Water scarcity and the need for increased agricultural production have led to greater utilization of non-conventional, marginal- to low-quality, sources of water for irrigation. These water sources mainly recycled municipal waste water and brackish groundwater, are typically characterized by high concentrations of contaminants including salts.
Agronomic success when
irrigating with water high in salts is contingent upon water management in
which salts are disallowed from accumulating in crop root zones. Salinity management
most often entails application of excess water for leaching and drainage collection
and disposal. Addition of salt to agricultural systems causes degradation of
soils and negative effects to crops. Leaching of salts leads to contamination
of deep soils and groundwater or to drainage waters requiring treatment and
disposal solutions.
An additional aspect of
water-source and quality specific management is found in plant nutrition-fertilization
practices. Interactions between salts and nutrient minerals in soils and plants
require rethinking of traditional fertilization methods and regimes.
The recent addition of
desalinated water to address chronic water shortages in dry regions including
Israel, may coincidentally provide opportunity for a more sustainable solution
for agriculture. Desalination can supply very high-quality water to irrigate
high-value, salt- sensitive crops and leads to reduction of salinity of
recycled wastewater. While allowing less leaching and therefore more
sustainable irrigation, the utilization of desalinated water comes with its own
set of challenges including cost, unpredictable actual contents of minerals
when mixed with other water sources in distribution systems, and requirements
for provision of minerals, removed in desalination processes but needed in
agricultural applications.
Recent research has
provided understanding and tools for optimizing water and nutrient use efficiency
as a function of water quality. These include models for crops response which recently
have been coupled with economic data to offer tools for decision making for planners
and growers.