Classification and Mitigation of Soil Salinization

Author(s):  
Tibor Tóth

Soil salinity has been causing problems for agriculturists for millennia, primarily in irrigated lands. The importance of salinity issues is increasing, since large areas are affected by irrigation-induced salt accumulation. A wide knowledge base has been collected to better understand the major processes of salt accumulation and choose the right method of mitigation. There are two major types of soil salinity that are distinguished because of different properties and mitigation requirements. The first is caused mostly by the large salt concentration and is called saline soil, typically corresponding to Solonchak soils. The second is caused mainly by the dominance of sodium in the soil solution or on the soil exchange complex. This latter type is called “sodic” soil, corresponding to Solonetz soils. Saline soils have homogeneous soil profiles with relatively good soil structure, and their appropriate mitigation measure is leaching. Naturally sodic soils have markedly different horizons and unfavorable physical properties, such as low permeability, swelling, plasticity when wet, and hardness when dry, and their limitation for agriculture is mitigated typically by applying gypsum. Salinity and sodicity need to be chemically quantified before deciding on the proper management strategy. The most complex management and mitigation of salinized irrigated lands involves modern engineering including calculations of irrigation water rates and reclamation materials, provisions for drainage, and drainage disposal. Mapping-oriented soil classification was developed for naturally saline and sodic soils and inherited the first soil categories introduced more than a century ago, such as Solonchak and Solonetz in most of the total of 24 soil classification systems used currently. USDA Soil Taxonomy is one exception, which uses names composed of formative elements.

Land ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 154 ◽  
Author(s):  
Orestis Kairis ◽  
Vassiliki Dimitriou ◽  
Chrysoula Aratzioglou ◽  
Dionisios Gasparatos ◽  
Nicholas Yassoglou ◽  
...  

Two soil mapping methodologies at different scales applied in the same area were compared in order to investigate the potential of their combined use to achieve an integrated and more accurate soil description for sustainable land use management. The two methodologies represent the main types of soil mapping systems used and still applied in soil surveys in Greece. Diomedes Botanical Garden (DBG) (Athens, Greece) was used as a study area because past cartographic data of soil survey were available. The older soil survey data were obtained via the conventional methodology extensively used over time since the beginnings of soil mapping in Greece (1977). The second mapping methodology constitutes the current soil mapping system in Greece recently used for compilation of the national soil map. The obtained cartographic and soil data resulting from the application of the two methodologies were analyzed and compared using appropriate geospatial techniques. Even though the two mapping methodologies have been performed at different mapping scales, using partially different mapping symbols and different soil classification systems, the description of the soils based on the cartographic symbols of the two methodologies presented an agreement of 63.7% while the soil classification by the two taxonomic systems namely Soil Taxonomy and World Reference Base for Soil Resources had an average coincidence of 69.5%.


PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256355
Author(s):  
Elif Günal

Soil salinization is the widespread problem seriously affecting the agricultural sustainability and causing income losses in arid regions. The major objective of the study was to quantify and map the spatial variability of soil salinity and sodicity. Determining salinity and sodicity variability in different soil layers was the second objective. Finally, proposing an approach for delineating different salinity and sodicity zones was the third objective. The study was carried out in 871.1 ha farmland in Southeast of Dushak town of Ahal Province, Turkmenistan. Soil properties, including electrical conductivity (EC), soil reaction (pH), sodium adsorption ratio (SAR), calcium carbonate and particle size distribution (clay, silt and sand fractions) in 0–30, 30–60, 60–90 and 90–120 cm soil layers were recorded. The EC values in different soil layers indicated serious soil salinization problem in the study area. The mean EC values in 0–90 cm depth were high (8 dS m-1), classifying the soils as moderate to strongly saline. Spatial dependence calculated by the nugget to sill ratio indicated a strong spatial autocorrelation. The elevation was the primary factor affecting spatial variation of soil salinity in the study area. The reclamation of the field can be planned based on three distinct areas, i.e., high (≥12 dS m-1), moderate (12–8 dS m-1) and low (<8 dS m-1) EC values. The spatial trend analyses of SAR values revealed similar patterns for EC and pH; both of which gradually decreased from north to the south-west. The amount of water needed to leach down the salts from 60 cm of soil profile is between 56.4–150.0 ton ha-1 and the average leaching water was 89.8 tons ha-1. The application of leaching water based on the amount of average leaching water will result in higher or lower leaching water application to most locations and the efficiency of the reclamation efforts will be low. Similar results were recorded for sulfur, sulfuric acid and gypsum requirements to remediate sodicity. The results concluded that the best management strategy in planning land development and reclamation schemes for saline and sodic soils require accurate information about the spatial distribution of salinity and sodicity across the target area.


Author(s):  
Anthony S. R. Juo ◽  
Kathrin Franzluebbers

Several pedological soil classification schemes have been developed to classify soils worldwide based on morphological features, stage of weathering, and to some extent their chemical and physical properties. Three soil classification systems are commonly used as research and teaching tools in the tropics, namely, the USDA Soil Taxonomy classification, the FAO/UNESCO World Soil Legends, and the French soil classification system. Brazil, the country with the largest land area in the tropics, has its own national soil classification system. However, soil survey, classification, and interpretation are costly and time-consuming, and few countries in the tropics have completed soil maps that are at a scale detailed enough to be useful to farmers and land users. In the absence of soil information at state, county or farm level, the authors propose a simple descriptive grouping of major soils in the tropics based on clay mineralogy to facilitate discussion on soil management and plant production in the subsequent chapters of this book. Reference to the Soil Taxonomy classification will be made when such information is available. It should be pointed out that the main purpose of this technical grouping is to provide field workers, especially those who are less familiar with the various soil classification systems, with a simple framework for planning soil management strategies. It by no means replaces the national and international soil taxonomy and classification systems that are designed for communication among soil scientists and for more detailed interpretation of soil survey data and land-use planning. This technical scheme classifies major arable soils in the tropics into four groupings according to their dominant clay mineralogy. They are • kaolinitic soils • oxidic soils • allophanic soils • smectitic soils Kaolinitic soils are deeply weathered soils with a sand, loamy sand, or sandy loam texture in the surface horizon and a clayey B horizon (20-60%). Silt content is low (< 20%) throughout the profile. Kaolinite (> 90%) is the dominant mineral in the clay fraction. These soils have an effective CEC of less than 12 cmol/kg of clay in the lower B horizon. Kaolinitic soils have a relatively high bulk density, especially in the clayey subsoil horizons (> 1.40 Mg/m3). The structure of the subsoil horizons is usually massive or blocky.


Author(s):  
Halyna Ivanyuk

According to various data, the area of grey forest soils in the world is 94–120.2 million ha, in Ukraine – 4.7–5.5 million ha (about 9 % of the country’s territory). The diversity of conditions for the formation of these soils, discussions about their genesis are the causes of different approaches to the classification of grey forest soils. The history of the classification of grey forest soils is analysed; the most common variants of their classification in Ukraine are presented. Seeking to find approximate equivalents, an attempt to find grey forest soils in the classification systems of different countries (Russia, Moldova, Bulgaria, Romania, Czech Republic, Poland, USA, Canada), as well as in the legend of the FAO-UNESCO map and the WRB has been made. To establish exact analogues of soils practically it is impossible due to different principles of classification’s construction. Modern soil classifications of different countries are as close as possible to WRB and “Soil Taxonomy”. The following names of grey forest soils are identified as the most grounded: light grey forest, grey forest and dark grey podzolic. The following equivalents of the WRB nomenclature (2014) for sub-types of grey forest soils are offered: light grey forest – Albic Luvisols, grey forest – Haplic Luvisols, dark grey podzolic – Luvic Greyzemic Phaeozems. To the names of analogues of these soils with gleyic properties, the qualifier “Gleyic” should be added before the name of the reference soil group. The urgent task for soil scientists of Ukraine is to create a new soil classification that would preserve the acquisitions of genetic soil science but took into account the world trends: the allocation of diagnostic horizons and features that have clearly defined quantitative boundaries. In the new classification, it is proposed to combine the light grey and grey forest soils by a separate group, dark grey podzolic soils to be grouped together in a group with podzolic chernozems. The need for such selection is confirmed by the study of the dark grey soils position in different classification systems of the world, most of which these soils are in the chernozemic type group (Mollisols, Phaeozems and Chernozems). Key words: classification, grey forest soils, Greyzems, Luvisols, Mollisols, Phaeozems.


2020 ◽  
Author(s):  
Amirhossein Hassani ◽  
Adisa Azapagic ◽  
Nima Shokri

&lt;p&gt;Soil salinity is among the major threats affecting the soil fertility, stability and vegetation. It can also accelerate the desertification processes, especially in arid and semi-arid regions. An accurate estimation of the global extent and distribution of the salt-affected soils and their temporal variations is pivotal to our understanding of the salinity-induced land degradation processes and to design effective remediation strategies. In this study, using legacy soil profiles data and a broad set of climatic, topographic, and remotely sensed soil surface and vegetative data, we trained ensembles of classification and regression trees to map the spatio-temporal variation of the soil salinity and sodicity (exchangeable sodium percentage) at the global scale from 1980 to 2018 at a 1 km resolution. The User&amp;#8217;s Accuracies for soil salinity and sodicity classification were 88.05% and 84.65%, respectively. The 2018 map shows that globally &amp;#160;&amp;#820; 944 Mha of the lands are saline (with saturated paste electrical conductivity &gt; 4 ds m&lt;sup&gt;-1&lt;/sup&gt;), while &amp;#160;&amp;#820; 155 Mha can be classified as sodic soils (with sodium exchange percentage &gt; 15%). Our findings and provided dataset show quantitatively how soil salinization is influenced by a broad array of climatic, anthropogenic and hydrologic parameters. Such information is crucial for effective water and land-use management, which is important for maintaining food security in face of future climatic uncertainties. Moreover, our results combined with the quantitative methodology developed in this study will provide us with an opportunity to delineate the role of anthropogenic activities on soil salinization. This information is useful not only for developing predictive models of primary and secondary soil salinization but also for natural resources management and policy makers.&lt;/p&gt;


2008 ◽  
Vol 13 (4) ◽  
pp. 378 ◽  
Author(s):  
L. SLÅNBERG ◽  
L. HYLANDER

Classification of soils according to internationally agreed criteria forms a valuable base for scientifi c and political analyses. The objectives of this study were to evaluate two soil classification systems and relate them to agricultural and environmental concerns, principally phosphorus leakage, by classifying three Swedish, arable soils. The Bjärröd soil was classifi ed as a Rupti-Endogleyic Phaeozem according to the World Reference Base for Soil Resources and as a coarse-loamy, mesic Oxiaquic Hapludoll according to the Soil Taxonomy. Bjelkesta was classified as an Orthieutric Gleysol and a fi ne, frigid, Typic Endoaquept, respectively, and Götala as a Haplic Arenosol and a frigid Typic Udipsamment. We evaluated some changes to the classification systems proposed by Nordic scientists and found the classification of Bjärröd misleading and suggest it being classified as a Cambisol/Inceptisol and that information of the characteristically high base saturation in Bjelkesta and the spodic character in Götala being included in their names. This information is useful for decisions regarding agrarian and environmental management of the soils.;


2018 ◽  
Vol 8 ◽  
Author(s):  
Carlos Alexandre ◽  
Teresa Borralho ◽  
Anabela Durão

Due to its high land productivity, irrigated agriculture has an increasing role in food production. In the Alentejo region (southern Portugal) the irrigated area has grown since the completion of the Alqueva dam in 2002. Climatic change patterns foreseen for the Mediterranean region (more heat extremes, less precipitation and river flow, increasing risk of droughts and decrease in crop yields) are prone to soil salinization and sodification in irrigated areas in the region. The Roxo dam has some of the higher records of water salinity and sodicity in Portugal, which makes the Roxo irrigated area (RIA) a very interesting case study. This paper aimed at two main objectives for the RIA: (i) evaluate soil salinization and sodification, and make spatial predictions of soils susceptibility to these degradation types; (ii) monitor current salinity and sodicity of the water, and simulate the effect of empirical based scenarios of water salinity and sodicity. The RIA (8250 ha) extends ~20 km along the Roxo river (northern Aljustrel), in Cenozoic sedimentary formations. Main soils mapped are: Luvisols (~40%), Fluvisols and Regosols (~20%), Gleysols and Planosols (~20%) and Vertisols (~10%). However, there are only five soil profiles with detailed analytical data from a more recent soil survey with 83 profile descriptions in the RIA and surrounding area. Irrigation water of the Roxo dam and drainage water of the Roxo river were monitored almost monthly during Jul/2014-Nov/2015 and Jun/2016-Jan/2017, for determination of electrical conductivity (EC), sodium adsorption ratio (SAR), and other parameters. Soil salinity was not a significant problem in the RIA but a potential abundance of sodic soils was found that need future confirmation. A qualitative soil salinity index applied to the RIA suggests that soils most susceptible to salinity occur to a much smaller extent when this index is obtained from the soil profile data (approach B) than when it is based on information of the soil map (approach A). During the monitoring periods, both the water of the Roxo dam and of the Roxo river were slight to moderate saline for crop growth, with no restrictions for soil infiltration. The Roxo dam received water from the Alqueva dam for the first time between June and September 2016, and a small, though regular, decrease of the water EC (0.99 to 0.76 dS m<sup>-1</sup>) was observed during the same period. Three scenarios of irrigation water, identified by Low/High EC-SAR (L-L, H-H, L-H) were simulated with the Watsuit model. Low EC water (L-L and L-H) represent wet years and show no risk of soil salinity in the rootzone. However, the risk of waterlogging increases in sodic soils, especially with the scenario (L-H). High EC water (H-H) represents dryer years and results in severe saline conditions in the rootzone. In all three scenarios, prosodic and sodic soils are most sensible to degradation by salinization, sodification or both.


2019 ◽  
Vol 70 (3) ◽  
pp. 184-192
Author(s):  
Cezary Kabała

Abstract The Soil Science Society of Poland has elected chernozem to be the Soil of the Year 2019. Although chernozems cover less than 2% of Poland, they have high importance for agriculture due to their productivity and play a specific scientific role for understanding of soil development and functioning in an environment. Chernozems are also crucial for the reconstruction of Neolithic agriculture development and human impacts on soil and landscape. This introductory paper presents (a) a specific definition of chernozem in Poland, connected with a separate distinction of black earths and colluvial chernozemic soils; (b) a review of the present and former classification schemes for chernozems in Poland and their correlation with international soil classification systems (WRB and Soil Taxonomy); (c) the spatial distribution of chernozems in Poland, their agricultural evaluation and threats for chernozems’ quality and future existence related to intense land use.


2010 ◽  
Vol 59 (1) ◽  
pp. 93-98 ◽  
Author(s):  
M. Fuchs ◽  
A. Gál ◽  
E. Michéli

The soil cover of the world stores more carbon than that present in biomass and in the atmosphere, so the depth and distribution of soil organic matter (SOM) might be important in point of carbon sequestration and climate change mitigation. Texture, among several other factors, plays an important role in the distribution of SOM. Most national and the main international soil classification systems (Soil Taxonomy, World Reference Base for Soil Resources) have a separate unit for high clay content soils on the highest level of classification, as Vertisols. Due to the high swelling clay content, these soils open deep cracks when they are dry. During the process called “pedoturbation”, the high SOM content surface material falls into the cracks, where it accumulates and mixes with subsoil, and enhances the accumulation of SOM in great depth. Although the effect of texture on the stabilization, distribution and properties of SOM have been investigated, only little information is available on SOM distribution in high clay content soils. The objective of the present study was to analyze the vertical distribution of SOM in high clay content soils of Hungary. Our results, based on the investigations of the Hungarian TIM database supported the hypothesis that high clay content soils store significantly more SOM and in greater depth than other soils under similar climatic conditions.


Author(s):  
Anne N. Karuma

Four soil profiles (Yala, Galana, Baringo and Bondo) that represent different ecology, physiography and pedological variability were described to study their morphology, soil physico-chemical characteristics and to classify them using two internationally known soil classification systems. Soil samples were taken from designated pedogenic horizons for physical and chemical analysis in the laboratory. These soils are deep to very deep (> 110 cm) and well-drained except in Galana which was imperfectly drained, with varying textures. In Bondo, the soils are moderately acid (pH 5.6 – 6). In Baringo, the soil profile is acidic (< 5.0) while in Galana moderately alkaline (pH 7.3 - 8.3) and Yala soils are moderate to strongly acid (5.1 - 5.7). The organic carbon (< 0.6%) and organic matter levels (1 – 2%) were low and decreased down the profiles in all. The soils have low to moderate fertility. The base saturation of the studied soils is rated as very high (> 80%) in Galana and Baringo and low (< 50%) in Yala and Bondo pedons. The soils are non-saline as indicated by the low values of electrical conductivity (< 1.7dS/m) in the pedons. The soils are non-sodic (ESP < 6%) in Bondo and Yala, however moderately sodic (ESP 11-15%) in Galana and Baringo. Ochric horizon was the main diagnostic epipedon while ferralic, argillic and cambic horizons were the diagnostic B horizons. According to USDA Soil Taxonomy, the soils were classified as Typic Haplustox (Yala), Typic Haplocalcids (Galana), Typic Eutrudepts (Baringo) and Plinthic Haplustults (Bondo) corresponding to Haplic Ferralsols, Luvic Calcisols, Haplic Cambisol and Cutanic Plinthic Acrisols in the WRB for Soil Resources. The general fertility of the soils of the areas is discussed highlighting their potentials and constraints.


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