Document

Comparative analysis of soil salinity assessment techniques and statistical modeling of soil EC prediction from diverse salinity parameters.

Source
Master's thesis
Country
Oman
City
Muscat
Publisher
Sultan Qaboos University.
Gregorian
2024
Language
English
Thesis Type
Master's thesis
English abstract
Soil salinity is a growing problem worldwide, impacting crop production and food quality. It occurs when salt levels in the soil exceed plant tolerance, resulting in reduced yields and plant death. Natural factors like evaporation and low rainfall, as well as human activities such as improper irrigation and excessive fertilizer use, contribute to soil salinity. This hinders water absorption and nutrient uptake by plants, reducing growth and fertility. It also harms ecosystems by polluting water bodies and causing soil erosion and desertification. This study aimed to investigate the relationship between different methods of soil salinity analysis and electrical conductivity (EC) in the Al Batinah region of the Sultanate of Oman. Additionally, this study aimed to develop a statistical model for predicting EC values based on other salinity parameters and compare different analytical methods for elemental analysis and soil texture. In the first part of the study, it was crucial to identify the source of salinity by analyzing the soil properties in different areas. The study also analyzed the soil texture and quantified anions and cations. Furthermore, this study found that the irrigation water used in the area was saline with EC values ranging from 14-18 mS/cm. The second part is Comparing some of EC methods used to prepare the soil samples like: 1:1, 1:5 and satureated paste method (ECe). The simple linear regression test used to compare these methods. In the third part of the study, it aimed to compare the analysis results of calcium (Ca) and magnesium (Mg) in soil samples using different methods and instruments. Ten samples were collected from three farms and prepared using various methods. The samples were then analyzed using ICP-OES, IC, flame photometer, and XRF. The quantification of total alkali metals (Mg²⁺ and Ca²⁺) was carried out using various analytical methods. These methods included the open digestion method by ICP-OES, the 1:2.5 soil to water extract by flame photometer, the 1:5 soil to water extract by IC, and the fused bead method by WD-XRF. The results showed that the open acid digestion by ICP-OES and the fused bead method by XRF were the most reliable methods for determining the total concentration of Ca and Mg. These methods can be used effectively in quantifying the alkali metal content. In addition to these methods, XRD and soil texture tests were conducted to gather valuable information about the soil mineralogy in the study area. These tests provided further insights into the composition and characteristics of the soil. The study revealed a significant relationship between the open acid digestion method of ICP-OES and XRF results for Ca analysis. However, further analysis and statistical tests are required to fully understand this relationship. The study also found differences in the Ca and Mg concentrations between the different methods, which could be attributed to the sample preparation methods. The final stage of this study involves constructing a model using multiple linear regression to predict the electrical conductivity (ECe) of the soil based on other soil parameters. The predicted equation is as follows: ECe (dS m⁻¹) = 0.218 + 0.15 Na + 0.16 Ca + 0.113 Mg ± ɛ. To validate the accuracy of the model, a comparison was made between the observed and calculated ECe values using the initial dataset used for model construction. The relationship between the experimental ECe and the calculated ECe was examined using simple linear regression, which showed a strong relationship with an r² value of 0.72. In the second part of the validation process, mathematical modeling was applied to the research samples and the data was compared with the calculated values. The strength of this relationship was assessed using a linear regression test. However, the results indicate a weak relationship with an r² value of 0.2. This weak relationship may be attributed to the limited number of observations available for analysis. The results of this study will be beneficial for future research focused on addressing soil salinity in the specific area under investigation. The findings offer insights into the factors contributing to soil salinity and can inform future strategies to effectively mitigate this issue. Overall, this study contributes to the body of knowledge on soil salinity and provides valuable insights that can be used to address this issue in the specific area studied. It highlights the importance of continued research and collaboration to develop effective solutions for mitigating soil salinity and ensuring the long-term productivity and sustainability of agricultural systems in the region.
Arabic abstract
اظهرت نتائج الدراسة وجود علاقة قوية بين قيم التوصيلية الكهربائية التي تم الحصول عليها من خلال طرق الاستخلاص المشبعة 1 : 1 و5 : 1. وأظهر اختبار الانحدار بين طريقة المعجون المشبع ومستخلص التربة الماء (1:1) و (1:5) وجود علاقة عالية (85 = 0. r^2) ولذلك، يمكن للباحثين الاعتماد على هاتين الطريقتين التحديد قيم EC بدقة يمكن أن يؤدي تحويل قيم التوصيلية الكهربائية من مستخلص التربة الماء إلى التوصيلية الكهربائية بواسطة معجون مشبع إلى توفير الوقت وتقليل التكاليف.
كما قامت الدراسة في الجزء الثاني بتحليل المعادن القلوية (Mg+2 و Ca+2) باستخدام طرق تحليلية مختلفة مثل flame photometer ICP OES و IC و XRF و XRF لتكون التقنيات الأكثر موثوقية بالإضافة إلى ذلك، قدمت اختبارات XRD وسيح التربة معلومات قيمة عن التربة في منطقة الدراسة.
وفي الجزء الثالث من الدراسة، هدف الدراسة إلى مقارنة نتائج تحليل الكالسيوم (Ca) والمغنيسيوم (Mg) في عينات التربة باستخدام طرق وأدوات مختلفة تم القيام بجمع عشر عينات من ثلاث مزارع تحليلها باستخدام طرق XRF flame photometer IC ICP-OES مختلفة لم تم تحليل العينات باستخدام كشفت الدراسة عن وجود علاقة معنوية بين طريقة الهضم المفتوح لـ ICP OFS وصلح XRF‏ التحليل الكالسيوم ومع ذلك هناك حاجة إلى مزيد من التحليل والاختبارات الإحصائية لفهم هذه العلاقة بشكل كامل كما وجدت الدراسة اختلافات في تركيزات الكالسيوم والمغنيسيوم بين الطرق المختلفة، والتي يمكن أن تعدى إلى طرق الاستخلاص.




الجزء الأخير من هذه الدراسة هو بناء النموذج. الطريقة المستخدمة هي الانحدار الخطي المتعدد والمعادلة المتوقعة هي:
ECe (dS m⁻¹) = 0.218 + 0.15 Na + 0.16 Ca + 0.113 Mg + 0.7496. عملية التحقق من صحة النموذج، وتحديدًا في سياق مقارنة قيم ECe المرصودة والمحسوبة. يتم أيضًا استخدام البيانات الأولية المستخدمة لبناء النموذج للتحقق من دقته. تم فحص العلاقة بين ECe التجريبي وECe المحسوب من خلال إظهار العلاقة الجديدة. يتضمن الجزء الثاني من عملية التحقق تطبيق معادلة النموذج على عينات البحث ومقارنة البيانات بالقيم المحسوبة. تم تقييم قوة العلاقة باستخدام اختبار الانحدار الخطي. ومع ذلك، تشير النتائج إلى وجود علاقة ضعيفة، وربما تكون إلى العدد المحدود من الملاحظات المتاحة للتحليل. وستساعد نتائج هذه الدراسة في الاتجاهات المستقبلية للتخفيف من مشكلة ملوحة التربة في هذه المنطقة.
Category
Theses and Dissertations

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