Revista Temes Rurals núm. 1

Water resource
Paisatge i ecosistemes
Global climate change is affecting important natural resources
including water. Changes in the total amount of precipitation
and its frequency and intensity directly affect the magnitude
and timing of runoff and the intensity of floods and droughts
(IPCC, 2007). Increases in temperature will change the rate
of evaporation and transpiration, leading to variations in water
availability, ground water recharge and water consumed
by plants. Thus, competition for water will be a major future
challenge for agriculture. The increased frequency of extreme
weather events has started creating imbalances in the hydrological
cycle and is resulting in large year-to-year fluctuations
in crop yields and water productivity. In addition, the vegetative
season for deciduous plants will be prolonged (due to the
increase in temperature), increasing transpiration levels. It is
time for stakeholders and end-users to think about expected
changes in crop water requirements due to global warming
and to plan for development of future water resources. The
agricultural sector is one of the most susceptible to water scarcity.
For these reasons adaptation strategies for facing climate
change need to be adopted. Zwart and Bastiaanssen (2004)
reported that the great challenge of the agricultural sector is to
produce more food with less water, which can be achieved by
increasing crop water productivity. This could be obtained with
a deep knowledge of the soil-plant-atmosphere relationship or
increasing the dissemination of technological innovations to
end-users. For example, although localized irrigation has 90-
95% efficiency and it was introduced 70 years ago, it is still
only widespread at a global level for 8%.
Southern Italy is already facing situations of increasing temperatures,
depleting water resources, extreme events and their
impacts on crop water productivity. Under such conditions,
microclimatic modifications through soil and agronomic interventions
need to be studied for improving crop and water
productivity. The climate in Southern Italy is always more characterized
by low precipitation (500 mm/year), mild winters
and dry summers. To increase water productivity at farm level
it is necessary to increase the efficiency of irrigation systems,
the plant Water Use Efficiency (WUE) and optimize irrigation
management. First of all, it is necessary to increase the accumulation
of rainwater in the soil. If managed in a sustainable
way, arable soils can store large quantities of rainwater. Cover
crops increase rainwater infiltration into the soil, reducing the
loss due to runoff. A sustainable orchard management (nosoil
tillage, pruning residues and cover crop retention, compost
application) can improve soil structure and hydrological
properties, increasing the water storage. The increase of SOC
improves soil water holding capacity and reduces the irrigation
requirements of fruit orchards [Figure 8]. Several studies
conducted in Southern Italy revealed that environmentally friendly
management practices reduce approx. 1500 m3 ha-1 the irrigation
water supply in fruit orchards compared to conventional management.
In order to ensure water use for agricultural production
also in regions with water scarcity, innovative and sustainable
research and appropriate transfer of technologies are needed.
Integrated data from several knowledges involving agrometeorologists,
agronomists, soil water engineers and plant breeders
are required to manage the water resources and crop
water productivity under changing climatic conditions.
Figure 8: Macroporosity values in a sustainable system and a conventional one at different depths (from Palese et al., 2014). Sustainable and conventional systems
have the same values of macroporosity in the upper layer (0-10 cm) due to soil tillage, while in the deeper layers soil structure is different. This permitted an increase
of water storage during the rainy season (till 2 m depth) under sustainable management (4250 m 3 /ha vs. 2934 m 3 /ha under conventional).
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Fruit orchard management: How can we adapt to/face climate change?