Photosynthetic limits on carbon sequestration in croplands
- DOI
- Language of the publication
- English
- Date
- 2022-03-15
- Type
- Article
- Author(s)
- Janzen, Henry H.
- van Groenigen, Kees Jan
- Powlson, David S.
- Schwinghamer, Timothy
- van Groenigen, Jan Willem
- Publisher
- Elsevier
Abstract
How much C can be stored in agricultural soils worldwide to mitigate rising carbon dioxide (CO2) concentrations, and at what cost? This question, because of its critical relevance to climate policy, has been a focus of soil science for decades. The amount of additional soil organic C (SOC) that could be stored has been estimated in various ways, most of which have taken the soil as the starting point: projecting how much of the SOC previously lost can be restored, for example, or calculating the cumulative effect of multiple soil management strategies. Here, we take a different approach, recognizing that photosynthesis, the source of C input to soil, represents the most fundamental constraint to C sequestration. We follow a simple “Fermi approach” to derive a rough but robust estimate by reducing our problem to a series of approximate relations that can be parameterized using data from the literature. We distinguish two forms of soil C: ‘ephemeral C’, denoting recently-applied plant-derived C that is quickly decayed to CO2, and ‘lingering C,’ which remains in the soil long enough to serve as a lasting repository for C derived from atmospheric CO2. First, we estimate global net C inputs into lingering SOC in croplands from net primary production, biomass removal by humans and short-term decomposition. Next, we estimate net additional C storage in cropland soils globally from the estimated C inputs, accounting also for decomposition of lingering SOC already present. Our results suggest a maximum C input rate into the lingering SOC pool of 0.44 Pg C yr−1, and a maximum net sequestration rate of 0.14 Pg C yr−1 – significantly less than most previous estimates, even allowing for acknowledged uncertainties. More importantly, we argue for a re-orientation in emphasis from soil processes towards a wider ecosystem perspective, starting with photosynthesis.
Subject
- Agriculture
Keywords
- carbon sequestration,
- croplands,
- decomposition,
- photosynthesis
Peer review
Yes
Open access level
Gold
Identifiers
- ISSN
- 1872-6259
Article
- Journal title
- Geoderma
- Journal volume
- 416
Citation(s)
Janzen, H., van Groenigen, K., Powlson, D., Schwinghamer, T., van Groenigen, J. (2022). Photosynthetic limits on carbon sequestration in croplands. Geoderma, 416. https://doi.org/10.1016/j.geoderma.2022.115810