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
1525 Frank Kelliher, Principal Scientist (AgResearch) & Professor (Lincoln University)
Frank's presentation covered the New Zealand work on soil carbon.
He explained the concept that, like planting trees, increasing soil carbon stocks can “offset” greenhouse gas emissions and that if New Zealand could increase soil carbon stocks by 1 tonne of carbon per hectare over 1 million hectares, this could offset the rise in greenhouse gases since 1990.
Frank also pointed out that, like trees, soil carbon can take decades to accumulate but this gain can be reversed quickly if land-management practices change again. Additionally it is difficult to measure and often “you don’t know what you’ve got until it’s gone”.
Research into the New Zealand soil carbon situation has shown that although soil carbon stocks are high in many areas of New Zealand, there is strong evidence that more soil carbon could be stored.
How can this be achieved?
The team is running a major field trial at Troughton farm that is looking at farm management practices and determining the effects on soil carbon. Preliminary data suggests that pasture renewal depletes soil carbon, but that the lost soil carbon is ‘restored’ within about a year.
Pasture diversity also appears to increase soil carbon levels.
Additionally, modelling indicates that supplementary feeding may increase soil carbon levels as more carbon is being applied to the soil via excreta.
The effects of irrigation on soil carbon stocks are uncertain currently.
- 11_KelliherSoilC28April2015.pdf (1.51MB)
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