TABLE 2.
Average indicator bacterial counts by sample type and farming system
| Sample type | Organic farms |
Conventional farms |
||||||
|---|---|---|---|---|---|---|---|---|
| No. of samples | Avg count, log CFU/g or log CFU/ml (% positive samples)a |
No. of samples | Avg count, log CFU/g or log CFU/ml (% positive samples) |
|||||
| APC | E. coli | Total coliforms | APC | E. coli | Total coliforms | |||
| Leafy greens | 178 | 5.71 a* (99) | 0.10 b (7) | 2.04 b* (71†) | 191 | 5.37 a* (99) | 0.12 b (6) | 1.30 a* (51†) |
| Irrigation water | 67 | 0.74 c (64) | 0.10 b (12) | 0.52 c (57) | 57 | 0.62 c (51) | 0.13 a (25) | 0.58 b (47) |
| Field soil | 26 | 5.89 a (96) | 0.48 a* (23†) | 3.00 a* (85) | 34 | 5.67 a (100) | 0.00 a* (0†) | 1.71 a* (71) |
| Compost | 11 | 5.70 ab (91) | 0.83 a (27) | 2.59 ab (91) | 0 | — | — | — |
| Pond Sediment | 3 | 4.07 b (100) | 0.54 ab (67) | 1.31 abc (67) | 10 | 4.11 b (100) | 0.16 a (30) | 2.00 a (80) |
a
Data for sample types having different letters were significantly different (P < 0.05) within the column. *, statistically significant difference between indicator bacterial counts of organic and conventional samples for a given sample type. †, statistically significant difference between percent positive for organic and conventional samples for a given sample type. —, no samples of that type were collected from that farming system. Data were log transformed prior to statistical analysis.