Abiotic stress and water scarcity: Identifying and resolving conflicts from plant level to global level

Irrigated crops are increasingly facing water scarcity and other forms of abiotic stress, including the presence of salts and other pollutants in soil and irrigation water, waterlogging and flooding of soils, low pH in acid sulfate soils, and anaerobic and toxic conditions in the rootzone. More progress has been made with the alleviation of some of these stresses than with others. This paper examines why salinity of soil and irrigation water is common and nearly inevitable in the irrigated lands of the semi-arid tropics and subtropics. It considers opportunities for and constraints in making management changes that would increase the productivity of water (i.e., the yield per unit of water diverted from the source or Consumed in evapotranspiration) at system and basin level. Success of water management interventions in reducing the impact of abiotic stresses on rice production under saline conditions and oil acid soils depends oil improved control over the components of the water and ion balances at field and basin level. One of these measures is the installation of drainage systems. The benefits and costs of sub-surface drainage are illustrated by an example from Egypt's Nile Delta. An integrated approach to water resource management is an essential but not sufficient condition to prevent conflicts between different users and consumers of the scare resource. (c) 2005 Elsevier B.V. All rights reserved.