Egypt produces approximately 2.4 million m3 of secondary treated wastewater (TWW) annually, used for irrigation directly or indirectly by blending with agricultural drainage water (BDW). The annual re-use of (BDW) is approximately 4 million m3. The safe and efficient use of marginal water (BDW and TWW) is a core objective of this study which has been operating from 1997 to date. After six growing seasons the main results can be summarized as follows: MAXIMIZING CROP PRODUCTION: TWW can be used for high production of oil crops (canola, soybean sunflower or maize) compared to fresh water, while BDW can be used for high production of tolerant crops (cotton and sugar beet). CROP QUALITY: using marginal water increases the concentration of elements (Pb, B, Ni, Co) in all crops but these elements were under critical levels (there were no toxicity hazards). It is better to use alternative irrigation with fresh water under a drip irrigation system to maximise crop production and minimise the adverse effects of such water in field crops quality. SOIL POLLUTION AND SALINITY BUILD UP: A drip irrigation system under alternative irrigation by fresh with TWW or BDW reduces salinity build up risks and the levels of elements (Pb, B, Ni, Co) in soil compared to re-use marginal water. SOIL PATHOGENS: Using marginal water slightly contaminated the soil with total faecal coliform (TFC), mites, shigella and salmonella. PLANT ANATOMY: No great changes in anatomical disturbance where induced in different structures of plants which were reduced at maturity stage. PRIMARY GUIDELINES FOR RE-USING MARGINAL WATER: From obtained results it can be recommended to use marginal water with salinity content ranged between 1.1 to 3.64dS/m, and elemental contents (Pb 3.0-3.51 ppm), (B 0.05-1.67 ppm), (Co 0.04-0.07 ppm), (Ni 0.08-0.15 ppm) for safe (field, vegetable and medicinal) crops production. REUSE BIO SOLIDS FOR CROP PRODUCTION: Sewage sludge produced from treated wastewater can be safely used by mixing with rice straw (1:1 w/w) for economic crop production and saving mineral fertilisers. GENERAL CONCLUSION: In the North Nile Delta, marginal water (especially BDW) can be safely used without significant negative impact on the environment, but there is a need for multi-disciplinary, long-term research to investigate irrigation with marginal water in terms of the environment, public health and agricultural productivity.

A pot experiment was carried out at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate, during the growth season of 2005/2006 to investigate the effectiveness of Gibberellin (GA3) in improving the salt irrigation water tolerance of barley (Hordeum vulgare L.) and its effect on barley plant growth and yield components.GA3 significantly improve in shoot weight of barley plant by 30-39 %, shoot fresh weight by 23-34 %, shoot dry weight by 22-31 % and leaf area by 7-26 % compared to unsprayed treatment. Also, spike length increased by 31 %, 100-grain weights by 8-16 %, number of grains per spike by 22-35 % and weight of grains per spike by 22 % compared to unsprayed treatment.

The soil samples were collected from the west to east side of the region. Most of the collected soil samples were highly saline, but salinity levels decreased as we headed east. The EC values ranged from 4014 t0 26.16. The viable counts of R. leguminosarum bv. viceae, R. leguminosarum bv. trifolii and Azotobacter varied through different sites,they ranged from log to log 5.84; log 2.39 to 5.84; log 2.23 to 4.26, respectively and the variations between readings were ,sometimes, significant. But, there were no significant correlations between the estimated bacterial types and soil salinity. Total bacterial readings, however, showed high values, but, lowered in soil samples collected from the west sites.These bacterial counts were decreased as we headed east. They ranged from log 7.36 to log 9.46. However, there was no significant correlation between bacterial counts and soil salinity.