Soil - Soil biodiversity

Title

Resistance and resilience of the soil microbial biomass to severe drought in semiarid soils: The importance of organic amendments

Reference

Applied Soil Ecology
Volume 50, October 2011, Pages 27-36

Author(s)

S. Hueso,  T. Hernández, C. García

Study type

Peer Review Journal

Abstract

Changes in mean global air temperature and precipitation patterns, leading to longer drought periods and more extremely dry years, are predicted. The objective of this work was to assess whether a long period of severe drought can affect the growth and activity of the microbiota of a semiarid soil, as well as the effect of organic amendments on soil resistance and resilience to this severe drought. A soil incubation experiment was carried out over 60 days, under controlled conditions (25 °C and 60/80% day/night relative humidity), with two treatments: unamended (US) and amended (AS) with manure compost (100 t ha−1). Two levels of irrigation were imposed: (1) well-watered (MUS and MAS), the soil being maintained at 60% of its water-holding capacity (WHC), and (2) dry, without irrigation (DUS and DAS). Then, a single level of irrigation was established for 37 days, dry soils being irrigated under the same conditions than well-watered soils, to assess soil resilience to this period of drought. Under well-watered conditions, the soil water-soluble nitrogen contents were 73 and 88% higher, the microbial biomass carbon 63 and 48% higher, alkaline phosphomonoesterase activity 46 and 32% higher, β-glucosidase activity 16 and 25% higher and urease activity 30 and 19% higher for the US and AS treatments, respectively, compared with the dry conditions at the end of the experimental period. Furthermore, the organic amendment helped the soil to retain moisture and encouraged the growth and activity of soil microbial populations. However, a 2-month drought seems insufficient to destroy the native microbial biomass in the arid soil used in this study, indicating that it is well adapted to adverse climate conditions. Thus, microbiological and biochemical parameters experienced a rapid recovery after soil rewetting, DUS and DAS showing values similar to MUS and MAS, after rewetting, highlighting the resilience of this type of soil against drought stress.

Policy theme(s)

Agriculture >> Agricultural management >> Soil management
Climate change and energy >> Climate change adaptation >> Agricultural adaptation         
Soil >> Soil biodiversity

Keywords

Drought; Rewetting; Semiarid soils; Organic amendments; Microbiological properties; Soil enzymes

Entry Source:

Shortlisted for Science for Environment Policy News Alert

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http://www.sciencedirect.com/science/article/pii/S0929139311001582

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shuesomartos@yahoo.es

Title

Toxicity to Eisenia andrei and Folsomia candida of a metal mixture applied to soil directly or via an organic matrix

Reference

 Ecotoxicology and Environmental Safety
Volume 74, Issue 6, September 2011, Pages 1715-1720

Author(s)

T. Natal-da-Luz, G. Ojeda, J. Pratas, C.A.M. Van Gestel, J.P. Sousa

Study type

Peer Review Journal

Abstract

Regulatory limits for chemicals and ecological risk assessment are usually based on the effects of single compounds, not taking into account mixture effects. The ecotoxicity of metal-contaminated sludge may, however, not only be due to its metal content. Both the sludge matrix and the presence of other toxicants may mitigate or promote metal toxicity. To test this assumption, the toxicity of soils recently amended with an industrial sludge predominantly contaminated with chromium, copper, nickel, and zinc and soils freshly spiked with the same mixture of metals was evaluated through earthworm (Eisenia andrei) and collembolan (Folsomia candida) reproduction tests. The sludge was less toxic than the spiked metal mixture for E. andrei but more toxic for F. candida. Results obtained for the earthworms suggest a decrease in metal bioavailability promoted by the high organic matter content of the sludge. The higher toxicity of the sludge for F. candida was probably due to the additive toxic effect of other pollutants.

Policy theme(s)

Chemicals >> Impacts >> Mixture toxicity
Soil >> Soil biodiversity
Soil >> Threats to soil >> Soil contamination

Keywords

Toxic units; Joint effect; Metal-contaminated sludge; Mixture toxicity

Entry Source:

Shortlisted for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

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http://www.sciencedirect.com/science/article/pii/S014765131100162X
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tiagonluz@iav.uc.pt

Title

Comparing the sensitivity of soil invertebrates to pesticides with that of Eisenia fetida

Reference

Chemosphere doi:10.1016/j.chemosphere.2011.07.032

Author(s)

Michiel A. Daam, Sara Leitão, Maria José Cerejeira, J. Paulo Sousa

Study type

Peer Review Journal

Abstract

The sole routine testing of the standard earthworm Eisenia fetida for the terrestrial risk assessment of pesticides has been under much debate since other soil invertebrates may be more sensitive than this standard test species. However, the very low availability of laboratory toxicity data for taxa other than E. fetida has greatly hampered sensitivity comparisons. In the present study, the relative tolerance (Trel) approach was used to enable comparing toxicity thresholds obtained from the US-EPA ECOTOX database, for main terrestrial taxonomic groups and pesticidal types of action (insecticides, fungicides, herbicides, and other) separately. Analyses confirmed previously reported lower and higher sensitivity of collembolans to fungicides and insecticides, respectively. However, various other discrepancies in susceptibility relative to E. fetida were encountered as indicated by species sensitivity distributions and/or calculated 95% confidence intervals of Trel values. Arachnids and isopods were found to be more sensitive to insecticides, and nematodes to fungicides, as compared to E. fetida. Implications of study findings for the terrestrial risk assessment of pesticides are discussed.

Policy theme(s)

Agriculture >> Agricultural pollution >> Pesticide pollution
Chemicals >> Pollutants/hazardous substances >> Pesticides
Chemicals >> Impacts >> Ecosystem impacts
Soil >> Soil biodiversity

Keywords

Environmental risk assessment; Soil invertebrates; Eisenia fetida; Relative tolerance; Terrestrial ecotoxicology

Entry Source:

Shortlisted for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

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http://www.sciencedirect.com/science/article/pii/S004565351100868X
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madaam@utl.pt

Title

Diversity and Activity of Free-Living Nitrogen-Fixing Bacteria

Reference

Applied and Environmental Microbiology, 2010; 77 (3): 911
DOI: 10.1128/AEM.01250-10

Author(s)

C. H. Orr, A. James, C. Leifert, J. M. Cooper, S. P. Cummings.

Study type

Peer Review Journal

Abstract

Agricultural soils are heterogeneous environments in which conditions affecting microbial growth and diversity fluctuate widely in space and time. In this study, the molecular ecology of the total bacterial and free-living nitrogen-fixing communities in soils from the Nafferton Factorial Systems Comparison (NFSC) study in northeast England were examined. The field experiment was factorial in design, with organic versus conventional crop rotation, crop protection, and fertility management factors. Soils were sampled on three dates (March, June, and September) in 2007. Total RNA was extracted from all soil samples and reverse transcribed. Denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) were used to analyze nifH and 16S rRNA genes in order to study free-living diazotrophs and the total bacterial community, respectively. Crop rotation was shown to have a significant effect on total bacterial diversity (and that of free-living N fixers) (P 0.001). On all three dates, nifH activity was higher in the conventional crop rotation. In contrast, qPCR analysis of free-living N fixers indicated significantly higher levels of activity in conventionally fertilized plots in June (P = 0.0324) and in plots with organic crop protection in September (P = 0.0143). To our knowledge, the effects of organic and conventional farming systems on free-living diazotrophs have never been studied. An increased understanding of the impacts of management practices on free-living N fixers could allow modifications in soil management practices to optimize the activity of these organisms.

Policy theme(s)

Agriculture>> Agricultural management>>Soil management
Agriculture>>Agricultural management>>Organic farming
Soil>>Soil biodiversity

Keywords

N/A

Entry Source:

N/A

Referred to in EC doc:

Shortlisted for Science for Environment Policy News Alert

View this study at:

http://aem.asm.org/cgi/content/abstract/77/3/911 
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stephen.cummings@unn.ac.uk

Title

Land application of organic waste - Effects on the soil ecosystem

Reference

Applied Energy
Volume 88, Issue 6, June 2011, Pages 2210-2218

Author(s)

M. Odlare, V. Arthurso, M. Pell, K. Svensson, E. Nehrenheim and J. Abubaker

Study type

Peer Review Journal

Abstract

Growing populations and the increasing use of existing resources has led to growth in organic waste emissions. Therefore, a sustainable approach to managing this waste has become a major concern in densely populated areas. Biological treatment is an efficient method for reducing the amount of organic waste, and for producing energy. A large number of biogas plants and compost facilities that use organic waste as a substrate for electricity and fuel production are being built around the world. The biological treatment process in these plants produces large amounts of organic waste, and there is therefore a growing need to find a sustainable use for this material. Organic waste, such as biogas residues and compost can be a valuable fertilizer for agricultural soils. They can serve as a source of plant nutrients and can also improve soil structure and water holding capacity. However, as organic residues are known to contain both heavy metals and organic contaminants there is a need for long term field experiments to ensure that soil and plant quality is maintained. In order to investigate the potential risks and benefits of using organic waste in agriculture, an 8 year field experiment was established in central Sweden. Under realistic conditions, compost and biogas residues from source-separated household waste were compared with traditional mineral fertilizer. We examined crop yield and soil chemical and microbiological properties. The main conclusion from the field experiment was that biogas residues resulted in crop yields almost as high as the mineral fertilizer NPS. In addition, several important soil microbiological properties, such as substrate induced respiration, potential ammonium oxidation and nitrogen mineralization were improved after application of both biogas residues and compost. Moreover, no negative effects could be detected from using either of the organic wastes. In particular the genetic structure of the soil bacterial community appeared to resist changes caused by addition of organic waste.

Policy theme(s)

Agriculture >> Agricultural management >> Soil management
Soil >> Soil biodiversity
Soil >> Threats to soil >> Soil contamination

Keywords

Microbial soil properties, Organic waste, Soil fertility, Soil properties

Entry Source:

Shortlisted for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://www.sciencedirect.com/science/article/pii/S0306261910005635
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monica.odlare@mdh.se

Title

Assessing soil quality under intensive cultivation and tree orchards in Southern Italy

Reference

Applied Soil Ecology
Volume 47, Issue 3, March 2011, Pages 184-194

Author(s)

Giuliano Bonanomi, Rosaria D'Ascoli, Vincenzo Antignani, Manuela Capodilupo, Lucia Cozzolino, Rossana Marzaioli, Gerardo Puopolo, Flora A. Rutigliano, Rosalia Scelza, Riccardo Scotti, Maria A. Rao and Astolfo Zoina

Study type

Peer Review Journal

Abstract

Concerns about groundwater contamination as well as pesticide residues in food and soil have fuelled vigorous debates about the sustainability of chemical-intensive agriculture. Search has been prompted for agronomic strategies with lower environmental hazards. In this multidisciplinary study we compared the characteristics of soils from 20 agricultural farms selected in five geographical areas of Southern Italy with different soil types. In each farm, fields with management regime classified as high-input (HIMR, intensive cultivation under plastic tunnels) or low-input (LIMR, tree orchards) were selected. Soil samples were analyzed for 31 parameters including physical and chemical properties (bulk density, water holding capacity, texture, pH, limestone, electrical conductivity, organic C to a depth of 0-20 and 20-40 cm, total N, P2O5, Ca2+, Mg2+, K+, Na+, cation exchange capacity), enzymatic activities (dehydrogenase, arylsulphatase, β-glucosidase, phosphatase and urease) and microbiological features (potential respiration, functional diversity of microbial populations by BIOLOG EcoPlates™, microbial biomass, fungal mycelium, culturable actinomycetes, bacteria and fungi, pseudomonads and bacterial species richness by 16S rDNA-DGGE). Finally, a soil bioassay was performed in order to evaluate the plant growth of a biotest plant (Lactuca sativa) and soil suppressiveness of the Rhizoctonia solani-L. sativa pathosystem.
Results showed that many soil properties were influenced by management regime more than by the sampling area. Compared to LIMR, HIMR soils consistently had reduced soil organic C (-24%), enzymatic activities, microbial biomass and fungal mycelium (-40% and -18%, respectively), functional diversity (-18%) and bacterial species richness (-14%). On the contrary, the same soils showed a remarkable increase in the values of the parameters related to the mineral soil fraction (electrical conductivity +370%; P2O5 +72%; Na+ +86%). Management regime did not affect cation exchange capacity, pH, limestone and soil texture. The lettuce bioassay showed a higher plant growth (+17%) in the LIMR compared to HIMR soils, despite the lower content of mineral nutrients. Suppression of R. solani was not influenced by management regime, but significant differences were recorded among farms. Differences among the assessed soil parameters indicate a trend of soil quality deterioration under the high-input management regime.

Policy theme(s)

Agriculture >> Agricultural management >> Soil management
Soil >> Soil biodiversity

Keywords

Agricultural management, Soil chemical and biological properties, Enzymatic activities, Microbial diversity, Rhizoctonia solani

Entry Source:

Selected for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

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http://www.sciencedirect.com/science/article/pii/S0929139310002647
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giuliano.bonanomi@unina.it

Title

Influences of non-herbaceous biochar on arbuscular mycorrhizal fungal abundances in roots and soils: Results from growth-chamber and field experiments

Reference

Applied Soil Ecology
Volume 46, Issue 3, November 2010, Pages 450-456

Author(s)

Daniel D. Warnock, Daniel L. Mummey, Brooke McBride, Julie Major, Johannes Lehmann and Matthias C. Rillig,

Study type

Peer Review Journal

Abstract

Biochar holds promise as an amendment for soil quality improvement and sequestration of atmospheric carbon dioxide. However, knowledge of how biochar influences soil properties, especially soil microorganisms, is limited. Three separate studies were conducted, with two studies using Plantago lanceolata as the AMF hosting plant, and a third being conducted in the field. Each of the three studies employed a different soil type. Furthermore, a total of five different biochars, and ten different biochar application rates, were used across the three experiments. All experiments had the goal to examine biochar influences on arbuscular mycorrhizal fungal (AMF) abundance in roots and AMF abundance (hyphal lengths) in soils. AMF abundance was either decreased or remained unchanged across all biochar treatments. When AMF abundances decreased, significant changes in soil properties, primarily in soil P availability, were observed. Application of large quantities (2.0% and 4.0%, w/w) of a lodgepole pine biochar, led to significant declines in AMF abundance in roots of 58% and 73% respectively, but not in soils. These declines in AMF abundance were accompanied by significant declines (28% and 34%) in soil P availability. After addition of a peanut shell biochar produced at 360 °C, P increased by 101% while AMF root colonization and extraradical hyphal lengths deceased by 74% and 95% respectively. Field application of mango wood biochar at rates of 23.2 and 116.1 t C ha−1 increased P availabilities by 163% and 208% respectively and decreased AMF abundances in soils by 43% and 77%. These findings may have implications for soil management where the goal is to increase the services provided by AMF.

Policy theme(s)

Agriculture >> Agricultural management >> Soil management
Soil >> Soil biodiversity

Keywords

Arbuscular mycorrhizal fungi, Root colonization, Extraradical hyphae, Biochar, Black carbon

Entry Source:

Shortlisted for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://www.sciencedirect.com/science/article/pii/S0929139310001654
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Contact the study author at:

matthias.rillig@fu-berlin.de