Water Storage Efficiency (\( \xi_s \)):

\[ \xi_s = 100 \cdot \frac{W_s}{W_n} \]

Where:

• \( \xi_s \) is the water storage efficiency, in percentage (%).
• \( W_s \) is the water stored in the root zone during irrigation, in cubic meters (m³).
• \( W_n \) is the water needed in the root zone prior to irrigation, in cubic meters (m³).