23
food supply and raising the income of farmers in developing countries, thereby,
balancing higher food demands and lower water utilization (Yin et al. 2015). Qin
et al. (2013) described intercropping as a systematic approach that makes full use of
nutrient and water resources, achieves agricultural biodiversity, and increases yield
significantly in comparison with crop monocultures. Thus, intercropping increases
unit land productivity (harvest two types of crops from the same area), increases
water productivity (using amount of irrigation water applied to one crop to irrigate
two crops) and increase farmers income (reduce risks from crop failure)
(Anderson 2007).
Intercropping with legumes can use moisture and nutrients from deeper soil layers (Machado 2009). Sorghum intercropped with cowpea system reduced runoff by
20–30% compared to sorghum sole planting and reduced runoff by 45–55% compared to cowpea monoculture (Lithourgidis 2011). Rahman et al. (2017) indicated
that, in maize-soybean relay intercropping system; soil evaporation and soil water
content was reduced, compared to sole planting. Hu et al. (2015) found the wheat
and maize intercropping system used more water and enhanced water use efficiency
by an average of 26%. In addition, wheat and maize yield was increased by 42 and
23%, respectively over the sole planting. Furthermore, Yang et al. (2011) revealed
that wheat and maize intercropping system increased water use by 2–16% compared to sole cropping of wheat and maize. Water use efficiency of wheat was
increased by 31–75% and water use efficiency of maize was increased by 33–38%,
compared to sole cropping of wheat or maize. Lithourgidis (2011) proved that intercropping sorghum with either cowpea resulted in better productivity and water use
efficiency. Coll et al. (2012) indicated that improvement of water productivity of
intercropped soybean with maize occurred, compare to the sole planting is due to
increase water capture efficiency.
Water equivalent ratio is a measurement used to quantify the amount of water
that would be needed in single crop to achieve the same yield as produced with one
unit of water in intercrops (Mao et al. 2012). Feng et al. (2016) showed that water
equivalent ratio of two peanut-millet intercropping patterns ranged from 1.17 to
1.22, which implied an increase in water use efficiency of the two patterns by 17 and
22%. Furthermore, El-Mehy et al. (2018) indicated that intercropping sunflower
with peanut system can utilize irrigation water more efficiently than monoculture of
either crop by about 25 and 26%, respectively. Whereas, Ouda et al. (2018) indicated that irrigation water utilization of sunflower and peanut system was higher
that the sole cropping by 49 and 50%, respectively.
2.7 Conclusion
Because water shortage is prevailing around the world and irrigated agriculture
is the main user of water resources, efficient management of water resources is
required. Deficit irrigation practice can play an important role in water conservation
2 Deficit Irrigation and Water Conservation
food supply and raising the income of farmers in developing countries, thereby,
balancing higher food demands and lower water utilization (Yin et al. 2015). Qin
et al. (2013) described intercropping as a systematic approach that makes full use of
nutrient and water resources, achieves agricultural biodiversity, and increases yield
significantly in comparison with crop monocultures. Thus, intercropping increases
unit land productivity (harvest two types of crops from the same area), increases
water productivity (using amount of irrigation water applied to one crop to irrigate
two crops) and increase farmers income (reduce risks from crop failure)
(Anderson 2007).
Intercropping with legumes can use moisture and nutrients from deeper soil layers (Machado 2009). Sorghum intercropped with cowpea system reduced runoff by
20–30% compared to sorghum sole planting and reduced runoff by 45–55% compared to cowpea monoculture (Lithourgidis 2011). Rahman et al. (2017) indicated
that, in maize-soybean relay intercropping system; soil evaporation and soil water
content was reduced, compared to sole planting. Hu et al. (2015) found the wheat
and maize intercropping system used more water and enhanced water use efficiency
by an average of 26%. In addition, wheat and maize yield was increased by 42 and
23%, respectively over the sole planting. Furthermore, Yang et al. (2011) revealed
that wheat and maize intercropping system increased water use by 2–16% compared to sole cropping of wheat and maize. Water use efficiency of wheat was
increased by 31–75% and water use efficiency of maize was increased by 33–38%,
compared to sole cropping of wheat or maize. Lithourgidis (2011) proved that intercropping sorghum with either cowpea resulted in better productivity and water use
efficiency. Coll et al. (2012) indicated that improvement of water productivity of
intercropped soybean with maize occurred, compare to the sole planting is due to
increase water capture efficiency.
Water equivalent ratio is a measurement used to quantify the amount of water
that would be needed in single crop to achieve the same yield as produced with one
unit of water in intercrops (Mao et al. 2012). Feng et al. (2016) showed that water
equivalent ratio of two peanut-millet intercropping patterns ranged from 1.17 to
1.22, which implied an increase in water use efficiency of the two patterns by 17 and
22%. Furthermore, El-Mehy et al. (2018) indicated that intercropping sunflower
with peanut system can utilize irrigation water more efficiently than monoculture of
either crop by about 25 and 26%, respectively. Whereas, Ouda et al. (2018) indicated that irrigation water utilization of sunflower and peanut system was higher
that the sole cropping by 49 and 50%, respectively.
2.7 Conclusion
Because water shortage is prevailing around the world and irrigated agriculture
is the main user of water resources, efficient management of water resources is
required. Deficit irrigation practice can play an important role in water conservation
2 Deficit Irrigation and Water Conservation