Global SOC, Annual NPP & CO 2 Turnover Time ( τ )

: Interlinked issues of global soil organic carbon (SOC), annual net primary productivity (NPP) and atmospheric CO 2 turnover time ( τ ) are updated. Soil is confirmed as both the greatest sink and source for excess atmospheric CO 2 . Most terrestrial NPP (~218 Gt C/yr) is ultimately processed in topsoil and SOC stocks now total >10,000–12,000 Gt. More excess carbon is released into the air and water from SOC loss (>20 Gt C/yr) due to land clearance for pasture/crops, fires, agrichemical poisoning and erosion, than from fossil fuels (~10 Gt C/yr). NOAA’s Barrow bounce and isotopic analyses support high terrestrial flux up to ~800 Gt C/yr and CO 2 turnover time of ~1–4 years. Earth’s re-humification via compost in organic farming offers the best and only practical/time-critical fix for climate, strategy for species extinction plus a remedy for human health


Introduction
A 10-yr case study by the author (Blakemore 2018b Soil Sys. 2, 64) [1] presented a reasoned argument that undulating and rugose terrain was being neglected in almost all accounts of natural resources.
When considered, fractal land-surface area at least doubles, from prior flat 15 Gha to >30 Gha with three major and ecologically interlinked consequences: 1/.Soil organic carbon (SOC) raised from 1,500-3,000 to >8,580 Gt; 2/.Global biomass & biodiversity at least doubled; and 3/.Net primary production (NPP) grew from ~60 to ~218 Gt C/yr.The latest atmospheric isotope research implicitly supports these land recalibration results with rapid CO2 turnover times (τ) of 1-4 years.
Three likely errors in the original study require clarification as does status of prior SOC stocks.

Subsequent Studies Supporting SOC Stock Raise
Overall, the original study (Blakemore 2018b: tab.5) [1] found flat soil surfaces are about doubled for measurements down to sample size of cm 2 , or quadrupled at mm 2 scale.Greater soil area accommodates more plants/biocrust/phytomenon and has more exposure to the elements thereby validating productivity (NPP) and soil organic matter (SOC) increases.Grounded studies subsequent to the 2018 terrain/topsoil recalibration paper tend to confirm new concepts and support elevated results, in particular SOC stocks reasonably raised above 8,580 Gt to >10,000-12,000 Gt partly due to starting values now much higher than just 1,500-3,000 Gt C, e.g.: 1. IPCC's most recent report (IPCC 2019a: 2-97) [7] 2C) [16] falsely claims just 1,500 Gt SOC (from 4p1000.org?), but their SoilGrids dataset graph has 4,595 Gt to 2 m (pers.obs.) that may be doubled for terrain and soil deeper than 2 m, plus an extra 510 Gt peat, to >10,000 Gt SOC (Figure 1).clearly demonstrating relative importance and geographical allocations of flammable trees and other aboveground vegetation vs. soil SOC carbon storage to just 2 m (yet base of boreal permafrost may reach 1.5 km!).Forests are cleared and land degraded mainly to satisfy excessive red-meat diets [13,15].Options for re-greening of dishes and of deserts, especially in over-grazed Australia, India, N. Africa and Mid East, offer greatest global potential for restoration of lost humus/SOC.
The most feasible explanation for increased GPP and flux rates (assuming LAI leaf-area-indices are accurate) is land area raised as per Blakemore (2018b) [1].Factoring in terrain best justifies newly modeled values.Furthermore, the ocean is a closed-system passively absorbing as little as 0.4 Gt C/yr from excess atmospheric CO2 (Lee et al. 1998) [20], or just 4% of the 10 Gt C/yr emitted by fossil fuels, thus it is not a main consideration of this report, neither should it be for IPCC nor for other carbon-cycle models.Land/soil:sea:fossil flux partition ratios are reported as 817:80:10 Gt C/yr [26].

Corroboration and Consequences
As a general rule, carbon turnover time (τ) is a carbon stock reservoir divided by its flux (often GPP or just NPP).Rapid replacement of all 860 Gt C in atmospheric CO2 is realistic if land's active GPP is ~200-800 Gt C/yr (τ = 860 / GPP = ~1-4 yrs) with a lesser, passive exchange of net ~0.4-2.4Gt C/yr into CO2 + HCO3 saturated seas.As NPP is about half GPP, a terrestrial NPP of ~218 has τ = ~2 yrs.
Independent agreement for terrestrial NPP of ~218 Gt C/yr -or above -with potential NEP of 20 Gt C/yr and CO2 turnover time of 1-4 yrs are from diverse studies, e.g.: 1. NOAA's Barrow site net summer drawdown of ~20 Gt C/yr (Fig. 3) from Taiga/Tundra being just ~9% of annual global NPP (Blakemore 2018a: fig.Gha topsoil mantle this is 5,460 Gt/yr humus processing.At an average cast carbon content of ~4% gives 218.4 Gt C/yr or about the entire annual NPP, as to be expected for balanced Nature. 3. Duursma & Boisson (1994: 124, 134-5) [31] for oceans state: "The turnover time of water masses, which transport CO2 into the deep sea in polar regions, where the CO2 is released at lower latitudes, is of the order of a thousand years (650 year in the Atlantic to 2000 in the Pacific)… Increased atmospheric CO2 will only slightly affect the CO2 level in the oceans, since the latter contain 55 times more CO2 than the atmosphere.Thus there will be no feedback based on increased atmospheric CO2, or at most very little (<2 % of effects on land)...The average annual primary production of the world oceans of 30 gigatons carbon".7. Prof. Rattan Lal [34][35][36] endorses SOC and NPP rate re-evaluations from [1] as reasonable.
In addition to higher NPP contributions into the SOC pools, other factors affecting storage rates in, on, or from soil are, for example: Leaf litter/log necromass, roots, earthworm castings with biogenic calcite in 'inorganic' carbon (SIC) and earthworm bodies washing off into rivers (Blakemore 2019d) [41], plus dissolved organic/inorganic carbon (DOC/DIC) leaching [34].Total SOC from values herein of up to 12,000 Gt, may be increased 27% for glomalin (Comis 2002) [42] to 15,000 Gt (or ten times 4p1000.orgestimate!) with an additional >1,000 Gt in plant root/mycorrhiza and 600 Gt in surface litter/logs (Figs.1,3) to likely sum >16,600 Gt C. Plus a partly biogenic inorganic SIC pool of >1,558 to 2 m (Lal 2019a: tab. 1) [34] with a dissolved inorganic DIC pool of 1,404 (= 2,962 Gt C), doubled for depth/terrain to ~6,000 Gt, yields >22,600 Gt soil carbon in toto.

Conclusions
Whittaker & Likens (1973) [43] said: "Despite the immensity of the biosphere, man has reduced its biomass and is beginning, with pollution, to affect its productivity."As natural flux and/or GPP carbon cycling (400-800 Gt C/yr) is up to 80 times fossil fuel emissions (~10 Gt C/yr), the cause of CO2 accumulation in air is inability of biomes to fix and reabsorb excess due to biomass clearing, grazing, poisoning, burning and an unwitting destruction of topsoil with critical decline of earthworms [39,44].
Referring to taiga and the steppes (from whence the author has recently described new earthworm species [45]), Bartsev et al. (2012: fig. 3)[29] also noted: "measures taken by the world community to reduce greenhouse gas emissions are of less importance than preservation of wild natural resources." The latest, 1,542 page, IPCC (2019a) [7] land report (not marine) mentions "compost" just 14 times, "earthworm" once (both inappropriately linked to "biochar" that offers no advantage over time-proven compost and may actually harm soils' essential functions and beneficial fauna), and hits for "humus" are zero but "fish" get >100!Yet immediate application of natural, organic vermi-compost helps restore humic SOC and S/ECCS [41] offering a scalable, mostly cost-free and completely safe remedy to time-critical global species extinctions caused by interlinked and cumulative factors of agrichemical poisons plus topsoil erosion that are exacerbated by climate [39].
Terrain allowance thus raises all land values (Fig. 1) and best explains annual global carbon flux from isotopic analyses, as noted above, of up to 722-817 or as high as 900 Gt C/yr.An NPP value of ~218 Gt C/yr (Tab. 1) may therefore be entirely reasonable and is substantiated by Barrow drawdown data (Fig. 2).A justifiable GPP of ~418 Gt C/yr gives a ~2 year CO2 turnover time (Fig. 3).
Certainties are that CO2 is rising, land is not flat and ignorance of soil outweighs knowledge.
Figures in this report are not definitive although more realistic than those by proponents of just 60 Gt C/yr NPP, 15 Gha terrain, or just 1,500 Gt SOC who must now raise their manifestly low values.

Figure 1 .
Figure 1.Adapted from Crowther et al. (2019: fig.2C)[16] cf.Blakemore (2018: figs.11-12, tab.10)[1]clearly demonstrating relative importance and geographical allocations of flammable trees and other aboveground vegetation vs. soil SOC carbon storage to just 2 m (yet base of boreal permafrost may reach 1.5 km!).Forests are cleared and land degraded mainly to satisfy excessive red-meat diets[13,15].Options for re-greening of dishes and of deserts, especially in over-grazed Australia, India, N. Africa and Mid East, offer greatest global potential for restoration of lost humus/SOC.

Figure 2 .
Figure2.Human activities disrupt plant/soil fluxes more than fossil fuel (FF) burning does: Mauna Loa's flux of +10ppm or >20 Gt C just for winter months is greater than annual FF +10 Gt C/yr that, if it were sole influence, would raise rates by 4.7 ppm rather than current 2.2 ppm.Natural rhythm in Barrow's short summer drawdown flux (above rhs in blue of ~20 ppm = NPP >40 Gt C) is in boreal region with just ~15% of total vegetation (Fig.1).At twice Mauna Loa's flux (~10 ppm), full-yearly global NPP is seemingly within 200-400 Gt C/yr.Despite corona virus industrial shutdowns, 2020's peak spiked to 420 ppm showing FF CO2 reduction has disproportionately lesser effect on carbon totals that are more dependent upon relentless soil SOC loss.Fewer cars or less red meat help cut GHG emissions, but drawdown is possible only with organic humus restoration.(Temperatures may yet rise due to lower aerosol radiative forcing of smog plus its cloud seeding effects).

Figure 3 .
Figure 3. Carbon cycle relevant to atmospheric CO2 accumulation and land sequestration fixes (after Houghton 2007: fig.1)[28] updating IPCC, NASA/NOAA data with details provided in Blakemore (2020)[15].Ocean loading from topsoil erosion, wash-off, drainage and ash far exceeds atmospheric input.Dissolved soil organic/inorganic C (DOC/DIC) also leaches into groundwater or flows to seas.

Table 1 .
Land productivity vs. human emission (assumed as fossil fuels FF but also due to SOC loss) showing soil humus is both Earth's greatest emission source and natural carbon capture store (CCS).
Lee et al. 1998d Le Quéré et al. all also have a passive, mostly self-cancelling ocean/air exchange of ~80-90 Gt C/yr from surface ocean dissolved organic carbon DOC stock of 700-1000 Gt C (all the rest is DIC), here discounted as a relatively small net effect (ca. -0.4-2.4GtC/yr-seeLe Quéré et al.[19]cf.Lee et al. 1998 [40] et al. (2010)GPP estimates herein, how reliable is the current 'official' data?Before remarking on the uncertainties and complexities of previous 18 OC16O isotope standard estimates,Beer et al. (2010)[40]said: "In the absence of direct observations, a combined GPP of all terrestrial ecosystems of 120 Pg C year -1 was obtained by doubling global biomass production estimates without an empirical basis of spatially resolved biomass production and its relationship to GPP."In other words, it was a best guess.Their source was IPCC TAR-3 report (2001: tab.3.2)[18] with NPP of ~60 Gt C/yr, but from a 'flat-Earth' of just ~15 Gha.When doubled for terrain to ~30 Gha this NPP becomes ~120 Gt C/yr, but may be increased further to account for often neglected sub-soil NPP, root exudates, etc.