of soil to select the best combination for testing fertilizers. The selected soil matrix for this lysimeter study was composed of 10 cm topsoil and 30 cm washed builders’ sand. For this study, four different soil packs were trialled in lysimeters with the combination of two soil moisture conditions (dry/damp and wet) and two packing depth increments (5 and 10 cm). The flow rate and saturated hydraulic conductivity were measured. Subsequently, several pore volumes of water (around 5 – 6) was allowed to pass through the soil column and the soil subsidence level was measured for each packing method. Both soil moisture condition and packing increment level have influenced the flow rate and saturated hydraulic conductivity of the soil matrix. The saturated hydraulic conductivity of the dry-5 cm, dry-10 cm, wet-5 cm and wet-10 cm packing were 3.99, 6.70, 3.56 and 6.53 cm hr- 1 , respectively. Soil subsidence was also influenced by both the soil moisture condition and increment level. The highest soil subsidence was exhibited by dry-10 cm packing (13 mm) and lowest by wet-5 cm (2 mm) (p<0.05). This preliminary study showed that both moisture condition and increment level influence the soil hydraulic property and compaction level. Further study needs to be conducted to understand the influence of soil moisture and incremental level on other physical and hydraulic properties of soil packing.
- ItemThe Nitrogen Dynamics of Newly Developed Lignite-Based Controlled-Release Fertilisers in the Soil-Plant Cycle(MDPI AG, 29/11/2022) Gunaratnam A; Grafton M; Jeyakumar P; Bishop P; Davies C; McCurdy MThe effect of newly developed controlled-release fertilisers (CRFs); Epox5 and Ver-1 and two levels of Fe2+ applications (478 and 239 kg-FeSO4 ha−1) on controlling nitrogen (N) losses, were tested on ryegrass, in a climate-controlled lysimeter system. The Epox5 and Ver-1 effectively decreased the total N losses by 37 and 47%, respectively, compared to urea. Nitrous oxide (N2O) emissions by Ver-1 were comparable to urea. However, Epox5 showed significantly higher (p < 0.05) N2O emissions (0.5 kg-N ha−1), compared to other treatments, possibly due to the lock-off nitrogen in Epox5. The application of Fe2+ did not show a significant effect in controlling the N leaching loss and N2O emission. Therefore, a dissimilatory nitrate reduction and chemodenitrification pathways were not pronounced in this study. The total dry matter yield, N accumulation, N use efficiency and soil residual N were not significantly different among any N treatments. Nevertheless, the N accumulation of CRFs was lower in the first month, possibly due to the slow release of urea. The total root biomass was significantly (p < 0.05) lower for Epox5 (35%), compared to urea. The hierarchical clustering of all treatments revealed that Ver-1 outperformed other treatments, followed by Epox5. Further studies are merited to identify the potential of Fe2+ as a controlling agent for N losses.
