Table 1 The properties of the different sulfur substrates
Code | Sulfur substrate | Sulfur content | Particle size | Source | Note |
|---|---|---|---|---|---|
S | Sulfur powder | ≥ 99.5% | 200–300 μm | Shijiazhuang Jiyanzhengnong corporation | – |
SC | Sulfur-covered biochar particles | 70% | Irregular particles with size of about 5 mm | Prepared by the laboratory | Prepared by solidifying melted elemental sulfur on the surface of the bamboo biochar |
R | Sulfur powder mixed with rhamnolipid | ≥ 99.5% | 200–300 μm | VICTEX corporation | Rhamnolipid surfactant is secreted by Pseudomonas. The added concentration in the research was 0.3 g/L [10] |
C | None | – | – | – | Control check group, no sulfur substrate added |
N | None | – | – | – | Sterilization treatment group, added 200 mg/L NaN3 |