## 4 Results
### Soil Water Content  
The volumetric soil water content at saturation (\(\theta_{s}\)) and that at pressure heads, \(h\), of \(-\)10 (\(\theta_{10}\)), \(-\)100 (\(\theta_{100}\)), and \(-\)15,300 (\(\theta_{15,300}\)) cm increased with the amendment rate, \(ar\), according to statistically significant relationships for both soils and the three amendments (Table 2). The \(R^{2}\) values of the fitted relationships varied from 0.35 to 0.97, depending on the considered combination among the pressure head, the soil, and the amendment. These relationships were marginally stronger in the more unsaturated conditions, since the  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameter** & **Soil** & **Amendment** & **Intercept** & **Slope** & **R\({}^{2}\)** & **Minimum** & **Maximum** \\ \hline \multirow{6}{*}{\(P_{MAC}\) (cm\({}^{3}\)/cm\({}^{3}\))} & \multirow{3}{*}{CAS} & COM & 0.0128 & 8 \(\times\) 10\({}^{-5}\) & 0.3144 s & - & - \\ \cline{3-8}  & & VER & 0.0099 & 0.0002 & 0.4033 s & - & - \\ \cline{3-8}  & & BIO & 0.0052 & 9 \(\times\) 10\({}^{-6}\) & 0.0379 ns & - & - \\ \cline{2-8}  & \multirow{3}{*}{GIN} & COM & 0.0105 & 8 \(\times\) 10\({}^{-5}\) & 0.4150 s & - & - \\ \cline{3-8}  & & VER & 0.0066 & 0.0001 & 0.7784 s & - & - \\ \cline{3-8}  & & BIO & 0.0095 & \(-\)4 \(\times\) 10\({}^{-5}\) & 0.3946 s & - & - \\ \hline \multirow{6}{*}{\(AC\) (cm\({}^{3}\)/cm\({}^{3}\))} & \multirow{3}{*}{CAS} & COM & 0.2424 & \(-\)8 \(\times\) 10\({}^{-5}\) & 0.0241 ns & - & - \\ \cline{3-8}  & & VER & 0.2907 & \(-\)0.0006 & 0.2400 s & 117.8 & - \\ \cline{3-8}  & & BIO & 0.2244 & \(-\)0.0005 & 0.6211 s & 8.8 & 148.8 \\ \cline{2-8}  & \multirow{3}{*}{GIN} & COM & 0.2533 & \(-\)0.0003 & 0.2764 s & 111.0 & - \\ \cline{3-8}  & & VER & 0.2564 & \(-\)0.0001 & 0.0417 ns & - & - \\ \cline{3-8}  & & BIO & 0.2470 & \(-\)0.0006 & 0.8049 s & 45.0 & 161.7 \\ \hline \multirow{6}{*}{\(PAWC\) (cm\({}^{3}\)/cm\({}^{3}\))} & \multirow{3}{*}{CAS} & COM & 0.1371 & 0.0005 & 0.5531 s & 25.8 & 165.8 \\ \cline{3-8}  & & VER & 0.0913 & 0.0008 & 0.6328 s & 73.4 & 160.9 \\ \cline{3-8}  & & BIO & 0.1411 & 0.0011 & 0.7755 s & 8.1 & 71.7 \\ \cline{2-8}  & \multirow{3}{*}{GIN} & COM & 0.1562 & 0.0002 & 0.1771 ns & - & - \\ \cline{3-8}  & & VER & 0.1326 & 6 \(\times\) 10\({}^{-5}\) & 0.0174 ns & - & - \\ \cline{3-8}  & & BIO & 0.1529 & 0.0012 & 0.9390 s & 0 & 55.9 \\ \hline \multirow{6}{*}{\(RFC\) (-)} & \multirow{3}{*}{CAS} & COM & 0.4829 & 0.0008 & 0.4860 s & 146.4 & - \\ \cline{3-8}  & & VER & 0.4161 & 0.0017 & 0.5790 s & 108.2 & 167.0 \\ \cline{3-8}  & & BIO & 0.5195 & 0.0015 & 0.7874 s & 53.7 & 120.3 \\ \cline{2-8}  & \multirow{3}{*}{GIN} & COM & 0.5129 & 0.0010 & 0.5930 s & 87.1 & 233.9 \\ \cline{3-8}  & & VER & 0.5240 & 0.0006 & 0.3287 s & 126.7 & - \\ \cline{3-8}  & & BIO & 0.5170 & 0.0016 & 0.9062 s & 51.9 & 114.4 \\ \hline \hline \end{tabular} \(BD\) = dry soil bulk density; \(P_{MAC}\) = macroporosity; \(AC\) = air capacity; \(PAWC\) = plant available water capacity; \(RFC\) = relative field capacity; CAS = Castellaneta field site; GIN = Ginosa field site; COM = compost VER = vermicompost; BIO = biochar. s: correlation coefficient, \(R\), significantly greater than zero according to a two-tailed \(t\) test at \(P\) = 0.05; ns: \(R\) not significantly greater than 0.  
\end{table}
Table 1: _Cont._median of \(R^{2}\) was equal to 0.79 for both the \(\theta_{\rm s}\) and \(\theta_{10}\), and to 0.83 for both the \(\theta_{100}\) and \(\theta_{15,300}\), and at GIN than at CAS (medians of \(R^{2}\) = 0.86 and 0.81, respectively). Stronger \(\theta\) vs. _ar_ relationships were obtained with the BIO and the COM than with the VER, since the medians of \(R^{2}\) were equal to 0.85, 0.83, and 0.64, respectively.