المنشورات العلمية لـكلية الزراعة طرابلس

احصائيات منشورات كلية الزراعة طرابلس

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Estimation of Sunshine Duration using Statistical Approach:‎ Libya As A case Study

Sunshine duration (SD) is an essential atmospheric indicator which is used in many agriculture, ‎architects and solar energy applications. In many situations where data of sunshine duration may not be ‎available due to temporal and financial constraints, developing alternative indirect methods based on ‎theoretical considerations for determining SD are essentially required. In this study, seven models were ‎developed using stepwise regression technique to estimate monthly sunshine duration for Libya. The ‎predictors which were used as inputs differ from one model to another and they included monthly ‎cloudiness index, total day length, mean relative humidity, depth of precipitation, mean maximum ‎temperature, altitude and longitude over 16 meteorological stations spread across Libya during the ‎period of 1961 – 2000 . The evaluation of the developed models was performed using a set of data of ‎four meteorological stations representing different physiogeographic and climatic zones during 2001 ‎and against Abdelwahed and Snyder (2015) equations which were developed for estimating sunshine ‎duration for Libya. The statistical parameters of evaluation criteria included mean absolute error (MAE), ‎root mean square error (RMSE), (RMSE %) and Nash and Sutcliffe Efficiency (NSE). The linear regression ‎equation relating predicted with measured data with intercept equals zero and determination coefficient ‎‎(R2) were also used for evaluation purpose. According to the performance indicators, it was detected ‎that six of the developed models were superior to the model with one parameter (cloudiness index) in ‎estimating the sunshine hours. It was also found that all the developed models have better performance ‎in estimating the sunshine duration as compared with Abdelwahed and Snyder (2015) equations. ‎However, due to its few required variables, a model with two parameters (cloudiness index and total ‎day length) is sufficient and can be used with confidence in estimating sunshine duration for Libya. ‎ Keywords: Sunshine duration, Stepwise regression, Statistical model.‎ arabic 15 English 69
ِAhmed Ibrahim Ekhmaj, Milad Omran Alwershefani(12-2016)
موقع المنشور

المقارنة بين طريقتي كريكنج الإعتيادية (OK) ومقلوب المسافة الموزونة (IDW) لتقدير تلوث مياه الخزانات الجوفية الضحلة بمياه البحر في مدينة طرابلس - ليبيا

تم استخدام طريقة كريكينج من النوع الاعتيادي (OK)وطريقة مقلوب المسافة الموزونة (IDW) للتنبؤ المكاني لتلوث مياه الخزانات الجوفية الضحلة لمنطقة طرابلس بمياه البحر عام 2016 .استعملت نسبة سيمبسون كمؤشر لتلوث المياه الجوفية بمياه البحر على عدد 42 عينة. طبقت طريقة كريكنج من النوع الاعتيادي على البيانات قبل وبعد إجراء التحويل اللوغاريتمي، وتم تقدير التركيبة المكانية عبر استخدام النماذج الكروية والأسية والكأسية. وقد استخدمت تقنية التحقق المتقاطع لتقييم عملية الاستنباط الناتجة عن استخدام طريقة (OK) وطريقة (IDW) بقيم أس تتراوح بين (1،5). تم تقييم أداء نماذج الفاريوجرام (Variogram) باستخدام معامل التحديد ( R2) ومجموع مربعات البواقي (RSS)، واستخدم كل من الجذر التربيعي لمربع الخطأ (RMSE) ومتوسط الخطأ النسبي (MRE) لتقييم دقة النتائج المتحصل عليها من تقنية التحقق المتقاطع. أظهرت النتائج أن أداء نماذج الفاريوجرام قبل التحويل اللوغاريثمي كان أكثر دقة، من ذلك المتحصل عليها بعد التحويل اللوغاريثمي، وأن أفضلهم أداءً هو النموذج الكأسي قبل عملية التحويل اللوغاريثمي بقيمة 0.463، 4.30 ،وذلك لكل من(R2) و(RSS) ،على التوالي. كما بينت النتائج وفقاً لتقنية التحقق المتقاطع أن طريقة (OK) عبر استخدام النموذج الكأسي قبل التحويل اللوغاريثمي وطريقة (IDW) بأس مسافة يساوي 1 أعطت النتائج الأكثر دقة، مع الأفضلية لطريقة (OK) بقيم 0.535، 0.246، 0.249 وذلك لكل من (RMSE)، (MRE) و(R2)، على التوالي. وقد أوضحت الخريطة المتحصل عليها من تطبيق طريقة (OK) باستخدام النموذج الكأسي، أنه على الرغم من أن 55.76 %من مساحة منطقة الدراسة صنفت مياهها الجوفية بأنها ذات تلوث طفيف بمياه البحر، إلا أن هناك زيادة في خطورة تلوث المياه الجوفية في الحدود الجنوبية شرقية والشمالية الغربية منها. الكلمات المفتاحية: المياه الجوفية، تداخل مياه البحر، نسبة سيمبسون، الإحصاء المكاني، التحقق. arabic 261 English 5
أحمد إبراهيم خماج, عبدالرحمن أحمد الرياني(10-2020)
موقع المنشور

A novel use of social media to evaluate the occurrence of skin lesions affecting wild dusky grouper, Epinephelus marginatus (Lowe, 1834), in Libyan coastal

The social media network Facebook™ was used to gather information on the occurrence and geographical distribution of dusky grouper dermatitis, a skin lesion affecting the dusky grouper, Epinephelus marginatus. Dusky grouper are common targets for spear fishermen in the Mediterranean and by monitoring spearfishing activity in Libyan waters, it was possible to document skin lesions from their entries on Facebook. Thirty-two Facebook accounts and 8 Facebook groups posting from 23 Libyan coastal cities provided a retrospective observational data set comprising a total of 382 images of dusky grouper caught by spearfishing between December 2011 and December 2015. Skin lesions were observable on 57/362 fish, for which images were of sufficient quality for analysis, giving a minimal prevalence for lesions of 15.75%. Only dusky grouper exceeding an estimated 40 cm total length exhibited lesions. The ability to collect useful data about the occurrence and geographical distribution of pathological conditions affecting wild fish using social media networks demonstrates their potential utility as a tool to support epidemiological studies and monitor the health of populations of aquatic animals. To our knowledge, this represents the first time that such an approach has been applied for assessing health in a wild population
Jamila taher ahmed rizgalla(1-2017)
موقع المنشور

Ulcerative dermatitis in wild dusky grouper Epinephelus marginatus (Lowe) from Libyan waters

In the period 2013–2015, wild dusky grouper, Epinephelus marginatus (Lowe), caught in Libyan coastal waters and ranging in size from 42 to 92 cm in total length, were observed to have distinctive skin lesions of unknown aetiology. Histopathologically, the lesions comprised a multifocal, unilateral or bilateral dermatitis, involving the epidermis, superficial dermis and scale pockets, and sometimes, in severe cases, the hypodermis. Severe lesions had marked epidermal spongiosis progressing to ulceration. Healing was observed in some fish. Bacteria and fungi could be isolated from severe lesions, although they were not seen histopathologically in early‐stage lesions. By contrast, metazoan parasite eggs were observed in the dermis and epidermis of some fish with mild and moderate dermatitis. Unidentified gravid digenean trematode parasites carrying similar eggs were also seen within the blood vessels of the deep and superficial dermis. The cause of this distinctive condition, termed dusky grouper dermatitis (DGD), and its potential impact upon already threatened Mediterranean wild dusky grouper populations and upon cultured grouper more widely have yet to be established.
Jamila taher ahmed rizgalla(5-2016)
موقع المنشور

Assessing Ecosystem Services of Atmospheric Calcium and Magnesium Deposition for Potential Soil Inorganic Carbon Sequestration

Many soil regulating ecosystem services (ES) are linked to Earth’s atmosphere, but associated monetary values often are unknown or difficult to quantify. Atmospheric deposition of calcium (Ca2+) and magnesium (Mg2+) are abiotic flows (wet, dry, and total) from the atmosphere to land surfaces, which potentially can become available to sequester carbon (C) as soil inorganic carbon (SIC). However, these processes typically have not been included in economic valuations of ecosystem services. The primary objective of this study was to demonstrate an approach for valuing non-constrained potential SIC sequestration from atmospheric Ca2+ and Mg2+ deposition based on the concept of the avoided social cost of carbon dioxide emissions (SC-CO2). Maximum monetary values associated with the non-constrained potential SIC sequestration were compiled for the contiguous United States (U.S.) by soil order, land resource region (LRR), state, and region using available deposition data from the National Atmospheric Deposition Program (NRSP-3). For the entire contiguous U.S., an average annual monetary value for the non-constrained potential SIC sequestration due to atmospheric Ca2+ and Mg2+ deposition was $135M (i.e., $135 million U.S. dollars, where M = million = 106). Mollisols, Alfisols, and Entisols were soil orders with the highest average annual monetary values for non-constrained potential SIC sequestration. When normalized by land area, however, Vertisols had the highest average annual monetary values followed by Alfisols and Mollisols for non-constrained potential SIC sequestration. From a more agricultural perspective, the LRRs with the highest average annual monetary values for non-constrained potential SIC sequestration were the Western Range and Irrigated Region (D), the Central Feed Grains and Livestock Region (M), and the Central Great Plains Winter Wheat and Range Region (H). When normalized by area, the LRRS with the highest average annual monetary values were the Southwest Plateaus and Plains Range and Cotton Region (I) and the Florida Subtropical Fruit, Truck Crop and Range Region (U). Among the U.S. states, the highest average annual monetary values for non-constrained potential SIC sequestration were Texas, Kansas, and New Mexico, but when normalized by area the highest values by state were Kansas, Iowa, and Texas. Geographical regions in the contiguous U.S. with the highest average annual monetary values for non-constrained potential SIC sequestration were the South Central, Midwest, and West; when normalized by area, the highest values by region were South Central, Midwest, and Northern Plains. Constraints on maximum monetary values, based on physical, chemical, biological, economic, social, and political limitations, need to be considered and quantified to obtain more precise and accurate accounting of the ES associated with SIC sequestration due to atmospheric Ca2+ and Mg2+ deposition. arabic 14 English 112
Elena A. Mikhailova, Hamdi A. Zurqani, Christopher J. Post, Mark A. Schlautman(5-2020)
موقع المنشور

Assessing the value of soil inorganic carbon for ecosystem services in the contiguous United States based on liming replacement costs

Soil databases are very important for assessing ecosystem services at different administrative levels (e.g., state, region etc.). Soil databases provide information about numerous soil properties, including soil inorganic carbon (SIC), which is a naturally occurring liming material that regulates soil pH and performs other key functions related to all four recognized ecosystem services (e.g., provisioning, regulating, cultural and supporting services). However, the ecosystem services value, or “true value,” of SIC is not recognized in the current land market. In this case, a negative externality arises because SIC with a positive value has zero market price, resulting in the market failure and the inefficient use of land. One potential method to assess the value of SIC is by determining its replacement cost based on the price of commercial limestone that would be required to amend soil. The objective of this study is to assess SIC replacement cost value in the contiguous United States (U.S.) by depth (0–20, 20–100, 100–200 cm) and considering different spatial aggregation levels (i.e., state, region, land resource region (LRR) using the State Soil Geographic (STATSGO) soil database. A replacement cost value of SIC was determined based on an average price of limestone in 2014 ($10.42 per U.S. ton). Within the contiguous U.S., the total replacement cost value of SIC in the upper two meters of soil is between $2.16T (i.e., 2.16 trillion U.S. dollars, where T = trillion = 1012) and $8.97T. States with the highest midpoint total value of SIC were: (1) Texas ($1.84T), (2) New Mexico ($355B, that is, 355 billion U.S. dollars, where B = billion = 109) and (3) Montana ($325B). When normalized by area, the states with the highest midpoint SIC values were: (1) Texas ($2.78 m−2), (2) Utah ($1.72 m−2) and (3) Minnesota ($1.35 m−2). The highest ranked regions for total SIC value were: (1) South Central ($1.95T), (2) West ($1.23T) and (3) Northern Plains ($1.01T), while the highest ranked regions based on area-normalized SIC value were: (1) South Central ($1.80 m−2), (2) Midwest ($0.82 m−2) and (3) West ($0.63 m−2). For land resource regions (LRR), the rankings were: (1) Western Range and Irrigated Region ($1.10T), (2) Central Great Plains Winter Wheat and Range Region ($926B) and (3) Central Feed Grains and Livestock Region ($635B) based on total SIC value, while the LRR rankings based on area-normalized SIC value were: (1) Southwest Plateaus and Plains Range and Cotton Region ($3.33 m−2), (2) Southwestern Prairies Cotton and Forage Region ($2.83 m−2) and (3) Central Great Plains Winter Wheat and Range Region ($1.59 m−2). Most of the SIC is located within the 100–200 cm depth interval with a midpoint replacement cost value of $2.49T and an area-normalized value of $0.34 m−2. Results from this study provide a link between science-based estimates (e.g., soil order) of SIC replacement costs within the administrative boundaries (e.g., state, region etc.). arabic 19 English 114
Garth Groshans, Elena Mikhailova, Christopher Post, Mark Schlautman, Hamdi Zurqani, Lisha Zhang(12-2018)
موقع المنشور

Determining farm-scale site-specific monetary values of “soil carbon hotspots” based on avoided social costs of CO2 emissions

A “soil carbon hotspot” (SCH) is a geographic area having an abundance of soil carbon, and therefore higher ecosystem services value based on avoided social costs of CO2 emissions. Soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) are critical data to help identify SCH at the farm scale, but monetary methods of hotspot evaluation are not well defined. This study provides a first of its kind quantitative example of farm-scale monetary value of soil carbon (C), and mapping of SCH based on avoided social cost of CO2 emissions using both Soil Survey Geographic (SSURGO) database and field measurements. The total calculated monetary value for TSC storage at the Willsboro Farm based on the SSURGO database was about 7.3 million U.S. dollars ($7.3 M), compared to $2.8 M based on field data from averaged soil core results. This difference is attributed to variation in soil sampling methodology, laboratory methods of soil C analyses, and depth of reported soil C results. Despite differences in total monetary valuation, observed trends by soil order were often similar for SSURGO versus field methods, with Alfisols typically having the highest total and area-normalized monetary values for SOC, SIC, and TSC. Farm-scale C accounting provides a more detailed spatial resolution of monetary values and SCH, compared to estimates based on country-level reports in soil survey databases. Delineation and mapping of SCH at the farm scale can be useful tools to define land management zones, to achieve social profit for farmers, and to realize United Nations (UN) Sustainable Development Goals (SDGs) based on avoided social cost of CO2 emissions. arabic 24 English 105
Elena Mikhailova, Christopher Post, Mark Schlautman, Gregory Post, Hamdi Zurqani(1-2020)
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Comparing Field Sampling and Soil Survey Database for Spatial Heterogeneity in Surface Soil Granulometry: Implications for Ecosystem Services Assessment

Lithospheric-derived resources such as soil texture and coarse fragments are key soil physical properties that contribute to ecosystem services (ES), which can be valued based on "soil" or "mineral" stocks. Soil survey data provides an inexpensive alternative to detailed field measurements which are often labor-intensive, time-consuming, and costly to obtain. However, both field and soil survey data contain heterogeneous information with a certain level of variability and uncertainty in data. This study compares the potential of using field measurements and information from the Soil Survey Geographic database (SSURGO) for coarse fragments (CF), sand (S), silt (Si), clay (C), and texture class (TC) in the surface soil (Ap horizon) for the 147-hectare Cornell University Willsboro Research Farm, NY. Maps were created based on following methods: (a) utilizing data from the SSURGO database for individual soil map unit (SMU) at the field site and using representative or reported values across individual SMU; (b) averaging the field data within a specific SMU boundary and using the averaged value across the SMU; and (c) interpolating field data within the farm boundaries based on the individual soil cores. This study demonstrates the important distinction between mapping using the "crisp" boundaries of SSURGO databases compared to the actual spatial heterogeneity of field interpolated data. Maps of CF, S, Si, C, and TC values derived from interpolated field core samples were dissimilar to maps derived by using averaged core results or SSURGO values over the SMUs. Dissimilarities in the maps of CF, S, Si, C, and TC can be attributed to several factors (e.g., official soil series data being collected from "type locations" outside of the study areas). Correlation plot of clay estimates for each SMU showed statistically significant correlations between SSURGO and field-averaged (r = 0.823, p = 0.003) and field-interpolated clay (r = 0.584, p = 0.028) estimates, but no correlation was found for CF, S, and Si. Ecosystem services provided by quantitative data such as CF, S, Si, and C may not be independent from each other and other soil properties. Key soil properties should also include categorical data, such as texture class, which is used for another key soil property-available soil water ratings. Current valuation of soil texture is often linked to specific mineral commodities, which does not always address the issue of soil based valuation including indirect use value. arabic 19 English 133
Elena Mikhailova, Christopher Post, Patrick Gerard, Mark Schlautman, Michael Cope, Garth Groshans, Roxanne Stiglitz, Hamdi Zurqani, John Galbraith(9-2019)
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