| Element | Effect on microbial diversity |
| pH | Maximum diversity at neutral pH (6 - 8). Extreme pHs lead to decreased diversity. |
| Vegetation | Different plants may stimulate and/or inhibit different microbial populations. |
| Water content | Greater diversity with moderate water content. Water-saturated conditions decrease diversity due to less spatial isolation of organisms and also the generation of anaerobic conditions. |
| Oxygen concentration | Greater diversity under aerobic conditions. |
| Temperature | Extremely high or low temperatures reduce diversity. |
| Organic matter content | Higher organic matter content results in higher diversity. |
| Soil depth | Decreasing diversity with increasing depth from surface. |
| Addition of organic substrates | Addition of a single, organic substrate often results in a reduction in diversity due to the stimulation of a subset of the microbial community. |
| Soil tillage | Decreased diversity due to soil homogenization and reduction in microsite variation. |
| Addition of organic pollutants | Similar to organic substrates in general, often a reduction in diversity due to stimulation of specific populations but also potentially toxicity of the xenobiotic to other populations. |
| Addition of metal pollutants | Reduction in diversity due to toxicity to some populations. |