# Biomass Refined: 99% of Organic Carbon in Soils
## 3 Results and Discussion
### Refinement of Soil Carbon Stocks (Terrain, Depth, Gomalin, Saprock)
#### 3.3.3 Glomalin Unstuck with Glomalin Related Soil Protein (GRSP)  
As already covered in the Introduction, a summary paper by [103] confirmed that glomalin-related soil proteins (GRSP) represent ca. 20% of the soil organic carbon and aid carbon sequestration by stabilizing soil aggregates. For farmlands, USDA (www.ars.usda.g ov/ARSUserFiles/30640500/Glomalin/Glomalinbrochure.pdf, accessed on 11 November 2024) had: _\"Glomalin accounts for a large amount (about 15 to 20%) of the organic carbon in undisturbed soils\"_. Possibly, degraded farmland soils suffer depleted fungal activities since, as noted in the Introduction, ref. [15] report higher values of GRSP accounting for around 27% of total SOC. In an ancient, oxidized soil (supposedly \(>\)4 million years old), it was less at about 4% of total C, whereas in a peat, purified GRSP was as high as 52% of total SOC. The \"[PERSON] et al. _2000_\" reference from [PERSON] et al. appears to be mistaken, but another paper by [104] does have 52% glomalin in a peat, viz. : _\"GRSP accounted for 25% and 52% of total C in the mineral soils and organic soil_ [peat], _respectively_\". This implies an allowance for difficult-to-extract glomalin in measured Peat SOC may (always?) be doubled. It was shown that GRSP can contribute about 27% of SOC while soil humus may contribute only 8%; thus, carbon capacity of GRSP is 2-24 times that of soil humus [12]. The GRSP status of Permafrost is uncertain and urgently requires greater depth of study as, if it is similar to Peat, its contribution is not insubstantial. For mineral soils, adding of about +25% seems reasonable. Conversely, ref. [105], while admitting some studies at that time indicated glomalin as high as +27% in SOC, claimed 0.7 to 2.4% appear more common for Agroecosystems. This may be partly true for intensive, agrichemical fields, which are depleted in both humus and soil biota (as reported by [67]). Their understanding suggested values much above 2% of SOC were unreasonable based on NPP they calculated would be required to support AMF hyphal growth (in their Appendix II). In other words, if glomalin was as high as reported, NPP models would need to be modified. This is not a proper Scientific approach as data should be followed, regardless of any ideal model outcomes. Since glomalin often measures at 30% or up to 52% of SOC, what they unwittingly support is need for terrestrial models to be substantially increased, perhaps as herein, to recognize NPP up to, or much above, >220 Gt C/yr. See too the [PERSON] study. Current information is scant and based upon few studies, but confirmation of the importance and contribution of GRSP to total SOC as outlined in [103] are found in a case study by [106] showing GRSP (in total?) in cropland and forests making up 24% and 18% of the 20-25 g/kg SOC, respectively. They reported total GRSP accounted for 8.19%-73.70% of SOC totals 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. This demonstrates that glomalin is a non-trivial SOC addition. Their summary figure gives an indication of respective Fungal-to-Bacterial ratios (Figure 11). Figure 11: From figure 12 in ref. [106] of SOC with abbreviations of MNC for Microbial Necromass-C; EE- and T-GRSP for easily extractable and total Glomalin-Related Soil Proteins; AMF for Arbuscular mycorrhizala; 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 of FRC and GRSP-C, bacterial BRC contributed about 15% of their absolute total SOC carbon across both study habitats. It is likely mistaken to claim increases from Crop to Woodland, as woodlands are cleared for crops. A recent study by [107] found glomalin particularly important in (fungal dominated?) acid soils of coniferous forests that are abundant in the boreal North.