Lincoln University

Potential for forage diet manipulation in New Zealand pasture ecosystems to mitigate ruminant urine derived N2O emissions: a review

Gardiner, C. A., T. J. Clough, et al. (2016). "Potential for forage diet manipulation in New Zealand pasture ecosystems to mitigate ruminant urine derived N2O emissions: a review." New Zealand Journal of Agricultural Research 59(3): 301-317.

ABSTRACTNitrous oxide (N2O) emissions from agricultural soils account for more than 10% of New Zealand?s greenhouse gas emissions. Livestock urine deposition drives N2O losses from these soils. It has been speculated that non-urea nitrogen compounds (UNCs) in ruminant urine could reduce or inhibit urine patch N2O emissions. However, we hypothesise that UNCs will have no effect on N2O emissions due to their potentially rapid degradation by plants and soil microbes. Our review suggests that plant secondary metabolites (PSMs) are more likely to perform a role in reducing N2O emissions since many PSMs have known antimicrobial properties. Aucubin, found in Plantago, and isothiocyanates, found in Brassica, have been shown to inhibit a key step in N2O production. Future studies should explore this promising research gap by evaluating forages for potential inhibitory PSMs, assessing whether PSMs are excreted in urine after consumption, and determine whether excretal PSM concentrations are sufficient to reduce N2O emissions.

http://dx.doi.org/10.1080/00288233.2016.1190386

The potential of using alternative pastures, forage crops and gibberellic acid to mitigate nitrous oxide emissions

Di, H. J., Cameron, K. C., Podolyan, A., Edwards, G. R., de Klein, C. A. M., Dynes, R., & Woods, R. (2016). The potential of using alternative pastures, forage crops and gibberellic acid to mitigate nitrous oxide emissions. [Article]. Journal of Soils and Sediments, 16(9), 2252-2262.

Purpose

In grazed pastures, nitrous oxide (N2O), a powerful greenhouse gas and an ozone depletion substance, is mostly emitted from animal excreta, particularly animal urine-N returned to the soil during grazing. We conducted a series of four field lysimeter and plot experiments to assess the potential of using gibberellic acid (GA) and/or alternative pastures or forage crops to mitigate N2O emissions from outdoor dairy farming systems.

Materials and methods

Pasture and forage plants assessed in the experiments included Italian ryegrass (Lolium multiflorum L.), lucerne (Medicago sativa L.), diverse pastures (including plantain (Plantago lanceolata L.), chicory (Cichorium intybus L.), perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.)), fodder beet (Beta vulgaris L.), kale (Brassica oleracea L.), as well as the standard perennial ryegrass and white clover (RG/WC) pastures. N2O was determined using a standard static chamber method in the field either on top of lysimeters or field plots.

Results and discussion

The results showed that the application of GA to urine-treated lysimeters with Italian ryegrass, lucerne or RG/WC pastures did not result in lower N2O emissions. However, the use of diverse pastures which included plantain with a lower urine-N loading rate at about 500 kg N ha−1significantly decreased N2O emissions by 46 % compared with standard RG/WC with a urine-N loading rate at 700 kg N ha−1. However, when urine-N was applied at the same rates (at 500 or 700 kg N ha−1), the N2O emissions were similar between the diverse and the standard RG/WC pastures. This would indicate that it is the N-loading rate in the urine from the different pastures that determines the N2O emissions from different pastures or forages, rather than the plants per se. The N2O emissions from cow urine from fodder beet were 39 % lower than from kale with the same urine-N application rate (300 kg N ha−1).

Conclusions
These results suggest that N2O emissions can potentially be reduced by incorporating diverse pastures and fodder beet into the grazed pasture farm system. Further studies on possible mechanisms for the lower N2O emissions from the different pastures or forages would be useful.

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Potential for forage diet manipulation in New Zealand pasture ecosystems to mitigate ruminant urine derived N2O emissions: a review

Gardiner, C. A., T. J. Clough, et al. (2016). "Potential for forage diet manipulation in New Zealand pasture ecosystems to mitigate ruminant urine derived N2O emissions: a review." New Zealand Journal of Agricultural Research 59(3): 301-317.

ABSTRACT

Nitrous oxide (N2O) emissions from agricultural soils account for more than 10% of New Zealand’s greenhouse gas emissions. Livestock urine deposition drives N2O losses from these soils. It has been speculated that non-urea nitrogen compounds (UNCs) in ruminant urine could reduce or inhibit urine patch N2O emissions. However, we hypothesise that UNCs will have no effect on N2O emissions due to their potentially rapid degradation by plants and soil microbes. Our review suggests that plant secondary metabolites (PSMs) are more likely to perform a role in reducing N2O emissions since many PSMs have known antimicrobial properties. Aucubin, found in Plantago, and isothiocyanates, found in Brassica, have been shown to inhibit a key step in N2O production. Future studies should explore this promising research gap by evaluating forages for potential inhibitory PSMs, assessing whether PSMs are excreted in urine after consumption, and determine whether excretal PSM concentrations are sufficient to reduce N2O emissions.

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Camilla Gardiner

Camilla Gardiner moved to Canterbury from the USA at the end of July 2015. Originally from Seattle, Camilla has had a passion for agriculture since high school. "I spent a term at a farm school in rural Vermont in my third year of high school", Camilla says. "Four months with forty-five other sixteen year olds, spending three hours a day on the farm plus learning about the land-based environmental sciences. I was hooked". This interest in farming led Camilla to UC Berkeley to study Environmental Sciences with honours in Soil Biogeochemistry. It was a mentor at Berkeley that encouraged her to investigate PhD options in New Zealand and provided some key contacts. Fortuitously Dr Tim Clough was looking for a student at the time and the rest is now history.

Camilla's previous research work at Berkeley primarily focused on the use of compost to sequester soil carbon, so the move to focus on nitrous oxide and urine patches has involved a steep learning curve. Her PhD project involves studying nitrogen compounds and plant metabolites in urine and identifying those which might minimise N2O emissions. The project started with a literature review and this has produced a number of interesting leads, particularly from plantain. This review is currently being revised for publication, with an aim to publish by mid-2016.

Preferring to be out in the field, rather than at the lab bench, Camilla is looking forward to her first field trial. She is currently running a lab-scale study, whilst gearing up to a larger on-farm trial. "Planning a big trial is a huge learning experience", she says. "I've previously only worked with established trials". Camilla is surrounded by a wealth of knowledge though. "I'm the youngest member in the team by quite a long way", says Camilla. "There is a lot of expertise around here to tap into!"

Moving to New Zealand has turned out to be everything that Camilla thought it would be, and more. As a keen skier and tramper, Camilla has been out exploring the scenic South Island as much as she can. The relaxed kiwi lifestyle is also growing on her. "Up until now I've lived in busy big cities. I love the laid back approach to life here in New Zealand".

Honours Student: Larissa Kingsbury

Larissa is in her fourth year (Honours) of a Bachelor of Agricultural Science in the  Agricultural life sciences (AGLS) department at Lincoln University. Larissa is supervised by Dr Rachael Bryant.

Larissa is undertaking a research project looking at whether pre-mowing pasture affects pasture intake, quality, milk production, nitrogen intake and subsequent nitrogen partitioning. 

Having grown up on northern Otago (Waitaki Plains) farm, Larissa has a strong interest in the sector and the science: "I find the science behind both the running and success of a farm extremely interesting"

Through tertiary study Larissa has "developed knowledge on animal nutrition, which includes animal health, feeding, soil science and animal production" that will help in her as an  animal nutritionist. Larissa is keen to help develop on-farm solutions so that farmers can get the best from their farm and animals.

 

Honours Student: Daniel Martin-Hendrie

Daniel Martin-Hendrie is a fourth year agricultural science student at Lincoln University. Under the supervision of Professor Tim Clough, Daniel is investigating DCD and ammonium in a lowland Canterbury Stream and what effect stream bed sediments, aquatic plants, and aeration regime have on their fate in a mesocosm study.

Daniel is a rural South Cantabrian whose discovered his interest in soil science once he started studying at Lincoln University. He is co-president of the Lincoln University Soil Society and is aiming for a career focused on rural soil management.

Honours Student: Bianca Dias

Bianca's Honours year was funded by the NZAGRC Student Scholarship Fund. For her Honours project, Bianca worked on diurnal fluctuations of nitrous oxide from the soil. She was supervised by Professor Tim Clough.

Bianca was also a Future Leader Scholar in the Environmental Science Programme at Lincoln University. She was a Co-Founder of the Lincoln University Soil Society with Aimee Robinson (NZAGRC Masters Student). 

Bianca is undertaking her PhD in Australia (Brisbane) and received a Doctoral Scholarship.

Effects of trampling of a wet dairy pasture soil on soil porosity and on mitigation of nitrous oxide emissions by a nitrification inhibitor, dicyandiamide

Ball, B.C., Cameron, K.C., Di, H.J. and Moore, S. (2012). Effects of trampling of a wet dairy pasture soil on soil porosity and on mitigation of nitrous oxide emissions by a nitrification inhibitor, dicyandiamide. Soil Use and Management.

Abstract
Urine patches in dairy pastures are major sources of nitrous oxide (N2O). Wet winters result in compaction damage to pastures because of animal trampling. The nitrification inhibitor, dicyandiamide (DCD), is effective at reducing N2O emissions from urine patches. Here, we assessed the extent of damage to the physical quality of the soil by trampling and whether this influenced the ability of DCD to mitigate N2O emissions. A field experiment was conducted where a sandy loam soil was trampled by a mechanical hoof just before urine and DCD application. Trampling reduced air permeability and pore continuity, but this had no effect on bulk density. Urine appeared to have contributed to pore collapse and blockage. Trampling increased average cumulative N2O emissions from 1.74 to 4.66% of urine-N applied. This effect was attributed to increased water-filled pore space, aggregate destruction and suppression of grass growth. DCD was highly effective in reducing N2O emissions, with the N2O emission factor of the urine-N being decreased by 58–63%. Trampling did not significantly affect the effectiveness of DCD in reducing N2O emissions.

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Sixty years of seasonal irrigation affects carbon storage in soils beneath pasture grazed by sheep

Kelliher, F. M., Condron, L. M., Cook, F. J., & Black, A. (2012). Sixty years of seasonal irrigation affects carbon storage in soils beneath pasture grazed by sheep. Agriculture, Ecosystems and Environment, 148, 29-36

Abstract

For sixty years at Winchmore, South Island, New Zealand (43°48′S, 171°48′E, 160 masl), stoney soils under continuous pasture grazing by sheep have received rainfall (nil irrigation) or rainfall and irrigation as required during summer. This consistently managed, replicated field trial presents a unique opportunity to examine long-term treatment effects on pastoral soil. Samples were recently excavated at intervals to a depth of 1 m and the total carbon (C) storage measured. In the irrigated plots, soil C storage (9.1 ± 0.3 kg C m−2, mean ± standard error, n = 3) was significantly less (p < 0.05) than in plots receiving rainfall alone (13.4 ± 0.8 kg C m−2). We estimated irrigation induced a 36% increase of C inputs to the soil on an annual basis, mostly as litter fall. Using a respiration model based on soil temperature and water content inputs, irrigation was also estimated to have induced a 97% increase in rate of annual C loss to the atmosphere. On this basis, the estimated irrigation effects had reduced C storage by 61% (97–36%), reasonably accounting for the 47% treatment effect determined by soil sampling.

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New centre at Lincoln University gets the measure of greenhouse gas emissions

Release Newsletter - August 2011

New Centre at Lincoln University (1.24MB)

 

Nitrification inhibitors - a win/win technology

Release Newsletter - December 2010

Nitrification Inhibitors (0.83MB)