ادارة واستصلاح الاراضي الزراعية في وادي الجرفان بمنطقة البطنان

Abstract

In this study, we evaluated the properties of soil and water used for irrigation in the Wadi AlJarfan area, which is about 115 km east of the city of Tobruk in the state of Libya. The soil of this valley was evaluated by taking a group of samples from different areas in the valley, so that these samples represent all agricultural lands in the valley. The water in that valley was also studied by analyzing well water samples. Various analyzes were conducted to identify the physical properties of the soil, such as texture, density, porosity, and chemical properties such as pH and electrical conductivity, as well as the total dissolved cations and anions, calcium carbonate concentration, organic matter percentage, and cation exchange capacity and to apply the mathematical equations used internationally to obtain the values of each of the concentrations of adsorbed sodium (SAR), the rate (adj SAR), residual sodium carbonate, percentage of dissolved sodium and exchangeable sodium. The results showed that the prevailing soil texture in the valley area is a sandy loam texture, with a pH between 6.6 and 8, Also, 85% of the soil samples the electrical conductivity value did not exceed 2 dS/m, and sodium adsorption ratio (SAR) is less than 10 and therefore according to the American Salinity Laboratory classification it is classified as non-saline soil and Its sodium content is low. The soil cation exchange capacity (CEC) ranged between 5-19 meq/100g. Because the study area is located within the arid and semi-arid regions, climatic conditions play an important role in influencing these properties. For example, it was noted that the concentration of calcium carbonate varies from one site to another. as it was found in some areas in the range of 15% and in other areas it reached 36%. It is also known that increasing the concentration of calcium carbonate leads to an increase in the pH value, which makes the soil tend to be basic soil. also the average organic matter content ranged between 02.7% and 2.02% for the years 2018 and 2019, while in some sites it decreased to 0.2% and varies from one site to another. As for irrigation water analyses, which in this study are water from wells located within this valley, analyzes were conducted for 8 wells in the valley delta area containing irrigated farms over 3 periods: month 12 of 2018, month 3 of 2019, and month 12 of 2019. the water was evaluated based on the American Salinity Laboratory, and it was found that the electrical conductivity value of most wells falls within the C4 classification of water with very high salinity, while well No. 3 falls within the C3 classification, all of which are outside the permissible rating limits for irrigation water, while the SAR for most wells falls within Permissible limits (S1, S2) sodium risk is low to moderate. While the values of residual sodium carbonate (RSC) were negative for most wells, this indicates that there is no risk of alkalinity in the irrigation water. The results also showed high values of chloride ions compared to the standards of the Food and Agriculture Organization of the United Nations (FAO), and this increases their impact on the soil and plants and the occurrence of problems in If this water is used for irrigation purposes. The well water that was studied is considered to have high salinity and is therefore considered unsuitable for irrigation except in certain cases, such as irrigation of soil with high permeability and good drainage and growing crops that are highly tolerant to salinity and its use requires adding sufficient amounts of water for washing purposes.