Topic
Sodic soil
About: Sodic soil is a research topic. Over the lifetime, 1127 publications have been published within this topic receiving 18417 citations.
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Papers
TL;DR: In this paper, an account of clay behavior in relation to Na and electrolyte concentration is presented before exploring these new realms of sodicity, from which it emerges that the effects of Na are manifested in measurable and often sizeable proportions down to very low levels far below those previously used to define sodic soils.
Abstract: There are large areas of the world where soils are adversely affected by the presence of sodium (Na) as an exchangeable cation. Unlike their saline counterparts which are more extensive, sodic soils have received less attention in the literature. There has been considerable disagreement concerning the definition of sodicity, owing largely to the fact that many experiments used in the development of definitions did not account for the presence of salts in the water used to measure hydraulic properties. These problems are discussed and the conclusion is reached that a single simple definition is no longer possible. This problem is further exacerbated by the fact that many soils which would never have fallen into a previously defined sodic category, do in fact exhibit sodic properties. The major focus of this account of sodicity will therefore be the soils which contain relatively low levels of exchangeable Na. As such soils are widespread in both humid and subhumid areas of the world and are responsible for the production of a large proportion of the world cereal crop, they deserve special attention. Because swelling and dispersion are the primary processes responsible for the degradation of soil physical properties in the presence of Na, an account of clay behaviour in relation to Na and electrolyte concentration is presented before exploring these new realms of sodicity. Pure clay systems are not always suitable for use as models of soil behaviour in terms of dispersion and flocculation. However, as far as swelling is concerned, the correspondence is much better. Nevertheless, the effects of the exchangeable cations on dispersion are predictable albeit usually only qualitatively. This is partly due to the phenomenon of 'demixing' in which the cations are not distributed over all surfaces in the same proportions. The effects of Na and electrolyte concentration in relation to hydraulic conductivity, infiltration, crusting, runoff, erosion and hardsetting are discussed from which it emerges that the effects of Na are manifested in measurable and often sizeable proportions down to very low levels far below those previously used to define sodic soils. The primary processes responsible for physical degradation are swelling at relatively high levels and clay dispersion throughout the range of exchangeable Na percentage (ESP). Provided that the total electrolyte concentration (TEC) is below the critical flocculation concentration (CFC), clays will disperse spontaneously at high ESP values, whereas at lower ESP levels, inputs of energy are required for dispersion. The TEC of the ambient solution, because of its effects in promoting clay flocculation, is crucial in determining soil physical behaviour.
597 citations
TL;DR: In this paper, a classification of sodic soils based on sodium adsorption ratio, pH and electrolyte conductivity is outlined to form the necessary bases for practical solutions in the long term and to define areas for research.
Abstract: Sodic soils are widespread in Australia reflecting the predominance of sodium chloride in groundwaters and soil solutions. Sodic soils are subject to severe structural degradation and restrict plant performance through poor soil-water and soil-air relations. Sodicity is shown to be a latent problem in saline-sodic soils where deleterious effects are evident only after leaching profiles free of salts. A classification of sodic soils based on sodium adsorption ratio, pH and electrolyte conductivity is outlined. Current understanding of the processes and the component mechanisms of sodic soil behaviour are integrated to form the necessary bases for practical solutions in the long term and to define areas for research. The principles of organic and biological amelioration of sodicity, as alternatives to costly inorganic amendments, are discussed.
469 citations
TL;DR: In this article, the authors reviewed soil processes that commonly occur in saline and sodic soils, and their effect on C stocks and fluxes to identify the key issues involved in the decomposition of soil organic matter and soil aggregation processes which need to be addressed to fully understand C dynamics in salt-affected soils.
Abstract: Soil salinity (high levels of water-soluble salt) and sodicity (high levels of exchangeable sodium), called collectively salt-affected soils, affect approximately 932 million ha of land globally. Saline and sodic landscapes are subjected to modified hydrologic processes which can impact upon soil chemistry, carbon and nutrient cycling, and organic matter decomposition. The soil organic carbon (SOC) pool is the largest terrestrial carbon pool, with the level of SOC an important measure of a soil's health. Because the SOC pool is dependent on inputs from vegetation, the effects of salinity and sodicity on plant health adversely impacts upon SOC stocks in salt-affected areas, generally leading to less SOC. Saline and sodic soils are subjected to a number of opposing processes which affect the soil microbial biomass and microbial activity, changing CO fluxes and the nature and delivery of nutrients to vegetation. Sodic soils compound SOC loss by increasing dispersion of aggregates, which increases SOC mineralisation, and increasing bulk density which restricts access to substrate for mineralisation. Saline conditions can increase the decomposability of soil organic matter but also restrict access to substrates due to flocculation of aggregates as a result of high concentrations of soluble salts. Saline and sodic soils usually contain carbonates, which complicates the carbon (C) dynamics. This paper reviews soil processes that commonly occur in saline and sodic soils, and their effect on C stocks and fluxes to identify the key issues involved in the decomposition of soil organic matter and soil aggregation processes which need to be addressed to fully understand C dynamics in salt-affected soils. © 2009 The Authors. Journal compilation
401 citations
TL;DR: In this paper, the influence of different combinations of tillage and residue management on carbon stabilization in different sized soil aggregates and also on crop yield after 5 years of continuous rice-wheat cropping system on a sandy loam reclaimed sodic soil of north India.
Abstract: Conservation tillage and residue management are the options for enhancing soil organic carbon stabilization by improving soil aggregation in tropical soils. We studied the influence of different combinations of tillage and residue management on carbon stabilization in different sized soil aggregates and also on crop yield after 5 years of continuous rice–wheat cropping system on a sandy loam reclaimed sodic soil of north India. Compared to conventional tillage, water stable macroaggregates in conservation tillage (reduced and zero-tillage) in wheat coupled with direct seeded rice (DSR) was increased by 50.13% and water stable microaggregates of the later decreased by 10.1% in surface soil. Residue incorporation caused a significant increment of 15.65% in total water stable aggregates in surface soil (0–15 cm) and 7.53% in sub-surface soil (15–30 cm). In surface soil, the maximum (19.2%) and minimum (8.9%) proportion of total aggregated carbon was retained with >2 mm and 0.1–0.05 mm size fractions, respectively. DSR combined with zero tillage in wheat along with residue retention (T6) had the highest capability to hold the organic carbon in surface (11.57 g kg−1 soil aggregates) with the highest stratification ratio of SOC (1.5). Moreover, it could show the highest carbon preservation capacity (CPC) of coarse macro and mesoaggregates. A considerable proportion of the total SOC was found to be captured by the macroaggregates (>2–0.25 mm) under both surface (67.1%) and sub-surface layers (66.7%) leaving rest amount in microaggregates and ‘silt + clay’ sized particles. From our study, it has been proved that DSR with zero tillage in wheat (with residue) treatment (T6) has the highest potential to secure sustainable yield increment (8.3%) and good soil health by improving soil aggregation (53.8%) and SOC sequestration (33.6%) with respect to the conventional tillage with transplanted rice (T1) after five years of continuous rice–wheat cropping in sandy loam reclaimed sodic soil of hot semi-arid Indian sub-continent.
300 citations
TL;DR: The economic, social, and environmental impacts of different soil-amelioration options must also be considered as discussed by the authors, and a holistic approach is therefore needed to consider the cost and availability of the inputs needed for amelioration, the soil depth, the level to which sodicity needs to be reduced to allow cropping, the volume and quality of drainage water generated during ameling, and the options available for drainage-water disposal or reuse.
Abstract: Currently at least 20 per cent of the world's irrigated land is salt-affected. However, projections of global population growth, and of an increased demand for food and fibre, suggest that larger areas of salt-affected soil will need to be cropped in the future. About 60 per cent of salt-affected soils are sodic, and much of this land is farmed by smallholders. Ameliorating such soils requires the application of a source of calcium (Ca2+), which replaces excess sodium (Na+) at the cation exchange sites. The displaced Na+ is then leached from the root zone through excess irrigation, a process that requires adequate flows of water through the soil. However, it must now be recognized that we can no longer conduct sodic soil amelioration and management solely with the aim of achieving high levels of crop productivity. The economic, social, and environmental impacts of different soil-amelioration options must also be considered. A holistic approach is therefore needed. This should consider the cost and availability of the inputs needed for amelioration, the soil depth, the level to which sodicity needs to be reduced to allow cropping, the volume and quality of drainage water generated during amelioration, and the options available for drainage-water disposal or reuse. The quality and cost of water available for post-amelioration crops, and the economic value of the crops grown during and after amelioration should also be taken into account, as should farmers' livelihoods, the environmental implications of amelioration (such as carbon sequestration), and the long-term sustainable use of the ameliorated site (in terms of productivity and market value). Consideration of these factors, with the participation of key stakeholders, could sustainably improve sodic soil productivity and help to transform such soils into a useful economic resource. Such an approach would also aid environmental conservation, by minimizing the chances of secondary sodicity developing in soils, particularly under irrigated agriculture. Copyright © 2006 John Wiley & Sons, Ltd.
242 citations
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Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 15 |
| 2024 | 45 |
| 2023 | 38 |
| 2022 | 95 |
| 2021 | 44 |
| 2020 | 51 |