Figure 1.
Conceptual workflow of the Plant Trek two-stage regolith-to-soil framework for Martian crop production. Stage I focuses on microbial perchlorate reduction and initial geochemical conditioning of PTMM, followed by a structure-building transition into Stage II, where plant growth, substrate evolution, and agricultural performance are integrated into a closed-loop regolith biomanufacturing system.
Figure 2.
Discrete water-extractable perchlorate measurements in PTMM during Stage I treatment from Day 0 to Day 72. (A) Absolute perchlorate concentrations in the sterile PTMM + perchlorate Day 0 proxy, non-microwaved and microwaved PTMM controls, and aerobic and anaerobic treatment samples. (B) Perchlorate remaining relative to the Day 0 proxy.
Table 1.
Replicate total carbon and nitrogen concentrations (wt.%) measured in anaerobic and aerobic PTMM treatments following Stage I microbial conditioning and Stage II plant growth.
| Stage | Variable | Anaerobic mean ± SD | Aerobic mean ± SD | Welch's t | p-value | q-value | FDR significant? |
|---|---|---|---|---|---|---|---|
| Stage I | wt.% N | 0.00575 ± 0.00458 | 0.00965 ± 0.00090 | 1.869 | 0.1298 | 0.2596 | No |
| Stage I | wt.% C | 0.54547 ± 0.03315 | 0.56941 ± 0.02270 | 1.333 | 0.2240 | 0.2987 | No |
| Stage II | wt.% N | 0.00501 ± 0.00344 | 0.01068 ± 0.00168 | 3.317 | 0.0169 | 0.0676 | No |
| Stage II | wt.% C | 0.55525 ± 0.03202 | 0.56191 ± 0.01057 | 0.441 | 0.6780 | 0.6780 | No |
Figure 3.
pH of PTMM following Stage I microbial conditioning and after Stage II plant growth under anaerobic and aerobic treatments. Large markers indicate means ± SD, smaller markers represent individual replicates, and both treatments show a modest decline in pH during early soil development.
Figure 4.
Stage I bulk and NH4OAc-extractable elemental concentrations in PTMM following microbial conditioning: (a) anaerobic beneficial elements, (b) aerobic beneficial elements, (c) anaerobic non-desirable elements, and (d) aerobic non-desirable elements. Points show mean concentrations of ten replicate samples per treatment (n = 10), and error bars represent standard deviation where visible. Circles represent bulk concentrations, and squares represent exchangeable concentrations. Dashed reference lines indicate literature-based terrestrial soil screening values used for contextual comparison with the exchangeable, operationally defined plant-available fraction rather than the bulk elemental inventory. Minimum agricultural soil-test sufficiency references are shown for beneficial nutrients, including P, K, Mg, Mn, Zn, and Cu from Horneck et al. (2019), Ca from Marx et al. (1999), and Fe from Flynn (2015). Maximum screening references are shown for non-desirable elements, including Na from Agriculture Victoria (2025), Ti from OECD (2016), Cr, Co, As, Cd, and Pb from CCME (2007), and Ni from CCME (2015). These values are used as screening references and are not crop-specific thresholds.
Table 1a.
Bulk elemental concentrations.
| Element | Anaerobic Bulk | Aerobic Bulk | Welch p-value | FDR q-value | Significant after FDR? |
|---|---|---|---|---|---|
| Na | 11,703.4 ± 597.46 | 12,219.5 ± 1,188.37 | 0.224 | 0.553 | No |
| Mg | 66,592.6 ± 4,128.04 | 65,053.2 ± 2,630.37 | 0.346 | 0.692 | No |
| P | 1,191.6 ± 69.31 | 2,602.8 ± 112.81 | 1.69 × 10−15 | 2.71 × 10−14 | Yes |
| K | 5,629.3 ± 345.98 | 5,393.5 ± 221.83 | 0.0892 | 0.476 | No |
| Ca | 80,579.9 ± 3,774.82 | 79,985.9 ± 4,297.50 | 0.732 | 0.780 | No |
| Ti | 1,845.7 ± 89.48 | 1,819.9 ± 123.90 | 0.603 | 0.743 | No |
| Cr | 564.7 ± 62.88 | 555.3 ± 44.37 | 0.704 | 0.780 | No |
| Mn | 672.9 ± 44.35 | 661.9 ± 31.43 | 0.529 | 0.743 | No |
| Fe | 59,438.7 ± 3,766.03 | 57,549.7 ± 2,034.80 | 0.185 | 0.553 | No |
| Co | 33.97 ± 2.36 | 33.19 ± 1.59 | 0.400 | 0.710 | No |
| Ni | 384.2 ± 20.24 | 378.7 ± 19.89 | 0.552 | 0.743 | No |
| Cu | 18.07 ± 1.50 | 17.05 ± 1.25 | 0.127 | 0.507 | No |
| Zn | 51.75 ± 3.86 | 55.50 ± 19.85 | 0.571 | 0.743 | No |
| As | 3.381 ± 0.304 | 3.430 ± 0.439 | 0.782 | 0.782 | No |
| Cd | 0.0201 ± 0.0105 | 0.0202 ± 0.00028 | Not tested | Not tested | Not tested |
| Pb | 3.815 ± 0.294 | 3.430 ± 0.250 | 0.00941 | 0.0753 | No |
Table 1b.
Exchangeable elemental concentrations.
| Element | Anaerobic Exchangeable | Aerobic Exchangeable | Welch p-value | FDR q-value | Significant after FDR? |
|---|---|---|---|---|---|
| Na | 3,143.2 ± 462.2 | 5,054.2 ± 511.4 | 7.41 × 10−8 | 2.47 × 10−7 | Yes |
| Mg | 1,034.9 ± 61.6 | 920.4 ± 50.9 | 2.50 × 10−4 | 4.99 × 10−4 | Yes |
| P | 3.31 ± 2.47 | 222.16 ± 24.15 | 2.79 × 10−10 | 2.79 × 10−9 | Yes |
| K | 529.7 ± 44.5 | 556.8 ± 37.3 | 0.157 | 0.197 | No |
| Ca | 20,621.6 ± 1,433.2 | 21,705.2 ± 1,552.6 | 0.122 | 0.175 | No |
| Ti | 0.00 ± 0.00 | 0.12 ± 0.06 | 2.02 × 10−4 | 4.99 × 10−4 | Yes |
| Cr | 0.00 ± 0.00 | 0.00 ± 0.00 | Not tested | Not tested | Not tested |
| Mn | 5.68 ± 0.71 | 5.77 ± 0.57 | 0.758 | 0.758 | No |
| Fe | 39.75 ± 2.8 | 39.42 ± 3.5 | 0.567 | 0.630 | No |
| Co | 0.06 ± 0.05 | 0.10 ± 0.00 | 0.0368 | 0.0613 | No |
| Ni | 0.55 ± 0.04 | 0.30 ± 0.01 | 1.30 × 10−9 | 6.49 × 10−9 | Yes |
| Cu | 0.30 ± 0.10 | 0.20 ± 0.10 | Not tested | Not tested | Not tested |
| Zn | 0.00 ± 0.00 | 0.00 ± 0.00 | Not tested | Not tested | Not tested |
| As | 0.00 ± 0.00 | 0.10 ± 0.10 | Not tested | Not tested | Not tested |
| Cd | 0.00 ± 0.00 | 0.00 ± 0.00 | Not tested | Not tested | Not tested |
| Pb | 0.00 ± 0.00 | 0.00 ± 0.00 | Not tested | Not tested | Not tested |