# Biomass Refined: 99% of Organic Carbon in Soils
## Appendix B Total Fungal Carbon (f-SOC)  
Fungal assay has three main considerations: Biomass, Necromass, and glomalin. In this study, these three are shown to vary widely at 320-3760 Gt f-SOC. Current official \"best guess\" global fungal biomass that range just 12-15 f-SOC are thus wholly inadequate, underestimating likely total f-SOC stock by one or two orders of magnitude. Ref. [28], as with [86], combined soil depths of 0-1 m and 1-8 m, saying that microbial biomass below 1 m averages 2-30% of the total microbial biomass as found in the top 1 m of soil. They then took a geometric mean of the fraction of fungal biomass from total biomass of soil microbes they estimated as 60% that translated to an estimate for total biomass of soil fungi of \(\approx\)12 Gt C. Components of this were 0.2 Gt C in Etomycorrhizal fungal (EM) found mainly in boreal and temperate forest soils, and total 2.0 Gt C in widespread Arbuscular-Mycorrhiza (AM). For Bacteria (and Archaea), ref. [28] had 8 Gt to give a Fungal:Bacteria ratio in soil of 12:8, or about 1.5:1. Although [144] mostly agreed with a global biomass carbon budget of 12 Gt C for Fungi, they had a lower value of just 4 Gt C of Bacteria in topsoil for an F:B ratio of 12:4 or about 3:1. A revised bacterial estimate in table 5 in ref. [64] and [38] has Bacteria at about 210 Gt C; if the same ratios apply, then soil fungal biomass would truly be \(\times\)25-50 higher at about 300-600 Gt f-SOC. Conversely, ref. [144] for _\"Global stocks of living microbial biomass\"_ estimated fungi at 12.56 Gt C. But this is only _\"in 0-30 cm topsoil\"_ within their global estimate of 684-724 Gt SOC (also 0-30 cm) thus they said 1.8% of total SOC is stored in soil fungi. This contrasts to [167] who found: _\"AMF biomass accounts for 20-30% of the total soil microbial biomass, and roughly 15% of the SOC pool in diverse terrestrial ecosystems\"_ which is about a ten times greater proportion. But perhaps Arbuscular-Mycorrhizal fungi (AM) are only about half of total fungi in which case this \(\approx\)60% of total biomass in [28] may well be correct? Yet, it is difficult to reconcile [PERSON] et al. 's 15% with [PERSON] et al. 's mere 1.8% of SOC, unless fungal biomass estimates are out by factorials. Compared to these, ref. [26] had 15 Gt C in [Eto-]mycorrhizal hyphae alone. If [PERSON] et al. 's EM + AM fungi are 0.2 + 2.0 Gt (or 1.6 + 16.7% = 18.3%) of total 12 Gt C (100%) then, should Robinson be correct, and EM alone are 15 Gt, just 1.6% gives total fungi of 1880 Gt C! Reasonably doubled for terrain, a total would be 3760 Gt C global fungal biomass which is much higher than soil Bacteria at \(\sim\)210 Gt C, as just stated above. An initial problem with [144] value is that it is only for _\"living microbial biomass\"_ and, for example, ref. [168] have _\"In temperate soils, up to 40% of DNA is from dead or compromised cells. In permafrost, the amount of relic DNA may be even higher because frozen conditions preserve DNA from dead cells\"_. This is highly pertinent to the glomalin in Permafrost issue covered in detail elsewhere. They cited just 25-26% viable cells in some Permafrost suggesting about 75% were dead or dormant. Other authors have similar or higher estimates, e.g., ref. [169] say: _\"Furthermore, a majority of the microbial cells or richness in soil is dormant, reportedly as high as 80%, representing a considerable pool of microbial functional potential. Finally, across heterogeneous soils, an average of 40% of the microbiome DNA was necromass that existed extracellularly. This suggests that DNA-based methods of determining microbiome dynamics include both inactive and necromass reservoirs...\"_. Thus, it is not unreasonable to (at least) double [PERSON] et al. 's living value for dormancy. 12.56 Gt C \(\times\) 2 for dormant/dead microbial cells = 25.12 Gt C.  
Also, [PERSON] et al. only measure microbes in the top 30 cm while SOC averages are of around 828 Gt and 1873 Gt, for 0-30 cm and 0-100 cm soil depths, respectively, or over double for depth.