Table 5.
Coefficients of determination (R2) for the correlation between soil physical indicators and vermicompost rate. R2 values with the minus sign indicate decreasing correlations. The significant regressions were marked with asterisks (**p < 0.01; *p < 0.05). For each significant regression, the calculated values between minimum and maximum vermicompost concentration (r = 0 and 43 %) are reported in brackets.
| Orleans (OR) | CREA (CR) | UNIPA (UN) | Ginosa (GI) | Castellaneta (CA) | |
|---|---|---|---|---|---|
| PMAC (cm3 cm−3) | 0.2525* (0.01–0.014) | 0.1170 (n.a.) | 0.0115 (n.a.) | 0.7809** (0–0.03) | 0.3924** (0.01–0.05) |
| AC (cm3 cm−3) | 0.8542** (0.09–0.23) | 0.0001 (n.a.) | 0.2652* (0.20–0.25) | −0.0621 (n.a.) | −0.2813* (0.29–0.18) |
| RFC (˗) | −0.6625** (0.78–0.57) | 0.0266 (n.a.) | −0.1394 (n.a.) | 0.3424** (0.52–0.63) | 0.5933** (0.41–0.72) |
| PAWC (cm3 cm−3) | 0.0013 (n.a.) | 0.1862 (n.a.) | 0.0200 (n.a.) | 0.6316** (0.08–0.18) | 0.8263** (0.002–0.24) |
| dmod (μm) | 0.7747** (16–38) | 0.0787 (n.a.) | 0.2138* (46–65) | 0.3833** (50–72) | −0.0005 (n.a.) |
| dmed (μm) | 0.7554** (4–26) | 0.0681 (n.a.) | 0.2705* (28–49) | 0.0251 (n.a.) | −0.3511** (61–28) |
| dm (μm) | 0.7454** (2–21) | 0.0615 (n.a.) | 0.2709* (22–42) | −0.0018 (n.a.) | −0.5343** (57–18) |
| SD (˗) | −0.2116* (62 to −36) | −0.0126 (n.a.) | −0.2446* (13–8) | 0.5222** (3–6) | 0.8521** (2–9) |
| Sk (˗) | 0.5755** (−0.6 to −0.3) | 0.0059 (n.a.) | 0.2223* (−0.4 to −0.3) | −0.5953** (−0.2 to −0.4) | −0.8699** (−0.2 to −0.5) |
| Ku (˗) | 0.0346 (n.a.) | −0.0035 (n.a.) | −0.1868 (n.a.) | 0.6153** (1.13–1.15) | 0.8145** (1.13–1.16) |
| hinf (cm) | −0.6001** (181–50) | −0.0002 (n.a.) | −0.2616* (66–43) | −0.2929* (59–41) | 0.1569 (n.a.) |
| θinf (cm3 cm−3) | 0.8326** (0.22–0.46) | 0.3911** (0.35–0.62) | 0.7913** (0.26–0.54) | 0.9300** (0.28–0.57) | 0.8492** (0.23–0.52) |
| S (˗) | 0.9123** (0.04–0.18) | 0.2202* (0.10–0.14) | 0.7288** (0.08–0.17) | −0.0514 (n.a.) | −0.2518* (0.13–0.10) |
| PORinf (cm3 cm−3) | −0.0182 (n.a.) | <0.0001 (n.a.) | −0.0584 (n.a.) | −0.3351** (0.37–0.32) | −0.3972** (0.35–0.31) |
| λinf (˗) | 0.5791** (0.22–0.51) | 0.0026 (n.a.) | 0.1968 (n.a.) | −0.6231** (0.81–0.38) | −0.7850** (0.81–0.24) |
PMAC, macroporosity; AC, air capacity; RFC, relative field capacity; PAWC, plant available water capacity; dmod, modal diameter; dmed median diameter; dm, mean diameter; SD, standard deviation, Sk, asymmetry, Ku, kurtosis of soil pores distribution; hinf, soil pressure head at the water retention curve inflection point; θinf, soil water content at the inflection point; S, Dexter's S index; PORinf, soil porosity at the inflection point; λinf, pore distribution index.