Microbial biomass and activity in salt affected soils under arid conditions
TL;DR: The results indicate that higher salinity resulted in a smaller, more stressed microbial community which was less metabolically efficient, and suggest that salinity is a stressful environment for soil microorganisms.
About: This article is published in Applied Soil Ecology.The article was published on 2007-02-01. It has received 354 citations till now. The article focuses on the topics: Soil salinity & Salinity.
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TL;DR: In this paper, the effects of soil salinity and water content on microbes are discussed to guide future research into management of saline soils, which is important for crop production, sustainable land use and rehabilitation of saline soil.
361 citations
TL;DR: A review of the available research on how salt affects decomposer microbial communities and carbon cycling in soil can be found in this paper, where the authors provide a brief overview and qualification of widely applied methods to assess microorganisms in soil to date.
Abstract: Salinization of soil is recognised as one of the most pressing environmental challenges to resolve for the next century. We here conduct a synoptic review of the available research on how salt affects decomposer microbial communities and carbon (C) cycling in soil. After summarizing known physiological responses of microorganisms to salinity, we provide a brief overview and qualification of a selection of widely applied methods to assess microorganisms in soil to date. The dominant approaches to characterise microbial responses to salt exposure have so far been microbial biomass and respiration measurements. We compile datasets from a selection of studies and find that (1) microbial biomass-carbon (C) per C held in soil organic matter shows no consistent pattern with long-term (field gradients) or short-term (laboratory additions) soil salinity level, and (2) respiration per soil organic C is substantially inhibited by higher salt concentrations in soil, and consistently so for both short-term and long-term salinity levels. Patterns that emerge from extra-cellular enzyme assessments are more difficult to generalize, and appear to vary with the enzyme studied, and its context. Growth based assessments of microbial responses to salinization are largely lacking. Relating the established responses of microbial respiration to that of growth could provide an estimate for how the microbial C-use efficiency would be affected by salt exposure. This would be a valuable predictor for changes in soil C sequestration. A few studies have investigated the connection between microbial tolerance to salt and the soil salinity levels, but so far results have not been conclusive. We predict that more systematic inquiries including comprehensive ranges of soil salinities will substantiate a connection between soil salinity and microbial tolerance to salt. This would confirm that salinity has a direct effect on the composition of microbial communities. While salt has been identified as one of the most powerful environmental factors to structure microbial communities in aquatic environments, no up-to-date sequence based assessments currently exist from soil. Filling this gap should be a research priority. Moreover, linking sequencing based assessments of microbial communities to their tolerance to salt would have the potential to yield biomarker sets of microbial sequences. This could provide predictive power for, e.g., the sensitivity of agricultural soils to salt exposure, and, as such, a useful tool for soil resource management. We conclude that salt exposure has a powerful influence on soil microbial communities and processes. In addition to being one of the most pressing agricultural problems to solve, this influence could also be used as an experimental probe to better understand how microorganisms control the biogeochemistry in soil. (C) 2014 Elsevier Ltd. All rights reserved. (Less)
336 citations
TL;DR: In this paper, the authors present a literature review that addresses the effects, both positive and negative, of wastewater use in agriculture, emphasizing the effects on the soil environment, and reveal that agricultural reuse significantly affects soil texture properties, while also causing possible alterations of the biomass and microbiota.
Abstract: For centuries, wastewater has been improperly used in agriculture, presenting potential risks to public health and the environment. In the context of scientific development, and confronted by an increasing water crisis, wastewater reuse merits consideration because the practice helps decrease water use pressure and moderates water pollution. Thus, this article presents a literature review that addresses the effects, both positive and negative, of wastewater use in agriculture, emphasizing the effects on the soil environment. The literature review reveals that, until the 1990s, research studies promoted the use of wastewater for irrigation purposes from a treatment approach, while proposing “end of pipe” conventional solutions. However, more recent research studies (2012–2016) reveal that agricultural reuse significantly affects soil texture properties, while also causing possible alterations of the biomass and microbiota. In addition, research in this period has been oriented to the quantitative evaluation of microbiological risk.
275 citations
Cites background from "Microbial biomass and activity in s..."
...Their results suggest that higher salinity content metabolically stresses soil microbiota [113]....
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TL;DR: In this paper, chemical, physical, and biological problems of salt-affected soils and different reclamation methods applied to rehabilitate these soils are discussed with a focus on biochar application as a potential new approach to increase the C content and improve soil properties.
Abstract: This paper reviews chemical, physical, and biological problems of salt-affected soils and different reclamation methods applied to rehabilitate these soils. Methods to increase C stocks in these lands are discussed with a focus on biochar application as a potential new approach to not only to increase the C content but also to improve soil properties. Gaps in research knowledge in this field are then identified. Given the concern on the continued worldwide expansion of salt-affected lands and the focus on C sequestration processes, this review has evaluated current knowledge on salt-affected soils and their remediation with organic materials and plants. The review of the published literature has highlighted important gaps in knowledge, which limit our current understanding of rehabilitation of salt-affected soils with organic amendments specially biochar and the associated carbon dynamic. Knowledge about application of biochar in salt-affected soils is scant, and to date, most studies have evaluated biochar use only in nonsalt-affected soils.
247 citations
Cites background from "Microbial biomass and activity in s..."
...Similarly, Yuan et al. (2007) observed that with increasing salinity, a shift in soil microbial community takes place, with lower metabolisms, which can be an adaptive mechanism to reduce salt stress....
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TL;DR: In this paper, a review of the current knowledge about the effects of soil salinization and sodication on microbial and enzyme activities and identify research gaps for future research is presented.
Abstract: Salinization and sodication are abiotic soil factors, important hazards to soil fertility and consequently affect the crop production. Soil salinization is of great concern for irrigated agriculture in arid and semi-arid regions of the world; sodicity is characterized by an excessively high concentration of sodium (Na) in their cation exchange system. In recent times, attention has been turned to study the impacts of these factors (salinity and sodicity) on soil microbial activities. Microbial activities play central role in degradation and decomposition of soil organic matter, mineralization of nutrients and stabilization of soil aggregates. To understand the ecology of soil system, therefore, it is important to be conversant with the soil microbial activities, which show quick response to little change in the soil environment. Microbial activities (generally measured as C–N dynamics, soil respiration–basal respiration, or CO2 emission), microbial abundance, microbial biomass, quotients (microbial and metabolic) and microbial community structure, and soil enzymes have been considered as potential indicators to assess the severity of the land degradation and the effectiveness of land use management. Therefore, it is important to synthesize the available information regarding microbial activities in use and management of salt-affected soils. The reclamation and management of such soils and their physico-chemical properties have been reviewed well in the literature. In this review, an attempt has been made to compile the current knowledge about the effects of soil salinization and sodication on microbial and enzyme activities and identify research gaps for future research. Copyright © 2015 John Wiley & Sons, Ltd.
202 citations
References
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01 Jan 1982
14,888 citations
TL;DR: In this paper, the effects of fumigation on organic C extractable by 0.5 m K2SO4 were examined in a contrasting range of soils and it was shown that both ATP and organic C rendered decomposable by CHCl3 came from the soil microbial biomass.
Abstract: The effects of fumigation on organic C extractable by 0.5 M K2SO4 were examined in a contrasting range of soils. EC (the difference between organic C extracted by 0.5 M K2SO4 from fumigated and non-fumigated soil) was about 70% of FC (the flush of CO2-C caused by fumigation during a 10 day incubation), meaned for ten soils. There was a close relationship between microbial biomass C, measured by fumigation-incubation (from the relationship Biomass C = FC/0.45) and EC given by the equation: Biomass C = (2.64 ± 0.060) EC that accounted for 99.2% of the variance in the data. This relationship held over a wide range of soil pH (3.9–8.0).
ATP and microbial biomass N concentrations were measured in four of the soils. The (ATP)(EC) ratios were very similar in the four soils, suggesting that both ATP and the organic C rendered decomposable by CHCl3 came from the soil microbial biomass. The C:N ratio of the biomass in a strongly acid (pH 4.2) soil was greater (9.4) than in the three less-acid soils (mean C:N ratio 5.1).
We propose that the organic C rendered extractable to 0.5 m K2SO4 after a 24 h CHCl3-fumigation (EC) comes from the cells of the microbial biomass and can be used to estimate soil microbial biomass C in both neutral and acid soils.
9,975 citations
TL;DR: In this paper, a direct extraction method for measuring soil microbial biomass nitrogen (biomass N) is described, which is based on CHC13 fumigation, followed by immediate extraction with 0.5 M K2SO4 and measurement of total N released by CHC 13 in the soil extracts.
Abstract: A new “direct extraction” method for measuring soil microbial biomass nitrogen (biomass N) is described. The new method (fumigation-extraction) is based on CHC13 fumigation, followed by immediate extraction with 0.5 M K2SO4 and measurement of total N released by CHC13 in the soil extracts. The amounts of NH4-N and total N extracted by K2SO4 immediately after fumigation increased with fumigation time up to 5 days. Total N released by CHC13 after 1 day fumigation (1 day CHC13-N) and after 5 days fumigation (5 day CHC13-N) were positively correlated with the flush of mineral N (FN) in 37 soils that had been fumigated, the fumigant removed and the soils incubated for 10 days (fumigation-incubation). The regression equations were 1 day CHC13-N = (0.79 ± 0.022) FN and 5 day CHC13-N = (1.01 ± 0.027) FN, both regressions accounting for 92% of the variance in the data. In field soils previously treated with 15N-labelled fertilizer, the amounts of labelled N, measured after fumigation-extraction, were very similar to the amounts of labelled N mineralized during fumigation-incubation; both were about 4 times as heavily labelled as the soil N as a whole. These results suggest that fumigation-extraction and fumigation-incubation both measure the same fraction of the soil organic N (probably the cytoplasmic component of the soil microbial biomass) and that measurement of the total N released by CHC13 fumigation for 24 h provides a rapid method for measuring biomass N.
4,631 citations
TL;DR: In this paper, the authors present an overview of the role of soil in the formation and evolution of Soil Microbiology and Biochemistry in Perspective, as well as its relationship with Soil Organisms.
Abstract: Soil Microbiology and Biochemistry in Perspective. Soil as a Habitat for Organisms and Their Reactions. Methods for Studying Soil Organisms. Components of the Soil Biota. Occurrence and Distribution of Soil Organisms. Carbon Cycling and Soil Organic Matter. Dynamics of Residue Decomposition and Soil Organic Matter Turnover. Ammonification and Nitrification. The Fate of Nitrates. Closing the Nitrogen Cycle: Return of Nitrogen to the Soil. Mycorrhizal Relationships. The Commercialization of Organisms. Phosphorus Transformations. Sulfur Transformations in Soil. Microbial Transformations of Metal. Chapter References and Suggested Reading. Subject Index.
3,190 citations
Book•
21 Jan 1996
TL;DR: In this article, the authors present an overview of the role of soil in the formation and evolution of Soil Microbiology and Biochemistry in Perspective, as well as its relationship with Soil Organisms.
Abstract: Soil Microbiology and Biochemistry in Perspective. Soil as a Habitat for Organisms and Their Reactions. Methods for Studying Soil Organisms. Components of the Soil Biota. Occurrence and Distribution of Soil Organisms. Carbon Cycling and Soil Organic Matter. Dynamics of Residue Decomposition and Soil Organic Matter Turnover. Ammonification and Nitrification. The Fate of Nitrates. Closing the Nitrogen Cycle: Return of Nitrogen to the Soil. Mycorrhizal Relationships. The Commercialization of Organisms. Phosphorus Transformations. Sulfur Transformations in Soil. Microbial Transformations of Metal. Chapter References and Suggested Reading. Subject Index.
2,974 citations