# Remote and Proximal Sensing Techniques for Site-Specific Irrigation Management in the Olive Orchard
## 3 Results
### Irrigation and Cluster Effect on Tree Water Status, Yield and Vegetative Growth  
One day after the beginning of the irrigation period (DOY 187) the tree water status was the same across all irrigation regimes and clusters, whereas significant differences in SWP between irrigation treatments were measured at DOY 219 (\(-\)1.49, \(-\)2.49 and \(-\)3.65 MPa in FI, DI and RF trees, respectively) and DOY 259 (\(-\)1.57, \(-\)2.65 and \(-\)3.89 MPa, respectively) (Table 2). Similar trends were measured in both clusters without any significant interaction between irrigation treatment and cluster on tree water status (data not shown). The fruit yield per tree and the TCSA increment were affected by irrigation, canopy NDVI, and soil EC\(\alpha_{1}\). Irrigation affected both fruit yield (23.890, 15.745 and 8.040 kg per tree in FI, DI, and RF trees, respectively) and the TCSA increment (0.37, 0.23 and 0.16 dm\({}^{2}\), respectively) (Figure 4). The two clusters obtained using both remote (NDVI) and proximal (EC\(\alpha_{1}\)) sensed indices showed differences in fruit yield (17.259 and 14.003 kg per tree in Cluster 1 and 2, respectively) and annual TCSA increment (0.26 and 0.24 dm\({}^{2}\), respectively) (Figure 4). The effect of irrigation on tree productivity and vegetative growth was different between the two clusters. The trees under deficit irrigation grown in the orchard area associated to Cluster 1 showed yields similar to those measured in fully irrigated trees of Cluster 2. Similarly, rainfed trees in Cluster 1 had yields similar to those of trees under deficit irrigation in Cluster 2. The vegetative growth showed significant differences between all the irrigation-cluster combinations (Figure 4). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Cluster 1** & \multicolumn{4}{c}{**Soil Horizons**} \\ \cline{2-5}
**(Profile 1)** & **Ap1** & **Ap2** & **Bt** & **Btg** \\ \hline Depth (m) & 0.8 & 0.40 & 1.00 & 1.50 \\ Clay (dag kg\({}^{-1}\)) & 13.9 & 22.5 & 17.7 & 22.1 \\ Slit (dag kg\({}^{-1}\)) & 45.5 & 33.2 & 44.4 & 39.3 \\ Sand (dag kg\({}^{-1}\)) & 40.6 & 44.3 & 37.9 & 38.6 \\ CF (\%vol) & 2 & 2 & 0 & 0 \\ CaCO\(\alpha_{3}\) tot (dag kg\({}^{-1}\)) & 2.4 & 2.5 & 2.3 & 2.1 \\ SOC (dag kg\({}^{-1}\)) & 31.4 & 11.0 & 9.0 & 7.2 \\ TN (g kg\({}^{-1}\)) & 24.4 & 9.8 & 9.7 & 7.7 \\ AWC (mm) & 12 & 45 & 84 & 70 \\ \hline
**Cluster 2** & \multicolumn{4}{c}{**Soil Horizons**} \\ \cline{2-5}
**(Profile 4)** & **Ap1** & **Ap2** & **Bt** & **Btg** \\ \hline Depth (m) & 0.10 & 0.35 & 0.90 & 1.15 \\ Clay (dag kg\({}^{-1}\)) & 18.4 & 16.1 & 16.8 & 24.7 \\ Slit (dag kg\({}^{-1}\)) & 37.3 & 35.4 & 36.9 & 35.6 \\ Sand (dag kg\({}^{-1}\)) & 44.3 & 48.5 & 46.3 & 39.7 \\ CF (\%vol) & 12 & 12 & 5 & 0 \\ CaCO\(\alpha_{3}\) tot (dag kg\({}^{-1}\)) & 2.4 & 2.3 & 2.3 & 2.3 \\ SOC (dag kg\({}^{-1}\)) & 9.0 & 13.1 & 9.0 & 6.8 \\ TN (g kg\({}^{-1}\)) & 9.1 & 13.0 & 8.9 & 7.5 \\ AWC (mm) & 11 & 28 & 66 & 33 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Description of the benchmark profiles which defined the two areas of the field, gravelly (P1) and not gravelly (P4). Legend: Ap1, surface horizon subjected to ploughing; Ap2, sub-surface horizon interested by deep ploughing; Bt, B horizon with clay illuviation process; Btg, B horizon with clay illuviation process and redoximorphic mottles due to temporary waterlogging (stagnic properties); CF, Coarse fragments; SOC, Soil Organic Carbon; TN, Total nitrogen; AWC, Available Water Capacity. The highest values of WUE\({}_{\text{f}}\) and WUE\({}_{\text{0}}\) were measured in DI trees in Cluster 1, whereas in Cluster 2 the WUE (both fruit and oil) increased with the amount of water used by the tree (Table 3). Differences in WUE between clusters emerged within each irrigation regime and became increasingly evident as the level of water deficit increased (Table 3).