THE EFFECT OF DIFFERENT WELL WATER QUALITY AND IRRIGATION METHODS ON SOME CHEMICAL PROPERTIES AND SALINITY DISTRIBUTION OF SOIL IN ARID AREAS: A CASE STUDY OF ISMAILIA GOVERNORATE

Abstract

The increasing demand for irrigation water to secure food for growing populations with limited water supply suggests re-thinking the use of non-conventional water resources. The study was conducted to monitor the salinity distribution in soil under different well water quality and irrigation methods in specific sites of Ismailia Governorate region. Water and soil samples were collected from hundred randomly selected sites. Both soil and water samples were analyzed for chemical characteristic which included salinity, cations, anions and SAR. The findings indicated that the mean soil pH was 7.35 while the mean EC value was 3.73 dS/m. The mean cations in the water samples were 7.43, 5.98, 0.17, and 23.33 meq/l for Ca2+, Mg2+, K+, and Na+, respectively and the a mean value of Sodium Adsorption Ratio (SAR) was 9.11. The mean bicarbonates concentration detected in the irrigation water was 4.43 meq/l, while the mean chloride and sulphate were 29.95 and 2.49meq/l, respectively. The mean values of EC of soil were 3.94, 5.98 and 4.56 for drip, sprinkler and surface irrigation methods in depth 0-20 cm, respectively. While, in soil depth 20-40 cm the mean values of EC were 6.78, 4.94 and 2.99 for drip, sprinkler and surface irrigation methods, respectively. The spatial distribution of soil salinity in the soil horizons were found to be higher at shallow depths of 0-20cm and decreasing gradually up to a depth of 20-40cm. This trend is clear with surface and sprinkler irrigation method. In drip irrigated method, the salinity distribution showed a different pattern from that observed in surface and sprinkler irrigation. Salinity was the lowest in the surface layer (0-20 cm), and increased gradually with soil depth (20-40 cm). Salt concentration factor (SCF) of Ismailia soil under studies ranged between0.14 to 6.33. The results showed that SCF varies according to water and soil quality and irrigation methods.EC of soil was positively and significantly correlated with Ca2+, Mg2+, Na+ , K+, Cl-, HCO-3 but positively and not significantly correlated with pH andSO2-4.The general trend showed that soil salinity increased with an increase in water salinity. Correlation coefficient (r) between EC of irrigation water and EC of soil was 0.550**.