87
showed that it improved soil quality (Limon-Ortega et al. 2002), which led to
enhanced root growth (Dey et al. 2015), it increased microbial functional groups and
enzyme activities and it increased availability of essential nutrients for crops by
stimulating microbial activity (Zhang et al. 2012). Raised beds planting also created
better soil physical environment throughout the crop growth period, which led to
higher crop productivity (Aggarwal and Goswami 2003).
Another strategy to face water scarcity is the application of deficit irrigation. Deficit
irrigation is a water saving strategy under which crops are exposed to a certain level of
water stress either during a particular developmental stage or throughout the whole
growing season (Pereira et al. 2002). Applying deficit irrigation for crops grown on
raised beds will lower the amount of applied irrigation water and it will involve yield
losses. The exception is that any yield reduction will be insignificant compared with
the benefits that gained from the conservation of water (Pereira et al. 2002).
Thus, an assessment of the potential effects of applying deficit irrigation to onion
and tomato grown on raised beds was done using data on its cultivated area and
productivity on governorate level in both the old and new lands. (See Chap. 2 for
more details on soil classification). This data was collected from the Ministry of
Agriculture and Land Reclamation in Egypt in 2017. Weather data for the winter
season of 2016/17 were obtained from NASA Prediction of Worldwide Energy
Resource website (https://power.larc.nasa.gov/data-access-viewer). Water requirements for each of these two crops were calculated on governorate level using BISm
model (Snyder et al. 2004). Irrigation application efficiency was assumed to be 60%
in the old lands under surface irrigation and 85% under drip systems in the new lands.
For onion and winter tomato, five production alternatives were quantified on
governorate level as followed:
1. Traditional cultivation: The cultivated area and productivity per hectare of each
crop in 2017 were multiplied to calculate total production. In addition, water
requirements for each crop were calculated.
2. Raised beds cultivation: We assumed that cultivation on raised beds will
increase productivity per hectare by 15%, and then the increase in the total production was calculated. We also assumed that 20% of the applied water under
surface irrigation will be saved. The saved irrigation water will be used to irrigate
new areas with each crop and this area will be added to the total cultivated area
of the studied crops to increase its total production.
3. Application of deficit irrigation: The effect of application of deficit irrigation
for both crops cultivated on raised beds. Because the amount of irrigation water
resulted from cultivation on raised beds produced higher yield than the traditional cultivation, we applied deficit irrigation to raised beds and the losses in
yield resulted from raised beds cultivation was calculated. The saved irrigation
water will be used to irrigate new areas with each crop and this area will be
added to the total cultivated area of the studied crops to increase its total production and compensate the loss in the productivity per hectare.
4. Calculation of production without investing the saved water in adding new
area: Under cultivation on raised beds, we assumed that the saved water will be
assigned to increase the cultivated area of another winter crop.
5 Vegetable Crops and Deficit Irrigation in Egypt
showed that it improved soil quality (Limon-Ortega et al. 2002), which led to
enhanced root growth (Dey et al. 2015), it increased microbial functional groups and
enzyme activities and it increased availability of essential nutrients for crops by
stimulating microbial activity (Zhang et al. 2012). Raised beds planting also created
better soil physical environment throughout the crop growth period, which led to
higher crop productivity (Aggarwal and Goswami 2003).
Another strategy to face water scarcity is the application of deficit irrigation. Deficit
irrigation is a water saving strategy under which crops are exposed to a certain level of
water stress either during a particular developmental stage or throughout the whole
growing season (Pereira et al. 2002). Applying deficit irrigation for crops grown on
raised beds will lower the amount of applied irrigation water and it will involve yield
losses. The exception is that any yield reduction will be insignificant compared with
the benefits that gained from the conservation of water (Pereira et al. 2002).
Thus, an assessment of the potential effects of applying deficit irrigation to onion
and tomato grown on raised beds was done using data on its cultivated area and
productivity on governorate level in both the old and new lands. (See Chap. 2 for
more details on soil classification). This data was collected from the Ministry of
Agriculture and Land Reclamation in Egypt in 2017. Weather data for the winter
season of 2016/17 were obtained from NASA Prediction of Worldwide Energy
Resource website (https://power.larc.nasa.gov/data-access-viewer). Water requirements for each of these two crops were calculated on governorate level using BISm
model (Snyder et al. 2004). Irrigation application efficiency was assumed to be 60%
in the old lands under surface irrigation and 85% under drip systems in the new lands.
For onion and winter tomato, five production alternatives were quantified on
governorate level as followed:
1. Traditional cultivation: The cultivated area and productivity per hectare of each
crop in 2017 were multiplied to calculate total production. In addition, water
requirements for each crop were calculated.
2. Raised beds cultivation: We assumed that cultivation on raised beds will
increase productivity per hectare by 15%, and then the increase in the total production was calculated. We also assumed that 20% of the applied water under
surface irrigation will be saved. The saved irrigation water will be used to irrigate
new areas with each crop and this area will be added to the total cultivated area
of the studied crops to increase its total production.
3. Application of deficit irrigation: The effect of application of deficit irrigation
for both crops cultivated on raised beds. Because the amount of irrigation water
resulted from cultivation on raised beds produced higher yield than the traditional cultivation, we applied deficit irrigation to raised beds and the losses in
yield resulted from raised beds cultivation was calculated. The saved irrigation
water will be used to irrigate new areas with each crop and this area will be
added to the total cultivated area of the studied crops to increase its total production and compensate the loss in the productivity per hectare.
4. Calculation of production without investing the saved water in adding new
area: Under cultivation on raised beds, we assumed that the saved water will be
assigned to increase the cultivated area of another winter crop.
5 Vegetable Crops and Deficit Irrigation in Egypt