Earthworms regulate ability of biochar to mitigate CO2 and N2O emissions from a tropical soil

Namoi, Nictor; Pelster, David E.; Rosenstock, Todd S.; Mwangi, Lukelysia; Kamau, Solomon; Mutuo, Patrick K.; Barrios, Edmundo

doi:10.1016/j.apsoil.2019.04.001

Cited by 14 publications

(8 citation statements)

References 76 publications

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“…In line with our rst hypothesis, we found not only that the presence of earthworms did not increase the CO 2 and N 2 O cumulative emissions over 12 weeks, but also that the endogeic species A. icterica actually reduced the cumulative N 2 O emissions by 44.8% on its own and by 34.6% when the anecic L. terrestris was also present. Whilst our results are in contrast to the conclusion of Lubbers et al ( 2013) meta-analysis and several other studies that emerged after 2013 [11][12][13][14][15] , they are however in line with several other studies indicating that earthworms can have either no signi cant effect 16,20,40 or even offset some of the CO 2 or N 2 O emissions, with two of these studies including soil moisture uctuations 18,19,21,22 . These highly variable ndings stress the very complex relationships between environmental conditions, earthworms and GHG emissions, which can be heavily in uenced by how close the experimental conditions are to natural conditions 20,41 .…”

Section: Discussioncontrasting

confidence: 74%

“…Such consideration may affect the choice of soil biodiversity-friendly agricultural policies that increase earthworm biomass such as no-tillage, super cial tillage, reduced pesticide use and organic fertilizer applications. However, although additional studies have been published that support the ndings of Lubbers et al (2013) meta-analysis [11][12][13][14][15] , a substantial number of laboratory 16,17 and eld studies included in the Lubbers et al ( 2013) meta-analysis as well more recent ones [18][19][20][21][22] are not in line with the overall conclusion that earthworms increase GHG emissions. Collectively, these observations suggest that we do not fully understand the factors thought which earthworms affect CO 2 and N 2 O emissions, calling for additional studies addressing some of the limitations of the previous studies in order to gain a mechanistic understanding of the factors leading to contrasting results.…”

Section: Introductionmentioning

confidence: 99%

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No evidence that earthworms increase soil greenhouse gas emissions (CO 2 and N 2 O) in the presence of plants and soil moisture fluctuations

Ganault

Nahmani

Capowiez

et al. 2022

Preprint

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Earthworms can stimulate plant productivity, but their impact on soil greenhouse gases (GHG) is still debated. Methodological challenges of measuring GHG in experiments with plants are presumably contributing to the status quo, with the majority of studies being conducted without plants. Here we report the effect of earthworms (without, anecic, endogeic and their combination) and plants (with and without) on GHG (CO2 and N2O) emissions in an experiment. N2O emissions were also 34.6 and 44.8% lower when both earthworm species and only endogeic species were present, respectively, while plants reduced the cumulative N2O emissions by 19.8%. No effects on CO2 were found. Estimates of soil macroporosity measured by X-ray tomography show that the GHG emissions were mediated by their burrowing activity affecting the soil aeration and water status. Both GHG emissions decreased with the macropore volume in the top soil, presumably due to reduced moisture and microbial activity. N2O emissions also decreased with macropore volume in the deepest layer, likely caused by a reduction in anaerobic microsites. Our results indicate that, under experimental conditions allowing for plant and earthworm engineering effects on soil moisture, earthworms do not increase GHG emissions and that endogeic earthworms may even reduce N2O emissions.

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Section: Discussioncontrasting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

No evidence that earthworms increase soil greenhouse gas emissions (CO 2 and N 2 O) in the presence of plants and soil moisture fluctuations

Ganault

Nahmani

Capowiez

et al. 2022

Preprint

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“…Other geo-environmental parameters, including climate [70], topography [71], soil microorganisms [72,73], and soil management practices such as tillage, irrigation, and fertilization [74], also affected the content of soil carbon. Namoi et al (2019) suggested that the presence of earthworms in biochar-amended soils at a loading of 25 tonne/ha suppressed greenhouse gases emissions (e.g., N 2 O) [75]. Wiesmeier et al (2019) demonstrated that general topographic parameters, namely, the topographic wetness index, affected CO 2 sequestration on a much smaller (e.g., regional) than larger (e.g., sub-continental) scale of applications [76].…”

Section: Inorganic Carbonsmentioning

confidence: 99%

The Role of Biochar in Regulating the Carbon, Phosphorus, and Nitrogen Cycles Exemplified by Soil Systems

Pan

Dong

et al. 2021

Sustainability

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Biochar is a carbon-rich material prepared from the pyrolysis of biomass under various conditions. Recently, biochar drew great attention due to its promising potential in climate change mitigation, soil amendment, and environmental control. Obviously, biochar can be a beneficial soil amendment in several ways including preventing nutrients loss due to leaching, increasing N and P mineralization, and enabling the microbial mediation of N2O and CO2 emissions. However, there are also conflicting reports on biochar effects, such as water logging and weathering induced change of surface properties that ultimately affects microbial growth and soil fertility. Despite the voluminous reports on soil and biochar properties, few studies have systematically addressed the effects of biochar on the sequestration of carbon, nitrogen, and phosphorus in soils. Information on microbially-mediated transformation of carbon (C), nitrogen (N), and phosphorus (P) species in the soil environment remains relatively uncertain. A systematic documentation of how biochar influences the fate and transport of carbon, phosphorus, and nitrogen in soil is crucial to promoting biochar applications toward environmental sustainability. This report first provides an overview on the adsorption of carbon, phosphorus, and nitrogen species on biochar, particularly in soil systems. Then, the biochar-mediated transformation of organic species, and the transport of carbon, nitrogen, and phosphorus in soil systems are discussed. This review also reports on the weathering process of biochar and implications in the soil environment. Lastly, the current knowledge gaps and priority research directions for the biochar-amended systems in the future are assessed. This review focuses on literatures published in the past decade (2009–2021) on the adsorption, degradation, transport, weathering, and transformation of C, N, and P species in soil systems with respect to biochar applications.

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“…An incubation study with 4 contrasting soils and oil mallee, wheat chaff, and poultry litter biochars resulted in Tenosol soil having the highest mitigation of N 2 O in that biochar limited the availability of NO 3− with the resultant rise in N 2 O including liming and increased microbial respiration [48]. Biochar used in an experiment to mitigate CO 2 and N 2 O from agricultural soils suppressed N 2 O at moderate levels without earthworms, and CO 2 and N 2 O emissions in the presence of earthworms increased, which was influenced by biochar type and application rates [189]. It was concluded that normal agricultural conditions suppress N 2 O under high biochar application and heightens CO 2 emissions [189].…”

Section: Ghgs Emissionmentioning

confidence: 99%

“…Biochar used in an experiment to mitigate CO 2 and N 2 O from agricultural soils suppressed N 2 O at moderate levels without earthworms, and CO 2 and N 2 O emissions in the presence of earthworms increased, which was influenced by biochar type and application rates [189]. It was concluded that normal agricultural conditions suppress N 2 O under high biochar application and heightens CO 2 emissions [189]. Biochar amendment can affect bacteria composition of N 2 Oreducing functional microbial traits in soil [39].…”

Section: Ghgs Emissionmentioning

confidence: 99%

Risk Evaluation of Pyrolyzed Biochar from Multiple Wastes

Ndirangu

Liu

et al. 2019

Journal of Chemistry

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This paper aims at demonstrating the significance of biochar risk evaluation and reviewing risk evaluation from the aspects of pyrolysis process, feedstock, and sources of hazards in biochar and their potential effects and the methods used in risk evaluation. Feedstock properties and the resultant biochar produced at different pyrolysis process influence their chemical, physical, and structural properties, which are vital in understanding the functionality of biochar. Biochar use has been linked to some risks in soil application such as biochar being toxic, facilitating GHGs emission, suppression of the effectiveness of pesticides, and effects on soil microbes. These potential risks originate from feedstock, contaminated feedstock, and pyrolysis conditions that favor the creation of characteristics and functional groups of this nature. These toxic compounds formed pose a threat to human health through the food chain. Determination of toxicity levels is a first step in the risk management of toxic biochar. Various sorption methods of biochar utilized low-cost adsorbents, engineered surface functional groups, and nZVI modified biochars. The mechanisms of organic compound removal was through sorption, enhanced sorption, modified biochar, postpyrolysis thermal air oxidation and that of PFRs degradation was through activation, photoactive functional groups, magnetization, and hydrothermal synthesis. Emissions of GHGs in soils amended with biochar emanated through physical and biotic mediated mechanisms. BCNs have a significance in reducing the health quotient indices for PTEs risk contamination by suppressing cancer risk arising from consumption of contaminated food. The degree of environmental risk assessment of HM pollution in biomass and biochars has been determined by using potential ecological risk index and RAC while organic contaminant degradation by EPFRs was considered when assessing the environmental roles of biochar in regulating the fate of contaminants removal. The magnitude of technologies’ net benefit must be considered in relation to the associated risks.

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Earthworms regulate ability of biochar to mitigate CO2 and N2O emissions from a tropical soil

Cited by 14 publications

References 76 publications

No evidence that earthworms increase soil greenhouse gas emissions (CO 2 and N 2 O) in the presence of plants and soil moisture fluctuations

No evidence that earthworms increase soil greenhouse gas emissions (CO 2 and N 2 O) in the presence of plants and soil moisture fluctuations

The Role of Biochar in Regulating the Carbon, Phosphorus, and Nitrogen Cycles Exemplified by Soil Systems

Risk Evaluation of Pyrolyzed Biochar from Multiple Wastes

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