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Table 8 Summary effect estimates for meta-analyses of concentration data

From: How does tillage intensity affect soil organic carbon? A systematic review

Tillage comparison Soil depth (cm) Summary effect estimate (g/kg) Standard error z statistic p value Lower 95% confidence interval Upper 95% confidence interval Number of studies
NT–HT 0–15 2.086 0.344 6.073 < 0.001 1.413 2.760 102
15–30 − 0.298 0.286 − 1.039 0.299 − 0.859 0.264 49
> 30 − 0.371 0.261 − 1.424 0.155 − 0.882 0.134 31
NT–IT 0–15 1.179 0.334 3.537 < 0.001 0.526 1.833 95
15–30 0.273 0.289 0.944 0.345 − 0.293 0.839 45
> 30 − 0.157 0.186 − 0.845 0.398 − 0.522 0.208 20
IT–HT 0–15 1.229 0.221 5.575 < 0.001 0.797 1.662 77
15–30 − 0.890 0.198 − 4.539 < 0.001 − 1.288 − 0.511 42
> 30 − 0.261 0.209 − 1.250 0.211 − 0.671 0.148 16
  1. NT no tillage, IT intermediate intensity tillage, HT high intensity tillage (see text for explanation)