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You searched for +publisher:"Lincoln University" +contributor:("Clough, Timothy"). Showing records 1 – 3 of 3 total matches.

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Lincoln University

1. Buckthought, Laura E. The interactive effects of nitrogen fertiliser and animal urine on nitrogen efficiency and losses in New Zealand dairy farming systems.

Degree: 2013, Lincoln University

The loss of nitrogen (N) through nitrate (NO₃⁻) leaching and nitrous oxide (N₂O) emissions from pastoral dairy systems is one of the largest challenges facing the New Zealand agricultural industry. Nitrate leaching contributes to nutrient enrichment and accelerated eutrophication of streams, lakes and estuaries, while N₂O is both a greenhouse gas and the dominant anthropogenic emission contributing to stratospheric ozone depletion. Urine patches are the primary source of N loss from pastoral systems due to the high N loading that occurs over a relatively small area. Excessive or inappropriately timed fertiliser applications can also add to N loss. Few studies have sought to determine the effect of concurrently deposited urine and fertiliser on the fate of N in pastoral systems, even though the application of fertiliser soon after grazing is commonly practised, while no studies have examined seasonal effects of any interaction. It is generally assumed that fertiliser applied over a urine patch will simply exacerbate the total N losses, as the urine-N saturates plant-N utilisation rates in pasture. This study, therefore, aimed to quantify the additional losses (if any) that occur as a result of fertiliser being applied concurrently onto a urine patch, and furthermore, determine the fate of the fertiliser N within the urine patch. To determine this, a two year lysimeter study was undertaken where urine patches were applied in either autumn or spring. Urea fertiliser enriched with ¹⁵N was applied to these lysimeters at rates of either 200 or 400 kg N ha⁻¹ according to the standard regional practice. The amount of fertiliser derived N was measured in the leachate, N₂O emissions, pasture and soil. Fertiliser 15N recovered in leachate and N2O emissions was <2.2% and <0.1%, respectively. Urine and fertiliser at the 400 kg N ha⁻¹ rate did increase total NO₃- leaching by up to 55 kg ha⁻¹ (p < 0.001), but this was as unlabelled N. Pasture uptake accounted for up to 52% of the fertiliser 15N recovery and increased plant uptake was observed under increasing fertiliser rates (p < 0.001). Recovery of fertiliser ¹⁵N in the soil at the end of the experiment was 22% with the majority of this in the top 10 cm soil. Total fertiliser ¹⁵N recovery ranged from 68-81% and it is suggested most of the unaccounted for ¹⁵N was lost as N₂ emissions and/or leached as dissolved organic N. To further this work, data from the lysimeter experiment was validated against simulated results from a dynamic, process based model, APSIM (Agricultural Production Systems Simulator). The APSIM simulation was designed to mimic the experimental conditions and management of the lysimeter trial for the purpose of later using it to extrapolate the lysimeter data beyond its current confines to a larger range of treatment scenarios, climatic regions and soil types. Most of the modelled outputs were within the 95% confidence interval of the experimental data. However, the model significantly overestimated N₂O emissions from under urine patches, and… Advisors/Committee Members: Clough, Timothy.

Subjects/Keywords: Nrogen use efficiency; ¹⁵N recovery; nitrate leaching; nitrous oxide emissions; fertiliser; urine; Nitrogen; pasture uptake; soil; APSIM; validation; effective area; wetted area

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Buckthought, L. E. (2013). The interactive effects of nitrogen fertiliser and animal urine on nitrogen efficiency and losses in New Zealand dairy farming systems. (Thesis). Lincoln University. Retrieved from http://hdl.handle.net/10182/5893

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Buckthought, Laura E. “The interactive effects of nitrogen fertiliser and animal urine on nitrogen efficiency and losses in New Zealand dairy farming systems.” 2013. Thesis, Lincoln University. Accessed October 15, 2019. http://hdl.handle.net/10182/5893.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Buckthought, Laura E. “The interactive effects of nitrogen fertiliser and animal urine on nitrogen efficiency and losses in New Zealand dairy farming systems.” 2013. Web. 15 Oct 2019.

Vancouver:

Buckthought LE. The interactive effects of nitrogen fertiliser and animal urine on nitrogen efficiency and losses in New Zealand dairy farming systems. [Internet] [Thesis]. Lincoln University; 2013. [cited 2019 Oct 15]. Available from: http://hdl.handle.net/10182/5893.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Buckthought LE. The interactive effects of nitrogen fertiliser and animal urine on nitrogen efficiency and losses in New Zealand dairy farming systems. [Thesis]. Lincoln University; 2013. Available from: http://hdl.handle.net/10182/5893

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Lincoln University

2. Owens, Jennifer. Understanding how pasture irrigation influences soil nitrous oxide fluxes and nitrous oxide reductase.

Degree: 2016, Lincoln University

This thesis is a combination of field and laboratory studies aimed at understanding how irrigation influences nitrous oxide (N₂O) emissions from grazed pastures in New Zealand. The general goal was to understand how nitrous oxide reductase (N₂OR) was affected by irrigation practices, and other factors, and to assess the potential to minimize N₂O emissions by encouraging N₂O reduction to dinitrogen (N₂). EXPERIMENT 1 (Chapter 4) - A field monitoring campaign measured N₂O fluxes for 35 days from urine and non-urine treated grazed and irrigated dairy pasture, situated on a free-draining soil. Two irrigation frequencies - a 3 day irrigation frequency and a 6 day irrigation frequency - applied the same total amount of water by the end of the experiment. The original hypothesis was that a more frequent irrigation regime would keep soil moisture higher, thereby lowering soil oxygen (O₂), resulting in greater N₂OR activity, and reduced N₂O emissions. Soil O₂ measurements showed that soil O₂ was lower at 50 and 100 mm soil depth in the more frequently irrigated soil. Denitrification potential measurements taken over the course of the experiment, using the acetylene inhibition method, showed that potential N₂O/(N₂O+N₂) was lower under the more frequent irrigation regime, suggesting greater potential for N₂OR. Contrary to the original hypothesis, however, there was no difference in the N₂O fluxes from the different irrigation frequencies, despite the soil chemical and biological differences. Estimates of soil relative gas diffusivity (DP/DO) showed that DP/DO was too high for N₂O to be reduced to N₂, according to the thresholds identified by Balaine et al. (2013). The results from this experiment raised questions warranting exploration. EXPERIMENT 2 (Chapter 5) Can we further explore and compare how well soil O₂ measurements and DP/DO an expression of soil O₂ diffusion, explain N₂O fluxes under variable hydrological conditions on a heavy soil? EXPERIMENT 3 (Chapter 6) Temporal dynamics of N₂OR and denitrification potential after a wetting event need to be better understood. Can we interpret whether lower N₂O/(N₂O+N₂) is attributed to just increased soil moisture, or is it also related to priming of the microbial pathway for N₂OR? EXPERIMENT 4 (Chapter 7) Is the diel cycling of soil O₂ temperature and respiration driven? Is there also diel cycling of N₂O and N₂OR related to plant dynamics, such as expulsion of root exudates? Can we isolate and explore these factors by measuring N₂O and ¹⁵N-N₂O and ¹⁵N-N₂ recovery from soils with and without plants in the absence of temperature change? EXPERIMENT 5 (Chapter 8) The effects of plants on N₂OR should be assessed by comparing rhizosphere and bulk soils to enable laboratory results, many of which do not include plants, to be transferred to field scenarios, where plants are common. Along this same thread, spatially variability in the field should be explored, as this variability can inform sampling strategies and extrapolation of local results. Advisors/Committee Members: Clough, Timothy.

Subjects/Keywords: irrigation frequency; urine; relative soil gas diffusivity; soil oxygen; pasture; soil chemistry; nitrous oxide; grazed pasture

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Owens, J. (2016). Understanding how pasture irrigation influences soil nitrous oxide fluxes and nitrous oxide reductase. (Thesis). Lincoln University. Retrieved from http://hdl.handle.net/10182/7637

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Owens, Jennifer. “Understanding how pasture irrigation influences soil nitrous oxide fluxes and nitrous oxide reductase.” 2016. Thesis, Lincoln University. Accessed October 15, 2019. http://hdl.handle.net/10182/7637.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Owens, Jennifer. “Understanding how pasture irrigation influences soil nitrous oxide fluxes and nitrous oxide reductase.” 2016. Web. 15 Oct 2019.

Vancouver:

Owens J. Understanding how pasture irrigation influences soil nitrous oxide fluxes and nitrous oxide reductase. [Internet] [Thesis]. Lincoln University; 2016. [cited 2019 Oct 15]. Available from: http://hdl.handle.net/10182/7637.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Owens J. Understanding how pasture irrigation influences soil nitrous oxide fluxes and nitrous oxide reductase. [Thesis]. Lincoln University; 2016. Available from: http://hdl.handle.net/10182/7637

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Lincoln University

3. Premaratne, Manjula. Nitrous oxide (N₂O) transfer velocity and the effect of Ammonium on N2O fluxes from an agricultural drain.

Degree: 2016, Lincoln University

Indirect nitrous oxide (N₂O) emissions from rivers and drains are poorly quantified and the uncertainity surrounding the emission factor for dissolved N₂O in rivers (EF5-r) is high. Scaling the exchange of N₂O across the water – air interface is important in order to estimate the indirect N₂O emissions from rivers and drains.Therefore, this study was designed to measure the drain water N₂O emission transfer velocity (kN₂O) and the effect of ammonium (NH₄⁺) on drain water N₂O yield. The field experiment released ¹⁵N-NH₄⁺, with Bromide (Br⁻) as a conservative tracer, RhodamineWT as a visual tracer, and propane (C₃H₈) as a conservative tracer gas, into a drain. Visual tracer and conservative tracers allowed the drain water velocity and dilution factor to be determined, respectively. The C₃H₈ and N₂O gases were collected using headspace equilibrium and floating chamber methods. The rate of C₃H₈ escape from water to air was used to measure the N₂O transfer velocity (kN₂O). The gas transfer velocity model which as explained by O’Connor and Dobbins (1958), equation 2.9 as interpreted by Wilcock (1982) was also used to measure kN₂O. The ¹⁵N₂O fluxes allowed the NH₄⁺ contribution to the N₂O flux to be determined. The ¹⁵N enrichment in biofilms and aquatic plants also allowed nitrogen assimilation to be evaluated. The measured kN₂O using headspace equilibrium and the kN₂O estimated from Wilcock (1982) were 7.49 ± 0.72 m day-1 and 8.65 ± 1.23 m day-1, respectively. To measure the hydro physical variations in kN₂O, the current study data and the data from other New Zealand studies were evaluated. The results showed that for shallow drains, water depth < 1 m, the value of kN₂O increased with decreasing water depth. There was an inverse relationship between ¹⁵N-NH₄⁺-N enrichment and the ¹⁵N enrichment of the N₂O evolved. However, there was no relationship between ¹⁵N-NO₃⁻ enrichment with ¹⁵N-N₂O enrichment indicating N₂O was produced due to nitrification of added NH₄⁺-N. Following ¹⁵N tracer addition, biotic components of the drain ecosystem were highly enriched but returned to near background levels after 10 days, demonstrating that NH₄⁺-N assimilation and mineralization occurred. The calculated EF5-r values were significantly lower than the IPCC default EF5-r value; 0.0025 kg (2.5 g) N₂O-N per kg NO₃⁻-N. The measured EF5-r values, derived using the surface C₃H₈ flux measurements and the headspace C₃H₈ equlibrium concentrations, were 7.66E-6 (7.66 mg) and 8.20E-6 (8.20 mg) kg N₂O-N per kg NO₃⁻-N, respectively. However, the EF5-r values derived using floating chambers were significantly lower (3.92E-11 kg; (0.0004 mg) N₂O-N per kg NO₃⁻-N) and showed chamber methodology as an inefficient technique for gas flux measurements on flowing water surfaces. In contrast, the kN₂O measured using the Wilcock (1982) model, that used drain water speed and depth produced higher EF5-r; 9.48 E-6 kg (9.48 mg) N₂O-N per kg NO₃⁻-N. Thus, this study demonstrated; (1) the tracer gas addition technique is a relaible and accurate method… Advisors/Committee Members: Clough, Timothy.

Subjects/Keywords: nitrogen; nitrous oxide; ammonium; nitrate; propane; Bromides; Rhodamine WT; nitrous oxide transfer velocity; 15N-labelled fertiliser (15N); EF5; agricultural drain

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Premaratne, M. (2016). Nitrous oxide (N₂O) transfer velocity and the effect of Ammonium on N2O fluxes from an agricultural drain. (Thesis). Lincoln University. Retrieved from http://hdl.handle.net/10182/7845

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Premaratne, Manjula. “Nitrous oxide (N₂O) transfer velocity and the effect of Ammonium on N2O fluxes from an agricultural drain.” 2016. Thesis, Lincoln University. Accessed October 15, 2019. http://hdl.handle.net/10182/7845.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Premaratne, Manjula. “Nitrous oxide (N₂O) transfer velocity and the effect of Ammonium on N2O fluxes from an agricultural drain.” 2016. Web. 15 Oct 2019.

Vancouver:

Premaratne M. Nitrous oxide (N₂O) transfer velocity and the effect of Ammonium on N2O fluxes from an agricultural drain. [Internet] [Thesis]. Lincoln University; 2016. [cited 2019 Oct 15]. Available from: http://hdl.handle.net/10182/7845.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Premaratne M. Nitrous oxide (N₂O) transfer velocity and the effect of Ammonium on N2O fluxes from an agricultural drain. [Thesis]. Lincoln University; 2016. Available from: http://hdl.handle.net/10182/7845

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.