1. Introduction

1.5. Soil Depth and Sampling Considerations

Unlike the atmospheric or oceanic inventories that are entire, soil carbon stocks are often inexplicably and unrealistically measured in only the top 20–30 cm or perhaps the top metre or so, and the Soil Survey soil depth was often to just 1 or 2 m. This is unrepresentative as peats can be 200 m deep, permafrost 1.6 km, and mineral soils up to 3.1 km with global mean soil depth 13.1 m blending into underlying bedrock often with several metres (mean ~8 m?) of friable saprock (Shangguan et al. 2017: Table 1, Hicks-Pries et al. 2023, Blakemore 2024 – https://vermecology.wordpress.com/2024/02/20/dtb-2/). Pettier et al. (2014) noted that sedimentary deposits in lowlands generally exceed the 2 m depth limit of most soil surveys.

Moreover, soil samples cores are taken perpendicular to the centre of the Earth and values extrapolated based upon planimetrically flat land biomes. Whereas actual land is sloping and hilly at macro-scale and the soil is bumpy and rugose at micro-scales.

Factoring in full soil depth and terrain, ups soil carbon stocks and rates considerably.

Stones are removed or sieved from soil samples and are reported separately, as are visible roots, earthworms and other larger biotic inclusion that may or may not be measured. For this reason, estimates of both roots and earthworms are provided in this report.

As a starting point for review, are unrefined soil data in the reports in Table 1.

Table 1. Summary of terrestrial organic carbon stocks and cycles (in Gt C or Gt C/yr).

Table 1. Summary of terrestrial organic carbon stocks and cycles (in Gt C or Gt C/yr).

Entity (Gt C) /Citation	IPCC (2013)*	Blakemore (2018b, 2023)	(IPCC 2021)*	GCB (2023)*
Soil Organic Carbon (SOC)	~1,950	>8,580	1,700	1,700
Permafrost (SOC)	1,700	(included)	1,200	1,400
Total soil SUC	~3,650	>8,580–15,000	2,900	3,100
Vegetation biomass	550	~2,000*	450	450*
NPP Gt C/yr	61.5	>220**	71***	65**

* Prior reports based upon non-desert, non-ice, flat land surface of ~12 Gha, rather than 24 Gha as per Blakemore (2018b), have only been modified slightly in the last decade. Most plant measurements are of above-ground parts, almost aways ignoring below-ground roots and exudates that likely double biomass and NPP data, plus terrain and soil relief that double values again. **Doubled for soil depth factors, 65 NPP is 130 Gt C/yr; doubled again for ignored terrain is 260 Gt C/yr. ***Rodin et al. (1975) NPP was 71 Gt C/yr.

2. Methods

3. Results and Discussion

3.6. Glomalin and Glomalin Related Soil Proteins (GRSP)

A summary paper by Irving et al. (2021) confirmed that glomalin-related soil proteins (GRSPs) are thought to represent c. 20% of the soil organic carbon and aid carbon sequestration by stabilising soil aggregates. For farmlands, USDA (www.ars.usda.gov/ARSUserFiles/30640500/Glomalin/Glomalinbrochure.pdf) say: “Glomalin accounts for a large amount (about 15 to 20%) of the organic carbon in undisturbed soils.” As noted in the introduction, He et al. (2020) report that GRSP may account for around 27% of total SOC but in ancient, oxidized soil (>4 million years old), GRSP was less at about 4% of total C, whereas in a peat soil, purified GRSP was as high as 52% of the total SOC. The "Rillig et al. 2000" reference from He et al. (2020) appears to be mistaken, but another paper by Schindler et al. (2007) does have 52% glomalin in peat, viz.: "GRSP accounted for 25% and 52% of total C in the mineral soils and organic soil [peat], respectively." This implies that to account for difficult-to-extract glomalin, measured peat SOC may (always?) be doubled. It has been shown that GRSP can contribute about 27% of SOC while soil humus may contribute only about 8% of carbon, thus the carbon contribution capacity of GRSP is 2–24 times that of soil humus (Rillig et al. 2001). The GRSP status of permafrost is uncertain and urgently requires more study as its contribution may be substantial.

Conversely, Sanderman et al. (2010) while admitting that some studies at that time indicated glomalin as high as +27% in SOC, claimed 0.7 to 2.4% appear more common for agroecosystems which may be partly true for intensive, agrichemical fields which are depleted in both humus and soil biota (as in Blakemore 20218a). Their understanding at that time suggested values much above 2% of SOC were unreasonable based on the NPP they calculated would be needed to support AMF hyphal growth (in their Appendix II). In other words, if glomalin was as high as reported they would need to change their NPP models. This is not a proper Scientific approach as the data should speak for itself, regardless of ideals. Since glomalin is measured up to 30 or 52% of SOC, what they have unwittingly done is support the need for NPP models to be substantially increased, as herein, up to 220 Gt C/yr.

Current information is scant and based upon few studies, but confirmation of importance and contribution of GRSP to total SOC as outlined in Irving et al. (2021) are found in a study by Zhang et al. (2023) showing GRSP (in total?) in cropland and forests making up 24% and 18% of the 20–25 g/kg SOC, respectively. They reported that total GRSP accounted for 8.19%–73.70% of SOC in the forest soils and 4.33%–86.11% in croplands, while easily extracted GRSP was obviously less, at 1.00%–10.38% or 1.09%–12.37%, respectively, of SOC totals. This demonstrates that glomalin is a non-trivial SOC addition. Their summary figure gives an indication of respective fungal and bacterial components (Figure 11).

Figure 11. From Zhang et al. (2023: Figure 8) of SOC with abbreviation of MNC for Microbial necromass-C; EE- and T-GRSP for easily extractable and total Glomalin Related Soil Proteins; AMF for Arbuscular mycorrhizal fungi; BRC and FRC for Bacterial and Fungal Residual carbon. GRSP made up 24% or 18% of 20.4 or 25.1 g/kg SOC stocks, respectively. Of note, outside GRSP, bacterial BRC contributes about 15% of total SOC carbon.

Figure 11. From Zhang et al. (2023: Figure 8) of SOC with abbreviation of MNC for Microbial necromass-C; EE- and T-GRSP for easily extractable and total Glomalin Related Soil Proteins; AMF for Arbuscular mycorrhizal fungi; BRC and FRC for Bacterial and Fungal Residual carbon. GRSP made up 24% or 18% of 20.4 or 25.1 g/kg SOC stocks, respectively. Of note, outside GRSP, bacterial BRC contributes about 15% of total SOC carbon.

Moreover, Cisse et al. (2023) recently found glomalin particularly important in (fungal dominated?) acid soils of coniferous forests which are abundant in the boreal North.

3.9. Total Global Soil SOC Refined

As noted in the Introduction, estimations for global soils differ widely, due in part to overlap between precise biomes definitions, due too to inadequate allowance for full soil depth (now >13 m on average), and neither for terrain factors nor errors from analyses.

Soils occupy about 12 Gha on a conventionally flat landscape of 15 Gha that is not ice-covered nor arid desert, now raised up to 24 Gha soil on 32 Gha total (Blakemore 2018).

Estimates of global SOC generally range around ~3,000 (IPCC or GCB in figures above) or as FAO (2022) summarize: "The global SOC stock of ice-free land contains about 1500-2400 Pg C (1 Pg = 1 Gt) in the top 1 m, 2300 Pg C in the top 3 m, and 3000 Pg C in the soil profiles.” Higher figures by Crowther et al. (2019: Figure 2C) have SoilGrid values to 4,595 Gt C (not 1,500 Gt C as stated) and Wang et al. (2022: Table 1) had SOC stock 0–2 m depth from latest WISE and SoilGrids data sets of 2,815–5,796 Gt C with median value of 4,305.5 Gt C.

Although almost any interim value from the wide range given could be taken as a starting point for refinement, a moderate median value is perhaps around 3,600 Gt SOC.

Doubled for depth and then again for terrain gives 14,400 Gt SOC, plus a third glomalin to total more than 19,000 Gt SOC plus +25% saprock sums up to ~23,750 Gt SOC.

Conversely, since glomalin and saprock are calculated as additions to baseline value, from ~3,600 Gt SOC, adding a third for glomalin/GRSP is 4,800 Gt, plus +25% for saprock is 6,000 Gt, then doubling for both depth and terrain gives approximately 24,000 Gt SOC.

For proper analysis, total values may to be divided into major soil constituents. In particular, SOC stocks are broadly sub-divided between mineral soils, Permafrost, peats, plus soil biota. Following is separate treatment for each component to compare outcomes.

3.9.1. Mineral Soils

Mineral soils are formed from biotic weathering of parent rocks and are primarily composed of inorganic material usually defined as having less than 17% living SOC compared to “Organic soils” like peat (not to be confused with the carbon enriched soils as found on organic farms). According to the Soil Classification Working Group, organic soil horizons may contain >17% SOC (or >30% of SOM) by weight, and these occur in Organic soils, or may be present at the surface of mineral soils. All soils are living entities, and a precise definition of a mineral soil is: “A soil consisting predominantly of, and having its properties predominantly determined by, mineral matter. It usually contains <20% organic matter [i.e., <10% SOC] but may contain an organic surface horizon up to 30 cm thick”. Permafrosts are perhaps entirely (or mostly?) excluded from this definition except where they are discontinuous or sporadic intergrades that may overlap with other soil types.

Mineral soils are the most productive for forest and farmland. Total mineral soil SOC is difficult to determine accurately but can be calculated from best current estimates, or deduced from total soil SOC less the peat and permafrost components.

Perhaps a reasonable starting point is Jackson et al. (2017) who explicitly account for mineral soils with 1,263 Gt SOC up to two metres depth and 199 Gt SOC in 2–3 m deep soil (with zero below this, thus omitting deeper delta, alluvia or loess) to total (1,263 + 199 =) 1,462 Gt SOC. Doubled for depth, and again for terrain is 5,848 Gt SOC. Adding 25–30% glomalin/GRSP is ~7,000 Gt SOC plus 26% saprock C possibly sums to 8,650 Gt SOC total.

This is the most conservative total as other calculations of basic mineral soil SOC are higher. For example, Georgiou et al. (2022: supplementary tables 1 and 2) for global “mineral soil” (excluding tundra, peatlands, and deserts) for what they call “topsoil” (<0.3 m) plus “subsoil” (0.3–1.0 m depth only!) of (700 + 701 =) had 1,401–1,765 Gt SOC from SoilGrids, with median value about 1,583 Gt SOC. This is above the mineral soils Jackson et al. to fully 3 m depth (1,462 Gt SOC) but seems to ignore Jackson et al.’s 199 Gt SOC in 2–3 m.

Surprisingly, Sokol et al. (2022: Figure 1) had higher SOC values (of Mineral Associated OM and Particulate OM) to just 1 m depth from various data set range 1,390–2,470 Gt SOC excluding peats, but, again, contribution of permafrost to these values is unclear (if at all).

Jobbágy and Jackson (2000) for all soil types found “Global SOC storage in the top 3 m of soil was 2344 Pg C, or 56% more than the 1502 Pg estimated for the first meter (which is similar to the total SOC estimates of 1500–1600 Pg made by other researchers). Global totals for the second and third meters were 491 and 351 Pg C, and the biomes with the most SOC at 1–3 m depth were tropical evergreen forests (158 Pg C) and tropical grasslands/savannas (146 Pg C).” Therefore, it may reasonably be assumed that SOC values are more than doubled for depth. There is some ambiguity if the forested permafrost is involved in “mineral soils” although tundra, the treeless land with underlying permafrost in the Arctic North, is explicitly excluded.

In summary, mineral soils of ~1,500 Gt SOC, doubled for terrain then full depth (× 4), is ~6,000 Gt SOC; adding ~25% glomalin/GRSP and ~25% saprock C, totals ~9,000 Gt SOC.

Conversely, 1,500 Gt plus 30% GRSP and 25% saprock is 2,500 Gt × 4 = 10,000 Gt SOC.

3.9.2. Permafrost

Permafrost, occupying 11–15% of land area, is a major soil SOC store and carbon cycle contributor. It is both remarkably old (>2.5 million years) and deep – areas with continuous permafrost are often >100 meters thick and the deepest in Siberia extends down 1,650 meters (https://nsidc.org/learn/parts-cryosphere/frozen-ground-permafrost/science-frozen-ground). It is treated in some detail already, also in Blakemore (2023) – “3.2.1 Biotic Boreal Permafrosts Reconsidered but Not Reconciled”. It is not intended herein to repeat all information provided there, rather just an updated summary.

Schuur et al. (2022), somewhat ambiguously, separated “waterlogged peatlands” from “organic carbon stored deep in permafrost mineral soils” within the northern circumpolar permafrost region they said was “tripled to 1,460–1,600 petagrams of carbon” (median 1,530 Gt C) including Yedoma and deeper delta deposits. They divided permafrost carbon thus:

1

Near-surface permafrost soils (0–3 m) – 1,035 Gt SOC;

2

Yedoma deposits of Siberia and Alaska (>3 m) – 327–466 (median 397 Gt C);

3

Arctic river deltas (at soil depth >3 and up to 60 m deep) – ~96 Gt C;

4

Qinghai-Xizang (Tibet) Plateau and northern China (to full depth?) – ~36 Gt C;

5

Deep deposits outside the Yedoma region (to > 3 m?) – 350–465 (median 408 Gt C);

6

[Subsea permafrost ∼560 Gt C herein ignored in the current terrestrial C stocks].

Strangely only including 1 to 3 categories, rather than median 1,530 Gt C, their new median value for permafrost to depth is (1,035 + 397 + ~96 + ~36 + 408 =) ~1,972 Gt SOC.

A surprising omission is citation of Shelef et al. (2017) who added 2,000 Gt C.

In brief, rather than ~1,972 as per Schuur et al. (2022) given above, the “official” IPCC and GCB data (Figures and Table in Introduction) show between 1,200–1,700 Gt SOC (median ~1,450 Gt SOC). But it was unclear whether or not this included peat. As noted, although Tarnocai et al. (2009) implied about 200 Gt C in permafrost peat, Jackson et al. (2017) estimated ∼300 Gt in the boreal region, whereas Hugelius et al. (2020) had Northern peatland store of 415 ± 147 Gt C, of which just 185 ± 66 Gt C is in permafrost-affected peatlands. Thus, a most conservative permafrost value would be about (1,450 - 300 =) 1,150 Gt SOC that is about the same as Jackson et al. figure, less peat, to >3 m depth. However, Tarnocai et al. (2009) higher permafrost figure to greater depth (3–25 m) of 1,672 Gt, of which 1,466 Gt was permafrost (i.e., ~206 Gt peat?). A baseline permafrost mineral soil is ~1,500–2,000 Gt SOC.

The baseline estimated in Shelef et al. (2017) was 1,300 Gt SOC for which: “Northern circumpolar permafrost soils contain more than a third of the global soil organic carbon pool (SOC).” Their study combined topographic models with (full?) soil profile data and topographic analysis to evaluate the quantity of permafrost SOC deposits finding an approximate >200% uncertainty that may also pertain at a circumpolar scale. For perennially frozen soil in the upper 3 m of circumpolar permafrost terrain, from an initial overall estimate of 822 Gt C, their uncertainty was up to >200% (or × 3 times) the prior estimates of SOC mass. They said: “SOC mass stored in perennially frozen hill toe deposits alone vary from few percents to more than double of current SOC estimates.” They indicate mean values of ∼550 and ∼720 Gt C for the linear and sigmoidal profile geometries, respectively, with a maximal uncertainty of >2,000 Gt C they said was similar to estimates of “global SOC mass” in 0–3 m depths amounting to 2000–3000 Gt SOC.

Their study somewhat validates the rationale to double soil samples for both depth and terrain. Moreover, their distinction between linear and sigmoid models (Shelef et al. 2017: Figure 3f–g) endorses the argument for using curved arc lengths rather than straight lines in Blakemore (2018: Figure 9). They found volume of ∼530 and ∼790 km³ for the linear and sigmoidal profile geometries (difference +49%). Their new mean carbon values were 25 vs. 25 and ∼550 vs. ∼720 Gt C for the linear and sigmoidal models (+31–40% different) indicating the importance of realistic and representative curves to topographic or terrain models, at all scales (as per Blakemore 2018).

Notwithstanding general terrain considerations, permafrost SOC has large uncertainties for proper depth sampling are perhaps slowly being resolved, thereby increasing SOC totals. Thus, rather than multiplying current estimates for both depth and terrain, it is perhaps more circumspect to combine almost certain underestimations (mainly for terrain rather than depth).

Adding to prior boreal Permafrost median value from Schuur et al. (2022) of ~1,972 Gt C to depth >3 would then possibly be doubled mainly for terrain, not extra depth, to ~4,000 Gt SOC.

It is unlikely deep permafrosts would gain much from saprock, but initial indications are of glomalin/GRSP achieves at least 25%, thereby possibly adding >1,000 Gt SOC.

This would be expected since research has shown a directly positive relationship (r=0.62) between GRSP and soil organic C content (Lovelock et al., 2004) and since glomalin, as a fungal derived product, is likely highest in the boreal peat and permafrost realms as per Hu et al. (2000: Tables 1–2, Figure 3a). There is preliminary evidence of glomalin/GRSP in boreal region (Vlček and Pohanka 2020, Wang et al. 2021) and frozen permafrost may have relatively undecomposed GRSP compared to typical soils. Despite evidence of importance, few reports are on GRSP in permafrost (nor peats!), an open arena that may merit greater research effort.

Thus, in conclusion, a refined evaluation of permafrost mineral soils is >5,000 Gt SOC.

3.9.2. Peat – Mired in Speculation

Despite occupying only about 2–4 % of land surface area (now, due to terrain, reduced to 1–2 %), peatland peat habitat potentially holds the single most abundant organic carbon stock on Earth, this without factoring in terrain due to them being waterlogged.

For peatlands, as was noted in the Introduction, Jackson et al. (2017), assuming a maximum depth (or mean depth?) of 2.3 m, summed ~675 Gt SOC. A subsequent Global Peatlands Assessment (UN 2022 https://globalpeatlands.org/resource-library/global-peatlands-assessment-state-worlds-peatlands-main-report) had a lower global peat total "in the range of 450,000 to 650,000 megatons [Mt] (FAO 2020)" (= 450–650 Gt C). This seemingly also ignored the >1,000 Gt C from Nichols and Peteet (2019, 2021) and global Peatlands with 1,123 Gt C from Loisel et al. (2021: Tables S4–S5). These latter authors stated: "The post-LGM C stocks estimated via expert elicitation (Tables S4 and S5) add up to 808 GtC and 315 GtC for high-latitude and tropical peatlands, respectively (based on arithmetic mean values)".

Strangely, Almesbury et al. (2019) had already arrived at this conclusion stating: "Northern peatlands store over 1000 Gt carbon, almost double previous estimates". This is more than double some other estimates of Northern peatland at 415 ± 147 Pg C in peat, of which 185 ± 66 Pg C is located in permafrost-affected peatlands (Hugelius et al., 2020).

Since Nicols & Peteet (2019, 2021) increased estimates of total northern peat carbon stocks from 545 Gt C to between 995–1,055 Gt, if Loisel et al.’s (2021) 315 Gt C of tropical peatland and UN-EP's 15 Gt C in southern peatlands are added to their northern peat values, the global peat total is 1,325–1,375 Gt C. This is more than twice an official 600 Gt C and slightly above the more modest 1,123 figure in Blakemore (2023), but this too is low.

Often peats are measured to only 30 cm or possibly a meter, with a weighted depth for northern peatlands of 2.3 m (Gorham 1991: Table 1). This is likely an underestimate. Hugelis et al. (2020 Table 1) had all peatland area of just 3.7 million km² and mean peat depth slightly more at 2.5 m. Yet, Nichols & Peteet (2021: Figure 2B,C) show mean depth about 4 m and area up to 5 million km² (just in the north), so possibly doubling of 1,325-1,375 Gt C for extent and depth may comply as being a reasonably correct adjustment.

Moreover, on tropical peat depth and carbon stocks, Verwer and van der Meer (2010) had: "The best estimate of average peat thickness was 5.5 m and 7 m for Indonesia and Malaysia respectively" and Page et al. (2011) expand on this: "The thickest peat deposits in this assessment are in Africa with best estimates of mean peat thickness of 11 m in Rwanda, 8 m in Burundi, 7.5 m in Congo, 5 m in Nigeria and 4 m in both Democratic Republic of Congo and Uganda. In Southeast Asia the thickest peat is in Malaysia and Brunei (7 m) followed by Indonesia (5.5 m). In Central America and the Caribbean, peat is thickest in Panama with a best estimate of 6 m, followed by Jamaica (5 m), Cuba (1.8 m) and Trinidad and Tobago (1.3 m). There is no information on peat thickness for most other countries in this region and the default best estimate of 0.5 m has been applied to them. South American peats seem to be shallower with a mean thickness of 4 m in Venezuela, 2 m in Brazil and 1.75 m in Peru." Their total tropical peat tally was 88.6 Gt C, as already noted, but Dargie (2015) revised tropical peats up to 115.8 Gt C, but this is lower than Ribeiro et al. (2021) with tropical peat, to mean depth around 3.5 m of up to 220 Gt C, yet lower than Loisel et al. (2021) with 315 Gt C in tropical peatlands. Gumbricht et al. (2017) found more tropical peatland in South America than in SE Asia, and to greater depths than previously estimated, they "report 350 GtC, more than three times current estimates" of 88 Gt C by Page et al. (2011). Ricardo et al. (2022) have: "Tropical peatlands play an important role in the global carbon cycle due to their immense storage capacity, preserving between 469 and 694 Gt C in a relatively small area (90–170 Mha), equivalent to one third of the total global carbon pool" but I cannot trace all their sources.

Omar et al. (2022) expand on SE Asia data but a summary in their report is elusive.

Scharlemann et al. (2014) clearly stated: "many peat soils in both the tundra and tropics have been reported to be, respectively, over 3 m deep containing 1672 Pg C and up to 11 m deep containing 89 Pg C, effectively doubling the global SOC stock estimates based on profiles to only 1 m depth. Jobbágy and Jackson report that measurements to 3 m depth yielded estimates of SOC stocks 1.5-times larger than those to 1 m depth”. Total peat in Scharlemann et al. (2014) is 1,683 Gt SOC, but errors regarding their peat depths are remarked on in the Introduction.

Additionally, Ribeiro et al. (2021) have tropical peat, to mean depth around 3.5 m, of up to 220 Gt C that although shallower, is twice Scharlemann et al.'s estimated 89 Gt C.

Therefore, assuming ~2 m peat depth seems unrepresentative so an estimated 1,325–1,375 Gt C, doubled for true depth ranges in boreal and tropical peats, is 2,246–2,750 Gt C.

However, if Nichols & Peteet (2019) value of ~1,030 Gt C in Northern peatlands does allow total depth, the additional 315 + 15 = 330 Gt C in other regions, doubled (or quadrupled?) for depth of 2 m (or 4 m?) to 660 (or 1,320?), when added, totals >1,690 Gt C (or 2,350 Gt C?), plus ~10-30% glomalin may round up to >2,400 Gt C in peat. But if missed glomalin is truly ~50% then total range is 2,535–3,525 with a median value ~3,030 Gt SOC.

Alternatively, Nichols & Peteet (2021: Figure 2) imply, mean boreal peat depth of 4 m rather than 3 m, then seemingly 25% may be added to this tundra peat to give about 2,230 Gt with 220 Gt in tropics and another 15 Gt in the southern peatlands, also doubled for depth to 30 Gt, to now total about 2,350 Gt C. If the missed 10-50% glomalin (upper value 1,175 Gt C?) is added a grand total is raised again, possibly as high as up to 3,525 Gt SOC.

Due to being waterlogged, peat does gain from terrain, and a recent report (Blakemore 2023 - https://vermecology.wordpress.com/2023/06/14/missed-peat//) summarizes peat carbon issues, noting the oft citation of a mere 600 Gt C in peatlands, yet the best guess answer to date from official “experts” is 1,325-1,375 Gt C global peat; at least doubled for peat > 1–2 metres (as justified in detail) to about 2,700 Gt C plus glomalin (as noted above) that may add 50% (2,700 + 1,350 =) then a new grand total is~4,050 Gt C.

A further consideration in broader view of total carbon is peat-derived fossil lignite.

Extending the issue and accepting OurWorldinData data ratio of lignite as ~30% of all coal totals, then lignite is around 3,000 Gt C which may be added to my global fresh peat estimate above of up to 4,500 Gt C. Global peat or peat products then sum as Earth’s largest single organic carbon store with total peat/product (4,500 + 3,000=) ~7,500 Gt C.

Difficulties are that lignite usually measured in fossil fuel inventory, thus is excluded, and glomalin likely reduced with depth/age, to restore a reasonable value 4,050 Gt C.

It was noted in a report from Exeter University around 2021 (https://web.archive.org/web/20211105134124/http://www.exeter.ac.uk/news/research/title_829842_en.html) that: "Peatlands are currently excluded from the main Earth System Models used for climate change projections – something the researchers say must be urgently addressed”. This is borne out by the current report enlarging peat biomass more than tenfold from 600 Gt to over 6,000 Gt with lignite, or a median value around for peat alone of 3,500 C.

In conclusion, peat of all ages or depths is >7,500 Gt C, less lignite is ~4,050 Gt SOC.

3.9.3. Sediment Organic Carbon (SeOC) Stocks

Landlocked aquatic or semi-aquatic systems are said to occupy 1–2% of land surface, now halved, as, unlike soils, they do not gain from terrain, and neither do their C budgets.

Herein the intermittently inundated areas, such as floodplains, thaw lakes, or paddy, are not included yet the carbon stored in permanent waterways and non-marine sediments is not trivial. Lake sediments alone are estimated to contain 820 Gt of organic carbon (SeOC) (Cole et al. 2007: 176, Tranvik et al. 2009: 2301). River storage is unknown but is probably at least as large (consider Mekong, Amazon, Yangzi, Congo or Indus, e.g. (Williams 2012). From Cole et al. (2007: Table 1) a rough estimate based upon carbon efflux rates may be twice the lake storage, or ~1,640 Gt SeOC riverine storage. The global total then best guessed around ~2,500 Gt SeOC.

This is relevant as a partial and rapid remedy for loss of topsoil, also a traditional practice, is to dredge waterways and lakes (after determining that levels of toxic metals and other poisons in the sediments are within tolerable levels. Like any other biological intervention, it does not need to be complete dredging, just a reasonable proportion to allow restoration of as much of the sediment, litterfall and dissolved organic matter (DOC) that originates in the topsoil before it is eroded/leached. Howard (1935) notes King’s mention of ancient Chinese practice of mixing fresh organic/leguminous plants with dredged canal mud silts for fertile composts.

3.9.4. Litter/Log Stock Biomass

Estimates of global litter carbon are scarce often, but not always, included in the total SOC. However, IPCC (2001: Figure 3.1d) and Houghton et al. (2007: Figure 1) separate soil “litter” at 300 Gt C and an annual input is supposedly ~60 Gt C/yr in NPP residues. Their 300 Gt C in soil litter (and logs?) was possibly derived from Matthews (1997) report of (160 fine + 150 coarse =) 310 Gt “dm = dry matter” with “rarely included” belowground litter. This value should properly be halved for carbon to 155 Gt C but doubled again for terrain to 310 Gt C. Matthews also noted “including standing and fallen dead wood may increase estimates of the fine litter pool by ~40%”. Compare this to Reiners (1973 from “Bolin 1970”) that has humus, mulch, etc. “detritus” at ~700 Gt C. Yet, if reasonably assuming Houghton’s 300 Gt C value was correct, as adopted herein, the updated total, doubled for terrain, remains as ~600 Gt C as per Blakemore (2020a, 2020c: Figure 3).

Interestingly, Bar-On et al. (2018) estimates based on global field observations of plant litter at about ≈80 Gt C. They say the microbe biomass (of bacteria, archaea, fungi and protists) is less than 1% of total organic carbon mass in litter, meaning microbial biomass in litter would not surpass 1 Gt C. However, if, as here, litter is 600 Gt C, its microbe biomass is ~6 Gt C.

As already noted, forest litter and logs have better estimates as being 73 Gt and 43 Gt, respectively, to total 116 Gt C. Often unrecorded are the below-ground dead root stock and root litter that may themselves possibly amount to at least half as much as the above-ground stocks, say ~60 Gt C. It may be assumed that the remaining 60% of non-forested land surface has a considerable stock too, possibly at least as large as the above-and below-ground forest litter, say (73 + 60 =) 133Gt C. The forest and non-forest, litter/logs then total (116 + 133 =) ~250 Gt C. In addition, crop residues and smaller inputs from animal herbivory and manuring contribute to a total validating the 300 Gt C as a reasonable amount. This estimated value is reasonably doubled for terrain, justifying the total global litter and log stock of ~600 Gt C.

3.9.5. Biocrust and Phytomenon – Biomass and Contribution to NPP

Biomass of biocrust and phytomenon (e.g. soil algae and cyanobacteria), although amounting to 10–20 Gt C (Blakemore 2023), are often ignored as relatively trivial components of the terrestrial biome. Yet their biomass exceeds the ocean’s and NPP also nears ocean NPP. Being surficial, they gain little for soil depth, but as they are ubiquitous in arid and frozen lands too, their multiplication for neglected terrain, not to mention microtopography, is entirely valid.

Biomass of cyanobacteria, including much proclaimed Prochlorococcus and Synechococcus, in arid land soil crusts alone is estimated to reach 0.054 Gt C and in endolithic communities an additional 0.014 Gt C to total 0.068 Gt C; comparatively, in lakes just 0.003 Gt C (Garcia-Pichel et al. 2003). As arid land makes up just about a third of total land area, this value may be easily doubled, and when doubled again for terrain the land cyanobacteria component is 0.27 Gt C on land vs. <0.17 Gt C in all the oceans (and 0.003 Gt C in aquatics). Moreover, these authors admit theirs was a conservative estimate excluding significant land reservoirs such as polar or subarctic areas and subhumid topsoils(!). Microbial biomass in biocrust and phytomeneon on land may far exceed that of all the ocean phytoplankton, at 10–30 Gt SOC.

Utilization of soil algae for fertilizer in the tropics is discussed by Howard and Wad (1931).

As well as tropical blooms, studies often miss algal blooms of the biocrust on polar or subarctic rocks, snow and ice (Underwood 2019) which may contribute to both biomass and productivity.

Jassey et al. (2022) found an average 5.5 million micro algae inhabit each gram of surface soil. They concluded that soil algae added a “so far not considered additional” 3.6 Gt C/yr NPP. This, they said, is slightly higher than the value reported for soil cryptogams, including bryophytes and lichens, of 0.34–3.3 Gt C/yr. However, Raich et al. (2002: Table 2) included cryptogamic “bare” earth biocrust and “Mosses and lichens” respiration (= NPP) as 2.76 and 1.73 Gt C/yr, respectively, to total 4.5 Gt C/yr. Moreover, Yuan et al. (2012) have photoautotrophic microbes comprised of bacteria and algae sequestration of 0.6 to 4.9 Gt C year-1 based upon a surface area of 14 Gha. If Jassey et al. terrestrial soil algal additional of 3.6 Gt C/yr is correct the combined sum is up to ~8.5 Gt C/yr NPP for a flat-land surface area.

Doubled for terrain (not yet for microtopography) biocrust is ~17.0 Gt C/yr NPP.

3.9.6. Dissolved Organic Carbon (DOC) in Soils

A DOC estimate of ~13 Gt DOC in soils to 1 m depth (Guo et al. 2020, Xu et al. 2021) doubled at least for depth and possibly again for terrain would raise this to 52 Gt DOC. Subsequently, Guo et al. (2024) estimated annual carbon release from DOC as 27.98 Gt C/yr they say is three times greater than global fossil fuel carbon emissions from IPCC (~9 Gt C/yr). Moreover, Langeveld et al. (2022) has ~2–5 Gt/yr DOC/DIC processed by water.These will increase as permafrost melts further (Xu et al. 2020, Heffernan et al. 2024).

DOC intergrades with Soil Inorganic and Dissolved Inorganic C: (SIC) and (DIC).

3.9.7. Soil Inorganic Carbon (SIC) and Dissolved Inorganic Carbon (DIC)

Earlier studies by Monger et al., (2015) were updated by Raza et al. (2024) who have “Inorganic C as soil carbonate (2255 Pg C down to 2 m depth) and as bicarbonate in groundwater (1400 Pg C) together surpass SOC (2400 Pg C) as the largest terrestrial C pool”. A recent report by Huang et al. (2024) claims soil inorganic carbon is slightly higher at 2,305 ± 636 (±1 SD) Gt SIC to 2 m soil depth. Doubled for depth and/or terrain ups values (2,305 + 1,400 =) 3,705 ×2 = 7,410 Gt SIC/DIC.

It is possible that those portions of SIC and DIC within the water-table are not so obviously increased, being at their own levels as is summarized in Figure 12.

Figure 12. Soil carbon to from Raza et al. (2024: Figure 1 - https://ars.els-cdn.com/content/image/1-s2.0-S0016706124000600-gr1_lrg.jpg). Note the depth (in blue) for DIC starts below 1 m but is only to 2.5 m whereas global average soil depth is >13 m plus 8 m saprock thus doubling for deeper soil seems entirely justified, not so much a terrain factor.

Figure 12. Soil carbon to from Raza et al. (2024: Figure 1 - https://ars.els-cdn.com/content/image/1-s2.0-S0016706124000600-gr1_lrg.jpg). Note the depth (in blue) for DIC starts below 1 m but is only to 2.5 m whereas global average soil depth is >13 m plus 8 m saprock thus doubling for deeper soil seems entirely justified, not so much a terrain factor.

As already noted, a mean soil depth of >13–21 m is six or eight times deeper than 2.5 m thus these values may truly be much higher; moreover, terrain may factor in yet higher.

Calcite (crystaline CaCO₃) that contains about 12% carbon, may be included in soil inorganic totals as a minor but valid earthworm exudate mainly from atmospheric CO₂. Blakemore (2019 https://vermecology.wordpress.com/2019/11/11/earthworm-cast-carbon-storage-eccs/ ), estimated about 1 Gt C/yr earthworm calcite which is more than all the solid CaCO₃ in shells of all marine organisms, of just 0.7 Gt C/yr (IPCC 2001: 198). Over the millennia this would be a sizeable contribution from earthworms to inorganic carbon in soils and solutions, especially since IPCC WG1 AR5 (2013: Figure 6.1) show rock-weathering at 0.1–0.3 Gt C/yr.

In addition to inorganic carbon, the dissolved organic component is ~52 Gt DOC.

Combined, these estimates for SIC/DIC/DOC add to (>7,410 + 52 =) >7,462 Gt C.

3.9.8. Summary of Soil Carbon Stocks Refinement

From a total global baseline of ~24,000 Gt SOC calculated above we may add sediment carbon in lakes and rivers (820 + 1,640 = 2,460 Gt SeOC). Then SOC total is (24,000 + 2,460 =) ~26,460 Gt SOC. Adding dissolved carbon in soils (SIC/DIC/DOC of approximately 7,462 Gt C as noted above), a grand land total is 33,922, or nearly 34,000 Gt C for all forms of soil carbon (approaching the 38,000 Gt C in ocean stock).

Disparity of terrestrial soil carbon stocks, ranging from 3,000 as noted in the Introduction, to 34,000 Gt C indicates the inadequacy of our basic knowledge of soils, their carbon stocks, and natural processes. To provide clarity in terms of a full soil biome inventory requires that living biomass, Dissolved Organic Carbon (DOC), and Sediment Organic Carbon (SeOC) and other factors be added for full depth and allowing for terrain.

Additional factors, as well as glomalin and saprock, are amounts of terrestrial biomass lost to the oceans each year. Siegenthaler and Sarmiento (1993: Figure 1b) had 0.8 Gt C/yr transported to ocean via rivers. Lower values were provided by Hedges et al. (1997) who estimated 0.25 Gt C of dissolved (<0.5 μm) organic carbon (DOC) and another 0.15 Gt C of particulate (>0.5 μm) organic carbon (POC) from lost from continents each year. Although tree logs and other larger woody materials appear substantial, current information indicates they are a minor contributor. An annual driftwood export to oceans of 4.7 million m³ equates to 1.41 Mt of carbon or just 0.0014 Gt C/yr (Wohl and Iskin 2021), compared to 0.4–0.8 Gt DOC/POC. Moreover, Lal (2006: Figure 3.2, Tables 3.4–3.5) showed 0.4–0.6 Gt C/yr (or about 10% of total soil erosion) flowing to the ocean via rivers which may be doubled for terrain (depending on data source or to allow for coastal erosion)) to over 1 Gt C/yr. Conversely, IPCC (2013: Figure 6.1) and IPCC (2021) already have 0.8–0.9 Gt C/yr, export of carbon to oceans that, depending upon source of data and calculations, may truly represent a substantial contribution to the ocean as well as a large value lost from land NPP and soil erosion.

3.12. Primary Productivity (NPP), Soil Respiration (SR) and CO₂ Drawdown

Despite an “official” estimates of around 60–70 Gt C/yr NPP on land (as in Table 1), evidence indicates rates may be much higher, and Liang et al. (2023) have terrestrial NPP likely at 120–190 Gt C/yr approaching the 218 Gt C/yr land NPP from Blakemore (2018). Support for these higher values is summarized in self-explanatory figures (Blakemore 2022 - https://vermecology.wordpress.com/2022/01/13/fossil-fuel-fallacy) (Figure 13 and Figure 14).

Figure 13. A rapid increase in atmospheric CO₂ estimated in the period 1900–2020 is from 280 ppm to 412 ppm, which is about a 32% rise while terrestrial GPP increased 35% over the same period, mainly due to a CO₂ greening effect. Inability of plants to drawdown excess CO₂ is likely due to forest clearance for crops and stock, erosion and topsoil loss.

Figure 13. A rapid increase in atmospheric CO₂ estimated in the period 1900–2020 is from 280 ppm to 412 ppm, which is about a 32% rise while terrestrial GPP increased 35% over the same period, mainly due to a CO₂ greening effect. Inability of plants to drawdown excess CO₂ is likely due to forest clearance for crops and stock, erosion and topsoil loss.

Is higher NPP justifiable? Evidence for the Northern Extra-Tropics (30–90^∘ N), or boreal region, are of 60–80 Gt C/yr, (median ~70 Gt C/yr) (Blakemore 2020 - https://vermecology.wordpress.com/2020/08/31/barrow/). This is supported as Bartsev et al. (2012: Figure 3) model a boreal flux of ±62 Gt C/yr mainly from the steppe then from forest, so the whole temperate North may be higher, at least 100 Gt C, and if this flux is about half, then global NPP comes out at well over 200 Gt C/yr. Indeed, Haverd et al. (2020) claim: “land north of 35°N contributes less than 25% to global GPP” then total may be at least (4 × 62 =) 248 Gt C/yr for global NPP. Comparatively, Ronin et al. (1975: Table 1) have proportion of NPP in polar, boreal and temperate/sub-boreal zones combined as just 14.8% (vs. 60% in tropics) for global or, for Continental NPP alone, this is 20% (vs. 80% in tropics). This northern contribution of just a fifth suggests a much higher (5 × 62 =) >310 Gt C/yr total land NPP.

Field et al. (1998; Table 1) estimated seasonal NPP flux on (flat!) land of 33.7 Gt C (or 60%) in northern summers (April to Sept) and 22.7 (or 40%) for the rest of the year in the rest of the world; thus, their summer spike accounts for about (33.7-22.7 =) 11.0 Gt C (or 20%) above background NPP. As Barrow measures a real 20 ppm summer drawdown equating to an NPP spike of ~40 Gt C, perhaps doubled for simultaneous soil respiration to ~80 Gt. Thus, logically, if this represents at most 20% of total annual NPP, then global total NPP is at least 5 × 40 = >200 Gt C/yr, possibly much higher (5 × 80 = 400 Gt C/yr?), and this yet again heralds a need to revise NPP estimates upwards as per Blakemore (2018, 2020 - https://veop.files.wordpress.com/2020/06/veop-4-5.pdf).

With atmospheric carbon values at the time of their publication, Welp, Keeling et al. (2011) CO₂ turnover was “approximately every 2 yr” implying (885/2 Gt C =) 443 Gt C/yr processed mostly on land. This can be explained by supporting higher NPP values of 220 Gt C/yr, or near the same as Blakemore (2018: Table 11) NPP for × 2 terrain of 218 Gt C/yr.

Liang et al. (2023) concur with a shorter turnover time at 1.5 yrs requiring (890/1.5 Gt C=) 593 Gt C/yr GPP that would correspond with a higher NPP of 296 Gt C/yr. This is lower than Blakemore (2018: Table 11) for × 4 terrain of 436 Gt C/yr, but similar to Ronin et al. (1975: Table 1) and Bartsev et al. (2012: Figure 3) data calculated above of NPP >310 Gt C/yr.

Furthermore, as noted above, this NPP is processed constantly, mainly through the intestines of earthworms and via microbial decomposition, supporting an entire atmospheric CO₂ turnover in about 2–4 yrs cycles via these agents in litter layers, the topsoil humus and deeper in subsoils. Maintaining this vital workforce of synergistic interactions between earthworms, microbes and fungi in healthy soils should be seen as a priority.

4. Summary, Conclusions, and Recommendations

References

1. Amesbury, M.J., Gallego-Sala, A., Loisel, J. Peatlands as prolific carbon sinks. Nat. Geosci. 12, 880–881 (2019) https://ore.exeter.ac.uk/repository/handle/10871/39306 ; https://www.nature.com/articles/s41561-019-0455-y.
2. Bahn, M., et al. 2010. Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes. Biogeoscience. 7 (7): 2147–2157. https://bg.copernicus.org/articles/7/2147/2010/bg-7-2147-2010.pdf.
3. Bar-On, Y.M.; Phillips, R.; Milo, R. (2018). The biomass distribution on Earth. Proc. Natl. Acad. Sci. USA 2018. https://www.pnas.org/doi/abs/10.1073/pnas.1711842115.
4. Barnes AE, Robinson RA, Pearce-Higgins JW. Collation of a century of soil invertebrate abundance data suggests long-term declines in earthworms but not tipulids. PLoS One. 2023. 18(4):e0282069. [CrossRef]
5. Bartsev S.I., Degermendzhi A, Ivanova Y, Shchemel A, Tchernetsky M. 2012. Boreal forests contribution to global seasonal dynamic of carbon dioxide in the atmosphere. Procedia Environ Sci. 13:194–201. 10.1016/j.proenv.2012.01.018. https://core.ac.uk/download/pdf/82433487.pdf.
6. Blakemore, R.J. (2018a). Blakemore, R.J. Critical Decline of Earthworms from Organic Origins under Intensive, Humic SOM-Depleting Agriculture. Soil Syst. 2018, 2, 33. http://www.mdpi.com/2571-8789/2/2/33/htm.
7. Blakemore, R.J. (2018b). Non-Flat Earth Recalibrated for Terrain and Topsoil. Soil Syst, 2, 64. [CrossRef]
8. Blakemore (2019 – Science eLetters Dec. 2, 2019 RE: Soil Carbon and Biomass: Flat Out Wrong?).
9. Blakemore, R.J. 2019. https://vermecology.wordpress.com/2019/11/11/earthworm-cast-carbon-storage-eccs/.
10. Blakemore, R.J. 2020. Global SOC, Annual NPP & CO2 Turnover Time (τ). Veop. 4: 1–8. Online: https://veop.files.wordpress.com/2020/06/veop-4-5.pdf. https://orgprints.org/id/eprint/38139/1/Veop-4.pdf.
11. Blakemore, R.J. 2022. New Global Species Biodiversity: Soil soars, Ocean flounders. Veop. 5: 1–9. Online: https://veop.wordpress.com/2022/09/10/volume-5/. Online: https://veop.files.wordpress.com/2022/09/new-addendum-file.pdf. [CrossRef]
12. Blakemore, R.J. (2023). Biotic SOC Stock: What We Had & What We Lost. Veop. 6: 1-59. https://veop.wordpress.com/new-publications/. Veop-6-pdf. [CrossRef]
13. Blakemore, R.J. (2024). Diversity Restated: >99.9% of Global Species in Soil Biota. Preprints. 2024041921. [CrossRef]
14. Blakemore 2024 – https://vermecology.wordpress.com/2024/02/20/dtb-2/.
15. Bratbak, G, Dundas I. Bacterial dry matter content and biomass estimations. Appl Environ Microbiol. 1984 Oct;48(4):755-7. [CrossRef]
16. Brovkin, V. et al. 2011. Plant-driven variation in decomposition rates improves projections of global litter stock distribution. Biogeosciences Discuss. 8: 8817–8844. www.biogeosciences-discuss.net/8/8817/2011/. [CrossRef]
17. Burkert A, Douglas TA, Waldrop MP, Mackelprang R. Changes in the Active, Dead, and Dormant Microbial Community Structure across a Pleistocene Permafrost Chronosequence. Appl Environ Microbiol. 2019 Mar 22;85(7):e02646-18. [CrossRef]
18. Chan, Y.K., McCoy, D. 2010. Soil carbon storage potential under perennial pastures in the mid-north coast of New South Wales, Australia. Tropical Grasslands. 44: 184–191.
19. Cissé, G. Essi, M. Kedi, B. Nicolas, M. Staunton, S. Accumulation and vertical distribution of glomalin-related soil protein in French temperate forest soils as a function of tree type, climate and soil properties, CATENA, Volume 220, Part A, 2023, 106635. (https://www.sciencedirect.com/science/article/pii/S034181622200621X). [CrossRef]
20. Cole, J., Prairie, Y., Caraco, N., Mcdowell, W., Tranvik, L., Striegl, R., Duarte, C., Kortelainen, P., Downing, J., Middleburg, J., & Melack, J. (2007). Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget. Ecosystems, 10(1), 171-184. [CrossRef]
21. Comis, D. 2002. Glomalin: hiding place for a third of the world's stored soil carbon. Agricultural Research USDA-ARS Sep 2002: 4–7. Available at: http://www.ars.usda.gov/is/AR/archive/sep02/soil0902.htm.
22. Crowther T.W., et al. 2019. The global soil community and its influence on biogeochemistry. Science. 365(6455):eaav0550. [CrossRef]
23. Damer, B. and Deamer, D. The hot spring hypothesis for an origin of life. Astrobiology. Vol. 20: 429. 2020. [CrossRef]
24. Darwin, C.R. (1881). The formation of vegetable mould, through the action of worms, with observations on their habits. London: John Murray. Pp. 315.
25. Davidson, E., Savage, K., Bolstad, P., Clark, D., Curtis, P., Ellsworth, D., Hanson, P., Law, B., Luo, Y., Pregitzer, K., Randolph, J., Zak, D. (2002). Belowground Carbon Allocation In Forests Estimated From Litterfall And IRGA-Based Soil Respiration Measurements, Agricultural And Forest Meteorology, 113(1-4), 39-51. https://harvardforest1.fas.harvard.edu/publications/pdfs/Davidson_AgriForestMeterology_2002b.pdf. [CrossRef]
26. Drawdown Review (2020). https://drawdown.org/sites/default/files/pdfs/TheDrawdownReview%E2%80%932020%E2%80%93Download.pdf.
27. Djokic, T., Van Kranendonk, M., Campbell, K. et al. Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits. Nat Commun. 8: 15263 (2017). [CrossRef]
28. Duursma, E.K., Boisson, M.P.R.M. 1994. Global oceanic and atmospheric oxygen stability considered in relation to the carbon-cycle and to different time scales. Oceanol. Acta 1994, 17, 117–141.
29. FAO (2018). Statistical Databases. http://apps.fao.org/.
30. FAO. 2022. Global Soil Organic Carbon Sequestration Potential Map – GSOCseq v.1.1. Technical report. Rome. [CrossRef]
31. Ferris, J., Ertem, G. 1998). Montmorillonite catalysis of RNA oligomer formation in aqueous solution. A model for the prebiotic formation of RNA.. Journal of the American Chemical Society, 115(26), 12270-5.
32. Field, C.B., Behrenfeld, M.J., Randerson, J.T., Falkowski, P. 1998. Primary production of the Biosphere: Integrating Terrestrial and Oceanic Components. Science. 281(5374): 237–240. https://escholarship.org/uc/item/9gm7074q. [CrossRef]
33. Follett CL, Repeta DJ, Rothman DH, Xu L, Santinelli C. Hidden cycle of dissolved organic carbon in the deep ocean. Proc Natl Acad Sci U S A. 2014 Nov 25;111(47):16706-11. [CrossRef]
34. Follmann, H. Brownson, C. (2009). Darwin’s warm little pond revisited: from molecules to the origin of life. , 96(11), 1265–1292. [CrossRef]
35. Garcia-Pichel, Ferran; Belnap, Jayne; Neuer, Susanne; Schanz, Ferdinand . (2003). Estimates of global cyanobacterial biomass and its distribution. Algological Studies, 109(1), 213–227. [CrossRef]
36. GCB (2023). Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Bakker, D. C. E., Hauck, J., Landschützer, P., Le Quéré, C., Luijkx, I. T., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Anthoni, P., Barbero, L., Bates, N. R., Becker, M., Bellouin, N., Decharme, B., Bopp, L., Brasika, I. B. M., Cadule, P., Chamberlain, M. A., Chandra, N., Chau, T.-T.-T., Chevallier, F., Chini, L. P., Cronin, M., Dou, X., Enyo, K., Evans, W., Falk, S., Feely, R. A., Feng, L., Ford, D. J., Gasser, T., Ghattas, J., Gkritzalis, T., Grassi, G., Gregor, L., Gruber, N., Gürses, Ö., Harris, I., Hefner, M., Heinke, J., Houghton, R. A., Hurtt, G. C., Iida, Y., Ilyina, T., Jacobson, A. R., Jain, A., Jarníková, T., Jersild, A., Jiang, F., Jin, Z., Joos, F., Kato, E., Keeling, R. F., Kennedy, D., Klein Goldewijk, K., Knauer, J., Korsbakken, J. I., Körtzinger, A., Lan, X., Lefèvre, N., Li, H., Liu, J., Liu, Z., Ma, L., Marland, G., Mayot, N., McGuire, P. C., McKinley, G. A., Meyer, G., Morgan, E. J., Munro, D. R., Nakaoka, S.-I., Niwa, Y., O'Brien, K. M., Olsen, A., Omar, A. M., Ono, T., Paulsen, M., Pierrot, D., Pocock, K., Poulter, B., Powis, C. M., Rehder, G., Resplandy, L., Robertson, E., Rödenbeck, C., Rosan, T. M., Schwinger, J., Séférian, R., Smallman, T. L., Smith, S. M., Sospedra-Alfonso, R., Sun, Q., Sutton, A. J., Sweeney, C., Takao, S., Tans, P. P., Tian, H., Tilbrook, B., Tsujino, H., Tubiello, F., van der Werf, G. R., van Ooijen, E., Wanninkhof, R., Watanabe, M., Wimart-Rousseau, C., Yang, D., Yang, X., Yuan, W., Yue, X., Zaehle, S., Zeng, J., and Zheng, B.: Global Carbon Budget 2023, Earth Syst. Sci. Data, 15, 5301–5369, 2023. [CrossRef]
37. Georgiou, K., Jackson, R.B., Vindušková, O. et al. Global stocks and capacity of mineral-associated soil organic carbon. Nat Commun 13, 3797 (2022). [CrossRef]
38. Gorham, E. (1991), Northern Peatlands: Role in the Carbon Cycle and Probable Responses to Climatic Warming. Ecological Applications, 1: 182-195. [CrossRef]
39. Gouldie, A.S. and Cuff, D.J. (eds.). (2002). Encyclopedia of Global Change: Environmental Change and Human Society, Oxford, Oxford University Press. Pp. 1406. ISBN: 9780195108255.
40. Guo, Z., Wang, Y., Wan, Z., Zuo, Y., He, L., Li, D., Yuan, F., Wang, N., Liu, J., Song, Y., Song, C., and Xu, X.: Soil dissolved organic carbon in terrestrial ecosystems: Global budget, spatial distribution and controls, Global Ecol. Biogeogr., 29, 2159–2175, 2020. [CrossRef]
41. Guo, Z., Wang, Y., Liu, J., He, L., Zhu, X., Zuo, Y., Wang, N., Yuan, F., Sun, Y., Zhang, L., Song, Y., Song, C., Xu, X. (2024). Mapping turnover of dissolved organic carbon in global topsoil Science of the Total Environment, 906, 167621–167621. [CrossRef]
42. Gumbricht T, Roman-Cuesta RM, Verchot L, et al. An expert system model for mapping tropical wetlands and peatlands reveals South America as the largest contributor. Glob Change Biol. 2017; 23: 3581–3599. [CrossRef]
43. Hansell, D.A., Carlson, C.A. 2001. Marine dissolved organic matter and the carbon cycle. Oceanography 14(4):41–49. [CrossRef]
44. Harper, R.J., Tibbett, M. 2013. The hidden organic carbon in deep mineral soils. Plant Soil. 368: 641–648. [CrossRef]
45. Hashimoto, S., Ito, A. & Nishina, K. Divergent data-driven estimates of global soil respiration. Commun Earth Environ 4, 460 (2023). [CrossRef]
46. Haverd V., Smith B., Canadell J.G., et al. 2020. Higher than expected CO2 fertilization inferred from leaf toglobal observations. Glob Change Biol. 2020;26:2390–2402. https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14950. [CrossRef]
47. Hawkins HJ, Cargill RIM, Van Nuland ME, Hagen SC, Field KJ, Sheldrake M, Soudzilovskaia NA, Kiers ET. Mycorrhizal mycelium as a global carbon pool. Curr Biol. 2023 Jun 5;33(11):R560-R573. [CrossRef]
48. He J. D., Chi G. G., Zou Y. N., Shu B., Wu Q. S., Srivastava A. K., et al. (2020). Contribution of glomalin-related soil proteins to soil organic carbon in trifoliate orange. Appl. Soil Ecol. 154:103592. 10.1016/j.apsoil.2020.103592.
49. He, L. et al. (2020), Global biogeography of fungal and bacterial biomass carbon in topsoil, Soil Biology and Biochemistry, Journal-article. [CrossRef]
50. He, L. Rodrigues, J. Soudzilovskaia, N. et al. Global Biogeography of Fungal and Bacterial Biomass Carbon in Topsoil. Authorea. 2020. [CrossRef]
51. Hedges, J. I., R. G. Keil, and R. Benner. 1997. What happens to terrestrial organic matter in the ocean? Org. GeMartin WF, Allen JF. An Algal Greening of Land. Cell. 2018 Jul;174(2):256-258. PMID: 30007415. https://www.cell.com/cell/pdf/S0092-8674(18)30802-X.pdf. [CrossRef]
52. Heffernan, L., Kothawala, D. N., and Tranvik, L. J.: Review article: Terrestrial dissolved organic carbon in northern permafrost, The Cryosphere, 18, 1443–1465, 2024. [CrossRef]
53. Hicks Pries, C.E., Ryals, R., Zhu, B., Min, K., Cooper, A.et al. (2023) The deep soil organic carbon response to global change. Annual Review of Ecology, Evolution, and Systematics 54, 375–401.
54. Hiederer, R., Köchy, M., 2012. Global soil organic carbon estimates and the harmonized world soil database. EU Joint Research Centre, Institute for Environment and Sustainability Publications Office. https://data.europa.eu/doi/10.2788/13267.
55. Hoffmann, G. et al. A model of the Earth’s Dole effect. Glob. Biogeochem. Cycles 18, 1008 (2004). [CrossRef]
56. Hoover, K.; Riddle, A.A. Forest Carbon Primer; CRS R46312; Congressional Research Service: Washington, DC USA, 2020; 34p.
57. Houghton, R.A. 2007. Balancing the Global Carbon Budget. Annual Review of Earth and Planetary Sciences. 35: 1, 313-347. https://www.annualreviews.org/doi/abs/10.1146/annurev.earth.35.031306.140057.
58. Howard, A. Wad Y.D. 1931. The Waste Products of Agriculture : their Utilization as. Humus, Oxford University Press, 1931. http://journeytoforever.org/farm_library/HowardWPA/WPAtoc.html.
59. Howard, A. (1933). THE WASTE PRODUCTS OF AGRICULTURE: THEIR UTILIZATION AS HUMUS. Journal of the Royal Society of Arts, 82(4229), 84–121. http://www.jstor.org/stable/41360014.
60. Howard, A. 1945. An Agricultural Testament. UK: Oxford University Press. https://web.archive.org/web/20100702222720/http:/ps-survival.com/PS/Agriculture/An_Agricultural_Testament_1943.pdf. http://journeytoforever.org/farm_library/HowardWPA/WPA3.html.
61. Huang, N., Wang, L., Song, X.-P., Black, T. A., Jassal, R. S., Myneni, R. B., Wu, C., Wang, L., Song, W., and Ji, D.: Spatial and temporal variations in global soil respiration and their relationships with climate and land cover, Sci. Adv., 6, eabb8508. 2020. [CrossRef]
62. Huang, Y., Song, X., Wang, Y.-P., Canadell, J.G., Luo, Y., Ciais, P., Chen, A., Hong, S., et al. (2024). Size, distribution, and vulnerability of the global soil inorganic carbon. Science. 384 (6692) 233-239. [CrossRef]
63. Hugelius, G., Loisel, J., Chadburn, S., Jackson, R. B., Jones, M., MacDonald, G., et al. (2020). Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw. Proceedings of the National Academy of Sciences, 117(34), 20438–20446. [CrossRef]
64. Hutchinson, G.E. 1954. The Biochemistry of the Terrestrial Atmosphere. In: G. P. Kuiper (Ed.): The Earth as a Planet. Pp. 371–433. Chicago: University of Chicago Press. https://articles.adsabs.harvard.edu/full/1954eap..book..371H.
65. IPBES 2018. Chapter 4: Status and trends of land degradation and restoration and associated changes in biodiversity and ecosystem fundtions. In: IPBES assessment report on land degradation and restoration. Secretariat of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem services, Bonn, Germany. Pp. 317-426. https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers19-02/010075051.pdf.
66. IPCC (2021) Canadell, J.G., P.M.S. Monteiro, M.H. Costa, L. Cotrim da Cunha, P.M. Cox, A.V. Eliseev, S. Henson, M. Ishii, S. Jaccard, C. Koven, A. Lohila, P.K. Patra, S. Piao, J. Rogelj, S. Syampungani, S. Zaehle, and K. Zickfeld, 2021: Global Carbon and other Biogeochemical Cycles and Feedbacks. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 673–816. https://www.ipcc.ch/site/assets/uploads/2018/02/TAR-03.pdf. [CrossRef]
67. Irving, T.B., Alptekin, B., Kleven, B. and Ané, J.-M. (2021). A critical review of 25 years of glomalin research: a better mechanical understanding and robust quantification techniques are required. New Phytol. 232: 1572-1581. [CrossRef]
68. Jackson, R. B., K. Lajtha, S. E. Crow, G. Hugelius, M. G. Kramer, and G. Piñeiro. 2017. The ecology of soil carbon: Pools, vulnerabilities, and biotic and abiotic controls. Annual Review of Ecology, Evolution, and Systematics 48: 419–445. https://jacksonlab.stanford.edu/sites/g/files/sbiybj20871/files/media/file/jackson_et_al._arees_2017.pdf.
69. Jassey, V. E. J., Walcker, R., Kardol, P., Geisen, S., Heger, T., Lamentowicz, M., Hamard, S., Lara, E. (2022). Contribution of soil algae to the global carbon cycle. The New Phytologist, 234, 64–76. [CrossRef]
70. Jobbágy, E.G., Jackson, R.B. 2000. The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation. Ecological Applications. 10: 423-436. [CrossRef]
71. Johannessen, S.C., Christian, J.R. Why blue carbon cannot truly offset fossil fuel emissions. Commun Earth Environ 4, 411 (2023). [CrossRef]
72. Kaplan, J.O., et al. 2010. Holocene carbon emissions as a result of anthropogenic land cover change. The Holocene. 21(5): 775–791. [CrossRef]
73. Kopittke PM, Menzies NW, Wang P, McKenna BA, Lombi E. 2019. Soil and the intensification of agriculture for global food security. Environ Int. 132:105078. [CrossRef]
74. Koren, G., et al. 2019. Global 3-D simulations of the triple oxygen isotope signature Δ¹⁷O in atmospheric CO₂. Journal of Geophysical Research: Atmospheres. 124. Online: https://edepot.wur.nl/498192. [CrossRef]
75. Lal, R. 2006. Influence of Soil Erosion on Carbon Dynamics in the Wold. Chapter 3. In: Science in Soil Science SOIL EROSION AND CARBON DYNAMICS Edited by Eric J. Roose, Rattan Lal, Christian Feller, Bernard Barthes, Bobby A. Stewart (2006). Pp 23-35. Online: https://library.oapen.org/bitstream/20.500.12657/41645/1/9781135460556.pdf.
76. Lal, R. 2009. Sequestering atmospheric carbon dioxide. Critical Reviews in Plant Science. 28: 90-96.
77. Lal, R. 2020. Soil Erosion and Gaseous Emissions. Appl. Sci. 2020, 10: 2784. [CrossRef]
78. Langeveld, J., Bouwman, A.F., van Hoek, W.J. et al. Estimating dissolved carbon concentrations in global soils: a global database and model. SN Appl. Sci. 2, 1626 (2020). [CrossRef]
79. Laskar, A.H. et al. 2019. Triple oxygen and clumped isotope compositions of CO₂ in the middle troposphere. Earth & Space Science. 6: 1205–1219. [CrossRef]
80. Le Quéré, C., Andrew, R. M., Friedlingstein, P., Sitch, S., Hauck, J., Pongratz, J., Pickers, P. A., Korsbakken, J. I., Peters, G. P., Canadell, J. G., Arneth, A., Arora, V. K., Barbero, L., Bastos, A., Bopp, L., Chevallier, F., Chini, L. P., Ciais, P., Doney, S. C., Gkritzalis, T., Goll, D. S., Harris, I., Haverd, V., Hoffman, F. M., Hoppema, M., Houghton, R. A., Hurtt, G., Ilyina, T., Jain, A. K., Johannessen, T., Jones, C. D., Kato, E., Keeling, R. F., Goldewijk, K. K., Landschützer, P., Lefèvre, N., Lienert, S., Liu, Z., Lombardozzi, D., Metzl, N., Munro, D. R., Nabel, J. E. M. S., Nakaoka, S., Neill, C., Olsen, A., Ono, T., Patra, P., Peregon, A., Peters, W., Peylin, P., Pfeil, B., Pierrot, D., Poulter, B., Rehder, G., Resplandy, L., Robertson, E., Rocher, M., Rödenbeck, C., Schuster, U., Schwinger, J., Séférian, R., Skjelvan, I., Steinhoff, T., Sutton, A., Tans, P. P., Tian, H., Tilbrook, B., Tubiello, F. N., van der Laan-Luijkx, I. T., van der Werf, G. R., Viovy, N., Walker, A. P., Wiltshire, A. J., Wright, R., Zaehle, S., and Zheng, B.: Global Carbon Budget 2018, Earth Syst. Sci. Data, 10, 2141–2194, 2018. [CrossRef]
81. Lee, K.E. (1985). Earthworms: their ecology and relationships with soils and land use. Sydney: Academic Press. Pp. 411. ISBN 978-0-12-440860-9.
82. Liang, M.C., Mahata, S., Laskar, A.H. et al. 2017. Oxygen isotope anomaly in tropospheric CO₂ and implications for CO₂ residence time in the atmosphere and gross primary productivity. Sci Rep. 7: 13180 (2017). [CrossRef]
83. Liang MC, Laskar AH, Barkan E, Newman S, Thiemens MH, Rangarajan R. 2023. New constraints of terrestrial and oceanic global gross primary productions from the triple oxygen isotopic composition of atmospheric CO₂ and O₂. Sci Rep. 2023 Feb 7;13(1):2162. [CrossRef]
84. Loisel, J., et al. 2021. Expert assessment of future vulnerability of the global peatland carbon sink. Nat. Clim. Chang. 11: 70–77 (2021). [CrossRef]
85. Loisel, J., Gallego-Sala, A.V., Amesbury, M.J. et al. Expert assessment of future vulnerability of the global peatland carbon sink. Nat. Clim. Chang. 11, 70–77 (2021). https://climatehomes.unibe.ch/~joos/papers/loisel20ncc.pdf.). [CrossRef]
86. Lovelock, C.E., Wright, S.F., Clark, D.A., Ruess, R.W., 2004a. Soil stocks of glomalin produced by arbuscular mycorrhizal fungi across a tropical rain forest landscape. Journal of Ecology, 92, 278-287.
87. Martin, W.F. Allen, J.F. An algal greening of land. Cell, 174 pp. 256-258. (2018). [CrossRef]
88. Martin FM, van der Heijden MGA. 2024. The mycorrhizal symbiosis: research frontiers in genomics, ecology, and agricultural application. New Phytologist 242: 1486–1506. [CrossRef]
89. Matthews, E. 1997. Global litter production, pools, and turnover times: Estimates from measurement data and regression models, J. Geophys. Res. 102: 18771–18800. agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/97JD02956. [CrossRef]
90. Miller, H.; Mulhall, J.; Pfau, L.A.; Palm, R.; Denkenberger, D.C. Can Foraging for Earthworms Significantly Reduce Global Famine in a Catastrophe? Biomass 2024, 4, 765-783.Mollison, B.C. 1988. Permaculture: A Designers’ Manual. Tagari Publications, Tyalgum. Pp. 576. [CrossRef]
91. Monger, H.C. et al. 2015. Sequestration of inorganic carbon in soil and groundwater. Geology. 43 (5): 375–378. [CrossRef]
92. Moreland K, Tian Z, Berhe AA, McFarlane KJ, Hartsough P, Hart SC, Bales R, O’Geen AT (2021) Deep in the Sierra Nevada critical zone: saprock represents a large terrestrial organic carbon stock. Environ Res Lett 16:124059. [CrossRef]
93. Mulkidjanian AY, Bychkov AY, Dibrova DV, Galperin MY, Koonin EV. Origin of first cells at terrestrial, anoxic geothermal fields. Proc Natl Acad Sci U S A. 2012 Apr 3;109(14):E821-30. [CrossRef]
94. Naorem, A.; Jayaraman, S.; Dalal, R.C.; Patra, A.; Rao, C.S.; Lal, R. Soil Inorganic Carbon as a Potential Sink in Carbon Storage in Dryland Soils—A Review. Agriculture 2022, 12, 1256. [CrossRef]
95. Nichols, J.E., Peteet, D.M. 2019. Rapid expansion of northern peatlands and doubled estimate of carbon storage. Nat. Geosci. 12: 917–921 (2019). [CrossRef]
96. Nichols, J.E., Peteet, D.M. 2021. J. E. Nichols & D. M. Peteet reply. Nat. Geosci. 14: 470–472. [CrossRef]
97. Nielsen, E.S. (1952). 1952. The Use of Radio-active Carbon (C¹⁴) for Measuring Organic Production in the Sea, ICES Journal of Marine Science. 18(2): 117–140. [CrossRef]
98. Nissan, A., Alcolombri, U., Peleg, N. et al. Global warming accelerates soil heterotrophic respiration. Nat Commun 14, 3452 (2023). [CrossRef]
99. Omar, M. S., Ifandi, E., Sukri, R. S., Kalaitzidis, S., Christanis, K., Lai, D. T. C., et al. (2022). Peatlands in southeast Asia: A comprehensive geological review. Earth-Science Rev. 232, 104149. [CrossRef]
100. Page, S., Rieley, J.O. and Banks, C.J. (2011) Global and regional importance of the tropical peatland carbon pool. Global Change Biology, 17 (2), 798-818. [CrossRef]
101. Pan, Y.; Birdsey, R. A.; Fang, J.; Houghton, R.; Kauppi, P. E.; Kurz, W. A.; Phillips, O. L.; Shvidenko, A.; Lewis, S. L.; Canadell, J. G.; Ciais, P.; Jackson, R. B.; Pacala, S. W.; McGuire, A. D.; Piao, S.; Rautiainen, A.; Sitch, S.; Hayes, D. . (2011). A Large and Persistent Carbon Sink in the World's Forests. Science, 333(6045), 988–993. [CrossRef]
102. Parish, F., Sirin, A., Charman, D., Joosten, H., Minayeva, T., Silvius, M. and Stringer, L. (Eds.) 2008. Assessment on Peatlands, Biodiversity and Climate Change: Main Report. Global Environment Centre, Kuala Lumpur and Wetlands International, Wageningen. Available at: http://www.imcg.net/media/download_gallery/books/assessment_peatland.pdf.
103. Paul, E.A. 2016. The nature and dynamics of soil organic matter: Plant inputs, microbial transformations, and organic matter stabilization. Soil Biology and Biochemistry 98:109-126. Pdf.: https://lter.kbs.msu.edu/pub/3636. [CrossRef]
104. Pelletier, J. D., P. D. Broxton, P. Hazenberg, X. Zeng, P. A. Troch, G.-Y. Niu, Z. Williams, M. A. Brunke, and D. Gochis (2016), A gridded global data set of soil, immobile regolith, and sedimentary deposit thicknesses for regional and global land surface modeling, J. Adv. Model. Earth Syst., 8, 41–65. [CrossRef]
105. Pribyl, D.W. A critical review of the conventional SOC to SOM conversion factor, Geoderma, Volume 156, Issues 3–4, 2010, Pages 75-83, ISSN 0016-7061. (https://www.sciencedirect.com/science/article/pii/S0016706110000388). [CrossRef]
106. Purschke, G. Terrestrial polychaetes – models for the evolution of the Clitellata (Annelida)?. Hydrobiologia 406, 87–99 (1999). [CrossRef]
107. Raich, J.W.et al. 2002. Interannual variability in global soil respiration, 1980-94. Glob Chang Biol. 8:800–812.
108. Raza, S., Irshad, A., Margenot, A., Zamanian, K., Li, N., Ullah, S., …Kuzyakov, Y. (2024). Inorganic carbon is overlooked in global soil carbon research: A bibliometric analysis. Geoderma, 443, Article 116831. [CrossRef]
109. Reiners, W.A. 1973. Terrestrial detritus and the carbon cycle. Brookhaven Symp Biol. 30: 303-27.
110. Retallack, G.J., Noffke, N. Are there ancient soils in the 3.7 Ga Isua Greenstone Belt, Greenland?, Palaeogeography, Palaeoclimatology, Palaeoecology (2018). [CrossRef]
111. Revelle R., Suess, H.E. 1957. Carbon Dioxide Exchange Between Atmosphere and Ocean and the Question of an Increase of Atmospheric CO2 during the Past Decades. Tellus. 9(1): 18-27. https://www.tandfonline.com/doi/pdf/10.3402/tellusa.v9i1.9075. [CrossRef]
112. Ricardo, S.-M., Paola, G.-A., Rolando, S.-G. et al. Exploring Dissolved Organic Carbon Variations in a High Elevation Tropical Peatland Ecosystem: Cerro de la Muerte, Costa Rica. Frontiers in Water, 2022. [CrossRef]
113. Richter, D.D. Markewitz, D. 1995. How Deep Is Soil? Soil, the zone of the earth's crust that is biologically active, is much deeper than has been thought by many ecologists, BioScience, Volume 45, Issue 9, October 1995, Pages 600–609. [CrossRef]
114. Riley, G.A. 1944. The carbon metabolism and photosynthetic efficiency of the earth as a whole. American Scientist. 32: 129–34.
115. Rillig, M.C.; Wright, S.F.; Nichols, K.A.; Schmidt, W.F.; Torn, M.S. Large contribution of arbuscular mycorrhizal fungi to soil carbon pools in tropical forest soils. Plant Soil. 2001, 233, 167–177. [CrossRef]
116. Robinson, D.: Scaling the depths: below-ground allocation in plants, forests and biomes, Funct. Ecol., 18, 290–295, 2004. [CrossRef]
117. Rodin L.E., Bazilevich N.I., Rozov N.N. 1975. Productivity of the world’s main ecosystems. In D. E. Reichle, J. F. Franklin, and D. W. Goodall (Eds.): Productivity of World Ecosystems. Pp. 13–26. Washington, D.C.: Natl. Acad. Sci. https://nap.nationalacademies.org/read/20114/chapter/3.
118. Rolando, J.L., Dubeux, J.C.B., Souza, T.C.D., Mackowiak, C., Wright, D.et al. (2021) Organic carbon is mostly stored in deep soil and only affected by land use in its superficial layers: A case study. Agrosystems, Geosciences and Environment 4(1), e20135. Rossel, R. A. et al. The australian three-dimensional soil grid: Australia’s contribution to the GlobalSoilMap project. Soil Research 53, 845–864 (2014). https://doi.org/10.1111/gcb.12569. [CrossRef]
119. Royer, D. L., Donnadieu, Y., Park, J., Kowalczyk, J., & Goddéris, Y. (2014). Error analysis of CO2 and O2 estimates from the long-term geochemical model GEOCARBSULF. American Journal of Science, 314(9), 1259–1283. [CrossRef]
120. Running, S.W. et al. 2004. A Continuous Satellite-Derived Measure of Global Terrestrial Primary Production, BioScience. 54(6): 547–560. [CrossRef]
121. Sanderman, J.; Farquharson, R.; Baldock, J. 2010. Soil carbon sequestration potential: A review for Australian agriculture. Urrbrae, S.A.: CSIRO; csiro:EP10121. [CrossRef]
122. Sangmanee, P., Dell, B., Harper, R.J. et al. Organic carbon compounds associated with deep soil carbon stores. Plant Soil 488, 83–99 (2023). [CrossRef]
123. Shelef, E., et al. 2017. Large uncertainty in permafrost carbon stocks due to hillslope soil deposits. Geophys. Res. Lett. 44: 6134–6144. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017gl073823. [CrossRef]
124. Scharlemann, J. P., Tanner, E. V., Hiederer, R., & Kapos, V. (2014). Global soil carbon: understanding and managing the largest terrestrial carbon pool. Carbon Management, 5(1), 81–91. [CrossRef]
125. Schindler FV, Mercer EJ, Rice JA. 2007. Chemical characteristics of glomalin related soil protein (GRSP) extracted from soils of varying organic matter content. Soil Biology & Biochemistry 39: 320–329. [CrossRef]
126. Schreiber M, Rensing SA, Gould SB. The greening ashore. Trends Plant Sci. 2022 Sep;27(9):847-857. [CrossRef]
127. Schroeder, H., 1919: Die jahrliche Gesamtproduktion der grunen Pflanzendecke der Erde. Naturwissenschaften. 7: 8.
128. Schuur, E. A. G., Abbott, B., Commane, R., Ernakovich, J., Euskirchen, E., Hugelius, G., et al. (2022). Permafrost and climate change: Carbon cycle feedbacks from a warming Arctic. Annual Review of Environment and Resources, 47: 28.1–28.29. [CrossRef]
129. Scurlock J.M.O., Johnson K. and Olson R.J. 2002. Estimating net primary productivity from grassland biomass dynamics measurements. Global Change Biology. 8: 736–753. https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2486.2002.00512.x.
130. Shangguan, W., T. Hengl, J. Mendes deJesus, H. Yuan, and Y. Dai (2017). Mapping the global depth to bedrock for land surface modeling, J. Adv.Model. Earth Syst., 9, 65–88. [CrossRef]
131. Siegenthaler, U. and Sarmiento, J.L. (1993) Atmospheric Carbon Dioxide and the Ocean. Nature, 365, 119-125. www.gfdl.noaa.gov/bibliography/related_files/us9301.pdf. [CrossRef]
132. Sokol NW, Whalen ED, Jilling A, Kallenbach C, Pett-Ridge J, Georgiou K. 2022. Global distribution, formation and fate of mineral-associated soil organic matter under a changing climate: A trait-based perspective. Functional Ecology 36 (6), 1411-1429. [CrossRef]
133. Sorensen J.W., Shade A. 2020. Dormancy dynamics and dispersal contribute to soil microbiome resilience. Phil. Trans. R. Soc. B37520190255. [CrossRef]
134. Tarnocai C, Canadell JG, Schuur EAG, Kuhry P, Mazhitova G, Zimov S. 2009. Soil organic carbon pools in the northern circumpolar permafrost region. Glob. Biogeochem. Cycles 23(2):GB2023. [CrossRef]
135. Torsvik, TH, Royer, DL, Marcilly, CM, Werner, SC. User-friendly carbon-cycle modelling and aspects of Phanerozoic climate change. Applied Computing and Geosciences, Volume 23, 2024, 100180, ISSN 2590-1974. (https://www.sciencedirect.com/science/article/pii/S2590197424000272). [CrossRef]
136. Tranvik, L. J., Downing, J. A., Cotner, J. B., Loiselle, S. A., Striegl, R. G., Ballatore, T. J., Dillon, P., Finlay, K., Fortino, K., Knoll, L. B., Kortelainen, P. L., Kutser, T., Larsen, S., Laurion, I., Leech, D. M., Leigh McCallister, S., McKnight, D. M., Melack, J. M., Overholt, E., ... Weyhenmeyer, G. A. (2009). Lakes and reservoirs as regulators of carbon cycling and climate. Limnology and Oceanography, 54(6 PART 2), 2298-2314. [CrossRef]
137. Treat, C. C., Virkkala, A.-M., Burke, E., Bruhwiler, L., Chatterjee, A., Fisher, J. B., et al. (2024). Permafrost carbon: Progress in understanding stocks and fluxes across northern terrestrial ecosystems. Journal of Geophysical Research: Biogeosciences, 129, e2023JG007638. [CrossRef]
138. UN 2022 https://globalpeatlands.org/resource-library/global-peatlands-assessment-state-worlds-peatlands-main-report).
139. Underwood, E. (2019), Mapping ice algal blooms from space. Eos: 100. 2019. [CrossRef]
140. van der Velde, I. R., Miller, J. B., Schaefer, K., van der Werf, G. R., Krol, M. C., Peters, W. (2014). Terrestrial cycling of 13CO2 by photosynthesis, respiration, and biomass burning in SiBCASA. Biogeosciences, 11(23), 6553–6571. [CrossRef]
141. van Oost, K., et al. 2012. Legacy of human-induced C erosion and burial on soil-atmosphere C exchange. PNAS. 109(47): 19492-7. https://bg.copernicus.org/articles/8/69/2011/bg-8-69-2011.pdf. [CrossRef]
142. Verwer, C. C., van der Meer, P. J. (2010). Carbon pools in tropical peat forest: towards a reference value for forest biomass carbon in relatively undisturbed peat swamp forests in Southeast Asia. (Alterra-report; No. 2108). Alterra. https://edepot.wur.nl/160910.
143. Vlček V, Pohanka M. Glomalin - an interesting protein part of the soil organic matter. Soil & Water Res.. 2020;15(2):67-74. [CrossRef]
144. Wang, Q., et al. Glomalin-related soil protein: The particle aggregation mechanism and its insight into coastal environment improvement, Ecotoxicology and Environmental Safety, Volume 227, 2021112940. [CrossRef]
145. Wang, M., Guo, X., Zhang, S. et al. 2022. Global soil profiles indicate depth-dependent soil carbon losses under a warmer climate. Nat Commun. 13: 5514 (2022). [CrossRef]
146. Weigert, A. et a. 2014. Illuminating the Base of the Annelid Tree Using Transcriptomics, Molecular Biology and Evolution, Volume 31, Issue 6, June 2014, Pages 1391–1401. [CrossRef]
147. Welp, L., Keeling, R., Meijer, H. et al. 2011. Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Niño. Nature. 477: 579–582 (2011). [CrossRef]
148. Whitman, W.B., Coleman, D.C. & Wiebe, W.J. (1998). Prokaryotes: The unseen majority. Proc Natl Acad Sci USA, 95, 6578–6583. https://www.pnas.org/doi/pdf/10.1073/pnas.95.12.6578.
149. Williams M. 2012. River sediments. Phil. Trans. R. Soc. A.3702093–2122. [CrossRef]
150. Winkler, K., Fuchs, R., et al. 2021. Global land use changes are four times greater than previously estimated. Nat Commun. 12: 2501 (2021). doi:/10.1038/s41467-021-22702-2.
151. Wohl, E. Iskin. E.P. Damming the wood falls. Science Advances, 2021; 7 (50). [CrossRef]
152. Woodwell, G.M., R.H. Whitaker, W.A. Reiners, G.E. Likens, C.C. Delwiche, and D.B. Botkin, The Biota and the World Carbon Budget, Science, 199 (1978), 141. [CrossRef]
153. Wright, S.F. and Upadhyaya, A. (1996) Extraction of an Abundant and Unusual Protein from Soil and Comparison with Hyphal Protein of Arbuscular Mycorrhizal Fungi. Soil Science, 161, 575-586. [CrossRef]
154. Xu, X,; Guo, Z;. Wang, Y.; Wan, Z. (2021). Soil dissolved organic carbon in terrestrial ecosystems: global budget, spatial distribution and controls [Dataset]. Dryad. [CrossRef]
155. Yan, F., Shangguan, W., Zhang, J. et al. Depth-to-bedrock map of China at a spatial resolution of 100 meters. Sci Data 7, 2 (2020). [CrossRef]
156. Ye P, Fang L, Song D, Zhang M, Li R, Awasthi MK, Zhang Z, Xiao R, Chen X. Insights into carbon loss reduction during aerobic composting of organic solid waste: A meta-analysis and comprehensive literature review. Sci Total Environ. 2023 Mar 1;862:160787. [CrossRef]
157. Yost, J.L., Hartemink, A.E. How deep is the soil studied – an analysis of four soil science journals. Plant Soil 452, 5–18 (2020). [CrossRef]
158. Yuan, H., Ge, T., Chen, C., O'Donnell, A. G., & Wu, J. (2012). Significant role for microbial autotrophy in the sequestration of soil carbon. Applied and Environmental Microbiology, 78, 2328-2336. [CrossRef]
159. Zamanian, K. et al. 2021. Soil carbonates: the unaccounted, irrecoverable carbon source. Geoderma, 384 (2021): 114817. [CrossRef]
160. Zhang, M., Che, R., Cheng, Z., Zhao, H., Wu, C., Hu, J., Zhang, S., Liu, D., Cui, X., Wu, Y. Decades of reforestation significantly change microbial necromass, glomalin, and their contributions to soil organic carbon, Agriculture, Ecosystems & Environment, Volume 346, 2023, 108362. Available at SSRN https://ssrn.com/abstract=4239406. [CrossRef]