
Figure 1:
GCMS chromatograms of extracts from Towers soil samples collected from treatments (A: wheat; B: fallow) and time points (1: pre-soybean; 2: mid-soybean; 3: post-soybean).

Figure 2:
GCMS chromatograms of extracts from Oakdale soil samples collected from treatments (A: wheat; B: fallow) and time points (1: pre-soybean; 2: mid-soybean; 3: post-soybean).

Figure 3:
GCMS chromatograms of extracts from Nashville soil samples collected from treatments (A: wheat; B: fallow) and time points (1: pre-soybean; 2: mid-soybean; 3: post-soybean).

Figure 4:
Principal component analysis (PCA) based on SVD comparing the chemical profiles of soil samples across time points (pre-soybean, mid-soybean, and post-soybean) and treatments (fallow or wheat) within a location (Nashville, Oakdale, and Towers). Analysis was performed using ClustVis (Metsalu and Vilo, 2015).
Table 1.
Comparison of chemical profile in soil samples collected from distinct locations (Nashville, Oakdale, and Towers) and samplings (pre-soybean, mid-soybean, and post-soybean). Numbers represent the ratio of a compound in wheat plots compared to fallow ((WT/FL)*100). Gray/white cells highlight higher compound concentrations in wheat or fallow plots under their respective fields and samplings.
| No. | Compound | Towers | Oakdale | Nashville | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pre-soy | Mid-soy | Post-soy | Pre-soy | Mid-soy | Post-soy | Pre-soy | Mid-soy | Post-soy | ||
| 1 | Propylene glycol, 2TMS | 67.47 | 112.52 | 112.58 | 144.03 | 126.04 | 71.9 | 0 | 63.77 | 84.46 |
| 2 | Benzene, 1,3-bis(1,1-dimethylethyl) | 64.31 | 112.28 | 123.28 | 0 | 80.49 | 70.98 | 43.56 | 75.45 | 96.67 |
| 3 | Unknown | 76.12 | 61.94 | 80.77 | 106.77 | 185.18 | 82.89 | 180.67 | 62.42 | 203.3 |
| 4 | Tetradecanoic acid, TMS | 110.09 | 69.67 | 186.51 | - | 181.16 | 122.92 | - | - | - |
| 5 | Pentadecanoic acid, TMS | 67.94 | 104.53 | 102.96 | 112.35 | 161.99 | 116.54 | 115.93 | 91.97 | 68.56 |
| 6 | 9-Hexadecenoic acid, TMS | 144.23 | 111.39 | 126.21 | 247.56 | 174.87 | 139.98 | 325.52 | 282.77 | 107.57 |
| 7 | Hexadecanoic acid, TMS | 97.64 | 93.02 | 91.35 | 143.37 | 122.12 | 110.23 | 160.63 | 123.02 | 73.03 |
| 8 | Cyclic octaatomic sulfur | - | - | - | - | - | - | - | - | - |
| 9 | Hetaptdecanoic acid, TMS | 75.17 | 107.28 | 88.7 | 107.98 | 136.74 | 126.6 | 53.35 | 104.59 | 93.8 |
| 10 | 10-Heptadecenoic acid, (Z)-, TMS | 74.04 | 133.24 | 102.98 | 124.76 | 130.28 | 118.56 | 136.32 | 113.68 | 75.51 |
| 11 | 9,12-Octadecadienoic acid, (Z,Z)-, TMS | 148.82 | 106.39 | 110.56 | 570.09 | 89.22 | 78.11 | 59.52 | - | 10.26 |
| 12 | 9-Octadecenoic acid, (E)-, TMS | 100.15 | 94.28 | 84.79 | 443.21 | 89.95 | 106.93 | 49.68 | 172.53 | 34.21 |
| 13 | 11-Octadecenoic acid, (E)-, TMS | 79.83 | 109.79 | 103.17 | 223.7 | 134.89 | 138.75 | 58.25 | 29.32 | 12.39 |
| 14 | Octadecanoic acid, TMS | 98.92 | 78.44 | 77.55 | 147.03 | 110.22 | 106.14 | 86.05 | 86.39 | 74.22 |
| 15 | 10-Nonadecenoic acid, (Z)-, TMS | 83.68 | 88.28 | 84.8 | 104.42 | 113.8 | 87.64 | 128.04 | 60.36 | 88.56 |
| 16 | 1-O-Pentadecylglycerol, 2TMS | 72.98 | 108.39 | 90.66 | 129.44 | 134.23 | 92.56 | 141.3 | 33.56 | 48.12 |
| 17 | 1-Eicosanol, TMS | 73.96 | 111.91 | 139.71 | 62.9 | 92.26 | 84.43 | 94.05 | 64.44 | 93.15 |
| 18 | Unknown | 95.75 | 124.82 | 110.63 | 87.27 | 95.56 | 112.57 | 113.83 | 72.35 | 103.82 |
| 19 | Unknown | 94.11 | 165.66 | 116.35 | 111.91 | 97.3 | 115.93 | 116 | 63.54 | 102.59 |
| 20 | Icosanoic acid, TMS | 98.79 | 128.39 | 108.26 | 47.48 | 76.04 | 136.91 | 76.73 | 94.16 | 90.82 |
| 21 | 2-Palmitoylglycerol, 2TMS | 89.27 | 157.61 | 124.42 | 102.03 | 202.86 | 109.46 | 110.74 | 59.52 | 109.05 |
| 22 | 2-Palmitoleoylglycerol, 2TMS | 105.35 | 149.11 | 104.52 | 72.17 | 120.79 | 142.35 | 109.14 | 67.75 | 77.69 |
| 23 | Heneicosanoic acid, TMS | 136.71 | 49.95 | 34.63 | 68.85 | 110.48 | 81.48 | 39.34 | 102.57 | 90.71 |
| 24 | Docosanol, TMS | 84.4 | 93.93 | 80.25 | 62.51 | 101.95 | 101.32 | 115.92 | 111.6 | 113.95 |
| 25 | 2-Mono-cis-heptdec-10-enoylglycerol, 2TMS | 110.37 | 161.62 | 132.2 | 69.17 | 176.9 | 98.22 | 223.75 | 106.78 | 93.99 |
| 26 | Behenic acid, TMS | 92.31 | 89.1 | 79.2 | 54.7 | 55.35 | 78.55 | 105.28 | 119.97 | 117.57 |
| 27 | Tricosanoic acid, TMS | 95.15 | 89.93 | 73.56 | 49.2 | 53.26 | 77.58 | 95.38 | 69.74 | 106.89 |
| 28 | Tetraconsanol acid, TMS | 98.25 | 90.4 | 92.22 | 51.41 | 75.01 | 69.45 | 118.23 | 97.42 | 134.49 |
| 29 | Lignoceric acid, TMS | 98.78 | 84.4 | 59.98 | 37.79 | 52.1 | 80.02 | 93.93 | 95.9 | 101.25 |
| 30 | Pentacosanoic acid, TMS | 98.11 | 145.67 | 113.9 | 34.02 | 63.62 | 87.25 | 110.21 | 83.82 | 87.33 |
| 31 | 1-Hexacosanol, TMS | 99.33 | 171.67 | 131.76 | 84.81 | 88.93 | 85.76 | 281.24 | 113.22 | 189.49 |
| 32 | Tetracosanol, TMS | 74.91 | 104.61 | 95.97 | 30.02 | 104.9 | 52.49 | 35.86 | 94.59 | 211.39 |
| 33 | 22-Hydroxydocosanoic acid, 2TMS | 70.18 | 101.46 | 88.67 | 46.8 | 99.01 | 81.98 | 121.02 | 93.49 | 113.94 |
| 34 | Hexacosanoic acid, TMS | 106.56 | 79.67 | 74.82 | 45.11 | 59.11 | 69.42 | 138.89 | 98.13 | 149.95 |
| 35 | Unknown | 50.61 | 103.99 | 107.68 | 44.12 | 76.54 | 68.81 | 80.76 | 111.63 | 162.1 |
| 36 | Unknown | 117.77 | 159.57 | 173.24 | 75.8 | 99.34 | 100.51 | 76.72 | 58.22 | 93.97 |
| 37 | Cholesterol, TMS | 95.23 | 155.2 | 243.49 | 88.52 | 130.04 | 105.37 | 58.28 | 75.19 | 99.37 |
| 38 | 1-Octocosanol, TMS | 179.08 | 223.9 | 133.62 | 104.99 | 113.58 | 95.96 | 326.9 | 139.31 | 235.07 |
| 39 | 24-Hydroxytetracosanoic acid, 2TMS | 89.36 | 42.77 | 82.24 | 61.27 | 67.04 | 88.76 | 136 | 89.6 | 127.77 |
| 40 | Unknown | 78.66 | 65.32 | 96.83 | 58.68 | 78.03 | 100.82 | 80.88 | 25.97 | 90.2 |
| 41 | Campesterol, TMS | 108.82 | 80.77 | 116.27 | 102.73 | 98.05 | 76.07 | 106.11 | 98.38 | 111.96 |
| 42 | Octacosanoic acid, TMS | 112.96 | 131.88 | 92.38 | 45.85 | 73.59 | 73.42 | 161.76 | 130.73 | 200.57 |
| 43 | Unknown | 107.46 | 111.39 | 114.51 | 50.7 | 92.01 | 77.16 | 64.42 | 68.6 | 152.82 |
| 44 | Stigmasterol, TMS | 105.87 | 104.4 | 112.88 | 71.35 | 77.19 | 75.24 | 59.46 | 69.94 | 108.47 |
| 45 | 5alpha-Stigmast-7-en-3beta-ol, TMS | 98.5 | 90.94 | 79.79 | 50.24 | 73.88 | 72.51 | 104.95 | 103.38 | 106.73 |
| 46 | Unknown | 112 | 317.17 | 98.08 | 94.92 | 96.4 | 316.59 | 78.24 | 74.68 | 178.13 |
| 47 | Stigmast-5-ene, 3beta-TMS, (24S)- | 108.91 | 78.49 | 96.98 | 78.74 | 63.32 | 74.47 | 119.09 | 97.77 | 86.97 |
| 48 | Stigmastanol, TMS | 94.13 | 99.07 | 160.9 | 68.09 | 68.95 | 70.67 | 107.33 | 65.1 | 180.53 |
| 49 | 1-Triacontanol, TMS | 88 | 134.47 | 118.4 | 37.59 | 45.67 | 59.61 | 137.74 | 85.9 | 122.03 |
| 50 | gamma-Sitostenone | 74.83 | 136.96 | 116.28 | 41.02 | 143.39 | 102.62 | 89.31 | 98.91 | 64.9 |
| 51 | Tricontanoate, TMS | 122.73 | 96.25 | 66.52 | 39.05 | 47.58 | 62.35 | 100.78 | 87.35 | 159.01 |
Table 2.
Functional group profiles in soil samples collected from distinct locations (Nashville, Oakdale, and Towers) and samplings (pre-soybean, mid-soybean, and post-soybean). Numbers represent the ratio of the total relative area of a chemical in wheat plots compared to fallow ((WT/FL)*100). Gray/white cells highlight higher concentrations of a chemical group in wheat or fallow plots under their respective fields and samplings.
| Compound | Towers | Oakdale | Nashville | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Pre-soy | Mid-soy | Post-soy | Pre-soy | Mid-soy | Post-soy | Pre-soy | Mid-soy | Post-soy | |
| n-fatty acids | 93.23 | 96.39 | 93.61 | 124.33 | 110.72 | 106.24 | 89.82 | 104.37 | 78.57 |
| saturated fatty alcohol | 120.82 | 122.21 | 91.15 | 63.42 | 85.42 | 88.94 | 168.19 | 111.9 | 155.62 |
| Sterols | 106.29 | 88.63 | 110.96 | 77.96 | 72.72 | 75.63 | 108.38 | 93.67 | 100.14 |
| Unknown | 97.49 | 129.97 | 108.43 | 74.11 | 97.97 | 130.11 | 82.55 | 70.61 | 132.07 |
| n-aldehydes | 89.01 | 132.93 | 110 | 43.85 | 98.61 | 63.16 | 90.81 | 100 | 204.74 |
| propane-1,2-diols | 67.68 | 112.64 | 112.63 | 144.16 | 125.86 | 71.64 | 0 | 64.04 | 84.51 |
| Steroid ketones | 74.58 | 136.71 | 116.67 | 41.05 | 143.64 | 101.59 | 89.61 | 98.67 | 64.85 |
| fatty acid glycerol | 102.56 | 154.02 | 116.28 | 80.46 | 157.78 | 116.67 | 133.33 | 75 | 92.16 |
| alkylbenzene | 63.16 | 111.11 | 122.22 | 0 | 80.28 | 70.59 | 43.66 | 75 | 96.7 |