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Soil Respiration

  • Soil Health

  • Biological

Summary

Soil respiration is a process wherein soil microorganisms break down organic matter, releasing carbon dioxide (CO2) into the atmosphere (Allen et al., 2011). It has been recognized as an indicator of ecosystem function and soil health, closely linked to carbon and nutrient cycling, regulation of CO2 emissions, and microbial activity (Bispo et al., 2009; Griffiths et al., 2016; Arias et al., 2005).

Additionally, soil respiration measurements have proven useful as indicators of pesticide and heavy metal toxicity (Neiendam Nielsen et al., 2002).

Functioning as an overall indicator of microbial activity in the soil, soil respiration provides insights into the rate at which organic matter, encompassing both plant litter and soil organic matter, is undergoing decomposition (Allen et al., 2011).

For more information on soil respiration you can follow the link from the South Dakota Soil Health Coalition: https://www.sdsoilhealthcoalition.org/technical-resources/biological-properties/soil-respiration/

Methodology summary

There are different methods to measure soil respiration. It can be measured by capturing and quantifying carbon dioxide (CO2) released from a re-wetted sample of air-dried soil held in an airtight jar for 4 days. Greater CO2 release is indicative of a larger, more active soil microbial community (CASH 2016). It can also be measured by determining oxygen consumption (Bispo et al., 2009).

Some commercial laboratories offer the CO2 burst test and can provide guidance. For these tests, soil is dried and re-wetted to measure a burst of biological activity. One of the most commonly used is the Solvita test (Soil Association). For a step-by-step guide on the Solvita test follow the link to Soil Association on page 12. https://www.soilassociation.org/media/8179/martinwood.pdf

See also the detailed protocol from the Cornell Soil Health Laboratory Comprehensive Assessment of Soil Health (CASH).

To collect samples for sending to a laboratory, follow detailed information on soil sampling such as where to take the samples from, how many, the best time to sample, and depth of sampling at the Farm Carbon Toolkit.

Test it yourself:
DIY basal soil respiration tests kits are available where soil is tested in its natural state. It takes just 24 hrs to complete with minimal equipment. Soil should be moist but not waterlogged, and at a temperature of 18-24ºC, when carrying out the test. Follow the link for more information.

View a video from the soil association for a tutorial.

Metric threshold or direction of change

The AHDB:

  • CO2-C benchmarks for UK mineral soils under grassland suggest a respiration rate > 180mg/kg to be soil with good microbial activity.
  • CO2-C benchmarks for UK mineral soils under cropland suggest a respiration rate of >135 mg/kg to be indicative of good microbial activity

Technological innovations

Soil microbial fuel cell (SMFC) is an innovative device initially created to produce electricity by harnessing the power of microorganisms from organic matter in soil. SMFC-based biosensors are emerging as a promising avenue for conducting real-time and swift monitoring of soil respiration to quantify microbial activity. In contrast to traditional biosensors, SMFC-based biosensors offer distinct benefits, including cost-effectiveness, straightforward design, in-situ capability, and sustained self-powering for long-term monitoring. These features make SMFC-based biosensors an appealing choice for extended, on-site assessments of soil (Abbas et al., 2022; Jin et al., 2020).

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  • Agricultural
  • Forest
  • Grassland
  • Peatland
  • Saltmarsh
  • Wetland

Scale

  • Community

Cost

  • Medium

Tier

  • Tier 2

Technical expertise

  • High

Standardised methodology

  • Yes