Liyin Liang was as a research fellow who came to work with us from UC Riverside. Liyin led our efforts to develop eddy covariance measurements of nitrous oxide fluxes from grazed pastures. While technically very challenging these methods offer the advantage of measuring fluxes at paddock scales almost continuously.He also worked on using macromolecular rate theory to successfully predict leaf respiration rates. Liang et al (2018) Macromolecular rate theory (MMRT) provides a thermodynamics rationale to underpin the convergent temperature response in plant leaf respiration. Global Change Biology. 24: 1538–1547. Liyin has moved to a scientist position at Manaaki Whenua – Landcare Research and we already have joint projects in mind.
Esther Peerlings investigated the recovery of pasture after grazing by dairy cows. Specifically she was interested in how CO2 fluxes (i.e. CO2 uptake and emission) measured with the Eddy Covariance technique can be used to determine the recovery of a paddock’s photosynthesising biomass. Her supervisors were Dave Campbell and Aaron Wall. Esther’s 4-month internship was part of her MSc Earth and Environment (specialisation in Meteorology and Air Quality) at Wageningen University, The Netherlands.
Jack Pronger completed a PhD on water use efficiency of diverse pastures that have a deeper and greater root biomass than traditional ryegrass/clover swards. He was supported by the Flower Trust, University of Waikato and DairyNZ. Jack talks about his work here (at about 5:00 minutes) and in a video on his water use efficiency here. Previously, Jack determined rates of peat subsidence in the Waikato for his BSc (Hons). He showed current rates of peat subsidence are about 2cm per year. His BSc (Hons) was in collaboration with Waikato Regional Council (Reece Hill) and Landcare Research (Malcolm McLeod).
Pronger, J.; Campbell, D.I.; Clearwater, M.J.; Rutledge, S.; Wall, M.J.; Schipper, L.A. (2016) Low spatial and inter-annual variability in evaporation from a year round intensively grazed temperate pasture system. Agriculture Ecosystems and Environment. 232:46-58.
Pronger, J.; Schipper, L.A.; Hill, R.; Campbell D.I.; McLeod, M. (2014) Subsidence rates of drained agricultural peatlands in New Zealand and the relationship with time since drainage. Journal of Environmental Quality. 43: 1442-1449
Mahdiyeh Salmanzadeh completed a PhD on Cd accumulation in agricultural soils. Cd has accumulative effects and is a potentially biotoxic metal. Cd is found in some fertilisers commonly used in agriculture. Mahdiyeh has a master’s degree in environmental engineering where she examined PAHs and heavy metal pollution and their ecological risk assessment in street dust of Tehran, Iran. Mahdiyeh’s main supervisor was Megan Balks and co-supervised by Adam Hartland and Louis Schipper. She received funding from University of Waikato PhD scholarship, DairyNZ and FertResearch.
Salmanzadeh, M.; Schipper, L.A.; Balks, M.R.; Hartland, A.; Mudge, P.L. (2017) The effect of irrigation on cadmium losses from agricultural soils. Agriculture, Ecosystems and Environment. 247: 84-90
Salmanzadeh, M.; Hartland, A.; Stirling, C.; Balks, M; Schipper, L.A., Chaitanya, J.; George, E. (2017) Long-term change in the cadmium isotopic composition of agricultural soil arising from phosphate fertilizer applications. Environmental Science & Technology. 51: 7369 – 7377.
Olivia Petrie conducted a MSc looking at the temperature dependence of microbial respiration in soils taken from adjacent irrigated and dryland soils. This followed on a study that demonstrated lower soil carbon stocks under irrigated soils. Olivia demonstrated respiration in irrigated soil was lower and had a temperature optimum nearly 10C higher than the adjacent dryland pasture soils.
Olivia was supervised by Tanya O’Neill, Louis Schipper and Paul Mudge (Landcare Research).
Peter Lafleur (left in photo, with Joss Ratcliffe at Kopuatai bog) is a professor from Trent University School of the Environment in Ontario, Canada, specializing in ecosystem-atmosphere interactions in northern peatlands and Arctic tundra. Peter’s visit is an extension of his long-time association with Dave Campbell and their shared interest in the energy, water and carbon fluxes from peatland ecosystems. While at WaiBER during Feb. and March of 2017, Peter enjoyed occasional visits to the local research sites and many insightful discussions with Dave and others about ecosystems research. Peter presented his initial work on the long-term NEE from the Mer Bleue bog and its controlling factors, exploring 17 years of continuous CO2 flux data. The Mer Bleue peatland observatory has been a key research site for investigating northern peatland ecology and functioning since 1998.
Susanna was a research fellow investigating approaches for increasing soil carbon content of pasture soils using eddy covariance approaches coupled to other measures of C flux and turnover.
She led work on whether higher diversity pastures can increase soil C content and the effects of pasture renewal through funding from the NZ Agricultural Greenhouse Gas Research Center. Susanna completed her PhD thesis on photodegradation. See: Rutledge et al (2010) Global Change Biology. 16(11): 3065-3074.
Rutledge, S.; Mudge, P.; Campbell, D.; Woodward, S.; Goodrich, J.; Wall, A.; Kirschbaum, M.; Schipper L. (2015) CO2 and carbon balance of an intensively grazed temperate dairy pasture over four years. Agriculture Ecosystems and Environment. 206: 10-20.
Katharyn Duffy (a.k.a. Arizona Kate) is a Ph.D candidate at Northern Arizona University visiting on a joint National Science Foundation and Royal Society of New Zealand grant to collaborate with Vic Arcus and Louis Schipper on macro-molecular rate theory and its potential applications. Her research focuses on quantifying the sensitivity of land-atmosphere carbon exchange on a biome-to-global scale, and attributing current inter-annual variability in the land sink to discrete environmental drivers. Kate’s supervisor is Christopher Schwalm at NAU and Woods Hole.
Adrea Noyes investigated soil C,N and P recovery following landslides at Whatawhata Research Station for her MSc thesis. Aerial photographs were used to date the landslides were sampled and analysed for C, N and P to understand of soil recovery rates on Waikato Steepland soils.
Sophie Burke was a Fulbright graduate fellow from the University of New Hampshire working with Dave Campbell and Louis Schipper on a research project involving methane flux from the Moanatuatua and Kopuatai peat bogs. For her PhD, Sophie’s research involves acoustically monitoring methane ebullitive flux from thaw ponds at a peatland site in subarctic Sweden. She enjoyed her experience with WaiBER expanding her understanding of peatland ecosystems and the threats they face due to climate change. After Waiber experience, completing a PhD at University New Hampshire.
Sam completed his PhD on the contribution of roots from different pasture species in contributing to soil carbon. He is measuring root stocks and rates of roots turnover for different pasture species. Supervised by Louis Schipper, Susanna Rutledge, Daniel Laughlin, Mike Dodd (AgResearch), Johan Six (ETH Zurich). Funding support from New Zealand Agricultural Greenhouse Gas Research Centre and DairyNZ. After Waiber, took up a Postdoc at Plant and Food.
McNally, S.R.; Laughlin, D.C.; Rutledge, S.; Dodd, M.B.; Six, J.; Schipper, L.A. (2015) Root carbon inputs under moderately diverse sward and conventional ryegrass-clover pasture: implications for soil carbon sequestration. Plant and Soil. 392: 289-299.
For her PhD, Doreen studied carbon storage and DNA preservation in allophanic soils and paleosols, which is part of the Marsden project aiming to test the reconstruction of environmental and climate change using genetic signal (DNA) preserved in buried paleosols. Doreen’s main supervisor is Prof David Lowe who is the leader of the Marsden project and was also supervised by Louis Schipper, Jock Churchman and Ray Cursons. After Waiber, postdoc at Umeå University, Sweden.
Huang, Y-T.; Lowe, D.J.; Churchman, G.J.; Schipper, L.A.; Cursons, R.; Zhang, H.; Chen, T.Y.; Cooper, A. (2016) DNA adsorption by nanocrystalline allophane spherules and nanoaggregates, and implications for carbon sequestration in Andisols. Applied Clay Science 120: 40–50.
Huang, Y-T.; Lowe, D.J.; Zhang, H.; Cursons, R.; Young, J.M.; Churchman, G.J.; Schipper, L.A.; Rawlence, N.J.; Wood, J.R.; Cooper, A. (2016) A new method to extract and purify DNA from allophanic soils and paleosols, and potential for paleoenvironmental reconstruction and other applications. Geoderma. 274:114-125 15.
Electra Kalaugher completed her PhD on adaptation of New Zealand dairy farms to climate change, with support from DairyNZ and a MAF/NIWA project. Her research combined computer modelling (using the DairyNZ Whole Farm model) and social research, for six case study farms in different locations in New Zealand. After Waiber, Electra became a scientist at Landcare Research.
Her chief supervisor was Dave Campbell.
Olivia Jordan investigated the effect of pasture sward mixes on root biomass in a grazed plot trial at DairyNZ’s Scott farm for her MSc thesis. Root biomass is a large contributor to soil carbon which has numerous benefits for soil stability and pasture production. Olivia measured root biomass in 14 different pasture combinations to determine whether sward can increase root biomass and soil carbon and nitrogen. Biomass ranged between 1100-24000 kg DM ha-1 across the different mixtures and swards with herb species present had a lower total root biomass (average 2240 kg DM ha-1) compared with non-herb plots (average 3560 kg DM ha-1). After Waiber, Olivia took up a position at DairyNZ.
Olivia was co-supervised by Paul Mudge from Landcare Research.
Emma Bagley examined the occurrence and causes of pasture pulling under dairy farming on pumice soils in the central North Island for her MSc thesis. Pasture pulling occurs when livestock pulling whole clumps of pasture from the soil. She monitored 15 paddocks of different ages for a year and found that a number of soil characteristics contributed to pulling, including; limited rooting depth, low root density in the 5-10 cm depth, increased compaction with depth, less cohesive soil when it had low moisture, and the incidence of pasture growing in clumps.
Emma’s main supervisor was Dr Megan Balks and she worked with Gina Lucci at AgResearch receiving support from AgResearch, DairyNZ, University of Waikato and she also won a C Alma Baker postgraduate scholarship.
Jordan investigated carbon exchange in the large and relatively pristine Kopuatai peat bog, using eddy covariance techniques for his PhD. He examined the controls on CO2 and CH4 exchange, including the reaction of the plant canopy to the fraction of diffuse light, drought and the influence of plant phenology. Jordan’s PhD research contributed towards the first multi-year wetland ecosystem carbon budget to be determined for a southern hemisphere peatland. Jordan received funding through Landcare Research. After Waiber, postdoc at San Diego State University.
Goodrich, J.P.; Campbell, D.I.; Clearwater, M.J.; Schipper L.A. (2015) Over-riding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere raised bog. Journal of Geophysical Research – Biogeosciences. 120, doi:10.1002/2014JG002844
Goodrich, G.P.; Campbell, D.I.; Schipper, L.A.; Clearwater, M.; Rutledge S.; Keyte-Beattie, A. (2015) High vapour pressure deficit constrains GPP and the light response of NEE at a Southern Hemisphere bog. Agricultural and Forest Meteorology. 203: 54–63.
Brendon Welten (PhD 2014) tested whether DCD, a nitrification inhibitor, could be orally fed to cows and subsequently excreted in urine. This approach has the potential advantage of the inhibitor being spatially and temporally targeted to the main source of nitrate leaching – the urine patch. He used a mixture of barrel lysimeter and field trials.Stewart Ledgard (AgResearch) was a co-supervisor along with Megan Balks.
After his PhD, Brendon continued his work at AgResearch.
Welten, B.G.; Ledgard, S.F; Schipper, L.A.; Waller, J.E.; Kear, M.J.; Dexter, M.M.; (2013) Effects of prolonged oral administration of dicyandiamide to dairy heifers on excretion in urine and efficacy in soil. Agriculture Ecosystems and Environment. 173: 28-36.
Welten, B.G.; Ledgard, S.F; Schipper, L.A.; Judge A.A. (2013) Effect of amending cattle urine with dicyandiamide on soil nitrogen dynamics and leaching of urinary-nitrogen. Agriculture Ecosystems and Environment.167, 12-22.
Elyn Humphreys (Associate Professor, Carleton University) and her family visited for 3 months to learn more about NZ peatlands and interact with the WaiBER team to exchange ideas and techniques for analysis and interpretation of carbon and methane flux data.
This follows a sabbatical visit by Dave Campbell to Carleton in 2012.
Mark visited us on a sabbatical from USDA-ARS, Ames, Iowa after receiving funding from the New Zealand-U.S.A. Soil Science Exchange Travel Award. Mark and Louis are working on concepts of nitrogen saturation in agricultural soils. Nitrogen saturation has been of interest in New Zealand for several years. They are both interested in whether these concepts might be applied to soils in the Mississippi basin and the potential consequences.
Tim trialed a new coring method to measure C and N stocks of soil in adjacent dairy and drystock pastures for his MSc. He resampling sites sampled by Alice Barnett and Amy Taylor (see below) using a hand coring technique and using equivalent mass methods to estimate stocks. His objective was to develop a more pragmatic and inexpensive approach for measuring changes in soil organic matter. Tim was partly funded by University of Waikato, Landcare Research and DairyNZ. Tim has a position at Hawkes Bay Regional Council.
Noah Fierer visited on sabbatical with his family. Noah is an Associate Professor at the University of Colorado. Noah has a very broad range of interests in microbial ecology and biogeochemistry. An interesting general article over-viewing some of his work on microbial ecology, diversity and distribution can be found here.
While in New Zealand, he explored connections with the WaiBER team, Vic Arcus, Craig Cary, students and a number of others at the University of Waikato and beyond. Noah’s lab group can be found here.
Prof. Nigel Roulet, McGill University Canada, visited our group in March 2014 with his wife Kathy. Nigel’s goal was to find out about our carbon exchange and ecohydrology research in NZ peatlands, and to explore collaborative research opportunities with WaiBER and David Hamilton’s lakes research group.
Nigel is the James McGill Professor of Biogeoscience, McGill University Canada
Anna Carter (MSc candidate) Anna looked at how the rate of nitrate removal and decomposition of wood chips vary with temperature at a large denitrification bed near Karaka. This information will be used to optmise bed design for given nitrate concentration and flows rates.
Anna was partially supported by DairyNZ and University of Waikato.
Alex Keyte Beattie For her MSc research Alex investigated the ecohydrology of the plant canopy dominated by Empodisma robustum at Kopuatai peat bog. This plant canopy is globally unusual for a bog because it contains a large amount of standing dead litter and completely shades the moist peat surface. Alex measured the structural properties of this canopy, its spatial variation, water balance and effect on the bog energy balance, as well as its contribution to CO2 fluxes. Alex received funding from University of Waikato and the Stella Frances trust. After Waiber, Alex took a job at Tonkin & Taylor.
Nadia’s MSc thesis topic investigated the potential for improvement of soil moisture holding capacity using soil “flipping” in the central North Island of New Zealand. Experimental soil flipping trials in Galatea showed improved pasture growth in the flipped areas compared to the control areas (undisturbed soils). Nadia talks about her work on National Radio here.
Nadia’s main supervisor was Dr Megan Balks and she receives support from DairyNZ and University of Waikato. After completing her MSc, Nadia took a position at DairyNZ.
- Courtney Ruffell and Staci Boyte worked with us over the summer break on controls of CO2 production from soils and litter. Staci examined temperature controls of soil respiration and Courtney investigated photodegradation of plant litter in restiad bogs.
- Staci and Courtney were supported by the University of Waikato.
David Zweig was a Fulbright Fellow who came to Waikato after studying at University of Georgia. He determined the Km value of nitrate reduction in denitrification beds. This information will be combined with the temperature response of nitrate removal to develop a simple model that can be used for designing denitrification beds. David describes his journey to New Zealand and project here and on a Youtube video here. After returning home, David started study at Stanford University.
Alice Barnett completed aMSc thesis measuring soil C and N of adjacent drystock and dairy farms of the Waikato. With Amy Taylor (also an MSc student), they sampled 25 paired sites to a meter. Amy measured changes in soil physical properties. Both Amy and Alice received supervision by Megan Balks. Alice showed that dairy farm topsoils had less soil C than drystock. Funded by University of Waikato, DairyNZ, and the Waikato Regional Council. We are grateful for many farmers for access to their land. Alice subsequently worked at Waikato Regional Council and Tuwharetoa Maori Trust Board.
Barnett, A.L.; Schipper, L.A.; Taylor, A.; Balks, M.R.; Mudge P.L. (2014) Soil C and N contents in a paired survey of dairy and dry stock pastures in New Zealand. Agriculture Ecosystems and Environment. 185: 34– 40.
Liz Deakin aimed to quantify ecological impacts of agricultural land use intensification on native forest fragments in the Waikato region of New Zealand, with a particular focus on plant-insect interactions. Her PhD thesis was entitled “Impacts of land-use intensification on forest remnants embedded within production landscapes”. Liz was funded through a joint Marsden Project between the University of Canterbury, University of Waikato, and Landcare Research. After her PhD, Liz worked at CIFOR – Center for International Forestry Research and then Opus International Consultants Limited.
Didham, R.K.; Barker, G.M.; Bartlam, S.; Deakin, E.L.; Denmead, L.H.; Fisk, L.M.: Peters, J.M.R.; Tylianakis, J.M.; Wright, H.; Schipper, L.A. (2015) Agricultural intensification exacerbates spillover effects on soil biogeochemistry in adjacent forest remnants. PLoS ONE 10(1): e0116474. doi:10.1371/journal.pone.0116474
Emma measured the amount of dissolved organic carbon and nitrogen leaching from below pasture at a grazed dairy farm for her MSc thesis. She also demonstrated that carbon that leaches below the topsoil can be degraded to CO2 lower in the soil profile.
This data will be incorporated into a carbon budget of the dairy farm being determined by Susanna Rutledge and Aaron Wall. Emma received funding from University of Waikato, DairyNZ and a Stella Frances scholarship. Emma took a position at Auckland Regional Council.
Catherine conducted an MSc study of Kopouatai peat bog to determine the magnitude of dissolved organic carbon (DOC) leaching. DOC leaching is often considered an important but poorly quantified loss of carbon from wetlands.This data will be combined with CO2 exchange data collected by Jordon Goodrich when developing a carbon budget of the bog. Catherine worked at Sinclair Knight Merz and Jacobs.
Scott Korom spent a 6 month sabbatical with Louis, Greg Barkle (AquaLinc) and John Hadfield (Waikato Regional Council). Scott helped establish methods for measuring denitrification in groundwater (tricky stuff) around Lake Taupo based on work he was leading at the University of North Dakota.
Scott has been back to New Zealand several times for ongoing collaborative research.
One possible explanation for organic matter loss from soil is increased mobilisation of organic matter by urine patches deposited by stock. Suzanne Lambie conducted a PhD project that investigated whether urine application can increase the degradation and/or leaching of soil organic matter derived from forestry or pastures.
Suzanne undertook her PhD part-time while working at Landcare Research and was jointly supervised by Megan Balks and Troy Baisden (GNS Science). Suzanne continued to work at Landcare Research after her PhD.
Lambie, S.M.; Schipper, L.A.; Balks, M.R.; Baisden, W.T. (2013) Priming of soil decomposition leads to losses of carbon in cow-urine-treated soil. Soil Research 51:513-520.
Lambie, S.M.; Schipper, L.A.; Balks, M.R.; Baisden, W.T. (2012) Carbon leaching from undisturbed soil cores treated with dairy cow urine. Soil Research. 50, 320–327.
Lambie, S.M.; Schipper, L.A.; Balks, M.R.; Baisden, W.T. (2012) Treatment with cow urine leads to large losses of carbon from soils under contrasting land use. Soil Research. 50: 50–57.
Paul Mudge (2008) and Dirk Wallace (2009) conducted MSc studies into how physical impacts (cultivation and pugging) alter the carbon balance of intensively-grazed pasture. They used a combination of chamber and eddy co-variance techniques at Scott farm managed by DairyNZ. The project received funding from DairyNZ and Landcare Research and the University of Waikato. On left, Dirk is thinking hard. Paul submitted his thesis PhD on the use of 15N as an indicator of past nitrogen cycling in pastures – see members page.
Paul subsequently completed his PhD on the utility of soil 15N as an indicator of the past intensity of nitrogen cyling of pastures. He was co-supervised by Troy Baisden (GNS Science) and Anwar Ghani (AgResearch). Paul took a position at Landcare Research and Dirk started a PhD at Plant and Food.
Mudge, P.L.; Schipper, L.A.; Ghani, A.; Upsdell, M.; Baisden, W.T. (2013) Changes in Natural 15N Abundance in Pastoral Soils Receiving Differing Amounts of Superphosphate Fertilizer and Irrigation for 50 Years. Soil Science Society of America Journal. 77, 830–841.
Mudge, P.L.; Wallace, D.F.; Rutledge, S; Campbell, D.I.; Schipper, L.A.; Hosking, C.L. (2011). Carbon balance of an intensively grazed temperate pasture in two climatically contrasting years. Agricultural Ecosystems and Environment. 144: 271-280.
Stevenson B.A., Parfitt R.L., Schipper L.A., Baisden T.; Mudge P. (2010) Relationship between soil δ15N, C/N and N losses across land uses in New Zealand. Agricultural Ecosystems and Environment 139: 736-741.
Jacinta Parenzee was a soil technician in charge of the Soil Ecosystems laboratory for five years supporting teaching and training graduate students.
She also supported research into changes in carbon, nitrogen, phosphorus, cadmium and uranium in long term pastures trials.
Schipper, L.A.; Dodd, M.; Fisk, L.M.; Power, I; Parenzee, J.; Arnold G. (2011) Trends in soil carbon and nutrients of hill-country pastures receiving different phosphorus fertilizer loadings for 20 years. Biogeochemistry. 104(1): 35-48.
James Blyth (MSc 2012) measured a range of peat indicators along a transect at Whangamarino swamp and demonstrated the invasion of the wetland by Manuka. The Manuka was able to migrate into the swamp replacing Empodisma because of increased flooding of the adjacent river. The floods carried sediments into the swamp increasing nutrient status and allowing Manuka to become more competitive. See short news story here.James worked in Australia and then Jacobs in Auckland.
Blyth, J.M.; Campbell, D.I. Schipper, L.A. (2013) Utilising soil indicators to explain historical vegetation changes of a peat bog subjected to flood inundation. Ecohydrology. 6, 104–116. DOI: 10.1002/eco.1247
Hannah Wright conducted an undergraduate thesis on changes in Olsen P along transects running from pasture into forests as part of our Marsden work with University of Canterbury and Landcare Research. This work also contributed to Hannah’s BSc(Hons) completed at Lancaster University entitled “Spatial Variation in Plant-Available Phosphorus in Pasture and Adjacent Native Forest Fragments within the Waikato Region, New Zealand” Hannah undertook a PhD at Lancaster University.
Louise Fisk worked in the lab as an analyst on soils from the long-term research trial at Whatawhata. She examined changes in soil carbon, nitrogen, phosphorus, cadmium and uranium under a range of phosphorus loading rates applied over 24 years. Louise completed a PhD at University of Western Australia and trained as a stunt women.
Schipper L.A.; Sparling G.P.; Fisk, L.M.; Dodd, M.B.; Power, I.L.; Littler, R.A. (2011) Rates of accumulation of cadmium and uranium in a New Zealand hill farm soil as a result of long-term use of phosphate fertilizer. Agricultural Ecosystems and Environment.144: 95– 101
Lauren Long (MPhil 2011) demonstrated that a denitrification wall is still removing nitrate from groundwater 14 years after it was construction. She measured changes in nitrate concentration in groundwater and sustained activity of denitrifiers. Lauren was funded through by a Fulbright scholarship and the University of Waikato. After Waiber, Lauren worked at Auckland Regional Council and MfE.
Long, L.; Schipper L.A.; Bruesewitz D.A. (2011) Long-term nitrate removal in a denitrification wall. Agricultural Ecosystems and Environment. 140: 514–520.
Soeren Warneke completed a PhD thesis on the microbial ecology of denitrification beds. He determined the environmental factors (including temperature response) that control denitrification and nitrous oxide emissions. He developed a rapid approach for assessing nitrate removal and demonstrated that denitrification was the main mechanism for nitrate removal. Soeren was funded by WaikatoLink, Hans Sauer Foundation and the University of Waikato. After his PhD, Soren took up a postdoc at CSIRO.
Warneke et al. (2011) Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds. Water Res. 45: 5463-5475.
Warneke et al. (2011) A comparison of different approaches for measuring denitrification rates in a nitrate removing bioreactor. Water Res. 45: 4141-4151.
Warneke et al (2011) Rates, controls and potential adverse effects of nitrate removal in a denitrification bed. Ecological Engineering. 37: 511-522.
Stewart Cameron (GNS Science) completed a PhD thesis on the flow of effluent through denitrification beds. Stewart used a combination of field and large scale barrel trials to determine the nitrate removal and hydraulic flows in a range of carbon substrates. He demonstrated that it is possible to increase the temperature of denitrification using simple passive solar heating. Funded by GNS Science and University of Waikato.
After his PhD, Stewart continued to work at GNS Science becoming a programme leader.
Cameron S.G.; Schipper L.A. (2010) Nitrate removal and hydraulic performance of carbon substrates for potential use in denitrification beds. Ecological Engineering. 36 (11): 1588-1595.
Cameron S.G. Schipper L.A. (2011) Evaluation of passive solar heating and alternative flow regimes on nitrate removal in denitrification beds. Ecological Engineering. 37: 1195-1204.
Cameron, S.G.; Schipper L.A. (2012) Hydraulic Properties and Hydraulic Efficiency of Organic Carbon Media for use in Denitrification Beds. Ecological Engineering. 41: 1-7.
Natalie Watkins completed an MSc thesis in 2007 looking at whether the application of the nitrification inhibitor DCD would alter other aspects of the nitrogen cycle. She specifically measured changes in denitrification rates at Scott farm. Funding from Technology Industry Fellowship scheme, University of Waikato, DairyNZ and Landcare Research. After Waiber, Natalie took a position a AgResearch.
Watkins, N.L.; Schipper, L.A.; Sparling, G.P.; Thorrold, B.; Balks M.R. (2013) Multiple small doses of the nitrification inhibitor dicyandiamide (DCD) are ineffective in reducing denitrification from dairy pasture in Waikato, New Zealand. New Zealand Journal of Agricultural Research. 56: 37-48.
Note that the ideas/descriptions/opinions on these pages are ours and may not reflect those of the University of Waikato.