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University of Waikato
The University of Waikato manages one of three NZAGRC Student Scholarship schemes (the others are managed by Massey and Lincoln universities) and has links back to the NZAGRC science programme.
Do glucosinolate hydrolysis products reduce nitrous oxide emissions from urine affected soil?
S.F. Balvert, J. Luo, L.A. Schipper, Do glucosinolate hydrolysis products reduce nitrous oxide emissions from urine affected soil?, Science of The Total Environment, Volume 603, 2017, Pages 370-380, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2017.06.089.
- The effectiveness of glucosinolate hydrolysis products at inhibiting N2O emissions in a high N environment was tested.
- Laboratory and field trials measuring N2O production and soil mineral N cycling were conducted.
- Some glucosinolate hydrolysis products reduced nitrification rates.
- Where inhibition occurred it was short lived.
- Glucosinolate hydrolysis products with different R groups did not inhibit soil nitrogen processes to the same degree.
Read more (external link)
Professor Louis Schipper talks about soil carbon
Louis Schipper talks to Bryan Crump on RNZ Nights about soil carbon. He talks about soil organic matter, soil density, nutrients (nitrogen, phosphorus, sulphur), land use and the ways we can store more carbon in soil to reduce the amount of carbon dioxide in the atmostphere without reducing food production.
Louis also talks about the 4 pour mille initiative and its challenge to increase carbon content of soils by 0.4% per year to offset fossil fuel emissions.
Listen (external link)
Professor Louis Schipper
Louis Schipper is a Professor at the University of Waikato who investigates soil biogeochemical processes at landscape scales and how they might be manipulated to achieve improved environmental performance while maintaining production. For the last decade, Louis has led teams determining changes in carbon stocks of pasture soils at paddock to national scales. This research demonstrated that while carbon in the majority of pastures on flat land was at steady state, some of our important soils had lost substantial carbon while hill-country soils have gained large amounts. These data have been central to developing a national picture of New Zealand’s carbon budget. They have also used micro-meteorological approaches to evaluate high-resolution fluxes of carbon at farm scales to identify practices that increase carbon stocks, generating in-depth understanding of climatic effects (e.g., drought, rainfall) and management impacts (pasture renewal, cultivation, new pasture species). Louis is an elected fellow of the New Zealand and American soil science societies with multiple awards from the NZ Society. He has published >130 papers (Scopus H-index of 36), supervised ~40 PhD/MSc students, and developed substantial soil and environmental resources for schools.
The carbon balance of temperate grasslands part I: The impact of increased species diversity
S. Rutledge, A.M. Wall, P.L. Mudge, B. Troughton, D.I. Campbell, J. Pronger, C. Joshi, L.A. Schipper, The carbon balance of temperate grasslands part I: The impact of increased species diversity, Agriculture, Ecosystems & Environment, Volume 239, 2017, Pages 310-323, ISSN 0167-8809, http://dx.doi.org/10.1016/j.agee.2017.01.039.
- Annual C balances were measured for four years over three pastoral blocks on a New Zealand dairy farm.
- Two blocks were renewed to low and high diversity swards, and one block left as an unmodified control.
- Pasture renewal to either sward increased dry matter production relative to unmodified control.
- Renewal to high diversity sward resulted in reduced C loss compared to renewal to low diversity.
- Renewal to neither high nor low diversity sward had benefits for C sequestration over the unmodified control.
Read more (external link)
A review of soil carbon change in New Zealand
Schipper, L. A., P. L. Mudge, et al. (2017). "A review of soil carbon change in New Zealand’s grazed grasslands." New Zealand Journal of Agricultural Research 60(2): 93-118.
Soil organic matter is a potential sink of atmospheric carbon (C) and critical for maintaining soil quality. We reviewed New Zealand studies of soil C changes after conversion from woody vegetation to pasture, and under long-term pasture. Soil C increased by about 13.7 t C ha−1 to a new steady state when forests were initially converted to pasture. In the last 3–4 decades, resampling of soil profiles demonstrated that under long-term pasture on flat land, soil C had subsequently declined for allophanic, gley and organic soils by 0.54, 0.32 and 2.9 t C ha−1 y−1, respectively, and soil C had not changed in the remainder of sampled soil orders. For the same time period, pasture soils on stable midslopes of hill country gained 0.6 t C ha−1 y−1. Whether these changes are ongoing is not known, except for the organic soils where losses will continue so long as they are drained. Phosphorus fertiliser application did not change C stocks. Irrigation decreased carbon by 7 t C ha−1. Carbon losses during pasture renewal ranged between 0.8 and 4.1 t C ha−1. Some evidence suggests tussock grasslands can gain C when fertilised and not overgrazed. When combined to the national scale, different data sets suggest either no change or a gain of C, but with large uncertainties. We highlight key land-use practices and soil orders that require further information of soil C stock changes and advocate for a better understanding of underpinning reasons for changes in soil C.
Read more (external link)
The carbon balance of temperate grasslands part II: The impact of pasture renewal via direct drilling
S. Rutledge, A.M. Wall, P.L. Mudge, B. Troughton, D.I. Campbell, J. Pronger, C. Joshi, L.A. Schipper, The carbon balance of temperate grasslands part II: The impact of pasture renewal via direct drilling, Agriculture, Ecosystems & Environment, Volume 239, 2017, Pages 132-142, ISSN 0167-8809, http://dx.doi.org/10.1016/j.agee.2017.01.013
- Two blocks had pastures renewed (PR) by direct drill. A third block was a control.
- The PR blocks had smaller positive NEPs than the control block during the PR year.
- Duration of fallow is important in determining total CO2 losses due to PR
- Pasture renewal led to a negative carbon balance (soil C loss) for the PR year
- Addition of C (e.g. manure, effluent, feed) helps to mitigate soil C loss due to PR.
Read more (external link)
The trade-offs between milk production and soil organic carbon storage in dairy systems under different management and environmental factors
Kirschbaum, M. U. F., L. A. Schipper, et al. (2017). "The trade-offs between milk production and soil organic carbon storage in dairy systems under different management and environmental factors." Science of the Total Environment 577: 61-72.
A possible agricultural climate change mitigation option is to increase the amount of soil organic carbon (SOC). Conversely, some factors might lead to inadvertent losses of SOC. Here, we explore the effect of various management options and environmental changes on SOC storage and milk production of dairy pastures in New Zealand. We used CenW 4.1, a process-based ecophysiological model, to run a range of scenarios to assess the effects of changes in management options, plant properties and environmental factors on SOC and milk production. We tested the model by using 2 years of observations of the exchanges of water and CO2 measured with an eddy covariance system on a dairy farm in New Zealand's Waikato region. We obtained excellent agreement between the model and observations, especially for evapotranspiration and net photosynthesis.
For the scenario analysis, we found that SOC could be increased through supplying supplemental feed, increasing fertiliser application, or increasing water availability through irrigation on very dry sites, but SOC decreased again for larger increases in water availability. Soil warming strongly reduced SOC. For other changes in key properties, such as changes in soil water-holding capacity and plant root:shoot ratios, SOC changes were often negatively correlated with changes in milk production.
The work showed that changes in SOC were determined by the complex interplay between (1) changes in net primary production; (2) the carbon fraction taken off-site through grazing; (3) carbon allocation within the system between labile and stabilised SOC; and (4) changes in SOC decomposition rates. There is a particularly important trade-off between carbon either being removed by grazing or remaining on site and available for SOC formation. Changes in SOC cannot be fully understood unless all four factors are considered together in an overall assessment.
Read more (external link)
Estimates of annual leaching losses of dissolved organic carbon from pastures on Allophanic Soils grazed by dairy cattle, Waikato, New Zealand
Sparling, G. P., E. J. Chibnall, et al. (2016). "Estimates of annual leaching losses of dissolved organic carbon from pastures on Allophanic Soils grazed by dairy cattle, Waikato, New Zealand." New Zealand Journal of Agricultural Research 59(1): 32-49.
Dissolved organic carbon (DOC) flux on a conventional New Zealand dairy farm was measured for 1 year to assess the contribution from DOC to the total farm C budget. Soil solution was collected using ceramic cups at 60 cm depth. Soil drainage was calculated from a water balance model using rainfall, evaporation and soil water storage data from two eddy covariance systems. Solution was collected approximately every 14 days. The DOC concentration was 5.7±15.6 µg C ml-1 (mean and standard deviation). No significant differences (P<0.05) in DOC concentrations were detected between the four soil types, the two sampling areas, nor date of sampling. The accumulative amount of DOC leached was obtained by combining the soil solution concentrations with the daily estimates of drainage. The mean annual amount of DOC leached was 13?29 kg C ha-1 y-1and the contributed 2?5% to the net farm annual carbon balance.
Read more (external website)
KuDos to Aaron Wall of Waikato University
University of Waikato technician, and a pivotal player in the NZAGRC-funded soil carbon programme, Aaron Wall was a winner in last month’s 2015 KuDos Hamilton Science Excellence Awards.
The School of Science Technical Officer picked up the top award in the Hill Laboratories Laboratory Technologist Award section.
Aaron spends much of his time expertly managing the Troughton farm site for the NZAGRC programme. Additionally, he also manages the access to the site for related research by AgResearch, Plant and Food Research and Landcare Research. His excellent relationship with the farm owners, and unsung heros of the whole operation, Ben and Sarah, enables everything to run smoothly.
On top of overseeing what goes on and when at the Troughton site, Aaron is a key part of the NZAGRC research team. He has made considerable novel advances in analysis of eddy covariance data, collation of non-CO2 data and pushed the team to collect additional data that are now proving to be crucial. Aaron is able to bring together deeply technical analysis tools with on-farm understanding and his colleagues feel extremely lucky to have him in their team.
Well done Aaron!
See Aaron in action here: https://youtu.be/qFYZ4R1f-RA
Carbon balance of an intensively grazed temperate dairy pasture over four years
S. Rutledge, P.L. Mudge, D.I. Campbell, S.L. Woodward, J.P. Goodrich, A.M. Wall, M.U.F. Kirschbaum, L.A. Schipper, Carbon balance of an intensively grazed temperate dairy pasture over four years, Agriculture, Ecosystems & Environment, Volume 206, 1 August 2015, Pages 10-20, ISSN 0167-8809, https://doi.org/10.1016/j.agee.2015.03.011.
We estimated the net ecosystem carbon (C) balance (NECB) of a temperate pasture in the North Island of New Zealand for four years (2008–2011). The pasture was intensively managed with addition of fertiliser and year-round rotational grazing by dairy cows. Climatic conditions and management practices had a large impact on CO2 exchange, with a severe drought in one year and cultivation in another both causing large short-term (∼3 months) net losses of CO2–C (100–200 g C m−2). However, CO2 was regained later in both of these years so that on annual timescales, the site was a CO2 sink or CO2 neutral. Management practices such as effluent application and harvesting silage also influenced non-CO2–C fluxes, and had a large impact on annual NECB. Despite these major environmental or management perturbations, both NEP and NECB were relatively constant on annual timescales. It is likely that this apparent resilience of the CO2 and C balance to perturbations was at least partly attributable to the relatively warm temperatures, also in winter, providing good growing conditions year-round (in the absence of major perturbations such as moisture stress). In several instances, the farmer’s decisions aimed at maintaining a constant milk yield between years also appeared to contribute to a relatively stable C balance.
Averaged over the full four-year study period, the site was a net sink for both CO2 (NEP = 165 ± 51 g C m−2 y−1), and total C (NECB = 61 ± 53 g C m−2 y−1) after non-CO2–C fluxes were accounted for. Annual NEP and NECB values were similar to results collated from other managed temperate grasslands on mineral soils globally, for which average NEP and NECB were 188 ± 44 g C m−2 y−1 and 44 ± 33 g C m−2 y−1, respectively. In the global dataset, we noted a general trend for increased C sequestration with increasing NEP, suggesting that it may be possible to meet the dual goal of increased pasture production (thus milk, meat and fiber production) and increasing soil C storage in managed temperate grasslands. Identification of management practices that increase C storage while maintaining or enhancing pasture production requires more standardised reporting between NECB studies, and experiments involving side-by-side comparison of treatment and control plots.
Read more (external website)
Masters Student: Olivia Jordan
Olivia with NZ PM Rt Hon John Key (Oliva is second from the left)
Olivia is conducting an MSc thesis examining root biomass of different pasture swards in a trial at a New Zealand industry research farm.
This work is aligned to an investigation of above-ground plant traits by Landcare Research.
Olivia is supervised by Professor Louis Schipper at the University of Waikato.
Olivia has a background in farming is very interested in finding a career in the farming industry.
Undergraduate student: Alex Tressler
Alex Tressler is a fourth year undergraduate student at the University of Waikato. He is currently in his final year of a BMS studying Agribusiness and Strategic Management.
Alex's recent NZAGRC research project was to examine the potential for effective economic policy in regards to soil carbon within pastoral agriculture in New Zealand.
"The research included exploration of foreign policy and initiatives as well as comparisons of our own proposals, whilst assessing the viability of these ideas based on academic literature and theoretical real world applications."
Alex plans to complete his BMS and continue working in agribusiness to "help maintain and improve our country's competitive advantage."