Interactions between biochar stability and soil organisms: review and research needs
TL;DR: In this paper, a meta-analysis of data in the literature revealed that biochar mineralization rates decreased with increasing pyrolysis temperature, biochar-C content and time, and that increased release of CO2 after biochar addition to soil may result from priming of native SOC pools, biodegradation of biochar components from direct or indirect stimulation of soil organisms by biochar or from carbonates or chemi-sorbed CO2.
Abstract: Summary
The stability of biochar in soils is the cornerstone of the burgeoning worldwide interest in the potential of the pyrolysis/biochar platform for carbon (C) sequestration. While biochar is more recalcitrant in soil than the original organic feedstock, an increasing number of studies report greater C-mineralization in soils amended with biochar than in unamended soils. Soil organisms are believed to play a central role in this process. In this review, the variety of interactions that occur between soil micro-, meso- and macroorganisms and biochar stability are assessed. In addition, different factors reported to influence biochar stability, such as biochar physico-chemical characteristics, soil type, soil organic carbon (SOC) content and agricultural management practices are evaluated. A meta-analysis of data in the literature revealed that biochar-C mineralization rates decreased with increasing pyrolysis temperature, biochar-C content and time. Enhanced release of CO2 after biochar addition to soil may result from (i) priming of native SOC pools, (ii) biodegradation of biochar components from direct or indirect stimulation of soil organisms by biochar or (iii) abiotic release of biochar-C (from carbonates or chemi-sorbed CO2). Observed biphasic mineralization rates suggest rapid mineralization of labile biochar compounds by microorganisms, with stable aromatic components decomposed at a slower rate. Comparatively little information is available on the impact of soil fauna on biochar stability in soil, although they may decrease biochar particle size and enhance its dispersion in the soil. Elucidating the impacts of soil fauna directly and indirectly on biochar stability is a top research priority.
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TL;DR: An overview of biochar production technologies, biochar properties, and recent advances in the removal of heavy metals, organic pollutants and other inorganic pollutants using biochar is provided.
1,301 citations
Cites background from "Interactions between biochar stabil..."
...…its application in soil, technical, economical, and climate-related aspects of biochar (Atkinson et al., 2010; Beesley et al., 2011; Duku et al., 2011; Jeffery et al., 2011; Lehmann et al., 2011; Meyer et al., 2011; Manyà, 2012; Ameloot et al., 2013; Gurwick et al., 2013; Stavi and Lal, 2013)....
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...The available peer-reviewed scientific literatures about the biochar are mainly concerned about its application in soil, technical, economical, and climate-related aspects of biochar (Atkinson et al., 2010; Beesley et al., 2011; Duku et al., 2011; Jeffery et al., 2011; Lehmann et al., 2011; Meyer et al., 2011; Manyà, 2012; Ameloot et al., 2013; Gurwick et al., 2013; Stavi and Lal, 2013)....
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TL;DR: In this article, a meta-analysis revealed that slow pyrolyzed biochars produced from various feedstocks at temperatures from 300°C to 600°C consistently increased some physico-chemical properties (i.e., pH, cation exchange capacity and aggregation) and microbial parameters (e.g., abundance and community structure of microorganisms) in a vast number of soils during short (≤90 days) laboratory incubations and longer (1-3 years) field studies.
842 citations
Cites background or result from "Interactions between biochar stabil..."
...…was evident across a variety of soil textural classes (i.e., clay loam, silt loam, loamy sand, sandy loam, Kolb et al., 2009; Luo et al., 2013; Ameloot et al., 2013a; Sun et al., 2013; Domene et al., 2014; Wang et al., 2014) during 90–1095 days in controlled or in field conditions with…...
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...In contrast, Ameloot et al. (2013a) reported a 29% increase in MBC (P < 0.05) in sandy loam soil amended with willow wood biochar produced at 700 C during 117 days of pot experiment....
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...Available data reveals a variable effect of biochars on extracellular enzyme activities (Bailey et al., 2011; Awad et al., 2012; Daquan et al., 2012; Paz-Ferreiro et al., 2012; Ameloot et al., 2013a; Masto et al., 2013)....
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...An increase in soil pH following biochar application is frequently reported for across many soil types (e.g., Glaser et al., 2002; Ameloot et al., 2013a; Farrell et al., 2013; Masto et al., 2013; Stewart et al., 2013; Chintala et al., 2014b; Xu et al., 2014)....
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...This point is supported by Ameloot et al. (2013a), who reported a 47% reduction in dehydrogenase activity with biochar produced at 700 C, and a 73% increase in dehydrogenase activity with biochar produced at 350 C during a 117 days laboratory study....
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TL;DR: In this article, a meta-analysis of the biochar decomposition in soil was performed and the authors concluded that only a small part of biochar is bioavailable and that the remaining 97% contribute directly to long-term carbon sequestration in soil.
Abstract: The stability and decomposition of biochar are fundamental to understand its persistence in soil, its contribution to carbon (C) sequestration, and thus its role in the global C cycle. Our current knowledge about the degradability of biochar, however, is limited. Using 128 observations of biochar-derived CO2 from 24 studies with stable (13C) and radioactive (14C) carbon isotopes, we meta-analyzed the biochar decomposition in soil and estimated its mean residence time (MRT). The decomposed amount of biochar increased logarithmically with experimental duration, and the decomposition rate decreased with time. The biochar decomposition rate varied significantly with experimental duration, feedstock, pyrolysis temperature, and soil clay content. The MRTs of labile and recalcitrant biochar C pools were estimated to be about 108 days and 556 years with pool sizes of 3% and 97%, respectively. These results show that only a small part of biochar is bioavailable and that the remaining 97% contribute directly to long-term C sequestration in soil. The second database (116 observations from 21 studies) was used to evaluate the priming effects after biochar addition. Biochar slightly retarded the mineralization of soil organic matter (SOM; overall mean: −3.8%, 95% CI = −8.1–0.8%) compared to the soil without biochar addition. Significant negative priming was common for studies with a duration shorter than half a year (−8.6%), crop-derived biochar (−20.3%), fast pyrolysis (−18.9%), the lowest pyrolysis temperature (−18.5%), and small application amounts (−11.9%). In contrast, biochar addition to sandy soils strongly stimulated SOM mineralization by 20.8%. This indicates that biochar stimulates microbial activities especially in soils with low fertility. Furthermore, abiotic and biotic processes, as well as the characteristics of biochar and soils, affecting biochar decomposition are discussed. We conclude that biochar can persist in soils on a centennial scale and that it has a positive effect on SOM dynamics and thus on C sequestration.
654 citations
Cites background from "Interactions between biochar stabil..."
...Biochar may be moved to subsoil by bioturbation or particulate transport (Fig. 5, right; Skjernstad et al., 1999; Ameloot et al., 2013)....
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...It remains unclear, however, to what extent biochar is degraded and what its concomitant effects on native soil organic matter (SOM) turnover and other cascading impacts are (Lehmann et al., 2011; Ameloot et al., 2013; Lorenz & Lal, 2014)....
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...5, right; Skjernstad et al., 1999; Ameloot et al., 2013)....
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Journal Article•
TL;DR: In this paper, the authors investigated the fate of BC applied to a savanna Oxisol in Colombia at rates of 0, 11.6, 23.2 and 116.1 t BC ha -1, as well as its effect on non-BC soil organic C.
Abstract: Black carbon (BC) is an important pool of the global C cycle, because it cycles much more slowly than others and may even be managed for C sequestration. Using stable isotope techniques, we investigated the fate of BC applied to a savanna Oxisol in Colombia at rates of 0, 11.6, 23.2 and 116.1 t BC ha -1 , as well as its effect on non-BC soil organic C. During the rainy seasons of 2005 and 2006, soil respiration was measured using soda lime traps, particulate and dissolved organic C (POC and DOC) moving by saturated flow was sampled continuously at 0.15 and 0.3 m, and soil was sampled to 2.0 m. Black C was found below the application depth of 0-0.1 m in the 0.15-0.3 m depth interval, with migration rates of 52.4 ± 14.5, 51.8 ± 18.5 and 378.7 ± 196.9 kg C ha -1 yr -1 (± SE) where 11.6, 23.2 and 116.1 t BC ha -1 , respectively, had been applied. Over 2 years after application, 2.2% of BC applied at 23.2 t BCha -1 was lost by respiration, and an even smaller fraction of 1% was mobilized by percolating water. Carbon from BC moved to a greater extent as DOC than POC. The largest flux of BC from the field (20-53% of applied BC) was not accounted for by our measurements and is assumed to have occurred by surface runoff during intense rain events. Black C caused a 189% increase in aboveground biomass production measured 5 months after application (2.4-4.5 additional dry biomass ha -1 where BC was applied), and this resulted in greater amounts of non-BC being respired, leached and found in soil for the duration of the experiment. These increases can be quantitatively explained by estimates of greater belowground net primary productivity with BC addition.
622 citations
TL;DR: This review links microbial responses, including microbial activity, community structures and soil enzyme activities, with changes in soil properties caused by biochars, and summarized possible mechanisms that are involved in the effects that biochar-microbe interactions have on soil carbon sequestration and pollution remediation.
551 citations
References
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TL;DR: Recent advances in elucidating the role of root exudates in interactions between plant roots and other plants, microbes, and nematodes present in the rhizosphere are described.
Abstract: The rhizosphere encompasses the millimeters of soil surrounding a plant root where complex biological and ecological processes occur. This review describes recent advances in elucidating the role of root exudates in interactions between plant roots and other plants, microbes, and nematodes present in the rhizosphere. Evidence indicating that root exudates may take part in the signaling events that initiate the execution of these interactions is also presented. Various positive and negative plant-plant and plant-microbe interactions are highlighted and described from the molecular to the ecosystem scale. Furthermore, methodologies to address these interactions under laboratory conditions are presented.
3,674 citations
TL;DR: A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins as mentioned in this paper.
Abstract: Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins. However, no studies exist in the soil biologyliterature that recognize the observed largevariations ofbiochar physico-chemical properties. This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots. Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals. In most studies, microbial biomass has been found to increase as a result of biochar additions, with significant changes in microbial community composition and enzyme activities that may explain biogeochemical effects of biochar on element cycles, plant pathogens, and crop growth. Yet, very little is known about the mechanisms through which biochar affects microbial abundance and community composition. The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms. It is clear, however, that sorption phenomena, pH and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota. Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars. Sorption and therebyinactivation of growth-inhibiting substances likelyplaysa rolefor increased abundance of soil biota. No evidence exists so far for direct negative effects of biochars on plant roots. Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability,reducing theneedfor symbionts.Inthe shortterm,therelease ofavarietyoforganic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota. A road map for future biochar research must include a systematic appreciation of different biochar-types and basic manipulative experiments that unambiguously identify the interactions between biochar and soil biota.
3,612 citations
01 Jan 2007
TL;DR: The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
Abstract: The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to the Chief,
2,969 citations
TL;DR: Results from a 21-year study of agronomic and ecological performance of biodynamic, bioorganic, and conventional farming systems in Central Europe found crop yields to be 20% lower in the organic systems, although input of fertilizer and energy was reduced.
Abstract: An understanding of agroecosystems is key to determining effective farming systems. Here we report results from a 21-year study of agronomic and ecological performance of biodynamic, bioorganic, and conventional farming systems in Central Europe. We found crop yields to be 20% lower in the organic systems, although input of fertilizer and energy was reduced by 34 to 53% and pesticide input by 97%. Enhanced soil fertility and higher biodiversity found in organic plots may render these systems less dependent on external inputs.
2,624 citations
TL;DR: In this paper, the authors reviewed the available information about the physical and chemical properties of charcoal as affected by different combustion procedures, and the effects of its application in agricultural fields on nutrient retention and crop production.
Abstract: Rapid turnover of organic matter leads to a low efficiency of organic fertilizers applied to increase and sequester C in soils of the humid tropics. Charcoal was reported to be responsible for high soil organic matter contents and soil fertility of anthropogenic soils (Terra Preta) found in central Amazonia. Therefore, we reviewed the available information about the physical and chemical properties of charcoal as affected by different combustion procedures, and the effects of its application in agricultural fields on nutrient retention and crop production. Higher nutrient retention and nutrient availability were found after charcoal additions to soil, related to higher exchange capacity, surface area and direct nutrient additions. Higher charring temperatures generally improved exchange properties and surface area of the charcoal. Additionally, charcoal is relatively recalcitrant and can therefore be used as a long-term sink for atmospheric CO2. Several aspects of a charcoal management system remain unclear, such as the role of microorganisms in oxidizing charcoal surfaces and releasing nutrients and the possibilities to improve charcoal properties during production under field conditions. Several research needs were identified, such as field testing of charcoal production in tropical agroecosystems, the investigation of surface properties of the carbonized materials in the soil environment, and the evaluation of the agronomic and economic effectiveness of soil management with charcoal.
2,514 citations
"Interactions between biochar stabil..." refers background or methods in this paper
...Specific surface area varies from a few m2 g−1 to more than 400 m2 g−1 biochar, depending on the feedstock used and pyrolysis conditions (Glaser et al ., 2002; © 2013 The Authors Journal compilation © 2013 British Society of Soil Science, European Journal of Soil Science, 64, 379–390 Hilscher et al…...
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...…produced by pyrolysis, with the intent of improving soil functions while mitigating climate change by sequestering C. Research has shown that biochar can increase soil productivity by improving both chemical and physical soil properties (Glaser et al ., 2002; Lehmann, 2007; Jeffery et al ., 2011)....
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...One factor that should not be overlooked is the potential of biochar additions to increase soil water holding capacity (WHC) (Glaser et al ., 2002; Verheijen et al ., 2010; Jeffery et al ., 2011; Karhu et al ., 2011), thus increasing the suitability of amended soils as a microbial habitat....
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...Sometimes additions can increase the CEC of soils substantially, from 10% to more than 100% of the original CEC, depending on the soil and biochar type and on experimental conditions (Glaser et al ., 2002; Chan et al ., 2008; Steiner et al ., 2008; Van Zwieten et al ., 2010)....
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