ORCID Profile
0000-0001-6808-0244
Current Organisation
University of Adelaide
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Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 06-05-2013
Publisher: Elsevier BV
Date: 12-2018
Publisher: Springer Science and Business Media LLC
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 26-11-2016
Publisher: Wiley
Date: 20-07-2011
Publisher: Elsevier BV
Date: 06-2016
Publisher: Elsevier BV
Date: 05-2014
Publisher: Wiley
Date: 06-2005
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.SCITOTENV.2013.01.010
Abstract: Sorption is a very important factor in stabilization of dissolved organic carbon (DOC) in soils and thus C sequestration. Saline soils have significant potential for C sequestration but little is known about the effect of type and concentration of cations on sorption and release of DOC in salt-affected soils. To close this knowledge gap, three batch sorption and desorption experiments were conducted using soils treated with solutions either low or high in salinity. In Experiment 1, salinity was developed with either NaCl or CaCl2 to obtain an electrical conductivity (EC) in a 1:5 soil: water extract (EC1:5) of 2 and 4 dS m(-1). In Experiments 2 and 3, NaCl and CaCl2 were added in various proportions (between 25 and 100%) to obtain an EC1:5 of 0.5 and 4 dS m(-1), respectively. At EC1:5 of 4 dS m(-1), the sorption of DOC (derived from wheat straw) was high even at a low proportion of added Ca(2+) and did not change with proportion of Ca added, but at EC1:5 of 0.5 dS m(-1) increasing proportion of Ca(2+) added increased DOC sorption. This can be explained by the differences in exchangeable Ca(2+) at the two salinity levels. At EC1:5 of 4 dS m(-1), the exchangeable Ca(2+) concentration did not increase beyond a proportion of 25% Ca(2+), whereas it increased with increasing Ca(2+) proportion in the treatments at EC1:5 of 0.5 dS m(-1). The DOC sorption was lowest with a proportion of 100% as Na(+). When Ca(2+) was added, DOC sorption was highest, but least was desorbed (with deionised water), thus sorption and desorption of added DOC were inversely related. The results of this study suggest that DOC sorption in salt-affected soils is mainly controlled by the levels of exchangeable Ca(2+) irrespective of the Ca(2+) concentration in the soil solution which has implications on carbon stabilization in salt-affected soils.
Publisher: Elsevier BV
Date: 2021
Publisher: Springer Science and Business Media LLC
Date: 30-08-2013
Publisher: Springer Science and Business Media LLC
Date: 28-01-2021
Publisher: Elsevier BV
Date: 2007
Publisher: Springer Science and Business Media LLC
Date: 17-08-2020
Publisher: Springer Science and Business Media LLC
Date: 30-03-2016
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/S1001-0742(08)62214-7
Abstract: A greenhouse pot experiment was conducted to investigate the influence of soil moisture content on plant growth and the rhizosphere microbial community structure of four plant species (white clover, alfalfa, sudan grass, tall fescue), grown in idually or in a mixture. The soil moisture content was adjusted to 55% or 80% water holding capacity (WHC). The results indicated that the total plant biomass of one pot was lower at 55% WHC. At a given soil moisture, the total plant biomass of white clover and tall fescue in the mixture was lower than that in a monoculture, indicating their poor competitiveness. For leguminous plants, the decrease in soil moisture reduced the total microbial biomass, bacterial biomass, fungal biomass, and fungal/bacterial ratio in soil as assessed by the phospholipid fatty acid analysis, whereas, lower soil moisture increased those parameters in the tall fescue. The microbial biomass in the soil with legumes was higher than that in the soil with grasses and the two plant groups differed in soil microbial community composition. At high soil moisture content, microbial communities of the plant mixture were similar to those of the legume monoculture, and the existence of legumes in the mixture enhanced the bacterial and fungal biomass in the soil compared to the grasses grown in the monoculture, indicating that legumes played a dominant role in the soil microbial community changes in the plant mixture.
Publisher: Springer Science and Business Media LLC
Date: 05-2006
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 06-2012
Publisher: Wiley
Date: 10-11-2018
Publisher: Informa UK Limited
Date: 15-04-2016
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/SR15206
Abstract: Plant growth on sands is often constrained by water repellence, low fertility and low water-holding capacity (WHC). These soils also have low organic carbon (OC) concentration, particularly in a bleached A2 horizon. Addition of subsoil clay to sands (clay modification) can overcome these constraints and increase WHC however, little is known about the effect on OC concentration. Clay addition is predicted to increase OC storage via increased OC input from improved plant growth and increased stabilisation of OC by binding to clays. The objectives of this study were (i) to validate the number of soil s les required within a 25-m grid for accurate OC and bulk density measurement in clay-modified soils and (ii) to determine OC concentration, bulk density and OC stocks in clay-modified compared with unmodified soil. The study was carried out on two agricultural properties in South Australia, where unmodified controls (sands with 1–3% clay) were compared with three methods of modification using clay (clay spread, delved and spaded). Soil cores to 50cm depth were collected after harvest within a 25-m grid. The study showed that clay modification could increase OC stocks (0–30cm) by up to 14tha–1 in the South East and 22tha–1 in the Eyre Peninsula. However, the magnitude of the OC stock increase was influenced by the modification method and depended on concentration and depth of incorporation of the added clay and organic matter.
Publisher: Springer Science and Business Media LLC
Date: 11-05-2011
Publisher: Springer Science and Business Media LLC
Date: 10-2015
Publisher: Springer Science and Business Media LLC
Date: 08-08-2015
Publisher: Springer Science and Business Media LLC
Date: 03-04-2013
Publisher: Springer Science and Business Media LLC
Date: 06-08-2020
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 12-2006
Publisher: Elsevier BV
Date: 12-2018
Publisher: Informa UK Limited
Date: 12-2009
Publisher: Springer Science and Business Media LLC
Date: 18-06-2019
Publisher: American Chemical Society (ACS)
Date: 11-01-2012
DOI: 10.1021/ES2027345
Abstract: Soil organic carbon (SOC) models are used to predict changes in SOC stocks and carbon dioxide (CO(2)) emissions from soils, and have been successfully validated for non-saline soils. However, SOC models have not been developed to simulate SOC turnover in saline soils. Due to the large extent of salt-affected areas in the world, it is important to correctly predict SOC dynamics in salt-affected soils. To close this knowledge gap, we modified the Rothamsted Carbon Model (RothC) to simulate SOC turnover in salt-affected soils, using data from non-salt-affected and salt-affected soils in two agricultural regions in India (120 soils) and in Australia (160 soils). Recently we developed a decomposition rate modifier based on an incubation study of a subset of these soils. In the present study, we introduce a new method to estimate the past losses of SOC due to salinity and show how salinity affects future SOC stocks on a regional scale. Because salinity decreases decomposition rates, simulations using the decomposition rate modifier for salinity suggest an accumulation of SOC. However, if the plant inputs are also adjusted to reflect reduced plant growth under saline conditions, the simulations show a significant loss of soil carbon in the past due to salinization, with a higher average loss of SOC in Australian soils (55 t C ha(-1)) than in Indian soils (31 t C ha(-1)). There was a significant negative correlation (p < 0.05) between SOC loss and osmotic potential. Simulations of future SOC stocks with the decomposition rate modifier and the plant input modifier indicate a greater decrease in SOC in saline than in non-saline soils under future climate. The simulations of past losses of SOC due to salinity were repeated using either measured charcoal-C or the inert organic matter predicted by the Falloon et al. equation to determine how much deviation from the Falloon et al. equation affects the amount of plant inputs generated by the model for the soils used in this study. Both sets of results suggest that saline soils have lost carbon and will continue to lose carbon under future climate. This demonstrates the importance of both reduced decomposition and reduced plant input in simulations of future changes in SOC stocks in saline soils.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Elsevier BV
Date: 11-2011
Publisher: Springer Science and Business Media LLC
Date: 10-2005
Publisher: Elsevier BV
Date: 04-2017
Publisher: Springer Science and Business Media LLC
Date: 29-08-2013
Publisher: Springer Science and Business Media LLC
Date: 30-11-2012
Publisher: Elsevier BV
Date: 05-2014
Publisher: Elsevier BV
Date: 05-2010
Publisher: Springer Science and Business Media LLC
Date: 08-12-2013
Publisher: Springer Science and Business Media LLC
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 2016
Publisher: Elsevier BV
Date: 11-2016
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/SR15103
Abstract: In previous research, we found that the reduction in soil respiration with increasing salinity was smaller in soils amended with rapidly decomposable residues (low C:N ratio) compared with slowly decomposable residues (high C:N ratio). However, with a single residue addition, available organic carbon will be quickly decomposed until only recalcitrant compounds remain. A more consistent supply of residues may improve the tolerance of microbes to salinity, but this effect could depend on residue decomposability. A 56-day incubation experiment was conducted with four loam soils having electrical conductivity (EC1:5) of 0.1, 1, 2.7 and 3.7dSm–1 amended 1–4 times with finely ground slowly decomposable canola (C:N=82) and rapidly decomposable kikuyu residues (C:N=19) with a total addition of 10gCkg–1 soil. There was a greater reduction in soil respiration with increasing salinity following addition of canola than addition of kikuyu. At all salinity levels and with both residues, cumulative respiration two weeks after addition of 10gCkg–1 was higher with multiple additions than with a single addition. The reduction of cumulative respiration with increasing salinity was smaller with repeated addition of rapidly decomposable residue than with only a single addition. However, this was not the case with slowly decomposable residue. The results suggest that for amelioration of saline soils, addition of rapidly decomposable residue is more effective than adding slowly decomposable residues, particularly when rapidly decomposable residues are added repeatedly.
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR12191
Abstract: Addition of carbon (C) and nitrogen (N) to soil can enhance microbial tolerance to salinity, but it is not known if salinity changes the response of microbial activity and biomass to addition of C and N, or how nutrient addition affects microbial tolerance to salinity. We prepared salinity treatments of non-saline soil [electrical conductivity (EC1 : 5) 0.1 dS m–1] without salt addition or adjusted to four salinity levels (2.5, 5.0, 7.5, 10 dS m–1) using a combination of CaCl2 and NaCl. The soils were amended with 2.5 mg C g–1 as glucose or as mature wheat straw (C/N ratio 47 : 1), with NH4Cl added to glucose to achieve a C/N ratio similar to that of wheat straw, or with NH4Cl added to glucose or wheat straw to achieve a C/N ratio of 20. Soil respiration was measured over 30 days. Microbial biomass C and N (MBC, MBN), dissolved organic C (DOC), and total dissolved N (TDN) were measured on day 30. Cumulative respiration and MBC concentration decreased with increasing EC, less so with glucose than with wheat straw. The MBC concentration was more sensitive to EC than was cumulative respiration, irrespective of C source. Addition of N to glucose and wheat straw to bring the C/N ratio to 20 significantly decreased cumulative respiration and MBC concentration at a given EC. This study showed that in the short term, addition of a readily available and easily decomposable source of energy improves the ability of microbes to tolerate salinity. The results also suggest that in saline soils, irrespective of the C substrate, N addition has no impact, or a negative impact, on microbial activity and growth.
Publisher: Springer Science and Business Media LLC
Date: 21-03-2007
Publisher: Springer Science and Business Media LLC
Date: 06-2005
Publisher: Informa UK Limited
Date: 09-05-2020
DOI: 10.1080/09593330.2019.1612953
Abstract: Wheat straw amendment to sandy soil can remove nitrogen (N) and phosphorus (P) from wastewater but it is unclear whether prior decomposition affects removal. Sand mixed with finely ground wheat straw at 12.5 g straw kg
Publisher: Elsevier BV
Date: 04-2005
DOI: 10.1016/J.MICRES.2005.01.003
Abstract: The actinomycete Gordonia sp. and the bacterium Pseudomonas fluorescens Pf-5 were grown in liquid media (pH 6.5) with phosphate adsorbed to the Fe-oxide/hydroxide goethite (Goe-P) and with soluble phosphate (0.1 mM or 1.0 mM P as KH2PO4). The two isolates showed distinct differences in their physiology. The pH of the medium was increased by Gordonia sp. by 1.1-1.7 units while it was decreased by P. fluorescens by 1.4-2.4 units. In all treatments the concentration of organic acids in the media with Gordonia sp. was up to 10 times lower (0.4-10.9 micromol L(-1)) than in media with P. fluorescens (33.4-84.4 micromol L(-1)). Gordonia sp. produced five different organic acids in varying amounts depending on P source and time. In contrast, P. fluorescens exuded mainly citrate and only small amounts of two to three other organic acids irrespective of P source or time.
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 09-2015
Publisher: Springer Science and Business Media LLC
Date: 09-2017
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.MYCRES.2007.08.022
Abstract: Lichens produce a erse array of secondary metabolites that have shown various biological activities. Of particular interest are the coupled phenolics that originate from polyketide pathways, such as depsides, depsidones and usnic acids, which are produced almost solely by lichens. Based on the presumed catalytic domains required for the synthesis of the key intermediates beta-orsellinic acid and methylphloroacetophenone, two pairs of degenerate primers were designed to target specifically the beta-ketoacylsynthase (KS) and C-methyltransferase (CMeT) domains of fungal non-reducing polyketide synthase (NR-PKS) genes with CMeT domains. These primers were used to explore the genome of the lichen Xanthoparmelia semiviridis, which produces beta-orcinol depsidones and usnic acid. One of the two KS domains lified from genomic DNA of field-collected X. semiviridis was used as a probe to recover the candidate PKS gene. A 13 kb fragment containing an intact putative PKS gene (xsepks1) of 6555 bp was recovered from a partial genomic library. The inferred amino acid sequence indicated that xsepks1 encodes a protein of 2164 amino acids and contains KS, acyltransferase (AT), acyl carrier protein (ACP) and CMeT domains as expected. This demonstrated a successful strategy for targeting non-reducing PKS genes with CMeT domains. Integration of the 5' fragment of xsepks1, including the native promoter, into Aspergillus nidulans by cotransformation resulted in the transcription of the 5'xsepks1 and the splicing of a 63 bp intron, suggesting that A. nidulans could be a suitable heterologous host for xsepks1 expression.
Publisher: Elsevier BV
Date: 09-2006
DOI: 10.1016/J.ENVPOL.2005.11.003
Abstract: There are increasing concerns over the effects of veterinary antibiotics and heavy metals in agricultural soils. The widely used veterinary antibiotic oxytetracycline (OTC), Cu and their combination on soil microbial community function were assessed with the Biolog method. The microbial community was extracted from the soil and exposed to a 0.85% sodium chloride solution containing OTC (0, 1, 5, 11, 43, 109 and 217 microM), or Cu (0, 10, 20, 100 and 300 microM), or combination of the two pollutants (OTC 0, 5, 11 microM and Cu 0, 20 microM). Functional ersity, evenness, average well color development (AWCD) and substrate utilization decreased significantly with increasing concentrations of OTC or Cu (p < 0.005). The critical concentrations were 11 microM for OTC and 20 microM for Cu. The combination of OTC and Cu significantly decreased Shannon's ersity, evenness and utilization of carbohydrates and carboxylic acids compared to in idual one of the contaminants. The antibiotic OTC and Cu had significant negative effects on soil microbial community function, particularly when both pollutants were present.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2019
DOI: 10.1007/S11356-019-04580-W
Abstract: Wheat straw amendment to sandy soil has the potential to remove nutrients from wastewater. This study investigated the ability of wheat straw to remove inorganic nitrogen (N) and phosphorus (P) from wastewater when mixed into sand at different rates. Wastewater from a sewage treatment plant was added to sand alone and amended with different wheat straw rates 2.5, 5, 7.5, 10, and 12.5 g wheat straw kg
Publisher: Elsevier BV
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 14-10-2010
Publisher: Springer Science and Business Media LLC
Date: 17-05-2013
Publisher: Elsevier BV
Date: 06-2006
Publisher: Elsevier BV
Date: 09-2012
Publisher: Springer Science and Business Media LLC
Date: 10-11-2013
Publisher: Springer Science and Business Media LLC
Date: 12-2017
Publisher: Wiley
Date: 15-05-2018
DOI: 10.1002/ECO.1984
Publisher: Canadian Science Publishing
Date: 09-2008
DOI: 10.1139/B08-043
Abstract: For the first time, the phenotypes formed in the reduced mycorrhizal colonization (rmc) Solanum lycopersicum L. (tomato) mutant with different arbuscular mycorrhizal (AM) fungi were used to explore the potential of different fungal structures to support development of external fungal mycelium and spores. The life cycle of AM fungi with rmc was followed for up to 24 weeks. Results showed that production of external mycelium was slight and transitory for those fungi that did not penetrate the roots of rmc (Pen–) ( Glomus intraradices DAOM181602 and Glomus etunicatum ). For fungi that penetrated the root epidermis and hypodermis (Coi–, Glomus coronatum and Scutellospora calospora ) the mycelium produced varied in size, but was always smaller than with the wild-type 76R. Spores were formed by these fungi with 76R but not with rmc. The only fungus forming a Myc+ phenotype with rmc, G. intraradices WFVAM23, produced as much mycelium with rmc as with 76R. We observed lipid accumulation in hyphae and vesicles in both plant genotypes with this fungus. Mature spores were formed with 76R. However, with rmc, spores remained small and (presumably) immature for up to 24 weeks. We conclude that significant carbon transfer from plant to fungus can occur in Coi– interactions with rmc in which no cortical colonization occurs. We speculate that both carbon transfer and root signals are required for mature spores to be produced.
Publisher: Springer Science and Business Media LLC
Date: 05-03-1994
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.JHAZMAT.2015.05.013
Abstract: Sulfuric material is formed upon oxidation of sulfidic material it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: Elsevier BV
Date: 09-2019
Publisher: Springer Netherlands
Date: 2007
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/SR05042
Abstract: The aim of this study was to assess the influence of season, farm management (organic, biodynamic, integrated, and conventional), and soil chemical, physical, and biological properties on gross nitrogen (N) fluxes and bacterial community structure in the semi-arid region of Western Australia. Moisture availability was the dominant factor mediating microbial activity and carbon (C) and N cycling under this climate. In general, microbial biomass N, dissolved organic N, and potentially mineralisable N were greater in organic and biodynamic than integrated and conventional soil. Our results indicate that greater silt and clay content in organic and biodynamic soil may also partly explain these differences in soil N pools, rather than management alone. Although plant-available N (NH4+ + NO3–) was greater in conventional soil, this was largely the result of higher NO3– production. Multiple linear modelling indicated that soil temperature, moisture, soil textural classes, pH, electrical conductivity (EC), and C and N pools were important in predicting gross N fluxes. Redundancy analysis revealed that bacterial community structure, assessed by denaturing gradient gel electrophoresis of 16S rDNA, was correlated with C and N pools and fluxes, confirming links between bacterial structure and function. Bacterial community structure was also correlated with soil textural classes and soil temperature but not soil moisture. These results indicate that across this semi-arid landscape, soil bacterial communities are relatively resistant to water stress.
Publisher: Elsevier BV
Date: 04-2007
Publisher: Springer Science and Business Media LLC
Date: 09-2017
Publisher: Springer Science and Business Media LLC
Date: 02-05-2019
Publisher: Elsevier BV
Date: 12-2018
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13105
Abstract: Compost addition to soil can increase nutrient availability, but if added to sandy soils, nutrients can be rapidly leached. Clay added to compost could increase nutrient retention and reduce nutrient leaching due to binding to the clay. An incubation experiment was conducted to assess the effect of addition of a fine-textured soil (34% clay) to garden waste compost on nutrient availability and leaching in a sandy soil. The sandy soil was non-amended or amended with compost only, at a rate 27.3 g kg–1, or with a mixture of compost and 5% or 20% (w/w) of fine-textured soil. Two additional treatments included sandy soil amended with only the fine-textured soil at rates similar to those added with compost. Soil, compost, and fine-textured soil were mixed and packed to a bulk density of 1.22 g cm–3. Soil respiration was measured over 23 days. On days 1, 5, and 23, the soils were leached with 50 mL reverse-osmosis water, and the following parameters were measured in the leachate: water-soluble organic carbon (OC), inorganic nitrogen (N), and phosphorus (P) water-soluble OC and available N and P were measured in the soil after leaching. Compost increased nutrient availability and leaching compared with the non-amended control. Addition of the fine-textured soil to compost reduced cumulative respiration and N and P leaching, with the effect more pronounced at 20% (w/w). Addition of the fine-textured soil alone had no effect on nutrient availability and leaching because of the low nutrient concentration in this soil. This study showed that addition of fine-textured soil to compost can reduce N and P leaching, which could enhance and prolong the positive effects of compost on soil fertility.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/SR13104
Abstract: Adaptation of soil microbes to salinity requires substantial amounts of energy. We hypothesised that addition of glucose would increase microbial activity and growth and alleviate the negative effect of salinity on microbes. An incubation experiment was conducted with four salinity levels by using one non-saline and three saline soils of similar texture (sandy clay loam), with electrical conductivities (EC1:5) of 0.1, 1.1, 3.1 and 5.2 dS m–1. Glucose was added to achieve five organic carbon concentrations (0, 0.5, 1, 2.5, 5 g C kg–1). Soluble nitrogen (N) and phosphorus (P) were added to achieve a carbon (C) : N ratio of 20 and a C : P ratio of 200 to ensure that these nutrients did not limit microbial growth. A water content of 50% of the water-holding capacity (optimal for microbial activity in soils of this texture) was maintained throughout the incubation. Soil respiration was measured continuously over 21 days microbial biomass C and available N and P were determined on days 2, 5, 14 and 21. Cumulative respiration was increased by addition of glucose and was reduced by salinity. The percentage decrease in cumulative respiration in saline soils compared with non-saline soil was greatest in the unamended soil and lowest with addition of 5 g C kg–1. At this rate of C addition, the percentage decrease in cumulative respiration increased with increasing salinity level. Microbial biomass C (MBC) concentration on days 2 and 5 was strongly increased by ≥1 g C kg–1 but decreased over time with the strongest decrease at the highest C addition rate. The MBC concentration was negatively correlated with EC at all C rates at each s ling date. Addition of C resulted in N and P immobilisation in the first 5 days. Biomass turnover as a result of depletion of readily available C released previously immobilised N and P after day 5, particularly in the soils with low salinity. This study showed that over a period of 3 weeks, addition of glucose increased microbial activity and growth in saline soils and alleviated the negative impact of salinity on microbes.
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR12378
Abstract: Previously we showed that addition of legume residues affected the size of different soil phosphorus (P) pools in an alkaline loamy sand soil. Here, we tested whether the changes in soil P pools induced by residue addition are generally applicable or whether they are dependent on certain soil properties. Three legume residues differing in P concentration, faba bean (Vicia faba L.) (high P), chickpea (Cicer arietinum L.) (medium P), and white lupin (Lupinus albus L.) (low P), were added at a rate of 20 g residue kg–1 soil to three different soils with low Colwell-P concentration: Mt Bold (sandy clay loam, high organic carbon (C) content, pH 5.1), Monarto (loamy sand, low organic C content, pH 7.5), and Langhorne Creek (sandy loam, low organic C content, pH 8.1). Soil P pools were assessed by sequential P fractionation on days 0 and 42. In residue-amended soils from day 0 to day 42, the concentrations of water-soluble and microbial P decreased, whereas the concentrations of NaHCO3-Pi (inorganic P) and NaOH-Po (organic P) increased. The magnitude of these changes differed among soils, being greatest in the Mt Bold soil. Residue addition had little or no effect on the concentrations of NaOH-Pi and residual P, which also did not change significantly over time. Principal component analysis of the data showed that the size of the P pools was related to soil properties high concentrations of HCl-P were associated with high pH and calcium concentrations, high concentrations of NaOH-P and residual P were correlated with high aluminium, silt, organic C, and total nitrogen and P. In the unamended soil on day 0, the concentration of NaHCO3-Pi was correlated with the clay content, whereas on day 42, the concentrations of the labile P pools were related to amount of P added with the residues. It can be concluded that most effects of residue addition to soils on microbial activity and growth and soil P pools can be generalised across the three soil used in this study, but that the size of the P pools is affected by soil properties such as organic C content, pH, and texture.
Publisher: Elsevier BV
Date: 09-2013
Publisher: Informa UK Limited
Date: 31-12-2015
Publisher: Elsevier BV
Date: 07-2008
Publisher: Springer Science and Business Media LLC
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 17-05-2007
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 09-2005
Publisher: Springer Science and Business Media LLC
Date: 11-12-2007
Publisher: Elsevier BV
Date: 10-2013
Publisher: Wiley
Date: 27-06-2013
DOI: 10.1002/LDR.1134
Publisher: Elsevier BV
Date: 03-2005
Publisher: Springer Science and Business Media LLC
Date: 17-09-2011
Publisher: Elsevier BV
Date: 04-2007
Publisher: Oxford University Press (OUP)
Date: 03-2007
DOI: 10.1111/J.1574-6941.2006.00235.X
Abstract: The effects of agronomic management practices on the soil microbial community were investigated in a maize production system in New South Wales, Australia. The site has been intensively studied to measure the impact of stubble management and N-fertilizer application on greenhouse gas emissions (CO(2) and N(2)O), N-cycling, pathology, soil structure and yield. As all of these endpoints can be regulated by microbial processes, the microbiology of the system was examined. Soil s les were taken after a winter fallow period and the ersity of the bacterial and fungal communities was measured using PCR-denaturing gradient gel electrophoresis. Stubble and N shifted the structure of bacterial and fungal communities with the primary driver being stubble addition on the fungal community structure (P<0.05 for all effects). Changes in C, N (total and NO(3)), K and Na, were correlated (P<0.05) with variation in the microbial community structure. Quantitative PCR showed that nifH (nitrogen fixation) and napA (denitrification) gene abundance increased upon stubble retention, whereas amoA gene numbers were increased by N addition. These results showed that the management of both stubble and N have significant and long-term impacts on the size and structure of the soil microbial community at phylogenetic and functional levels.
Publisher: Springer Netherlands
Date: 2010
Publisher: Elsevier BV
Date: 06-2012
Publisher: Elsevier BV
Date: 06-2012
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 02-2016
Publisher: Springer Science and Business Media LLC
Date: 03-12-2020
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/SR05188
Abstract: The effects of various management practices on soil phosphorus (P) dynamics were investigated in a field experiment in New South Wales, Australia, during 24 years of different crop rotation, stubble management, and tillage treatments. Topsoil s les collected at the beginning of the trial and after 6, 12, 18, and 24 years were analysed for resin-extractable P, inorganic and organic P, and total P. According to the calculated P input–output budget, 9–14 of the 20 kg P/ha added as superphosphate annually remained in the system, depending on the treatment. The measured increase in total P in 0–0.20 m did not differ between treatments, showing an accumulation rate of only 9 ± 2 kg P/ha.year. These results suggest a loss of 4 ± 2 kg P/ha.year, presumably into lower soil layers. Resin-extractable P at 0–0.10 m increased by 1.7 kg P/ha.year, irrespective of the treatment. The increase in total P after 24 years was almost completely accounted for by the increase in total extractable inorganic P. Changes in organic P paralleled changes in organic carbon, with a significant loss in treatments with stubble burning (wheat–lupin rotation and continuous wheat), and a significant accumulation in a wheat–subterranean clover rotation with stubble retention and direct drilling. We conclude that on the time scale of this experiment, the dynamics of carbon and organic P are closely linked.
Publisher: Elsevier BV
Date: 03-2007
Publisher: Springer Science and Business Media LLC
Date: 27-01-2020
Publisher: Springer Science and Business Media LLC
Date: 10-09-2016
DOI: 10.1007/S11356-016-7597-X
Abstract: When previously oxidised acid sulphate soils are leached, they can release large amounts of protons and metals, which threaten the surrounding environment. To minimise the impact of the acidic leachate, protons and metals have to be retained before the drainage water reaches surrounding waterways. One possible amelioration strategy is to pass drainage water through permeable reactive barriers. The suitability of organic materials for such barriers was tested. Eight organic materials including two plant residues, compost and five biochars differing in feedstock and production temperature were finely ground and filled into PVC cores at 3.5 g dry wt/core. Field-collected acidic drainage water (pH 3, Al 22 mg L
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/SR13128
Abstract: Decomposition of mixed residues is common in many ecosystems, with residues from different species or above- and below-ground residues from the same species. Although decomposition of litter mixtures has been extensively studied, little is known about the changes in microbial biomass carbon (C) and available nitrogen (N) in the early stages of decomposition of mixtures of shoots and roots. An incubation experiment was carried out in a sandy clay loam with shoot and root residues of two grasses, annual barley (Hordeum vulgare L.), and perennial Stipa sp., added separately or as mixtures. Soil respiration was measured continuously, and soil microbial biomass C, extractable C and available N were measured by destructive s ling on days 0, 3, 6, 9, 12 and 18. Cumulative respiration and microbial biomass C concentration were higher with barley shoots alone or in mixtures than with Stipa residues alone. In the mixture of Stipa shoots and roots, which had similar decomposition rates when incubated in idually, the measured cumulative respiration was greater than the expected value (average of the cumulative respiration of the in idual residues), but this did not result in greater microbial biomass or changes in available N concentration compared with the in idual residues. Cumulative respiration of barley shoots alone was higher than of barley root and Stipa shoot incubated in idually. In the mixtures of barley shoots with barley roots or Stipa shoots, the measured cumulative respiration was either lower than the expected value or similar. Compared with barley shoots alone, microbial biomass C concentrations in the mixtures were generally lower in the first 3 days. It is concluded that mixing of residues with similar decomposition rates can stimulate microbial activity (respiration) but has little effect on microbial growth or concentrations of available N. Further, our findings provide information about extractable C and N dynamics during the early stages of decomposition of in idual residue and residue mixtures.
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 04-2016
Publisher: Springer Science and Business Media LLC
Date: 18-04-2012
Publisher: Springer Science and Business Media LLC
Date: 10-09-2020
Publisher: Informa UK Limited
Date: 02-06-2014
Publisher: Elsevier BV
Date: 05-2016
Publisher: Elsevier BV
Date: 04-2015
Publisher: Springer Science and Business Media LLC
Date: 14-08-2012
Publisher: Springer Science and Business Media LLC
Date: 30-07-2011
Publisher: Wiley
Date: 30-08-2013
Publisher: Springer Science and Business Media LLC
Date: 12-06-2014
Publisher: Elsevier BV
Date: 08-2016
Publisher: Elsevier BV
Date: 02-2012
Publisher: Springer Science and Business Media LLC
Date: 30-12-2012
Publisher: Elsevier BV
Date: 08-2005
Publisher: Elsevier BV
Date: 2007
Publisher: Springer Science and Business Media LLC
Date: 11-10-2007
Publisher: Wiley
Date: 17-08-1970
Publisher: Springer Science and Business Media LLC
Date: 06-02-2019
Publisher: Elsevier BV
Date: 07-2009
Publisher: Springer Science and Business Media LLC
Date: 22-04-2022
DOI: 10.1007/S00374-022-01642-Z
Abstract: The effect of rapid rewetting of dry soil to a water content optimal for microbial activity on soil respiration and nutrient cycling has been extensively studied. However, with smaller rainfall events, dry soil may also rewet more slowly with an interval between partial rewetting events. In this experiment, soil unamended or amended with faba bean residue (C/N 9) was incubated at 50% water-holding capacity (WHC) for 2 weeks, then the soil of the rewet treatments was air-dried and incubated dry for 2 weeks. Then, the air-dried soil was exposed to six rewetting treatments: rewet rapidly to 50% WHC once on day 0 (RR50), rewet partially to 25% WHC once on day 0 (PR25), or rewet slowly by two applications of 25% WHC each with the first rewetting on day 0 and the second after 6 h (SR6), 12 h (SR12), 36 h (SR36), or 60 h (SR60). Constantly moist (CM) soil was kept at 50% WHC throughout the experiment. The flush of respiration after the final rewetting followed the order SR6 RR50 SR12 SR36 PR25, SR60. Microbial biomass C on the first day after the final rewetting decreased in the order RR50 PR25 SR6 SR12 SR 36 SR60, CM. We conclude that slow rewetting can increase the flush of respiration compared to rapid rewetting, but only if the second partial rewetting occurs 6 h after the first. The size of the flush decreased with increasing time between the two rewetting events.
Publisher: Springer Science and Business Media LLC
Date: 05-2006
Publisher: Springer Science and Business Media LLC
Date: 11-01-0007
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.SCITOTENV.2012.08.028
Abstract: Saline soils cover 3.1% (397 million hectare) of the total land area of the world. The stock of soil organic carbon (SOC) reflects the balance between carbon (C) inputs from plants, and losses through decomposition, leaching and erosion. Soil salinity decreases plant productivity and hence C inputs to the soil, but also microbial activity and therefore SOC decomposition rates. Using a modified Rothamsted Carbon model (RothC) with a newly introduced salinity decomposition rate modifier and a plant input modifier we estimate that, historically, world soils that are currently saline have lost an average of 3.47 tSOC ha(-1) since they became saline. With the extent of saline soils predicted to increase in the future, our modelling suggests that world soils may lose 6.8 Pg SOC due to salinity by the year 2100. Our findings suggest that current models overestimate future global SOC stocks and underestimate net CO2 emissions from the soil-plant system by not taking salinity effects into account. From the perspective of enhancing soil C stocks, however, given the lower SOC decomposition rate in saline soils, salt tolerant plants could be used to sequester C in salt-affected areas.
Publisher: Springer Science and Business Media LLC
Date: 07-05-2014
Publisher: Springer Science and Business Media LLC
Date: 02-05-2019
Publisher: Wiley
Date: 22-11-2014
DOI: 10.1111/PBI.12145
Abstract: Cereal varieties with improved salinity tolerance are needed to achieve profitable grain yields in saline soils. The expression of AVP1, an Arabidopsis gene encoding a vacuolar proton pumping pyrophosphatase (H⁺-PPase), has been shown to improve the salinity tolerance of transgenic plants in greenhouse conditions. However, the potential for this gene to improve the grain yield of cereal crops in a saline field has yet to be evaluated. Recent advances in high-throughput nondestructive phenotyping technologies also offer an opportunity to quantitatively evaluate the growth of transgenic plants under abiotic stress through time. In this study, the growth of transgenic barley expressing AVP1 was evaluated under saline conditions in a pot experiment using nondestructive plant imaging and in a saline field trial. Greenhouse-grown transgenic barley expressing AVP1 produced a larger shoot biomass compared to null segregants, as determined by an increase in projected shoot area, when grown in soil with 150 mM NaCl. This increase in shoot biomass of transgenic AVP1 barley occurred from an early growth stage and also in nonsaline conditions. In a saline field, the transgenic barley expressing AVP1 also showed an increase in shoot biomass and, importantly, produced a greater grain yield per plant compared to wild-type plants. Interestingly, the expression of AVP1 did not alter barley leaf sodium concentrations in either greenhouse- or field-grown plants. This study validates our greenhouse-based experiments and indicates that transgenic barley expressing AVP1 is a promising option for increasing cereal crop productivity in saline fields.
Publisher: Elsevier BV
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 03-12-2014
Publisher: Elsevier BV
Date: 02-2019
Publisher: American Chemical Society (ACS)
Date: 30-06-2011
DOI: 10.1021/ES200515D
Abstract: Soil organic carbon (SOC) models such as the Rothamsted Carbon Model (RothC) have been used to estimate SOC dynamics in soils over different time scales but, until recently, their ability to accurately predict SOC stocks/carbon dioxide (CO(2)) emissions from salt-affected soils has not been assessed. Given the large extent of salt-affected soils (19% of the 20.8 billion ha of arable land on Earth), this may lead to miss-estimation of CO(2) release. Using soils from two salt-affected regions (one in Punjab, India and one in South Australia), an incubation study was carried out measuring CO(2) release over 120 days. The soils varied both in salinity (measured as electrical conductivity (EC) and calculated as osmotic potential using EC and water content) and sodicity (measured as sodium adsorption ratio, SAR). For soils from both regions, the osmotic potential had a significant positive relationship with CO(2)-C release, but no significant relationship was found between SAR and CO(2)-C release. The monthly cumulative CO(2)-C was simulated using RothC. RothC was modified to take into account reductions in plant inputs due to salinity. A subset of non-salt-affected soils was used to derive an equation for a "lab-effect" modifier to account for changes in decomposition under lab conditions and this modifier was significantly related with pH. Using a subset of salt-affected soils, a decomposition rate modifier (as a function of osmotic potential) was developed to match measured and modelled CO(2)-C release after correcting for the lab effect. Using this decomposition rate modifier, we found an agreement (R(2) = 0.92) between modelled and independently measured data for a set of soils from the incubation experiment. RothC, modified by including reduced plant inputs due to salinity and the salinity decomposition rate modifier, was used to predict SOC stocks of soils in a field in South Australia. The predictions clearly showed that SOC stocks are reduced in saline soils. Therefore both the decomposition rate modifier and plant input modifier should be taken into account when accounting for SOC turnover in saline soils. Since modeling has previously not accounted for the impact of salinity, our results suggest that previous predictions may have overestimated SOC stocks.
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.JENVMAN.2015.01.016
Abstract: Acid sulfate soils (ASS) with sulfuric material can be remediated through microbial sulfate reduction stimulated by adding organic matter (OM) and increasing the soil pH to >4.5, but the effectiveness of this treatment is influenced by soil properties. Two experiments were conducted using ASS with sulfuric material. In the first experiment with four ASS, OM (finely ground mature wheat straw) was added at 2-6% (w/w) and the pH adjusted to 5.5. After 36 weeks under flooded conditions, the concentration of reduced inorganic sulfur (RIS) and pore water pH were greater in all treatments with added OM than in the control without OM addition. The RIS concentration increased with OM addition rate. The increase in RIS concentration between 4% and 6% OM was significant but smaller than that between 2% and 4%, suggesting other factors limited sulfate reduction. In the second experiment, the effect of nitrate addition on sulfate reduction at different OM addition rates was investigated in one ASS. Organic matter was added at 2 and 4% and nitrate at 0, 100, and 200 mg nitrate-N kg(-1). After 2 weeks under flooded conditions, soil pH and the concentration of FeS measured as acid volatile sulfur (AVS) were lower with nitrate added at both OM addition rates. At a given nitrate addition rate, pH and AVS concentration were higher at 4% OM than at 2%. It can be concluded that sulfate reduction in ASS at pH 5.5 can be limited by low OM availability and high nitrate concentrations. Further, the inhibitory effect of nitrate can be overcome by high OM addition rates.
Publisher: Springer Science and Business Media LLC
Date: 18-09-2016
Publisher: Springer Science and Business Media LLC
Date: 03-08-2016
Publisher: Elsevier BV
Date: 12-2015
Publisher: Springer Science and Business Media LLC
Date: 06-09-2015
Publisher: Wiley
Date: 13-07-2011
Publisher: Elsevier BV
Date: 11-2017
Publisher: Elsevier
Date: 2012
Publisher: Springer Science and Business Media LLC
Date: 21-08-2016
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 10-2012
Publisher: Elsevier
Date: 2012
Publisher: Copernicus GmbH
Date: 27-08-2015
Abstract: Abstract. Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wildfire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content, which could be further modulated by wildfire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy mallee woodland, where part of the woodland experienced a wildfire which destroyed or damaged most of the aboveground plant parts 4 months before s ling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80 % of maximum water holding capacity (WHC) for 19 days in DRW, soils were dried for 4 days, kept dry for another 5 days, then rewetted to 80 % WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per gram of soil in CM and DRW was greater under trees, but lower when expressed per gram of total organic carbon (TOC). Organic matter content, available P, and microbial biomass C, but not available N, were greater under trees than in open areas. Wild fire decreased the flush of respiration per gram of TOC in the open areas and under shrubs, and reduced TOC and microbial biomass C (MBC) concentrations only under trees, but had little effect on available N and P concentrations. We conclude that the impact of wildfire and DRW events on nutrient cycling differs among vegetation patches of a native semi-arid woodland which is related to organic matter amount and availability.
Publisher: Wiley
Date: 12-09-2005
DOI: 10.1111/J.1469-8137.2005.01558.X
Abstract: Crop nutrition is frequently inadequate as a result of the expansion of cropping into marginal lands, elevated crop yields placing increasing demands on soil nutrient reserves, and environmental and economic concerns about applying fertilizers. Plants exposed to nutrient deficiency activate a range of mechanisms that result in increased nutrient availability in the rhizosphere compared with the bulk soil. Plants may change their root morphology, increase the affinity of nutrient transporters in the plasma membrane and exude organic compounds (carboxylates, phenolics, carbohydrates, enzymes, etc.) and protons. Chemical changes in the rhizosphere result in altered abundance and composition of microbial communities. Nutrient‐efficient genotypes are adapted to environments with low nutrient availability. Nutrient efficiency can be enhanced by targeted breeding through pyramiding efficiency mechanisms in a desirable genotype as well as by gene transfer and manipulation. Rhizosphere microorganisms influence nutrient availability adding beneficial microorganisms may result in enhanced availability of nutrients to crops. Understanding the role of plant–microbe–soil interactions in governing nutrient availability in the rhizosphere will enhance the economic and environmental sustainability of crop production.
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 2005
Publisher: Springer Science and Business Media LLC
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 18-09-2013
Publisher: Springer Science and Business Media LLC
Date: 25-11-2012
Publisher: Springer Science and Business Media LLC
Date: 2017
Publisher: Wiley
Date: 19-08-2019
Publisher: Springer Science and Business Media LLC
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 24-07-2010
Publisher: Elsevier BV
Date: 10-2017
Publisher: Springer Science and Business Media LLC
Date: 10-08-2020
Publisher: Springer Science and Business Media LLC
Date: 2016
Publisher: Informa UK Limited
Date: 16-02-2020
Publisher: Elsevier BV
Date: 03-2013
Publisher: Springer Science and Business Media LLC
Date: 08-02-2012
Publisher: Elsevier BV
Date: 02-2011
Publisher: Springer Science and Business Media LLC
Date: 15-07-2010
Publisher: Elsevier BV
Date: 2007
Publisher: Springer Science and Business Media LLC
Date: 08-04-2019
Publisher: Elsevier BV
Date: 09-2011
Publisher: Elsevier BV
Date: 05-2011
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 25-11-2020
Publisher: Springer Science and Business Media LLC
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 07-05-2008
Publisher: Springer Science and Business Media LLC
Date: 20-02-2020
Publisher: Springer Science and Business Media LLC
Date: 12-2005
Publisher: Elsevier BV
Date: 09-2020
Publisher: Springer Science and Business Media LLC
Date: 29-11-2012
Publisher: Elsevier BV
Date: 09-2011
Publisher: Springer Science and Business Media LLC
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 13-08-2019
Publisher: Elsevier BV
Date: 11-2012
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/SR11203
Abstract: The quantity and/or quality of soil organic matter (SOM) and its fractions regulate microbial community composition and associated function. In this study an established, replicated agricultural systems trial in a semi-arid environment was used to test: (i) whether agricultural systems which have increased plant residue inputs increase the amount of labile SOM relative to total SOM, or change the quality of SOM fractions and (ii) whether the size or quality of OM fractions is most strongly linked to the size, activity, functional ersity, and community structure of the soil microbial biomass. Soil (0–50 mm) was collected following 5 years of continuous wheat, crop rotation, crop–pasture rotation, annual pasture, or perennial pasture. Pastures were grazed by sheep. Direct drilling and non-inversion tillage techniques were compared in some cropping systems. Total carbon (C) increased with the proportion of pasture as a result of increased SOM inputs into these systems land use also significantly affected SOM fractions and their chemical and physical nature. While the size, function, and structure of the soil microbial community were somewhat related to total soil C, they were better correlated with SOM fractions. The C : nitrogen (N) ratio of light fraction organic matter could be used to predict the amount of potentially mineralisable N in soil, while the C : N ratio of total SOM could not. Measurement of bacterial community structure (using denaturing gradient gel electrophoresis) significantly discriminated between land uses, while community-level physiological profiles revealed fewer differences. Overall, our findings support the premise that labile fractions of SOM are more strongly related to microbial community structure and function than is total SOM.
Publisher: Elsevier BV
Date: 02-2014
Publisher: Springer Science and Business Media LLC
Date: 23-08-2018
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.SCITOTENV.2012.11.081
Abstract: Addition of clay-rich subsoils to sandy top soils is an agricultural management option to increase water and nutrient retention and may also increase organic carbon sequestration by decreasing the decomposition rates. An incubation experiment was carried out in a loamy sand top soil mixed with a clay-rich subsoil (84% clay) at 0, 10 and 30% (w/w) amended with finely ground mature shoot residues of two native perennial grasses and annual barley in idually or in 1:1 mixtures of two residues. Extractable C, microbial biomass C, available N and soil pH were analysed at days 0, 3, 14 and 28. Cumulative respiration after 28 days was highest with barley residue and lowest with Wallaby grass at all clay soil addition rates 30% clay soil addition reduced cumulative respiration, especially with barley alone. In the mixture of native grasses and barley, the measured respiration was lower than expected at a clay soil addition rate of 10%. A synergistic effect (higher than expected cumulative respiration) was only found in mixture of Kangaroo grass and barley at a clay soil addition rate of 30%. Clay soil addition also decreased extractable C, available N and soil pH. The temporal change in microbial biomass C and available N in residue mixtures differed among clay addition rates. In the mixture of Wallaby grass and Kangaroo grass, microbial biomass C (MBC) decreased from day 0 to day 28 at clay soil addition rates of 0 and 10%, whereas at 30% clay MBC increased from day 0 to day 3 and then decreased. Our study shows that addition of a clay-rich subsoil to a loamy sand soil can increase C sequestration by reducing CO2 release and extractable C which are further modulated by the type of residues present in idually or as mixtures.
Publisher: Informa UK Limited
Date: 30-01-2018
Publisher: Springer Science and Business Media LLC
Date: 15-02-2012
Publisher: Springer Science and Business Media LLC
Date: 24-07-2019
Publisher: Wiley
Date: 08-2018
DOI: 10.1002/ECS2.2386
Publisher: Springer Science and Business Media LLC
Date: 13-07-2010
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 05-2013
Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 02-2014
DOI: 10.1016/J.SCITOTENV.2013.10.002
Abstract: Clay sorption is important for organic carbon (C) sequestration in soils, but little is known about the effect of different clay properties on organic C sorption and release. To investigate the effect of clay content and properties on sorption, desorption and loss of water extractable organic C (WEOC), two experiments were conducted. In experiment 1, a loamy sand alone (native) or mixed with clay isolated from a surface or subsoil (78 and 96% clay) resulting in 90, 158 and 175 g clay kg(-1) soil. These soil treatments were leached with different WEOC concentrations, and then CO2 release was measured for 28 days followed by leaching with reverse osmosis water at the end of experiment. The second experiment was conducted to determine WEOC sorption and desorption of clays isolated from the loamy sand (native), surface soil and subsoil. Addition of clays isolated from surface and subsoil to sandy loam increased WEOC sorption and reduced C leaching and cumulative respiration in percentage of total organic C and WEOC added when expressed per g soil and per g clay. Compared to clays isolated from the surface and subsoil, the native clay had higher concentrations of illite and exchangeable Ca(2+), total organic C and a higher CEC but a lower extractable Fe/Al concentration. This indicates that compared to the clay isolated from the surface and the subsoil, the native clay had fewer potential WEOC binding sites because it had lower Fe/Al content thus lower number of binding sites and the existing binding sites are already occupied native organic matter. The results of this study suggest that in the soils used here, the impact of clay on WEOC sorption and loss is dependent on its indigenous organic carbon and Fe and/or Al concentrations whereas clay mineralogy, CEC, exchangeable Ca(2+) and surface area are less important.
Publisher: Elsevier BV
Date: 02-2017
Publisher: Springer Science and Business Media LLC
Date: 21-12-2008
Publisher: Elsevier BV
Date: 07-2014
Publisher: Springer Science and Business Media LLC
Date: 18-11-2012
Publisher: Springer Science and Business Media LLC
Date: 29-06-2013
Publisher: MDPI AG
Date: 10-01-2018
DOI: 10.3390/W10010055
Publisher: No publisher found
Date: 2008
DOI: 10.1264/JSME2.23.182
Abstract: Phytases are a group of enzymes capable of releasing phosphate from phytate, one of the most abundant forms of organic phosphate in the natural environment. Phytases can be found in many organisms in bacteria, they are particularly described in g-proteobacteria. In recent years, bacterial phytases have been isolated, characterized and proposed as potential tools in biotechnology. Microbial phytases have been applied mainly to animal (swine and poultry) and human foodstuffs in order to improve mineral bioavailability and food processing. Here, we summarize the current knowledge of bacterial phytases and phytase-producing bacteria, as well as their potential biotechnological applications, including new fields poorly explored, such as fish nutrition, environmental protection and plant nutrition. Despite the recognized importance in biotechnology, information on bacterial phytases and phytase-producing bacteria is clearly limited and major efforts are required to improve the knowledge of phytases present in bacteria and their utilization.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Oxford University Press (OUP)
Date: 12-11-2011
DOI: 10.1111/J.1574-6941.2010.00995.X
Abstract: Phytate is one of the most abundant sources of organic phosphorus (P) in soils, but must be mineralized by phytase-producing bacteria to release P for plant uptake. Microbial inoculants based on Bacillus spp. have been developed commercially, but few studies have evaluated the ecology of these bacteria in the rhizosphere or the types of enzymes that they produce. Here, we studied the ersity of aerobic endospore-forming bacteria (EFB) with the ability to mineralize phytate in the rhizosphere of pasture plants grown in volcanic soils of southern Chile. PCR methods were used to detect candidate phytase-encoding genes and to identify EFB bacteria that carry these genes. This study revealed that the phytate-degrading EFB populations of pasture plants included species of Paenibacillus and Bacillus, which carried genes encoding β-propeller phytase (BPP). Assays of enzymatic activity confirmed the ability of these rhizosphere isolates to degrade phytate. The phytase-encoding genes described here may prove valuable as molecular markers to evaluate the role of EFB in organic P mobilization in the rhizosphere.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.TPLANTS.2016.11.012
Abstract: Constitutive expression of the Arabidopsis vacuolar proton-pumping pyrophosphatase (H
Publisher: Elsevier
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 30-07-2011
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.SCITOTENV.2012.07.009
Abstract: Loss of dissolved organic matter (DOM) from soils can have negative effects on soil fertility and water quality. It is known that sodicity increases DOM solubility, but the interactive effect of sodicity and salinity on DOM sorption and how this is affected by soil texture is not clear. We investigated the effect of salinity and sodicity on DOM sorption in soils with different clay contents. Four salt solutions with different EC and SAR were prepared using combinations of 1M NaCl and 1M CaCl(2) stock solutions. The soils differing in texture (4, 13, 24 and 40% clay, termed S-4, S-13, S-24 and S-40) were repeatedly leached with these solutions until the desired combination of EC and SAR (EC(1:5) 1 and 5dSm(-1) in combination with SAR 20) was reached. The sorption of DOC (derived from mature wheat straw) was more strongly affected by SAR than by EC. High SAR (>20) at EC1 significantly decreased sorption in all soils. However, at EC5, high SAR did not significantly reduce DOC sorption most likely because of the high electrolyte concentration of the soil solution. DOC sorption was greatest in S-24 (which had the highest CEC) at all concentrations of DOC added whereas DOC sorption did not differ greatly between S-40 and S-4 or S-13 (which had higher concentrations of Fe/Al than S-40). DOC sorption in salt-affected soil is more strongly controlled by CEC and Fe/Al concentration than by clay concentration per se except in sodic soils where DOC sorption is low due to the high sodium saturation of the exchange complex.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/SR14053
Abstract: Addition of clay-rich subsoils to sandy soils can increase yield and may increase organic carbon (OC) retention in soils. The ability of clays to bind OC is likely to be influenced by clay properties, but little is known about the relative importance of properties of clay subsoils for binding of OC. A batch sorption experiment was conducted using seven clay subsoils collected from agricultural lands where claying was carried out. Clay subsoils were shaken for 17 h at 4°C with different concentrations of water-extractable OC (WEOC: 0, 2.5, 5.0, 7.5, and 9.0 g kg–1 soil) derived from mature wheat (Triticum aestivum L.) straw at a 1 : 10 soil : extract ratio. Sorption of WEOC was positively correlated with clay content, specific surface area and concentration of iron oxides. Further, WEOC sorption was negatively correlated with total OC content, sodium absorption ratio and cation ratio of soil structural stability. However, the relative importance of these properties for WEOC sorption differed among soils. In conclusion, OC retention in clay-amended sandy soils will be positively related to clay soil properties such as clay and Fe oxide content and specific surface area.
Publisher: Springer Science and Business Media LLC
Date: 06-07-2011
Publisher: Informa UK Limited
Date: 22-08-2017
Publisher: Springer Science and Business Media LLC
Date: 23-07-2006
DOI: 10.1007/S00253-005-0076-9
Abstract: Anaerobic co-digestion of food waste and biosolids was carried out in sequential batch and single-stage batch systems in four treatments. Methane yield, which was used as a functional process parameter, differed between treatments, with the single-stage batch system generating lower volumes than the sequential batch systems. Volatile fatty acid (VFA) concentrations and pH in the leachate also differed between treatments. VFA concentrations were highest and methane generation yields lowest in the single-stage batch system in comparison to the sequential batch systems. The anaerobic microbial community structure of the domains Archaea and Bacteria, determined by denaturing gradient gel electrophoresis, differed between treatments and was correlated to a number of environmental parameters such as pH, VFA concentration and methane generation rate. Methane generation rate was significantly correlated to the community structure of Bacteria but not Archaea. This indicated that the substrates that are produced by acetogens (Bacteria) are important for the growth and community structure of the methanogens (Archaea). Community structure of Archaea changed over time, but this had no observable effect on functional ability based on methane yields. Microbial ersity (H') was shown to be not important in developing a functionally successful anaerobic microbial community.
No related grants have been discovered for Petra Marschner.