Plants & GHGs

The NZAGRC’s former nitrous oxide and soil carbon work streams were combined into one programme this year. This ensures a strong overall framework, closer communication and full GHG analyses across the programme. The programme focusses on three key areas:

1. Identifying and prioritising plant traits for low GHG emissions;

2. Mitigation practices to maintain soil carbon and reduce nitrous oxide emissions at paddock scale; and

3. Defining the achievable soil carbon stabilisation capacity of New Zealand grassland soils.

Current progress and research stories

NZAGRC nitrous oxide programme focussing on the bigger picture

It's been said that in order to see the whole picture, you need to step out of the frame. That's the approach that the Principal Investigators of the NZAGRC nitrous oxide (N2O) programme and their team took whilst planning the work out to mid-2017. PIs Dr Cecile de Klein (AgResearch) and Professor Hong Di (Lincoln University) have ensured that the updated NZAGRC N2O research complements and is well coordinated with the broader nitrogen cycle and water quality related work being conducted in NZ.

"When investigating options for reducing N2O emissions, we must remember that any potential mitigation strategy is likely to have other environmental impacts", says Cecile. "Additionally, researchers that are trying to reduce nitrogen leaching, for example, need to ensure that their changes to the system aren't unintentionally increasing GHGs. Ideally, by aligning our research programmes, we can come up with win:win strategies that reduce on-farm GHGs whilst also minimising leaching and improving water quality".

In order to investigate the effect of forage species on N2O emissions, the NZAGRC-funded team is working closely with the "Forages for Reduced Nitrate Leaching" (FRNL) programme. This will allow the effects of a range of forage species on both leaching and emissions to be measured in the same trials.

FRNL is a six year Dairy-NZ led programme being conducted in partnership with AgResearch, Foundation for Arable Research, Landcare Research, Lincoln University and Plant & Food Research. The principal funder is the Ministry of Business, Innovation and Employment with all partners providing co-funding to the programme. The key aim is to reduce nitrate leaching losses by 20 percent by delivering proven, adoptable and profitable pasture and forage crop options. Dairy, arable (crop) and sheep and beef farms are involved in the cross-sector project which is focusing on three areas - alternative pasture species, crops and farm systems.

Experimental work involves investigating agronomically viable feeds that have a lower N content and feeds that have the ability to change the partitioning between urine and dung, and urine composition, such that both leaching and nitrous oxide emissions are reduced. Also, research is being conducted into the presence and role of natural nitrification inhibitors produced by the plants themselves. By sharing results with FRNL and the NZAGRC-PGgRc funded methane feeds programmes, the NZAGRC N2O team can gain a comprehensive insight into the effect of NZ based feeds and forages on N partitioning, and urinary output and composition. The overall goal is to develop feed management options for mitigating N2O emissions from NZ systems, where all major intended and unintended consequences of alternative species are well quantified.

"Working together does occasionally raise challenges, as the different groups all need to be on the same page regarding common approaches and methodologies before trials get underway", says Cecile. "On-farm trials generally need to be conducted at a specific time of year. Miss the right time, and the trial is delayed until the following year. So we don't always have as much time as we'd like to plan. However, overall there are great benefits from a scientific perspective to working collaboratively and we are much more likely to reach our goal of reducing on-farm GHGs".

 


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