Soil management practices that enable the sequestration of atmospheric carbon into soils are considered to be one of the tools in the effort to reduce atmospheric carbon.
Carbon sequestration is the process of capturing carbon dioxide (CO2) from the atmosphere and storing it in plant material or soil. Carbon stored in soils is called soil organic carbon (SOC) and constitutes 50% of Soil Organic Matter (SOM). Farmers should regularly measure and monitor their SOC so that they can realise maximum benefits from good grassland management techniques.
Why should I aim to increase SOC?
- The SOC ensures carbon is captured from the atmosphere and reduces carbon dioxide emissions.
- In pasture-based livestock production systems, SOC also improves soil quality, soil nutrient retention and water-holding capacity.
- Carbon sequestration has the potential to help the country meet its emission reduction targets, however, values can only be accounted for in the Intergovernmental Panel on Climate Change reporting framework when Ireland can produce evidence-based Measurement, Reporting and Verification of carbon sequestration.
How do I increase the SOC in my grassland?
For grassland, the following management practices aimed at increasing livestock forage production also have the potential for improving SOC and carbon sequestration.
- Improve soil fertility levels.
- Sow favourable forage grasses and legumes such as MSS.
- Reduce the frequency of use of heavy machinery in order to avoid soil compaction.
- Optimise grazing management.
- Establish a soil monitoring programme.
- Optimise slurry and manure application.
- Minimise soil disturbance during re-seeding.
Economic and Environmental Benefits
Improved agricultural practices can help mitigate climate change by reducing emissions from agriculture and other sources and by storing carbon in plant biomass and soils. The following co-benefits can be achieved from carbon sequestration activities.
- Improved soil health: soil carbon sequestration helps restore degraded soils, which can improve agricultural productivity.
- Increased climate resilience: healthier soils make farms more resilient against both droughts and heavy rainfall.
- Reduced fertiliser use: healthier soils require less fertiliser, saving farmers money and reducing environmental impacts.
Monitoring Reporting and Verification (MRV) of carbon removal via soil carbon sequestration is currently difficult and costly, however with advances in research, MRV standards would be available in future and carbon farming is likely to have some quantifiable financial benefits.
Research at Farm Zero C
At farm Zero C soil sampling for all grazing and silage paddocks was done. The soils were analysed and baseline values for the SOC were established.
In 2021 the Department of Agriculture, Food and the Marine established the National Agricultural Soil Observatory (NASCO) and subsequently Vista Milk SFI research launched a collaborative carbon sequestration project for measuring and promoting carbon sequestration in Ireland’s agricultural lands.
Key findings from previous research include:
- Under the project 4 per mile soil,using a blanket approach for profiling global SOC stock, agricultural-managed soils had the greatest potential for carbon sequestration (Minasny et al., 2017).
- In Ireland, 29 of the 36 sites sampled had a carbon deficit > 0 implying that Irish agricultural soils have the potential to sequester carbon.
- In Northern Ireland, no permanent till meadows had the greatest carbon sequestration potential, however, such grasslands had lower dry matter yields and reduced feed units compared to arable systems.
- Implementation of good grassland management techniques can help in carbon sequestration even at deeper soil depths (Castelli et al., 2017; Kiely et al., 2017; Rodrigues et al., 2021).
Links to more research
FAO guidelines measuring and modelling soil carbon stocks and stock changes in livestock production systems
SoilC-Feasibility of Grassland Soil Carbon Survey-EPA
Soil carbon sequestration is important to meet the following broad regulations on carbon reduction and water quality.
The Nitrates and water directive Ireland
Ag Climatize roadmap 2021– The management of agricultural lands in order to enhance carbon sequestration supports the following actions of the roadmap to climate-neutral agriculture.
“Action 15: Reduce the management intensity of at least 40,000ha of peat-based agricultural soils to reduce CO2 loss.”
“Action 17: Develop a pilot scheme in relation to on-farm carbon trading to reward farmers for the public goods they are providing.”
The following companies offer services for soil carbon analysis.