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)
What about biochar?
There is good evidence that biochar (organic matter carbonised under controlled conditions) represents a very stable form of carbon, so it could be used to store more carbon in soils. Research has indicated that specific biochars could also help reduce nitrous oxide emissions although the specific mechanisms are not yet clear; other potential benefits for improving soil functions and reducing emissions from pastures are also being tested. However, the main challenge at present to any widespread use of biochar in a pastoral system remains its cost, which makes this strategy not yet economically feasible for NZ farmers.
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