Soil salinity is one of the most important issues in arid and semi arid regions, which is directly linked to desertification and land degradation. Several studies related to soil and water salinity assessment, and mapping were conducted in Libya using traditional methods. However, they covered only the time of measurements and did not address the dynamic nature of salinity process. In addition, they lack cost and time effectiveness. Therefore, there is pressing need to use a high tech method that is cost, time and labor effective to assess the change in soil salinity in north- west of Libya. The aim of this paper is to identify the change in saline soils (Sehbkha) using Remote Sensing (RS) and geographic information system (GIS) techniques. Land Sat Satellite images data were acquired for 29 years (1972-1987-2001) to assess the pattern of change. The result revealed that there was a decrease saline soils area ( Sbehbka). Keywords: Libya, GIS, Remote Sensing, Soil, Soil Salinity, Sebkha. arabic 17 English 109
Hamdi Zurqani, Bashir Nwer, Azzeddin Elhawej(12-2012)

Summary: One of the main characteristics of trickle irrigation system is that water leaving an emitter enters the soil and moves both laterally and vertically. There has been much speculation on the shape and moisture distribution within the wetted soil volume. This knowledge is important in the design, operation and management of a trickle irrigation system. A simulation study of soil water distribution under a prairie field in Tripoli Libya, by the use of the two dimensional model Hydrus 2D model was carried out. Sandy soil was irrigated using surface point source with application rates of 1.5, 2, 2.7, 3, 3.5, 4.5, 4.8 and 6 l/h. The surface wetted radius, vertical advance of wetting front and the distribution of moisture content in the soil profile were determined. Three statistical criteria were used to compare the quality of simulation results, such as mean bias error (MBE), root mean square error (RMSE) and Theil’s Inequality coefficient (U). Simulation positions of the wetting front were in agreement relative to the observed measurements of the wetting front. Specifically, in the lateral, the experimentally determined wetting front was closely estimated by the model. In the downward direction the simulated wetting front advanced much slower than the observed especially at later stage of infiltration. Considering the difficulties in estimating the dynamic water conditions in the field there was generally good agreement (especially in the lateral direction) between the measured and simulated values. In the deeper downward direction the simulated moisture content distributions were less than the measured. On the other hand, the Hydrus_2D model described the water content distribution quite well at relatively high levels of moisture contents; however, it did not do as well at lower moisture content. The discrepancies between the simulated and measured values may be due to variation in the size of the surface source of water during infiltration and to the natural variation of soil properties. However, due to the complex mechanisms of water movement under the complicated boundary and initial conditions from a surface point source the results support the use of Hydrus 2D as a tool for investigating and designing point source trickle irrigation system. Keywords: Trickle irrigation, wetting front, soil moisture distribution, Hydrus _2D model
Ahmed Ibrahim Ekhmaj, M.S.M. Amin, Abdul Hakim Almdny, W. Aimrun, .M. Abdulaziz, (1-2006)

Abstract Laboratory experiment are conducted in the summer years (2010) to study the impact of adding a source of organic carbon (sawdust) on inorganic nitrogen in the soil Mixing (500 grams) soil texture sandy silt with rates by addition of compost poultry rates (0 - 15-30-60 ton/ ha), as well as the rates of carbon source sawdust (0.5-1%), where then mixed well with each other in order to become homogeneous, and placed in the pot and repeated three times each addition , just as the number of experimental units each experiment (180 experimental units), and incubated at room temperature while maintaining the moisture at field capacity gravimetric way through the different incubation periods, which is set in weeks (0-2-4-8-16 week) by using statistical decomposition split plot twice ( split-split-plot design) and determing the differences moral between averages using Duncan to isolate averages at the level of moral (5%) and analyze the results using a table (ANOVA), and then estimate the degree of interaction of soil (pH) and organic matter and nitrogen mineral and total ratio of carbon to nitrogen (C/N Ratio) during different incubation periods, The results showed fluctuations in the degree of interaction through different incubation periods were (pH) the highest value for (8.4pH) at the time of incubation (4-8 weeks) and the lowest value (7.8pH) at the time of incubation (16 weeks), the organic matter Tests showed an increase in organic matter with increased rates of adding compost and sawdust at the beginning of the period of incubation and decreases organic matter gradually with increasing duration of incubation (16 weeks) As a result of decomposition of organic matter by micro-organisms, while nitrogen mineral available results show an increased nitrogen available at the beginning of the period of incubation with increased rates of added fertilizer and organic sawdust With increasing time incubation fluctuation in the amount of nitrogen available Result of the succession of microbial occur collections and increasing the proportion of (C/N),The Results show in the amount of total nitrogen per transaction At the beginning of the period of incubation and after two weeks of incubation Results show increasing the amount of total nitrogen at a rate (60 ton / ha) and over a period of incubation at (16 weeks) results showed a decrease in the value of total nitrogen when treatment (60 ton / ha) and average (0.5%) sawdust, either carbon to nitrogen (C/N Ratio) Tests showed that the high proportion of carbon to nitrogen, with the rate Add compost and the proportion of sawdust at the beginning of the period of incubation with the passage of time and increase the period of incubation results show low (C/N Ratio) for each transaction with time as a result of mineral nitrogen liberate when the incubation period (4 weeks) and an increase of the period of incubation results show an increase ratio (C/N Ratio) for each transaction.
محمد الطاهر الفيتوري سالم (2013)