Published Date
Science of The Total Environment 1 January 2017, Vol.574:24–33,doi:10.1016/j.scitotenv.2016.08.190
Author
Junhui Chen a
Songhao Li b
Chenfei Liang a
Qiufang Xu a,,
Yongchun Li a
Hua Qin a
Jeffry J. Fuhrmann c
aZhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration, School of Environmental and Resource Sciences, Zhejiang A & F University, Lin'an, Hangzhou 311300, China
bAgricultural Technology Extension Centre, Lin'an Municipal Bureau of Agriculture, Lin'an, Hangzhou 311300, China
cDepartment of Plant and Soil Sciences, University of Delaware, Delaware 19716, USA
Received 31 May 2016. Revised 23 August 2016. Accepted 29 August 2016. Available online 10 September 2016. Editor: Simon Pollard
Highlights
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The fine biochar increased microbial abundances and altered community structure.
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The fine biochar resulted in higher CO2 emission than the other fractions.
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Higher addition rate generally reduced soil enzyme activities involving in C cycling.
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Biochar effects on soil microbial community are particle size and rate dependent.
Abstract Biochar incorporated into soil has been known to affect soil nutrient availability and act as a habitat for microorganisms, both of which could be related to its particle size. However, little is known about the effect of particle size on soil microbial community structure and function. To investigate short-term soil microbial responses to biochar addition having varying particle sizes and addition rates, we established a laboratory incubation study. Biochar produced via pyrolysis of bamboo was ground into three particle sizes (diameter size < 0.05 mm (fine), 0.05–1.0 mm (medium) and 1.0–2.0 mm (coarse)) and amended at rates of 0% (control), 3% and 9% (w/w) in an intensively managed bamboo (Phyllostachys praecox) plantation soil. The results showed that the fine particle biochar resulted in significantly higher soil pH, electrical conductivity (EC), available potassium (K) concentrations than the medium and coarse particle sizes. The fine-sized biochar also induced significantly higher total microbial phospholipid fatty acids (PLFAs) concentrations by 60.28% and 88.94% than the medium and coarse particles regardless of addition rate, respectively. Redundancy analysis suggested that the microbial community structures were largely dependent of particle size, and that improved soil properties were key factors shaping them. The cumulative CO2emissions from biochar-amended soils were 2–56% lower than the control and sharply decreased with increasing addition rates and particle sizes. Activities of α-glucosidase, β-glucosidase, β-xylosidase,N-acetyl-β-glucosaminidase, peroxidase and dehydrogenase decreased by ranging from 7% to 47% in biochar-amended soils over the control, indicating that biochar addition reduced enzyme activities involved carbon cycling capacity. Our results suggest that biochar addition can affect microbial population abundances, community structure and enzyme activities, that these effects are particle size and rate dependent. The fine particle biochar may additionally produce a better habitat for microorganisms compared to the other particle sizes. Graphical abstract
Published Date
Applied Soil Ecology November 2015, Vol.96:265–272,doi:10.1016/j.apsoil.2015.08.018 Author
Xiubin Wang a
Dali Song a,b
Guoqing Liang a
Qian Zhang a
Chao Ai a
Wei Zhou a,,
aInstitute of Agricultural Resource and Regional Planning, Chinese Academy of Agricultural Sciences/Key Lab of Plant Nutrition and Nutrient Cycling, Ministry of Agriculture, Beijing 100081, China
bSouthwest University, Chong Qing 400715, China
Received 30 June 2015. Revised 20 August 2015. Accepted 24 August 2015. Available online 7 September 2015.
Highlights
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SOC and total N contents markedly increased with increasing biochar addition rate.
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Exchangeable Ca and Mg contents decreased with increasing biochar addition rate.
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Lower amounts of MC addition increased soil enzyme activities involved in C cycling.
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Total N and exchangeable Ca were dominant factors affecting soil enzyme activities.
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PLFA biomarkers were negatively related to SOC and total N contents.
Abstract Biochar addition to soil has been proposed as a strategy to enhance soil quality and crop productivity, which may also affect microbial activity. However, the response of soil enzymes and microbial community composition to biochar addition and the main factors that drive their consequent behavior have rarely been studied. Therefore, to investigate the combined effect of different amounts of biochar (0, 0.5, 1.0, 2.5 and 5.0% by mass) and urea application on soil nutrients, enzymatic activities and microbial community in a fluvo-aquic soil, we conducted a 90-day laboratory study. Increased maize biochar addition led to significantly increased soil organic carbon (SOC), total N, and exchangeable K and reduced soil exchangeable Ca. Soil total N and exchangeable Ca were dominant factors affecting soil enzyme activities. Activities of soil extracellular enzymes involved in C and S cycling (except β-xylosidase) suggested lower amounts of biochar addition (0.5% by mass) could increase soil enzyme activities, while higher amounts of biochar addition reduce soil enzyme activities. However, the activities ofl-leucine aminopeptidase and urease, both of which are involved in N cycling, increased with the increase of biochar addition rate. Total phospholipid fatty acid content and the relative abundance of bacteria were significantly reduced with increasing biochar addition rate. The relative abundance of fungi in the urea-amended soil was significantly higher than that in the other treated soils, and abundance of actinomycetes did not show a clear response to biochar addition. The changes in the microbial community composition were mainly related to SOC and total N contents, with a significant negative correlation. We concluded that the effect of biochar addition on soil enzymes and microbial community composition was highly variable. There is an urgent need to further estimate both the positive and negative long-term effects of biochar on the soil quality and crop productivity in this region. Keywords
Maize biochar
Fluvo-aquic soil
Soil nutrient
Enzyme activity
Microbial community composition
Table 1
Table 1.
Table 2
Table 2.
Table 3
Table 3.
Table 4
Table 4.
Fig. 1.Fig. 2.The expression of "BC" was amended to "MC". Please see Fig.3 in attach file.Fig. 3.Fig. 4.
Published Date
Advances in Water Resources March 2016, Vol.89:1–9,doi:10.1016/j.advwatres.2015.12.018
Author
Margaret Shanafield a,,,
James L McCallum a
Peter G Cook a
Saskia Noorduijn a,b
aNational Centre for Groundwater Research and Training (NCGRT), School of the Environment, Flinders University, GPO Box 2100, SA 5001, Australia
bUniversity of Calgary, 844 Campus Place Northwest, Calgary, Canada
Received 1 May 2015. Revised 10 December 2015. Accepted 21 December 2015. Available online 4 January 2016.
Highlights
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Streambed dynamics require complex analyses for accurate understanding.
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Easier to acquire high resolution streambed temperatures than hydraulic and physical properties.
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We examine the limitations of unknown boundary conditions on 3D temperature tracer models.
Abstract Although streambed dynamics are known to be complex and three-dimensional, flux within the subsurface is often estimated with simplified models for convenience, despite the errors this incurs. While three-dimensional (3D) models have the advantage of being able to capture complex flow paths within the subsurface, they are also more data intensive, requiring a detailed knowledge of both thermal and hydraulic streambed properties. Temperature data are relatively easy to acquire at a high resolution within a natural stream environment; however, it is typically more difficult to capture hydraulic head measurements at this same resolution, making it difficult to apply appropriate boundary conditions to 3D models in order to estimate streambed fluxes from heat tracer techniques alone. In this study, we examine the consequences of the lack of detailed head data for parameterizing boundary conditions. We tested the abilities of three 3D heat and water transport models with increasingly complex boundary conditions to match observed thermal patterns and predict streambed fluxes. All three models showed similar spatial patterns of high and low fluxes. The amplitude of predicted daily temperature variation at a depth of 0.25 m and 0.5 m below the streambed was generally within 0.1 °C (i.e. within sensor error) of observed, while all three models typically underestimated daily temperature variation in advective areas at a depth of 0.1 m. The results of this study suggest that 3D heat transport models of streambeds may be more limited by the low sensitivity of hydraulic conductivity to small temperature variations than by the lack of detailed hydraulic head data for parameterizing boundary conditions. Graphical abstract
