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Soil pH is the most commonly requested analysis undertaken during farm advisory work. Determination of pH assists in understanding many reactions that occur in soil. Variations in pH between soils have been related to a number of other soil parameters. In this study thirty different soils were collected from agricultural areas to have a wide range of pH, salinity, and texture. The objective was to study the relationship between soil pH and salinity. A negative relationship was found between soil salinity and pH. The main factor contributing to this relationship was probably the presence of soluble Ca 2+ ion in soil. Variations in soluble Ca 2+ ion concentrations between soils were negatively related to soil pH and positively related to soil salinity. Other soil properties that may affect pH, including CEC, CaCO 3 , clay content, gypsum and sodium adsorption ratio (SAR), were also determined.

The occurrence of antibiotics in treated wastewater effluent has been a concern worldwide for various reasons: most importantly development of antibiotics resistance by bacteria and other microorganism, impact of antibiotics on animal life in surface water and likely consequences on humans if treated wastewater is used for drinking water supply through the process of managed aquifer recharge (MAR). Another potential area of concern is the uptake of these antibiotics by crops irrigated by treated wastewater. In Oman, wastewater treatment and reuse is pursued vigorously as a government policy. Treated wastewater is used for crop irrigation following government regulations, MAR is being contemplated and practiced in small scale and release of such waters in the ocean takes place from time to time. Some tests have been conducted on the wastewater effluent around the world to verify and detect the concentration of antibiotics in wastewater effluent. In the Sultanate of Oman, very little research has been performed on the occurrence of antibiotics in treated wastewater, removal efficiencies of treatment processes and development of antibiotics resistance. It is expected that wastewater reuse will increase substantially due to expansion of sewerage network in the capital city as well as many other cities and towns. As such, it is imperative that research be undertaken to find out various issues related to commonly used antibiotics such as ciprofloxacin, norfloxacin, erythromycin, linezolid, penicillin, ampicillin, chloramphenicol, streptomycin, minocycline, tetracycline and sulfamethoxazole in Oman and their ultimate fate through the treatment process. In addition, the development of guidelines is crucial in amounts of antibiotics acceptably occurring in treated wastewater effluent and if they could be suitable for agriculture without causing any harm. A review of the available literature and data are provided in this article. Research needs have been identified.

Wastewater treatment and sludge management in Oman have been evolving over the years. Sludge utilization has been a challenge due to its association with human waste. Therefore, composting of sewage sludge is the best option in agriculture activities. Sludge and wastewater utilization can add up positively in the economic aspects of the country in terms of creating jobs and improving annual income rate. The number of research projects done on wastewater reuse and other ongoing ones related to the land application of sewage sludge should encourage revision of existing standards, regulations, and policies for the management and beneficial use of sewage sludge in Oman.