Carbon and climate regulation includes soil processes that regulate the release of major greenhouse gases and contribute to the retention of carbon in the soil. An excess of greenhouse gases in the atmosphere are contributing to climate change. Carbon dioxide (CO2) is the most widely known greenhouse gas, but nitrous oxide (N2O) has a 300 times stronger effect on climate change and methane (CH4) 25 times. Soil biota play a critical role in controlling chemical reactions in the soil which contribute to the production of greenhouse gas emissions. However, the rate and amount of greenhouse gases released from the soil are strongly related to management practices, such as fertilizer application, tillage, and residue management[1].
The Carbon and climate regulation function can be defined by three main groups of processes which take place in the soil. Each group of processes are described below, these terms cover complex interactions, but simply put, they do the following:
(1) Decomposition: soil biota can breakdown dead organic matter into smaller organic or inorganic molecules in a series of small steps, for example decomposition of dead plant leaves into carbon dioxide-molecules by woodlice, springtails and fungi.
(2) Biochemical transformation: as part of their life style microorganisms can transform the chemical structure of organic matter, in a way that for example leads to the production of the most potent greenhouse gas: nitrous oxide, or the removal of methane.
(3) Resource reallocation: organic matter and soil can be mixed and/or moved around within the soil profile in different ways, for examples by earthworms that dig tunnels and pull dead leaves from the surface into the soil (bioturbation). Likewise, the threads weaved by many species of fungi glue together soil particles (aggregation). This reallocation of soil and organic matter in turn influences decomposition and biochemical transformations.
The reason that the Carbon and climate regulation function is so important, is in part because it controls the release of greenhouse gases. But processes supporting the Carbon and climate regulation function also recycle, relocate, and transfer organic material, storing molecules rich in carbon and nitrogen in such a way that they are not easily transformed into greenhouse gases. In that, the Carbon and climate regulation function is closely related to the Nutrient cycling function and it supports soil life in general.
[1] Paustrian K et al. 2016. Climate-smart soils. Nature 532: 49–57.
