December 5, 2023
Carbon sequestration (capturing carbon in soil) can be an effective tool to combat climate change. More accurate measurements of soil carbon levels require extensive and thorough attention to land use practices.
Agriculture contributes significantly to greenhouse gas (GHG) emissions. Sustainable soil management to increase stocks of soil organic carbon (SOC) provides an opportunity to offset these emissions. To achieve accurate baseline measurements and monitoring, it is essential to accurately quantify SOC levels in deeper soil layers across a variety of soil types, land uses, and management practices.
Carbon sequestration refers to the process of capturing carbon from the atmosphere and storing it in soil over time. This involves increasing the amount of carbon in the soil compared to previous baseline levels.
Giulia Bondi, Senior Researcher at Teagasc Environmental Research Center, explains: “Plants remove carbon from the atmosphere through photosynthesis and store it in tissues such as leaves and stems. When this tissue eventually dies, the carbon is deposited on the soil surface.
“Over time, this residue is broken down by soil microorganisms and some of the carbon is released into the atmosphere as part of heterotrophic respiration. carbon that has been removed from the soil and fixed or sequestered in the soil.”
stock option
The amount of these carbons sequestered in a particular soil is called the SOC stock, Julia continues.
“SOC stocks are typically expressed in units of mass per unit area, such as kilograms of carbon per hectare. Existing standard methods for assessing SOC stocks are expensive and time-consuming field and laboratory methods. Based on measurements at.
These methods include SOC concentrations measured from digested and burned soil samples in the laboratory and soil bulk density measured at depths of up to 60 cm in the field and extrapolated over a given area. will appear.
As Julia points out, carbon sequestration has the potential to be an important tool for tackling climate challenges such as global warming.
“Global warming is the long-term increase in Earth’s temperature due to the accumulation of greenhouse gases such as carbon dioxide in the atmosphere.2. Although there is a capacity for CO,2 It traps less heat than nitrous oxide or methane, and the concentration of CO2 It tends to be higher in the atmosphere. ”
Colorado in 20222 emissions account for 60.4% of the country’s total greenhouse gas emissions (excluding emissions from land use, land use change, and the forestry sector), but CHFour (methane) and N2O (nitrous oxide) accounted for 29% and 9.4%, respectively. Therefore, sequestration can help offset the warming effects associated with high concentrations of carbon dioxide and reduce global warming.2 In the atmosphere. But just as not all emissions are equal, not all soils have the same ability to store carbon.
For example, Julia explains: “Heavier soils have a better ability to bind carbon with fine soil particles such as silt and clay, and to protect carbon and form aggregates that are the basis of the soil’s physical structure. This carbon It remains protected in the soil for a long time. This is what we call sequestered carbon.”
Each soil is different and has different carbon sequestration potential. Therefore, management practices must be tailored to the carbon sequestration capacity of different soils.
Improving practice
Increasing SOC is a long-term process and results may not be immediate. Sustainable soil management practices benefit both agriculture and the environment by sequestering carbon and improving overall soil health. This process can be achieved through various practices based on reducing soil disturbance and improving land use management.
- Soil fertility management: Balanced nutrient management promotes healthy soil and plant growth, leading to improved SOC sequestration dynamics.
- Cover crops: Planting cover crops such as legumes and grasses during the main crop season is known to increase SOC, especially in the subsoil layer, due to organic matter input.
- Crop rotation: Rotating crops with different root structures and residue quality diversifies the organic matter input to the soil and increases the overall SOC content.
- Reducing traffic: Restricting heavy equipment traffic at the soil surface reduces the breakdown of soil aggregates, which protects SOC and prevents its loss to the atmosphere.
- Accumulates SOC: Applying carbon-rich organic materials such as compost, manure, and crop residue (straw) to the soil instantly increases SOC levels.
- Maintain good soil structure: Minimize soil compaction, as soil compaction reduces the rate of organic matter decomposition.
Improving SOC practices across Ireland is a key element of Teagasc’s Signpost program, Julia explains.
“The Signpost program aims to quantify SOC stocks in detail, investigate SOC landscape distribution patterns and identify factors influencing SOC stability in Irish farming systems.”
Signpost’s core principles include strategic location selection across a variety of soil types, land uses, and management scenarios.
“The Signpost program utilizes more than 100 farms and combines deep soil sampling with high-resolution analytical techniques, such as spectral analysis and SOC sequestration measurements, to elucidate the composition and stability of SOC within deep soil layers. doing.”
This study will help achieve a more accurate baseline for SOC quantification and SOC sequestration rates across different soil types, land use scenarios, and management practices. This is essential to improving the accuracy of Ireland’s soil carbon estimates from Tier 1 to Tier 2.
Ireland-specific SOC sequestration factors across the major mineral soils will be generated and can then be entered into the national inventory, Julia continues.
“This will provide the basis for incorporating agricultural soils into carbon trading schemes and life cycle assessments, supporting the sector in terms of carbon credits and reducing the carbon footprint of agricultural products.
“Signpost will contribute to the development and implementation of customized management practices to increase SOC stocks and a robust carbon accounting framework for sustainable agricultural systems. It will benefit society in managing its soils effectively.”
funding
Co-funded by a Teagasc grant and industry funding from Signpost’s funding partners. Additional support from Science Foundation Ireland and his DAFM-funded VistaMilk Research Center.
Contributor
- Julia Bondi, Senior Researcher at Teagasc-Johnstown Castle. Email: giulia.bondi@teagasc.ie
- Rachel Murphy, researcher at Teagasc Johnstown Castle.
- Connor Bracken, researcher at Teagasc Johnstown Castle.
- Karen Daley, Head of Teagasc Johnstown Castle Division (Environment, Soils and Land Use).
This article first appeared in the winter issue of TResearch and was republished in Teagasc Daily as part of World Soil Day. Click here to learn more about TResearch and access its publications.
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