Increasing the quantity of carbon stored in agricultural soils has the potential to offset emissions of greenhouse gases to the atmosphere, while soil carbon losses would further add to those emissions.
However, realising this mitigation potential is technically challenging when soil carbon stocks are already high (as they are in New Zealand), potential changes in soil carbon are small and spatial variability is high.
The current NZAGRC programme has three distinct components:
(1) testing specific management practices that may increase the long term soil carbon store in field situations;
(2) developing and using models to predict how a range of management practices may influence long and short tem soil carbon storage; and
(3) identifying those factors that influence the stability of current or newly added soil carbon.
We have also supported international work to map on farm soil carbon and will participate in the international research programme CIRCASA.
Dr David Whitehead, Manaaki Whenua - Landcare Research (2010-present)
Professor Frank Kelliher, AgResearch (2010-2017)
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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