**3. Results**

**Figure 1.** Soil moisture change in heritage and modern potato, oca and pumpkin squash cultivars under irrigation and

rain-fed conditions.

90 Irrigation in Agroecosystems

#### **3.1. Crop water use and yield summary**

Total consumptive water use (blue plus green water) for oca, potato and pumpkin squash in rain-fed and irrigation ranged from 5061 to 6824, 3470 to 5685 and 2551 to 4132 m<sup>3</sup> ha−1, respectively. Consumptive water use (m3 ha−1) was greatest in oca and lowest in pumpkin squash, while potatoes were intermediate, despite variation within cultivars. The modern and heritage crops differed in their relationship between their maximum water requirement and actual evapotranspiration, thus crop coefficient (k<sup>c</sup> ) and maturity (**Figure 2**). Taewa and Kamokamo used more water compared to modern cultivars (**Table 1**). Green water was approximately 62, 65, 58 and 70% of consumptive water use, under irrigated modern potato, Taewa, pumpkin squash and oca, respectively. Blue water for oca and potato was 2000 m<sup>3</sup> ha−1, while pumpkin squash received 1750 m<sup>3</sup> ha−1, applied to meet at least 100% of the crop's water requirement.

Grey water also significantly differed between cultivars with the highest in potato and oca. An equivalency of diluting requirement to the grey water for the applied N in potato or oca and

**Figure 2.** Blue, green and grey water footprint on total yield of potato, oca and pumpkin squash crop cultivars under irrigation and rain-fed condition in New Zealand, 2010. Error bar represents LSD0.05.

pumpkin squash was 425 and 398 m<sup>3</sup> ha−1, respectively (**Table 1**). An increase in N rate application raised the grey water in potato and oca compared to pumpkin squash. The actual crop water use for rain-fed crop in oca, potato and pumpkin squash was 74.9, 65.1 and 69% of the irrigated crop, respectively (**Table 1**). The total consumptive water use (m3 ha−1) was greatest in oca and lowest in pumpkin squash, while potato was intermediate, despite variation within cultivars. Heritage crops (Maori potato, Kamokamo) used more water because of its long growing season.

Differences in yields were observed to be influenced by water regime and crop cultivars among the eight selected crop cultivars. With exception of Tutaekuri, average yields continuously increased from rain-fed (16.7–67.7 t ha−1) to irrigated conditions (23.2–78 t ha−1). Kamokamo had the greatest yields while dark orange had the lowest yields under both water regimes. Average yields for other crops' varieties such as Agria, Moonlight and Moe Moe were similar but greatly lower than Kamokamo. Out of the crop cultivars, oca varieties and Tutaekuri proved to have lowest yield levels. Agria, Moonlight and Moe Moe also demonstrated an ability of partitioning more dry matter to economic yields basing on its harvest index (HI). In summary, the heritage crop cultivars extremely partition more to biomass unlike most of the modern cultivars which partition more to economic yields (**Table 1**).

water use (blue plus green water footprint or pure green water footprint) of total yield ranges was high in irrigated field and low in rain-fed field (**Table 2**). **Figure 1** evidently show that the blue water footprint in rain-fed crop was zero while the green water footprint of total yield and total biomass yield related to rain-fed environment were high compared to the green water

**Table 1.** Date of planting and harvesting, harvestable yield, total biomass yield and consumptive water use for heritage

In the irrigated crops, the blue water footprint comprised 27–39% while the grey water footprint made up to 6–9% of the total water footprint of total yield (**Figure 2**). The total water footprint of consumptive water use increased with irrigation in Moe Moe, Tutaekuri, Ebisu, Kamokamo and scarlet oca whilst Agria, Moonlight and dark orange oca decreased total

footprint of the irrigated field.

**Water regime/ cultivars**

*Irrigation*

*Rain-fed*

*Significance*

LSD0.05

**Planting date**

**Harvesting date**

**Total yield (t ha−1)** **Total biomass (t ha−1)**

Agria 10-11-10 17-05-10 51.7 58.7 3326.6 2000 5326.6 424.8 Moonlight 10-11-10 17-05-10 59.4 76.6 3255.6 2000 5255.6 424.8 Moemoe 10-11-10 17-05-10 52.6 76.1 3685.2 2000 5685.2 424.8 Tutaekuri 10-11-10 17-05-10 27.6 54.7 3670.2 2000 5670.2 424.8 Buttercup 09-12-10 29-03-10 54.7 97.7 2325.8 1750 4075.8 398.2 Kamokamo 09-12-10 31-03-10 78.0 149.1 2382.0 1750 4132.0 398.2 Dark O 10-11-10 22-06-10 23.2 55.8 4742.2 2000 6742.2 424.8 Scarlet 10-11-10 22-06-10 25.5 69.5 4824.2 2002 6824.2 424.8

Agria 10-11-10 17-05-10 34.0 43.3 3470.6 — 3470.6 424.8 Moonlight 10-11-10 17-05-10 39.7 52.1 3513.0 — 3513.0 424.8 Moemoe 10-11-10 17-05-10 40.1 60.0 3950.0 — 3950.0 424.8 Tutaekuri 10-11-10 17-05-10 30.0 52.8 3933.0 — 3933.0 424.8 Buttercup 09-12-10 29-03-10 47.4 89.6 2551.0 — 2551.0 398.2 Kamokamo 09-12-10 31-0310 67.7 142.7 2603.8 — 2603.8 398.2 Dark O 10-11-10 22-06-10 16.7 42.0 5094.2 — 5094.2 424.8 Scarlet 10-11-10 22-06-10 21.2 50.7 5061.0 — 5061.0 424.8

Cultivars <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 — Water regime <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001

Cultivar 10.7 6.23 — — — — Water regime 5.4 18.9 — — — —

and modern potato, oca and pumpkin squash crop cultivars in New Zealand, 2010.

**water**

Water Footprint Differences of Producing Cultivars of Selected Crops in New Zealand

**Consumptive water use (m<sup>3</sup> ha−1) Grey water (m<sup>3</sup> ha−1) Green** 

http://dx.doi.org/10.5772/intechopen.77509

**Total CWU**

93

**Blue water**
