IMPACT OF WATER QUALITY ON SOIL ENVIRONMENT AND GROWN PLANTS IN EAST NILE DELTA AREA

Abstract

This work aims to evaluate the suitability of the low quality waters, i.e., Nile water mixed with drainage, drainage water contaminated with sewage effluent and natural underground water for irrigating the soils having different properties at East Nile Delta area. Also, special concern was due to follow the build up of salinity and some pollutants in both the irrigated soils and plants grown. Monitoring the chemical characteristics of the available irrigation water resources show that the tested samples could be categorized in different classes according to their salinity and sodicity levels. In spite of the relatively high contents of nutritive and non-nutritive elements in the used low quality waters, yet they are still within the permissible limits. Moreover, increasing of problems are expected for the irrigated soils, since the ECiw of those low quality waters was ranged between 0.92 and 3. dS/m, in addition to the was more than 9 through the majority of studied irrigation water samples. Concerning the changes occurred in soil constituents, data clearly showed a relatively increase in the ECe, CaCO3, organic matter, pH value, HCO3-, somewhat Mg2+ and ESP in the soils irrigated with the low quality waters. While the reverse was true for bulk density, water constants, drainable pores, hydraulic conductivity, Ca2+ and organic matter, in addition CaCO3, organic matter and pH value in the soils irrigated with the sewage effluent. These changes were more pronounced in the treated soils with sewage effluent due to the relatively high contents of active organic acids which are depressed CaCO3 content and the accumulated organic residues, respectively. In a harmony status for both irrigation water and soil, special optimization for increasing the contents of total and available of macro- nutrients (N, P and K), micronutrients (Fe, Mn, Zn and Cu) and non-nutritive heavy metals (Pb and Cd) in soils irrigated with the studied low quality waters. A similar trend was noticed for the contents of these elements in the tissues of the grown plants of wheat and maize, particularly those irrigated with the sewage effluent contaminated water, which supports the active uptake of them. In conclusion, a gradual increase in both irrigation water and soil led to the reduction in the studied plant growth parameters and yield of grains which was not only limited by the soil salinity level, but also soil texture grade. Moreover, salinity should alleviate the plant nutrients disruption, as well as, the plants showed an adaptive mechanism to cope with salinity stress through the regulation of some organic solutes. At the same time, the mixing of saline water with fresh water must be achieved at a certain available level should be recommended, especially at the seedling stage.