*2.6. Water Productivity*

Two water productivity indices were calculated to compare the efficiency of irrigation water use and actual ET, using Equations (4) and (5):

$$\text{Irrigation water productivity (IWP)} = \frac{\text{Alf} \text{al } \text{dry matter}}{\text{Irrigation water applied}} \tag{4}$$

$$\text{Evaporation-Spin water productivity (ETWP)} = \frac{Afalfa \, dry \, matter}{ETa} \tag{5}$$

where the unit of alfalfa dry matter is kg ha−1, and the units of irrigation water applied and ETa are mm.
