In arid and semi arid areas in the Middle East countries, farmers who built their livelihoods on a reliable supply of freshwater are now faced with a critical shortage of this vital resource, impinging on all aspects of their relations with the environment. However, and over the past decade ACSAD had focused research on seeking the opportunities for improving agricultural productivity through the efficient use of semi saline and saline water. Major achievements have already been accomplished among which identification of salt tolerant crops, water requirements of strategic crops, management of two quality water resources, identification of the tolerance of phonological stages, monitoring salt balance as well as chemical equilibrium, suitability of irrigation method, doses and frequency of irrigation, leaching management, and optimum advantage of rainfall water. Research findings were obtained on open large filed experiment plots and in farmers fields and effort was made on extraction of such achievements in spread sheets guidelines and data basis covering water resources and their qualities, soil properties, climatic conditions and available plants tolerance data base.

Topics will cover:

-Yield functions of strategic crops versus salinity of irrigation water

-Moisture extraction pattern of some crops based on three years data and direct measurement of soil moisture with depth and growing period.

-The relation between ionic composition of saline water and ionic composition of soil solution extracted in field experiments using ceramic cups at field capacity.

-The impact of saline irrigation water on fruit and grain quality for some crops covering total sugars, carbohydrates, Vit.C, --

-The effect of management practices on yield; ie; alternate, continuous, cyclings, etc.

-Soil chemical equilibrium and precipitation of gypsum and CO3Ca .

-The impact of saline water on the ionic composition of water table.

The above said furnish the background for the inclusion of economic aspects, however, the economic aspects of using saline water was tackled by several researches such as Bresler etal 1983, Lefknoff and Steven 1990, knaps and Dinar 1984 and Dinar etal 1986. The key tool was linear programming procedures to determine the optimum solution based on experiences and targets and prices.

The procedures presented in the paper is appropriate for spreadsheet, software employing optimisation techniques (EXCEL) and actual constraints and the prevailing economical conditions using actual obtained relations and discussing the impact of threshold theory suggested by Mass and Hoffman(1986) and the validity of such concept on economical evaluation. Maximum profit takes also in consideration the boron content of irrigation water and the necessity of soil amendments with and without threshold.

Economical assessment considers the prices and constraint under Syrian conditions, however the spread sheet keys can be modified for other countries in the region.

Theoritical consideration are also presented.

Data are extracted from the research station belonging to ACSAD in Algeria, Morrocco, Tunisia, Lybia,Jordan, Iraq and Syria.

Key words:

Guidelines of saline water, irrigation management, salinity, optimisation.