**4. Discussion**

#### **4.1. Consumptive water use and yield differences of cultivars of selected crops**

Modern and heritage crops differ in their relationship between their maximum water requirement and actual evapotranspiration, thus crop coefficient (k<sup>c</sup> ), in addition to maturity. **Figure 1** shows how the crop coefficient (or growing stages) overlapped during the growing season between different crops leading to different water use. Application of one irrigation schedule in crops with different kc would result in over-irrigating pumpkin squash. Thus, irrigation scheduling (timing) based on soil water monitoring rather than some approximate modelling approach can significantly improve the water management [25], that is, the total water footprint. Differences in growth stages and date to maturity might contribute to great differences in crop water requirement and water footprint among the selected crops cultivars [15]. From the study, it is definite that Taewa and oca have the longest duration of growth to maturity compared to the other selected crop cultivars [13].

Most of heritage crop cultivars used more water than modern cultivars. Likely, the large biomass and longer growth cycle in heritage crop cultivars (Kamokamo, Tutaekuri, oca and Moe Moe) made them use more water than modern cultivars. This study considered actual evapotranspiration and other discharges in determining the water footprint, as suggested by Maes [23]. In this case, the water requirement was not equal to the actual total consumptive water use, thus remedying the over-estimation. This is in contrast to water footprint determination in other studies, where hypothetical crop yield and evapotranspiration were used [26]. Apart from, expected enormous variability in crop water use within the area in future, the current results provide a great benchmark of heritage and modern crop water requirement and water footprint for the studied area.

**Figure 3.** Average water footprint of total yield and total biomass in oca, potato and pumpkin squash cultivars. Error

cultivars (**Figure 3**, **Tables 2** and **3**). The pumpkin squash cultivars and Moonlight were not much different on total water footprint of total yield but were considerable different to Moe Moe, Agria, Tutaekuri and oca cultivars. Tutaekuri had the greatest total water footprint of total yield and total biomass among potato cultivars though extremely lower to oca cultivars. Nevertheless, the total biomass water footprint for Tutaekuri was not much different from Agria. Moonlight and Moe Moe were second from pumpkin squash in low water footprint of

Gross revenue on investment income; present value per ha from irrigation in 1st year; net present value was highest in Moe Moe among potato cultivars. Moe Moe also displayed shortest repayment period. The high market value and its intermediary yield response to full irrigation and low N-assisted Moe Moe to have high economic value among the selected potato cultivars. Agria, despite its highest yield response to full irrigation and nitrogen, ended up being the least economic crop enterprise. Agria gross revenue on investment income was NZ\$8740; present value per ha from irrigation in the 1st year was NZ\$7159; net present value was NZ41,764.5; and its repayment period was longer (0.92 years) than other enterprises. Low market value in Agria compared to Taewa contributed to its lowest economic status. An intermediary economic value was reported in Tutaekuri which had intermediary gross revenue on investment income; present value; net present value and intermediary repayment period. Tutaekuri outperformed modern potatoes in economic terms regardless of its low yield response to irrigation and N just

because of its novelty value and reduced water and nitrogen fertiliser requirement.

**4.1. Consumptive water use and yield differences of cultivars of selected crops**

ment and actual evapotranspiration, thus crop coefficient (k<sup>c</sup>

Modern and heritage crops differ in their relationship between their maximum water require-

), in addition to maturity. **Figure 1**

bar represents LSD0.05.

96 Irrigation in Agroecosystems

**4. Discussion**

total biomass (**Table 3** and **Figure 3**).

**3.3. Social-economic of the selected crop cultivars**
