Soil carbon stocks in stable tropical landforms are dominated by geochemical controls and not by land use

Reichenbach, Mario; Fiener, Peter; Hoyt, Alison M.; Trumbore, Susan E.; Six, Johan; Doetterl, Sebastian

doi:10.1111/gcb.16622

Cited by 17 publications

(19 citation statements)

References 132 publications

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“…However, since these soils have relatively high concentration in 1:1 clay minerals with limited capacity to stabilize SOC, higher C input will not necessarily lead to higher SOC concentrations (Table 2; Figures 2b and 5; Khomo et al., 2017; Six, Feller, et al., 2002; Wattel‐Koekkoek et al., 2003). The potential of deeply weathered soils that dominate these regions is often limited in its capacity to stabilize C inputs (Georgiou et al., 2022; Reichenbach et al., 2023), while microbial decomposition is high (Cusack et al., 2009). Our findings thus support the idea that some of the geochemically older tropical soils in humid climate zones may be closer to SOC ‘saturation’ (Six, Conant, et al., 2002).…”

Section: Discussionmentioning

confidence: 99%

“…The same soils may be less responsive to declining plant productivity if soil minerals can efficiently retain SOC via mineral adsorption (Torn et al, 1997;Figure 6c). In contrast, soil C stocks in predominantly old, deeply weathered soils with younger SOC ages (Figure 5) might not react to climatic changes if biomass productivity continues to exceed the limited capacity of these soils to stabilize C by minerals (Reichenbach et al, 2023;Torn et al, 1997). However, these soils may be very sensitive to decreases in biomass productivity and thus plant C inputs under drier climate conditions (Figure 6c; Feller, 1993;Good & Caylor, 2011).…”

Section: Future Scenarios Of Soc Persistencementioning

confidence: 99%

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Controls on timescales of soil organic carbon persistence across sub‐Saharan Africa

von Fromm,

Doetterl,

Butler

et al. 2023

Global Change Biology

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Given the importance of soil for the global carbon cycle, it is essential to understand not only how much carbon soil stores but also how long this carbon persists. Previous studies have shown that the amount and age of soil carbon are strongly affected by the interaction of climate, vegetation, and mineralogy. However, these findings are primarily based on studies from temperate regions and from fine‐scale studies, leaving large knowledge gaps for soils from understudied regions such as sub‐Saharan Africa. In addition, there is a lack of data to validate modeled soil C dynamics at broad scales. Here, we present insights into organic carbon cycling, based on a new broad‐scale radiocarbon and mineral dataset for sub‐Saharan Africa. We found that in moderately weathered soils in seasonal climate zones with poorly crystalline and reactive clay minerals, organic carbon persists longer on average (topsoil: 201 ± 130 years; subsoil: 645 ± 385 years) than in highly weathered soils in humid regions (topsoil: 140 ± 46 years; subsoil: 454 ± 247 years) with less reactive minerals. Soils in arid climate zones (topsoil: 396 ± 339 years; subsoil: 963 ± 669 years) store organic carbon for periods more similar to those in seasonal climate zones, likely reflecting climatic constraints on weathering, carbon inputs and microbial decomposition. These insights into the timescales of organic carbon persistence in soils of sub‐Saharan Africa suggest that a process‐oriented grouping of soils based on pedo‐climatic conditions may be useful to improve predictions of soil responses to climate change at broader scales.

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Section: Discussionmentioning

confidence: 99%

Section: Future Scenarios Of Soc Persistencementioning

confidence: 99%

Controls on timescales of soil organic carbon persistence across sub‐Saharan Africa

von Fromm,

Doetterl,

Butler

et al. 2023

Global Change Biology

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“…Multilayers of TOC or macromolecular OC-Fe complexes to preserve TOC when particle surfaces become saturated (Chen et al, 2014;Li et al, 2023). Previous study also reported that there was no correlation between TOC fractions and pH, Fe ox (1.7-4.2 g/Kg), or Al oxides Al ox (1.7-4.2 g/kg) in topsoils (0-20 cm) in subtropical China, while effects of Fe ox on soil properties was significant (Mao et al, 2020), and the specific mineralogical properties and reactivity determine TOC stocks in tropical forest and cropland and was constrained by soil mineralogy (Reichenbach et al, 2023). In additional, recent study found that maybe only carboxyl-rich TOC coprecipitated with ferrihydrite becomes more stable in the solid phase (Zhao et al, 2022), and in turn TOC occurrence can delay the conversion of Fe (hydroxyl) oxide to iron minerals with higher crystallity (Pasakarnis et al, 2014).…”

Section: Correlation Between Toc and Iron Statesmentioning

confidence: 90%

“…Most studies have discussed the mechanism for stabilizing TOC by iron minerals in continent soil and in the lakes, salt marsh wetlands, or ocean sediments (Lalonde et al, 2012;Ma et al, 2018;Reichenbach et al, 2023;Zhao et al, 2023). The TOC sequestration controlled by iron minerals is complicated and strongly related to the redox conditions of sediments (Hartnett et al, 1998;Hemingway et al, 2019).…”

Section: Correlation Between Toc and Iron Statesmentioning

confidence: 99%

Vertical distribution of Fe, P and correlation with organic carbon in coastal sediments of Yellow Sea, Eastern China

Gao

Chen

et al. 2023

Front. Mar. Sci.

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The coastal zone is considered as a major carbon pool. Iron minerals and phosphates are vital factors affecting the amounts and occurrence of total organic carbon (TOC) in sediments. However, coupling mechanisms of iron (Fe) and phosphorous (P) in the source-sink transition of TOC in coastal sediments is poorly understood. This study characterized the distribution of Fe, P and TOC contents of three independent 170 cm sediment cores sampled from a coastal aquaculture area in the eastern Jiangsu Province, and quantified the correlations among Fe, P, median grain diameter (Dx(50)), and TOC. The results showed total phosphorus (TP) content ranges in a scope of 337.4-578.0 mg/kg, and many depths recorded moderate P eutrophication. Inorganic phosphorus (DA + IP) and biogenic apatite were the primary components of TP, accounting for 25.19–55.00 and 26.71–49.62%, respectively. The Fe contents varied from 987.9 mg/kg to 2900.7 mg/kg, in which oxidized iron (Feox) accounted for about 62.2–79.4%. In the vertical profile, the TOC was positively correlated with the contents of low-crystallinity Fe-bearing carbonates (Fecarb), high crystallinity pyrite (FePy), iron-bound phosphorus (PCDB), manganeses (Mn), and nitrogen (N), while it was negatively correlated with DA + IP, organic phosphorus (OP), and Dx(50). Based on the the partial least squares (PLS) model, we proposed that the higher FePy, Mn, magnetite (FeMag), Fecarb, PCDB, amorphous exchangeable Fe (Ex-Fe), and authigenic apatite phosphorus (Bio-P) in sediments represent the high capacity for TOC sink, whereas, higher DA + IP, and OP indicate a TOC conversion to the source. The non-siginificat indication of Feox on TOC source-sink is due to its surplus and strong reactivity relative to TOC content. These revealed correlations provide a theoretical reference for understanding and regulating the burial rate and storage of TOC by changing the input of Fe minerals and P components into coastal sediments.

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“…Our study provides direct evidence to support the earlier call by Rasmussen et al (2018) to consider type and reactivity of minerals rather than only the clay content for predicting soil OM content. It adds to the demonstrated superiority of other predictors, such as the concentration of pedogenic oxides (Herold et al, 2014;Kirsten et al, 2021;Rasmussen et al, 2018;Reichenbach et al, 2023).…”

Section: Impli C Ati On S and Outlookmentioning

confidence: 99%

Formation of mineral‐associated organic matter in temperate soils is primarily controlled by mineral type and modified by land use and management intensity

Bramble,

Ulrich,

Schöning

et al. 2023

Global Change Biology

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Formation of mineral‐associated organic matter (MAOM) supports the accumulation and stabilization of carbon (C) in soil, and thus, is a key factor in the global C cycle. Little is known about the interplay of mineral type, land use and management intensity in MAOM formation, especially on subdecadal time scales. We exposed mineral containers with goethite or illite, the most abundant iron oxide and phyllosilicate clay in temperate soils, for 5 years in topsoils of 150 forest and 150 grassland sites in three regions across Germany. Results show that irrespective of land use and management intensity, more C accumulated on goethite than illite (on average 0.23 ± 0.10 and 0.06 ± 0.03 mg m−2 mineral surface respectively). Carbon accumulation across regions was consistently higher in coniferous forests than in deciduous forests and grasslands. Structural equation models further showed that thinning and harvesting reduced MAOM formation in forests. Formation of MAOM in grasslands was not affected by grazing. Fertilization had opposite effects on MAOM formation, with the positive effect being mediated by enhanced plant productivity and the negative effect by reduced plant species richness. This highlights the caveat of applying fertilizers as a strategy to increase soil C stocks in temperate grasslands. Overall, we demonstrate that the rate and amount of MAOM formation in soil is primarily driven by mineral type, and can be modulated by land use and management intensity even on subdecadal time scales. Our results suggest that temperate soils dominated by oxides have a higher capacity to accumulate and store C than those dominated by phyllosilicate clays, even under circumneutral pH conditions. Therefore, adopting land use and management practices that increase C inputs into oxide‐rich soils that are under their capacity to store C may offer great potential to enhance near‐term soil C sequestration.

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Soil carbon stocks in stable tropical landforms are dominated by geochemical controls and not by land use

Cited by 17 publications

References 132 publications

Controls on timescales of soil organic carbon persistence across sub‐Saharan Africa

Controls on timescales of soil organic carbon persistence across sub‐Saharan Africa

Vertical distribution of Fe, P and correlation with organic carbon in coastal sediments of Yellow Sea, Eastern China

Formation of mineral‐associated organic matter in temperate soils is primarily controlled by mineral type and modified by land use and management intensity

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