Download or read book Sodicity Hydraulic Conductivity and Swelling of Clay Soils written by Donald Sidney McIntyre and published by . This book was released on 1979 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Salinity Sodicity and Clay Mineralogy on the Soil Physical and Hydraulic Properties written by Victor Manuel Ruiz Vera and published by . This book was released on 2005 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling the Change in Conductivity of Soil Associated with the Application of Saline sodic Water written by Younes Daw Ezlit and published by . This book was released on 2009 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scarcity of fresh water has led to use of low quality waters (high sodicity and salinity) that were considered unsuitable for irrigation in the past. Mismanagement of irrigation using this water can increase the potential for soil degradation and limit crop production in the long term. Irrigation using highly saline-sodic water requires appropriate management to avoid long term development of sodicity and salinity problems. The main factors that control the sodicity and salinity problems are maintenance of sufficient leaching and avoidance of soil structure degradation due to sodicity. The management options are determined by complex factors such as soil type and condition, water quality, irrigation practice and crop type. Investigating the management options for using highly saline-sodic water in irrigation experimentally is costly and time consuming. However, it could be done using an appropriate modelling tool that can handle the degradation of soil structure due to sodicity along with the chemical reaction system within the soil profile. UNSATCHEM has been widely used to model sodicity and salinity effects under irrigation. It has a feature to deal with soil structure degradation along with water and solute movement, major ion chemistry, CO2 production and movement and heat transfer under sodic conditions. It uses a hydraulic conductivity reduction function to relate the change of chemical properties to the change in hydraulic properties of the soil. However, the evaluation of the hydraulic conductivity reduction function under high sodicity during simulation has not been done. Hence, the core of this research project has been to improve quantification of soil structure degradation under sodic conditions and enhance the modelling of water and solute movement under sodic conditions. The hydraulic conductivity reduction function incorporated in UNSATCHEM was evaluated using data obtained from soil column experiments. Columns of two local soils were used in an experiment to investigate the effect on soil structural stability of different amendments to highly saline-sodic water rich with bicarbonates (EC = 4.6 dS/m and SAR = 117). The column experiments were used to examine the effect of reducing water pH to different levels using sulphuric acid and combined gypsum and dilution treatments. It was found that reducing the pH of highly saline-sodic water did not enhance soil structural stability as the water applied has naturally high relative sodium concentrations. However, the application of diluted highly saline-sodic water amended with gypsum showed no significant effect on soil structure and permeability. It is concluded that different amendments associated with appropriate irrigation management can be applied to sustain irrigation and prevent long term salinity and sodicity problems. The data from the column experiments was used to evaluate the quantification of the soil structure degradation in UNSATCHEM. The resultant simulations for the soil columns showed that the estimated outflow and hydraulic conductivity were less than the experimental measurements, which suggested that the soil structure degradation was not accounted for properly. The sodicity effect was accounted for in UNSATCHEM by a reduction function, which is a combined function of the McNeal (1968) clay swelling model and the Simunek et al. (1996) pH effect equations. The empirical pH effect equation accounts for the reduction of the conductivity due to increasing pH and clay swelling. The evaluation of UNSATCHEM under highly sodic conditions suggests that the hydraulic conductivity reduction function is limiting the UNSATCHEM performance. Consideration of the first term of the hydraulic conductivity reduction function (i.e. the McNeal (1968) clay swelling model) has highlighted the weaknesses of the McNeal model and led to develop a generic clay swelling model (GCSM). Calibration of the GCSM using the data of McNeal showed good agreement between the estimated and measured relative conductivity data. Further calibration of the GCSM using relative conductivity data obtained for five local soils also showed good agreement between the model estimation and the measured data. Coding of the generic clay swelling model into UNSATCHEM and re-simulating the column experiments showed that the modelling process is improved compared with the UNSATCHEM version containing the McNeal (1968) clay swelling model. However, the outflow and conductivity values produced were still less than measured values. This result suggested that further investigations are required to identify the effect of pH on the change of hydraulic conductivity, cation exchange capacity, and the exchangeable sodium percentage. Further research is also required regarding bicarbonate chemistry during application of highly saline-sodic water.

Download or read book Prospects for the Drainage of Clay Soils written by David W. Rycroft and published by Food & Agriculture Org.. This book was released on 1995 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Soil ESP and Salinity on Soil Atterberg Limits Swelling and Hydrologic Properties written by Hans Walter Klopp and published by . This book was released on 2019 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil sodicity is a global issue decreasing economic outputs of soils. High solution sodium adsorption ratio (SAR) and low EC increases swelling of smectite clay and causes breakdown of soil aggregates. The effect of solution composition on soils has been commonly measured by saturated hydraulic conductivity which decreases as solution EC decreases and SAR increases with the effects most pronounced on smectite clay dominant soils, which also is the only clay type that has interlayer swelling from exchangeable sodium. Currently soil physical properties are not used to classify soils that are sensitive to soil sodicity. The objectives of this dissertation, are 1) to determine how properties related to soil swelling and hydrology change on soils of a range of clay mineralogy, 2) determine a soil physical property that can discriminate between soils that are sensitive to high ESP levels from soils that are not sensitive to soil sodicity and 3) to predict the change of soil properties in response to solution EC and SAR. Soil Atterberg limits, shrinkage and water retention were measured under soil ESP and EC combinations on soils of a range of textures and clay mineralogy, using a dry sodium carbonate treatment and mixtures of sodium and calcium chloride solutions. Soil saturated hydraulic conductivity decreased, and shrinkage, water retention and Atterberg limits increased in smectitic soils. Smectitic soils had a larger change in soil hydraulic conductivity and are the only soils that had pronounced changes in soil physical properties related to swelling from high ESP and low EC. Measuring soil liquid limit or water retention at points of -1/10 or -1/3 bar in a low EC-low ESP and a low EC-high ESP state can distinguish soils sensitive to sodicity from soils not sensitive to sodicity. Existing models to predict soil hydrologic properties performed poorly on smectitic soils. Accounting for the smectite content by cation exchange capacity improved prediction of soil hydrologic properties on smectitic soils. Soils that are smectitic can be rapidly identified by measuring soil swelling related property and have a narrower range of irrigation water qualities acceptable for use before soil hydrologic properties change.

Download or read book Clay Dispersion and Hydraulic Conductivity Characteristics of Soils as Influenced by Electrolyte Concentration Exchangeable Cation Composition and Clay Mineralogy written by Mohammad Yousaf and published by . This book was released on 1983 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Saline and Sodic Soils written by Eshel Bresler and published by Springer. This book was released on 1982 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Guideline for Salinity Assessment Mitigation and Adaptation Using Nuclear and Related Techniques written by Mohammad Zaman and published by Springer. This book was released on 2018-11-28 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book is an outcome of the collaboration between the Soil and Water Management & Crop Nutrition Section, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Department of Nuclear Sciences and Applications, International Atomic Energy Agency (IAEA), Vienna, Austria, and Dr. Shabbir A Shahid, Senior Salinity Management Expert, Freelancer based in United Arab Emirates.The objective of this book is to develop protocols for salinity and sodicity assessment and develop mitigation and adaptation measures to use saline and sodic soils sustainably. The focus is on important issues related to salinity and sodicity and to describe these in an easy and user friendly way. The information has been compiled from the latest published literature and from the authors’ publications specific to the subject matter. The book consists of six chapters. Chapter 1 introduces the terms salinity and sodicity and describes various salinity classification systems commonly used around the world. Chapter 2 reviews global distribution of salinization and socioeconomic aspects related to salinity and crop production. Chapters 3 covers comprehensively salinity and sodicity adaptation and mitigation options including physical, chemical, hydrological and biological methods. Chapter 4 discusses the efforts that have been made to demonstrate the development of soil salinity zones under different irrigation systems. Chapter 5 discusses the quality of irrigation water, boron toxicity and relative tolerance to boron, the effects of chlorides on crops. Chapter 6 introduces the role of nuclear techniques in saline agriculture.

Download or read book Effects of Dispersion and Swelling on Soil Hydraulic Conductivity written by H. Frenkel and published by . This book was released on 1978 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanisms of clay mineral dispersion and swelling, their effects on soil hydraulic conductivity, and their relevance to piping failures of earth-filled dams are discussed. It is concluded that clay dispersion could initiate piping failures of earthen dams. A method is recommended for evaluating the susceptibility of soil materials to disperse.

Download or read book The Effect of Salinity and Sodicity on the Structure and Hydraulic Conductivity of Soil written by A-M. Sameni and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Genesis and Management of Sodic Alkali Soils written by S.K. Gupta and published by Scientific Publishers. This book was released on 2017-10-01 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Land and water, the two crucial natural resources for agriculture, are decreasing as a result of burgeoning population of the country. At the same time, various forms of degradation are taking a toll on the productivity of these resources so much so that large areas have been taken out of plough. Current assessment reveal that already 6.73 million ha area has gone out of cultivation because of excessive salts or high sodicity and this area is likely to expand to 20 million ha by 2050 because of the faulty irrigation and drainage water management practices being adopted in irrigation commands. Of the current affected area, more than 50% is sodic in nature, which requires some kind of chemical amendment for reclamation. While our knowledge and understanding of the causes, nature and harmful effects of sodic soils have tremendously increased, availability of gypsum on account of environmental problems on its mining has caused concerns. Apparently, there is a need to push for other amendments especially the industrial wastes and publish the information in practical terms for various stakeholders. This book is an attempt in this direction. Taking into account the widely varying needs of the clients, the chapters of this book have been organized to include history, origin and genesis of sodic lands, basic principles of diagnosis, nature and properties of sodic lands, amendments, reclamation package and alternate land management. Since sodic water irrigation is one of the factors in the formation of sodic lands, a separate chapter deals with this issue highlighting the extent and distribution, chemical characteristic and management options for the use of sodic water. The economic analysis procedures and socio-economic issues of sodic land reclamation are included in a separate chapter with appropriate case studies. Since latest scientific information on new technologies with case studies is included, we believe that this book is an improvement over the existing books and is a useful addition to the literature on this subject. In our view the information contained in this book would be handy to field practitioners in the Government Departments and NGOs to plan and undertake large sodic land reclamation projects. Since the basic principles and practices have been very well elucidated, the book can be used as a text book in agricultural and engineering colleges. It can also be used as a source material in training programs being organized by various scientific organizations. We believe that the book would prove to be a handy reference resource to all those interested in sustainable irrigated agriculture for the food and nutritional security of the nation.

Download or read book Handbook of Soil Science written by Malcolm E. Sumner and published by CRC Press. This book was released on 1999-08-31 with total page 2240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Soil Science provides a resource rich in data that gives professional soil scientists, agronomists, engineers, ecologists, biologists, naturalists, and their students a handy reference about the discipline of soil science. This handbook serves professionals seeking specific, factual reference information. Each subsection includes a description of concepts and theories; definitions; approaches; methodologies and procedures; tabular data; figures; and extensive references.

Download or read book Soil Salinity under Irrigation written by I. Shainberg and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of irrigation in the world's agriculture is rapidly increasing. Although it is practised on a large scale mainly in arid and semi-arid zones, supplementary irrigation is becoming popular in semi-humid regions as well. The record of irrigation speaks for itself in terms of increased crop production. However, the question remains as to how permanent the achievement may be. Judging from history, it seems that irrigation eventually failed in many regions because the knowledge and technology available to society at the time were incapable of coping with the problems created. Undoubtedly soil salinity is the most prevalent and widespread problem limiting crop productivity in irrigated agriculture. It has, therefore, attracted the attention of the scientific community since the advent of modern agronomic research. Through the past six to seven decades a considerable body of information has been accumulated, which has promoted the understanding of the principles involved and helped to develop the technology for coping with the problems. Our present knowledge, if judiciously applied, is adequate for coping with many of the salinity problems resulting from mismanagement of irrigation and drainage. But for this knowledge to be used, it has to be generally known and understood and be re-examined from time to time.

Download or read book Soil Chemistry written by Daniel G. Strawn and published by John Wiley & Sons. This book was released on 2015-04-27 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil is key to sustaining life—affecting air and water quality, the growth of plants and crops, and the health of the entire planet. Soil Chemistry 4e provides comprehensive coverage of the chemical interactions among organic and inorganic solids, air, water, microorganisms, and the plant roots in soil. The fourth edition of Soil Chemistry has been revised and updated throughout and provides a basic description of important research and fundamental knowledge in the field. The text covers chemical processes that occur in soils, including: distribution and species of nutrients and contaminants in soils; aqueous chemistry of soil solutions and mineral dissolution; oxidation and reduction reactions in soils; soil mineral formation processes and properties; the formation and reactivity of soil organic matter; surface chemistry and cation, anion, and organic compound adsorption reactions; modelling soil chemical reactions; and reactions in acid and salt affected soils. Although extensively revised with updated figures and tables, the fourth edition maintains the focus on introductory soil chemistry that has distinguished earlier editions. New chapters on properties of elements relevant to soil chemistry, and a chapter with special focus on soil surface characteristics have been added. Special Topics boxes are also included in the Fourth Edition that includes examples, noteworthy topics, and case studies. End of chapter questions are included as a resource for teaching.

Download or read book Effect of Clay Species and Salt Concentration on Hydraulic Conductivity written by Mohammed Yousif Tayel and published by . This book was released on 1970 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Australian Sodic Soils written by R. Naidu and published by CSIRO Publishing. This book was released on 1995 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Sodic soils cover almost a third of the total land in Australia and are represented to some extent on all continents except Antarctica. They can occur naturally, as in Australia, or may develop as a result of the removal of salts from saline soils." "Sodicity impacts adversely on many soil properties and interferes with the proper functioning of the soil and of the plants grown in it. Problems arise as a result of the deterioration in soil structure, decreased retention and availability of water, decreased nutrient availability and impaired biological activity. Sodic soils are easily eroded and this causes severe land degradation and pollution of water resources." "The management of sodic soils is often difficult and challenging. Because they are so widespread in Australia, their impact on productivity is immense." "Australian Sodic Soils: Distribution, Properties and Management brings together for the first time the results of scientific studies carried out in Australia and presented at the first national conference on Australian sodic soils."--BOOK JACKET.Title Summary field provided by Blackwell North America, Inc. All Rights Reserved

Download or read book Soil Science written by David L. Rowell and published by Routledge. This book was released on 2014-06-03 with total page 873 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers a practical introduction to the various basic methods of assessing the properties of soil. Each method is explained in a concise and accessible manner, providing useful guidance on how each method might be used in a practical situation.