The Role of Leaching Type in the Reclamation and Sustainability of Soils Irrigated with Saline Well Water in Nineveh Governorate
Enfal Mohammed Tahir *
Department of Soil Sciences and Water Recourses, College of Agriculture and Forestry, University of Mosul, Iraq.
Khalid Ekhlayef N. Alhadidi
Department of Soil Sciences and Water Recourses, College of Agriculture and Forestry, University of Mosul, Iraq.
*Author to whom correspondence should be addressed.
Abstract
Water samples and soil samples (0-15 cm) were taken, irrigated with the same well water from three sites in Nineveh Governorate (Hamdanya, Namroud, and Mahlabia) to assess the quality of well water and determine its suitability for irrigation. The results showed that the electrical conductivity of well water ranged from 2.7 dS m-1 (Hamdanya 2) to 5.7 dS m-1 (Namroud 1). The results indicated that well water used for irrigation in all study sites can only be used in well-permeable soils, with emphasis on leaching requirements and the selection of crops with high salt resistance. The results showed that effect of soil depth to the depth of leaching water (Dw/Ds) on electrical conductivity values (ECt/ECo) for the outflow of washed salts. there is a decrease in the ratio (ECt/ECo) for the outflow in two stages. The first is fast, which includes the rapidly soluble salts, and the second is slow, reflecting the dissolution of the sparingly soluble salts. These curves also reflected the difference in salt leaching according to the soil texture, as Hamdaniya 3 and Mahallabiya 3 are characterized by high water conductivity compared to the other study sites, and thus increased movement of water and washed salts from them, due to their soft, clay texture, which is characterized by low water conductivity and thus low movement of water and salts. In the final stages of leaching, the values (ECt/ECo) for the outflow were characterized by convergence and stability in the decrease, and this reflects the dissolution of the sparingly soluble salts present in the small pores and narrow capillary tubes. After analyzing the type of salts through the Hypothetical combinationof the prevailing salts before leaching After completing the leaching process, the results showed an increase in the percentage of chloride and sulfate salts before leaching, at rates reaching (40%) compared to bicarbonate salts, which did not exceed (11%). After completing the continuous and intermittent leaching process, the percentage of chloride and sulfate salts decreased significantly, and new salts appeared, namely Sodium bicarbonate and magnesium bicarbonate, especially after intermittent leaching, which indicates that the soil was leaching and made suitable for agriculture.
Keywords: Irrigation, well water, soil salinity, Sodium adsorption ratio, CROSS