Open access peer-reviewed chapter
Abstract
The emerging concerns in sub-Saharan Africa are non-sustainability of agricultural and soil management practices threatening food security and environmental safety. Biochar, solid material obtained from thermochemical conversion of plants and/or animal biomass in an oxygen limited environment, is of great importance both agriculturally and environmentally. This chapter reviews the contributions of “biochar technology” to environmental sustainability and food security. This strategy addresses the declining food security issues, depleting soil and plant health challenges. When properly exploited, biochar will enhance soil fertility recovery, guarantee resilience to climate change challenges, and satisfy food production needs of growing global population. The positive impacts of biochar utilization on soil beneficial organisms in harnessing and controlling pests and diseases as well as revitalization of ecological niche make it a preferred option. Unfortunately, there is dearth of information on biochar mechanism to enhance bioremediation technology, which is still facing some challenges that need attention for adequate soil remediation. Many researchers have demonstrated bioremediation in laboratory scale under controlled environmental conditions; it may however be very problematic to establish the growth/survival of these biological entities in situ on heavily polluted soil where the environmental conditions cannot be controlled.
Keywords
- biochar
- plant productivity
- environmental safety
- bioremediation
- food security
1. Introduction
Food security and environmental safety are the emerging concern in sub-Saharan Africa due to non-sustainable agricultural and soil management practices [1]. Thus, giving rise to the limiting influence of biotic and abiotic stress factors on the plant and soil health [2]. Asides the resulting declined in agricultural production, the contributory effect of soil contamination by industrial pollution and excessive use of chemical in agriculture presently constitute a threat to food security and environmental safety. Therefore, this review examined the prospects of biochar in the sustainable agricultural production, plant protection and soil restoration. Biochar is a solid waste material obtained from thermochemical conversion of plant or animal biomass or both in an oxygen limited environment [3]. The thermal process is carried out on sources of biomass including agricultural wastes, green-waste, and animal manures (biomass feedstock) at temperatures ranging from 200 to 900°C [4, 5]. Biochar addition to soils was engineered by Amazonian terra preta soils, which were characterized by high levels of fertility as compared to adjacent soils where no organic carbon addition occurred [6]. The overall benefit of biochar to environment and production systems is based on three sustainability factors; use of sustainable biomass, sustainable production processes, and sustainable end-use [7]. While the main applications which prompted its recent scientific research include: its mitigation of climatic change, efficient and cost effective waste management, and the use of biochar as amendment to improve soil quality and sustain crop yield [8, 9]. Therefore, biochar amended soil causes alterations in soil health and this encompasses physical, chemical and biological features while it as well maintains the functions of both natural and managed ecosystems essential for sustainable agricultural fertility and productivity [10, 11].
2. Interaction of biochar with soil, plant, and microorganisms
2.1 Interactions between biochar and soil
Biochar exhibits natural oxidation through the formation of functional groups, thereby providing sites that can retain nutrients and other organic compounds [12]. Through the association of biochar particles with clay and silt-sized minerals, oxidized biochar particles may be bound to soil minerals, thereby decreasing the potential of its decomposition [13]. Hence, enhancing the ability of soil biochar complex to adsorb organic compounds present in the soil while biochar also interact directly with organic matter of soil by sorption [14]. Generally, soil health are restored with amendments by balancing its pH, increasing organic matter content and water holding capacity, re-establishing microbial communities, alleviating compaction and structure thereby allowing establishment of vegetation, recreate ecological function of soils, decrease bioavailability of toxic pollutants, leachability and mobility of contaminants, erosion, improve soil drainage and reduce costs compared to traditional remediation techniques [15]. The cations in biochar after pyrolysis are transformed into oxides, hydroxides, and carbonates (ash) which act as liming agents when applied to soil. Biochar is composed of low density material that reduces soil bulk density, thereby increasing water infiltration, root penetration, soil aeration and aggregate stability [16]. Biochar amendments on soil have positive effects on nutrient retention, particularly in highly weathered soils with low ion-retention capacities [17]. Biochar application to medium and coarse textured soils increased soil water holding capacity when analyzed [18]. Thus, biochar serves as soil amendment and carbon sequestration medium [19].
2.2 Impact of biochar on nitrogen fixation
Biochar as soil amendment enhances the biological nitrogen fixation, the nitrogen available in soil is usually lower than that of the biochar due to the high carbon/nitrogen (C/N) ratio of the biochar, and the resulting N immobilization [17, 19], as well, contains higher availability of nutrients, N, and almost neutral pH value [20]. Combination of factors related to soil nutrient availability and simulation of plant microbe interaction, along with nitrogen/nutrient levels also increases when biochar was applied to soil resulting in increased colonization of the host plant roots by
2.3 Effect of biochar application on plant productivity
The prevailing scientific understanding of biochar degradation in soils is that some portions of it are quite readily decomposable, while the core structure of the material is highly resistant to degradation. However, biochar promotes plant productivity and yield through several mechanisms, it changes the physical conditions of plants; its dark color alters thermal dynamics and facilitates rapid germination, allowing more time for growth compared with biochar un-amended soil [23]. Although, there are no specific recommended application rates for any soil but amendment of soils must be done based on extensive field testing. Chan et al. [24] reported that application of 5–50 tons of biochar per hectare, with appropriate nutrient management had positive effects on crop yields. Single application of biochar can provide beneficial effects over several growing seasons in a field due to its recalcitrance to decomposition in soil [25]. Therefore, biochar does not need to be applied in all cropping season, as is usually the case for manures, compost, and synthetic fertilizers. It effects on yield also occur as a result of changes in soil nutrition, water holding capacity and microbial activity and these effects vary due to soil type [26].
Many researcher has affirm the importance of biochar in plant growth enhancement, hardwood biochars and poultry manure biochars possesses nutrients, such as, high N content, which often enhance positive yield increases [26]. Petter et al. [27] reported that
Combined application of pine woodchip biochar at the rates of 5 and 10 mg/ha with N fertilizer to a fertile silt loam soil in northwest Arkansas significantly increased corn yield compared to sole application of N fertilizer [30]. Combined application of biochar with cow urine to the root zone of pumpkin also significantly increased pumpkin yield compared to all other soil amendment treatments. Ndor et al. [31] reported that rice husk and sawdust biochar significantly increased N, P and K uptake by maize plant, and also significantly increased maize number of leaves, plant height, fresh and dry weight of cobs. In another study, amendment of an alkaline soil with biochar derived from vegetable waste and
Figure 1.
Effect of biochar on the soil mineral component. Source: Bamboo biochar—Bio-organic fertilizer [
2.4 Effects of combined application of biochar and fertilizer
Application of biochar in combination with fertilizer to soil has been found to have positive effects on crop growth, this was probably due to the positive interaction between biochar and applied fertilizer that improved the availability of nutrients associated with enhanced plant uptake and reduced losses of these nutrients [25, 35, 36]. Most biochar materials are not substitutes for fertilizer, so adding biochar without necessary amounts of nitrogen (N) and other nutrients cannot be expected to provide improvements to crop yield [21]. Application of
3. Role of biochar in sustainable plant disease management
3.1 Plant disease management: the good and the bad
Due to the increasing global population, there is an ever increasing desire to increase agricultural efficiency in terms of producing maximum crop yields and produce. This is only achievable if pest and disease agents limiting crop productions are adequately checked. Cultural, biological, chemical and regulatory measures are the key methods of plant disease management. Since its introduction over a century ago, chemical method had assumed a position of importance and preferred over the existing cultural method due to its effectiveness in the control of diseases, pests or weeds. The relatively low cost of the chemicals, the ease with which they can be applied, availability, stability and fast-acting limits the damage done to crops. However, with the realization of the havoc caused by continuous and persistent use of chemicals either by misuse or abuse, with the consequent degradation of ecological community of most of the farm sites based on their effects on both the target and non-target organisms, has led to the destruction of beneficial organisms and the natural predator in the eco-system. They also obstruct the normal functioning of the ecosystem if the pests and organisms’ develop resistance to the chemicals used, thus resulting in pests evolution. However, agricultural workers often suffer occupational exposure to pesticides while exposure of the entire population is exposed to pesticides pollution primarily through the food chain and drinking water contaminated with pesticide residues which are carcinogenic [38, 39].
3.2 Biological control: novel strategy to safe agricultural practices
Humanity does not only dependent on the direct contributions of microbes within our bodies but also on the way they shape and maintain essential functions of our environment, including agricultural production systems where they provide “ecosystem services”. Therefore, the use of biological control in the management of pest and diseases pre-dates the modern pesticide era [40]. The host specificity, longer residual effect and non-toxicity to human and the environment makes biological control a novel strategy to safe agricultural practices and sustenance of the ecosystem structure [40]. Some of the control measures that have been widely explored in the management of plant pathogens include the use of beneficial organisms [41]. These are mostly members of the bacterial genera
3.3 Influence of biochar on soil biota
Soil biota is important to the functioning of soils and provides many essential ecosystem services. According to Wuddivira et al. [49], biochar amended soil provides suitable pH for the growth of microbes, especially fungal hyphae due to its porosity. Application of biochar into soils leads to initial degradation of biochar by chemical oxidation and microbial processes [50]. These processes that influence the energy flow and organic matter within the soil will impinge on bacterial and fungal-based energy channels, which will have impact at higher trophic levels [51]. Biochar and earthworms increased the availability of mineral nutrients in growing seedlings suggesting that this mechanism played important role [52]. Microbial population could be higher in black carbon rich soil, thus the interaction between biochar as a soil amendment approach plays a vital role in soil biota [53]. More so, biochar amendment resulted in increased soil microbial biomass and changes in the composition of soil microbial community [54].
3.4 Biochar: the refuge for microorganisms
Biochar provides “sanctuary” for microorganisms experiencing harsh environmental conditions and also provide a more habitable space for their proliferation. The types of biochar and soil environment are factors that are vital to how the char will affect the soil microbiota [41, 55]. The ability of biochar to act as refuge for soil microorganisms from their predators; protozoa, beneficial nematodes, and microarthropods was affirmed in the report of Verheijen et al. [56] which showed the electron microscopic images of bacteria and fungi on the surface or inside biochar pores. The larger biochar pores which are mostly the structural remnants of wood xylem, phloem vessels and other larger features have diameters >10 μm [57]. According to IUPAC conventions, biochar porosity has been classified by distinguishing between; micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm) [58, 59]. Whereas, the organisms that predate soil bacteria, including protozoa and nematodes, have diameters <10 μm therefore making access to the larger pores relatively easy [57]. Further protection from predation offered to the microbes by biochar has been associated with the hydrophobic adsorption of biochar although the hydrophobicity can decrease over time. Some microorganisms can be strongly attached to hydrophobic surfaces which create biofilms of several bacterial layers thick [57, 59].
3.5 Role of biochar in environmental safety and sustainable agriculture
The benefits of biochar on crop productivity and plant health have been related to four main mechanisms which include; increase in soil pH which is beneficial to acidic soils [18]. Biochar’s high water retention capacity results to improvement of water regime of the soil, this is of special advantage to sandy soil area where biochar will reduce the leaching away of moisture, thereby reducing water loss, while it reduces the risk of water-logging in clay soil by promoting water drainage [60, 61]. The third mechanism is associated with the capability of biochar to adsorb and neutralize phytotoxic organic molecules including anthropogenic, xenobiotics and natural allelopathic compounds. This detoxifying capability is directly related to the dramatic increases of specific surface area that occur during pyrolysis [62, 63, 64, 65]. The fourth mechanism is related to its capability to stimulate beneficial microbes, in bulk soil as well as in the rhizosphere [66]. By serving as a source of reduced carbon compounds and by increasing the availability of micronutrients, biochar may be beneficial to microbial populations, such as,
3.6 Biochar-microbe interaction: mode of action in plant disease control
Treatments with resistance inducers or beneficial microorganisms have been reported to provide long-lasting resistance for plants to a wide range of pathogens [72]. More so, induced resistance can be also conferred by plant-associated microorganisms, including beneficial bacteria and/or fungi [41]. Biochar does not have an indigenous population of microorganisms that can potentiate disease suppression, due to the high thermal treatment in its production [7]. However, its addition influences microbial populations and communities, thus causing changes which may include increase in beneficial microorganisms that directly protect plants against soil pathogens by; producing antibiotics, out-competing the pathogens, or grazing on the pathogens [7, 9, 73]. Investigations conducted on biochar and microbe interaction collated by Bonanomi et al. [9] proposed five different mechanisms by which biochar mitigate against plant diseases and these include: (i) induction of systemic resistance in the host plants; (ii) enhanced abundance and/or activities of beneficial microbes; (iii) modification of soil quality in terms of nutrient availability and abiotic conditions; (iv) direct fungitoxic effects of biochar; (v) sorption of allelopathic and phytotoxic compounds. This attributes have been further verified in some of the recent investigations [19, 72, 74, 75], thus biochar is an evolving strategy and a potent tool in plant pathology research, Figure 2. Therefore, biochar is gaining importance day by day as its application touches all facet of agriculture and has attracted tremendous attention in the practice of sustainable agriculture.
Figure 2.
Spatial association and colonization of biochar by microorganisms (a) fresh biochar showing fungal hyphae; (b) fresh corn biochar showing microorganisms in pores (arrows); (c) 100-year-old char from a forest fire isolated from a frigid entic Haplorthod; (d) 350-year-old char from a forest fire in a boreal forest soil. Source: Lehmann et al. [
3.7 Biochar interaction with mycorrhizae
Biochar and
4. Effects of biochar application on greenhouse gases
Global surface temperature has increased by 0.8°C in the last century primarily because of increased anthropogenic emissions of long-lived greenhouse gases (GHGs), such as, carbon (iv) oxide (CO2), nitrous oxide (N2O) and methane (CH4). Greenhouse gases are those that adsorb and emit radiation within the thermal infra-red range [77]. Application of biochar to soils can impact soil GHG fluxes by changing the composition and activity of soil microbes, soil pH and soil biogeochemical processes [24]. Effects of biochar amendment on soil GHG fluxes depend on the study conditions, duration of the experiment, biochar application rate, biochar feedstock and pyrolysis methods [78].
4.1 Effects of biochar application on soil CO2 emissions
Soil CO2 emissions can be derived from native soil organic matter, the mineralization of added carbon compounds (such as, dead plant material), root exudates or dead roots and the direct respiration from plant roots [79]. Lehmann et al. [19] suggested that a co-benefit of biochar amendment is a reduction of soil CO2 emissions and associated long-term increases in soil organic carbon (SOC) in the soil. Although the mechanisms governing the effects of biochar amendment on soil CO2 emission are uncertain, some authors suggested that increased CO2 emissions from soil might be as a result of the following mechanisms: biochar reduces the albedo of the soil increasing soil temperature; addition of liable carbon, increased substrate for soil carbon mineralizing enzymes [80]; agglomeration of soil carbon, microbes, nutrients on biochar surface and increased carbon use efficiency; reduction of carbon mineralizing enzymes activity and soil-derived CO2 precipitation onto the biochar surface as carbonates [81]. Wang et al. [82] reported that addition of wheat derived-biochar to acidic soil increased soil organic C and CO2 efflux on average by 61 and 19%, respectively.
4.2 Effects of biochar application on soil N2O emissions
Nitrous oxide is produced in soils primarily by microbial activity through nitrification, nitrifier denitrification, NO3 ammonification and denitrification [83]. Biochar amendment to soil can have significant effects on soil N2O emissions; however, the magnitude of effect varies widely. According to Yanai et al. [84] and Stewart et al. [85] short-term laboratory incubations have shown that biochar amendment can suppress soil N2O emissions, while Spokas [86] and Jones et al. [87] concluded that soil N2O emissions were not suppressed with biochar amendment in the longer term (up to 3 years after biochar addition). Biochar amendment causes changes to a range of soil physical and chemical properties that regulate N-cycling processes [86]. Some authors have explained the mechanisms of the effects of biochar amendment on soil N2O emission and these include: increased water holding capacity and decreased bulk density of the soil, increased soil aeration thereby reducing the activity of denitrifying microorganisms [84, 88], reduced N substrate for nitrifying and denitrifying enzymes thereby reducing enzymatic activities of soil microbes as a result of immobilization of soil inorganic N through absorption to biochar surface or increasing microbial immobilization [86], the N2O:N2 emission ratio produced during denitrification decreases as a result of increased soil pH [89]; N2O:N2 product ratio of denitrification is reduced by increased effects to the soil [90], reduced activity of soil nitrifying/denitrifying organisms through substances emitted by the biochar, such as, ethylene, α-pinene, PAHs, VOCs [91]. Rondon et al. [92] reported that biochar amendment reduced N2O emissions from pasture land and soybean soil by 80 and 50% respectively, because microbial conversion and denitrification were restricted. Application of biochar at a rate of 40 t/ha decreased N2O emission from paddy rice and maize fields by 21–28 and 10.7–41.8%, respectively but increased CH4 emission from a paddy rice field by 41% and CO2 emission from a maize field by 12% [93, 94]. Cayuela et al. [95] reported that biochar reduced soil N2O emissions by 28% in a similar field. Wang et al. [82] reported that addition of wheat derived biochar to acidic soil did not affect the annual N2O emissions (26–28 kg N/ha), but reduced seasonal N2O emissions during the cold period. Fan et al. [96] reported that biochar amendments generally stimulated the NH3 emissions with greater enhancement from wheat straw biochar than swine manure biochar.
4.3 Effects of biochar application on soil methane (CH4) emissions
Methane are produced by methanogens as a metabolic by-product of organic matter mineralization in anaerobic conditions; the two primary pathways being through CO2 reduction by H2 or through acetotrophy [97]. Soil methanotrophs are the only known biological sink for atmospheric methane, which oxidize methane and produce CO2 as a by-product [98]. Soil methanotrophs require oxygen as a terminal electron acceptor and their activity is highest around 60% water-filled pore space (WFPS) and decreases above this moisture content [88, 99]. Zhang et al. [93] and Wang et al. [100] reported that there are limited evidence to suggest that biochar amendment affects soil CH4 emissions, and evidence that supports it are mostly from studies in rice paddies. In saturated soils, such as, rice paddies but not in other aerobic crop soils, CH4 emissions are generally significant [97]. Increased availability of liable C substrates for methanogenic bacteria may explain increased methane emissions following the addition of biochar to soil [100]. Soil CH4 emissions were increased by 37% with biochar amendment in a paddy rice field [100]. Similar observation of an increase in soil CH4 emission from the same land use were also reported by Zhang et al. [93] and Knoblauch et al. [101]. Increased in soil methane uptake within arable soils following biochar amendment was observed by Karhu et al. [88]. In similar studies, with other crop types, no significant effect of biochar amendment on CH4 emissions in arable and pasture soils were reported [100, 102, 103] while in Finnish agricultural soil, a 96% increase in methane uptake was reported in biochar amended soils [88]. Application of biochar to waterlogged paddy rice soil in the laboratory, decreased CH4 and CO2 emissions in the soil and this was attributed to the restriction in methanogen activity and limitation of carbon on microbial biomass, as well as rise of pH value [104]. However, increase in CH4 and CO2 emissions were reported by Ameloot et al [105] and Van Zwieten et al. [106] studying the short-term CO2 and N2O emissions and microbial properties of biochar amended sandy loam soils, and effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soil fertility, respectively.
5. Characterization of biochar as an effective mediator of bioremediation mechanisms
5.1 Biochar as a soil additive to enhance soil restoration/remediation
Soil remediation efforts should be based on feasible, environment friendly and cost effective technologies, and many scientists today are advocating bioremediation mechanisms for meeting these criteria. It has also been widely reported that bioremediation can be enhanced through the use of traditional resources, such as, the application of soil additives. The basis for the use of soil additives during bioremediation is for enhanced bio-stimulation and bio-augmentation; these two mechanisms form the bed-rock for the immense roles of soil additives in bioremediation as reported by many researchers [45, 107, 108, 109, 110, 111, 112]. Biochar applications as a soil additive in contaminated soil is a potential management strategy for feasible and cost effective agricultural sustainability using degraded soils hence improving the food security. Many reports have identified biochar with high sorption capacity for many contaminants including persistent organic pollutants (POPs) and many inorganic pollutants, such as, heavy metals [113, 114]. It was reported, however, that the physicochemical properties of the original crop residue used for biochar preparation may determine its sorption efficiency [115, 116]. However, good knowledge of the pollutant type and its concentration may help in predicting the type of biochar that would be of best fit. Thus it is a crucial factor to clarify the correlation between the sorption efficiency and properties of a particulate. The use of biochar in nutrient sequestration according to Barrow [117] was from the discovery of “terra preta” which is a charcoal-rich fertile soil located at the central Amazon basin that is known for diverse agricultural roles. The importance of such biochar to soil has been reported [28, 105, 117, 118, 119, 120, 121, 122].
In a study by Gomez-Eyles et al., biochar was shown to reduce PAH accumulation in earthworm (
5.2 Biochar as a potential catalyst for phytoremediation
The use of plants for bioremediation is called “phytoremediation”; its success depends on establishment and good development of vegetation on the polluted site brought about by healthy root and shoot biomass [125, 126]. However, the major problem of phytoremediation is the establishment of degree/level of pollution of the polluted site. Many soil pollutants are very persistent, many form complexes with humus and soil nutrients and thus make them unavailable for plant use. In addition early research have reported that many soil pollutants, such as, aromatic and polycyclic hydrocarbons can create anaerobic condition and make seed germination and plant establishment difficult on the polluted soil. However, the use of amendments, such as, organic materials can enhance plant biomass yield and improved plant health growing on polluted sites [1, 111, 127]. The use of biochar for the amendment of polluted soils has been reported to enhance re-establishment of plants and supports massive plant biomass [125, 128]; this is a potential approach for effective phytoremediation mechanism [128]. Prendergast-Miller et al. [129] and Prendergast-Miller et al. [130]. The above reports present biochar as good candidate for positive soil enhancement although this is not yet fully exploited in contaminated sites. Biochar as soil amendment enhances nutrient availability and improves the activities of soil microorganisms around the root rhizosphere for effective nutrient mobilization for root uptake [116, 131, 132, 133]. This promotes root expansion and hence has potential to support phytoremediation. It was reported that plant growing on polluted soil may develop some disease malformations due to their response to the toxic pollutants [111] and reduced resistance to pests.
Biochar has however been reported to increase plant resistance to several soil and air-borne pathogen, it was reported that biochar stimulates several plant’s defense pathways and related gene expression [7, 134, 135]. Biochar has also been well reported for its pH enhancement capacity as it enhances the soil CEC [136, 137, 138, 139] and minimizes salt toxicity in polluted soils (142). According to Cheng and Lehmann [140] and Singh et al. [115], biochar is able to oxidize in soil to raise its carbon exchange capacity (CEC) as it disintegrates during tilling and weathering and there are some commercially available biochar purposefully used as soil nutrient enhancement. This can be very helpful in the enhancement of plants health during phytoremediation. Many researches have suggested the combination of phytoremediation with biochar for effective soil remediation. Hartley et al. [141] and Fellet et al. [142] reported that biochar’s combined use with
5.3 Biochar as a potential catalyst for enhancement of microbial response and bioremediation
The nutrient and soil amendment capability of biochar cannot be overemphasized. The fact that biochar improves soil nutrients means that it has some beneficial effects on the soil microbiota, this has been well studied [115], Ippolito et al. [144, 145] and Kuppusamy et al. [146] and they reported that biochar amendment was found to enhance increment in microbial biomass, diversity and enzyme activities [14, 147, 148]. Biochar was thought to increase bacterial and fungal population as they easily form pore habitats in biochar, although the mechanism could be varied but the overall effect might be as a result of nutrient recycling and soil water retention as enhanced by the biochar and this of course increases the resources available for the microbes to use.
Furthermore, microbial community shifts brought about by biochar amendments may vary due to particular characteristics, microbial response to soil conditions set by the biochar treatments, especially based on the biochar surface characteristics and its bioavailable compounds, as well as well as pH changes induced by the treatment [149]. Zimmerman et al. [80], for example, reported an increase in C mineralization in soil treated with biochar that was made from grasses under low temperatures of 250–400° C compared to biochar that was made from hard woods under higher temperatures of 525–600°C. In another study, Steinbeiss et al. [150] explained that fungi adapted more with biochar that was created from yeast but Gram-negative bacteria responds well to those created from glucose. Anderson et al. [151] reported varying results in microbial population dynamics due to different biochar treatments. The exploitation of biochar to increase microbial population for faster bioremediation requires complete understanding of the relationship of a particular biochar to be used and the type of native or introduced bacteria or fungi involved. Theoretically, biochar is not a degrading substrate and therefore cannot be degraded by microbes [149, 152]; however, it has a potent labile C source in itself [153]. When used in soil, biochar adsorbs active enzymes and nutrients and make them available for usage by microorganisms [154].
5.4 Prospects of biochar as a potential mediator for synergistic bioremediation mechanisms
Interest in combining different biodegradation mechanisms, such as, the use of plant and microbial communities for effective synergistic bioremediation has been vogue in some years past. It is believed that bioremediation which provides an environmentally friendly mechanism has gained acceptance by scholars and environmental managers. Biochar is a synergistic bioremediation mechanism known to yield speedy soil remediation if correctly implemented [155]. The synergistic combination of two or more biological entities for effective soil bioremediation requires that the two or more organisms to be combined must integrate well and can coexist together leading to exchange of mutual benefits between one another. This requirement is paramount in such settings as bioremediation such that many researchers have suggested the use of soil supplements/additives to enhance this technology [112, 155]. Having established the importance of biochar for plant and microbes, the smart way therefore is to think about using it for combine plant-microbial bioremediation technology. Nutrient enhancement by biochar fosters root elongation and hence increases the microbial populations in the rhizospheres [18, 156]. It is anticipated that effective combinations of different bioremediation technologies may eventually yield a feasible, speedy and effective means of restoration of many polluted soils, and basic roles of biochar in this area cannot be overlook. However, this requires a good understanding and interest in biochar properties, mode of production and their actions in different polluted environments need to be well studied. Large and small scale laboratory and field trials are needed for proper exploitation of this technology.
6. Conclusion
Considering the arrays of biochar benefits, it is a potentially untapped asset for sustainable soil health. However, the dearth of adequate research and knowledge of biochar use as soil amendment today is a still big gap. This therefore necessitates mechanistic understanding and research to unveil the mechanisms of biochar action on soil health. It would as well enhance knowledge on the optimal rate for a particular biochar application, its quality parameters/suitability to different soil and climatic conditions, in relation to economic factors, feedstock properties and optimize designed pyrolysis conditions needed for its production toward specific end use. In addition, most of the studies on biochar so far are generally based on short term; long-term experiments are needed to understand the effect of biochar aging. Having fulfilled these recommendations, biochar may well be one of the prominent scientific breakthroughs for benefit of mankind.
References
- 1.
Chukwuka KS, Omotayo OE. Soil fertility restoration potentials of Tithonia green manure and water hyacinth compost on a nutrient depleted soil in South Western Nigeria using Zea mays L. as test crop. Research Journal of Soil Biology. 2009;1 (1):20-30 - 2.
Atkinson NJ, Urwin PE. The interaction of plant biotic and abiotic stresses: From genes to the field. Journal of Experimental Botany. 2012; 63 (10):3523-3543 - 3.
International Biochar Initiative.Standardized product definition and product testing guidelines for biochar that is used in soil. IBI biochar standards. 2015. Available from: https://www.biochar-international.org/wp-content/uploads/2018/04/IBI_Biochar_Standards_V2.1_Final.pdf [Last accessed: 21-05-2019] - 4.
Yuan JH, Xu RK. The amelioration effects of low temperature biochar generated from nine crop residues on an acidic Ultisol. Soil Use and Management. 2011; 27 :110-115 - 5.
Conversa G, Bonasia A, Lazzizera C, Elia A. Influence of biochar, mycorrhizal inoculation, and fertilizer rate on growth and flowering of Pelargonium (Pelargonium zonale L.) plants. Frontiers in Plant Science. 2015;6 :429 - 6.
Harder B. Smoldered-earth policy: Created by ancient Amazonian natives, fertile, dark soils retain abundant carbon. Science News. 2006; 169 :133 - 7.
Elad Y, Cytryn E, Harel YM, Lew B, Graber ER. The biochar effect: Plant resistance to biotic stresses. Phytopathologia Mediterranea. 2011; 50 :335-349 - 8.
Sohi SP, Krull E, Lopez-Capel E, Bol R. A review of biochar and its use and function in soil. Advances in Agronomy. 2010; 105 :47-82 - 9.
Bonanomi G, Ippolito F, Scala F. A “black” future for plant pathology? Biochar as a new soil amendment for controlling plant diseases. Journal of Plant Pathology. 2015; 97 (2):223-234 - 10.
Chintala R, Owen R, Kumar S, Schumacher TE, Malo D. Biochar impacts on denitrification under different soil water contents. World Congress of Soil Science. 2014; 6 :157-167 - 11.
Kumar S, Nakajima T, Mbonimpa EG, Gautam S, Somireddy UR, Kadono A, et al. Long-term tillage and drainage influences on soil organic carbon dynamics, aggregate stability, and carbon yield. Soil Science & Plant Nutrition. 2014; 60 :108-118 - 12.
Cheng CH, Lehmann J, Engelhard MH. Natural oxidation of black carbon in soils: Changes in molecular form and surface charge along a climosequence. Geochimica et Cosmochimica Acta. 2008; 72 :1598-1610 - 13.
Brodowski S, John B, Flessa H, Amelung W. Aggregate-occluded black carbon in soil. European Journal of Soil Science. 2006; 57 :539-546 - 14.
Hammes K, Schmidt WI. Changes of biochar in soil. In: Lehmann J, Joseph S, editors. Biochar for Environmental Management: Science and Technology. London: Earthscan; 2009. pp. 169-182 - 15.
U.S. EPA. The Use of Soil Amendments for Remediation, Revitalization and Reuse. Hazardous Waste Clean-up Information System (Clu-In). 2007. Available from: www.Clu-in.org/pub1.cfm - 16.
Laird DA, Fleming PD, Davis DD, Horton R, Wang B, Karlen DL. Impact of biochar amendments on the quality of a typical Midwestern agricultural soil. Geoderma. 2010; 158 :443-449 - 17.
Glaser B, Lehmann J, Zech W. Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal—A review. Biology and Fertility of Soils. 2002; 35 (4):219-230 - 18.
Jeffery S, Verheijen FGA, Van Der Velde M, Bastos AC. A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agriculture, Ecosystems and Environment. 2011; 144 :175-187 - 19.
Lehmann J, Rillig MC, Thies J, Masiello CA, Hockaday WC, Crowley D. Biochar effects on soil biota—A review. Soil Biology and Biochemistry. 2011; 43 :1812-1836. DOI: 10.1016/j.soilbio.2011.04.022 - 20.
Oguntunde P, Fosu M, Ajayi A, Giesen N. Effect of charcoal production on maize yield, chemical properties and texture of soil. Biology and Fertility of Soils. 2004; 39 :295-299 - 21.
Rondon M, Lehmann J, Ramirez J, Hurtado M. Biological nitrogen fixation by common beans ( Phaseolus vulgaris L.) increases with bio-char additions. Biology and Fertility of Soils. 2007;43 :699-708 - 22.
Yamato M, Okimori Y, Wibowo IF, Anshiori S, Ogawa M. Effects of the application of charred bark of Acacia mangium on the yield of maize, cowpea and peanut, and soil chemical properties in South Sumatra, Indonesia. Soil Science and Plant Nutrition. 2006;52 :489-458 - 23.
Genesio L, Miglietta F, Baronti S, Vaccari FP. Biochar increases vine-yard productivity without affecting grape quality: Results from a four years field experiment in Tuscany. Agriculture, Ecosystems and Environment. 2015; 201 :20-25 - 24.
Chan KY, van Zwieten L, Meszaros I, Downie A, Joseph S. Using poultry litter biochars as soil amendments. Australian Journal of Soil Research. 2008; 46 :437-444 - 25.
Steiner C, Teixeira WG, Lehmann J, Nehls T, Macedo JLV, Blum WEH, et al. Long-term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered central Amazonian upland soil. Plant and Soil. 2007; 291 :275-290 - 26.
Spokas KA, Cantrell KB, Novak JM, Archer DA, Ippolito JA, Collins HP, et al. Biochar: A synthesis of its agronomic impact beyond carbon sequestration. Journal of Environmental Quality. 2012; 41 :973-989 - 27.
Petter FA, Madari BE, de Silva MAS, Cameiro MAC, Carvalho MTM, Ben HM Jr, et al. Soil fertility and upland rice yield after biochar application in the. Cerrado Pesq agropec bras Brasília. 2012; 47 (5):699-706 - 28.
Liu X, Zhang A, Ji C, Joseph S, Bian R, Li L, et al. Biochar’s effect on crop productivity and the dependence on experimental conditions: A meta-analysis of literature data. Plant and Soil. 2013; 373 :583-594 - 29.
Hossain MK, Strezov V, Chan KY, Nelson PF. Agronomic properties of wastewater sludge biochar and bioavailability of metals in production of cherry tomato ( Lycopersicon esculentum ). Chemosphere. 2010;78 :1167-1171 - 30.
Brantley KE et al. Pine woodchip biochar impacton soil nutrient concentrations and corn yield in a silt loam in the mid-southern U.S. Agriculture. 2015; 5 (1):30-47 - 31.
Ndor E, Ogara JI, Bako DA, Osuagbalande JA. Effect of biochar on macronutrients release and plant growth on degraded soil of Lafia, Nasarawa State, Nigeria. Asian Research Journal of Agriculture. 2016; 2 (3):1-8 - 32.
Muhammad FQ , Muhammed A, Suhan D, Muhammad KS, Muhammad AA. Effects of various biochars on seed germination and carbon mineralization in an alkaline soil. Pakistan Journal of Agricultural Sciences. 2015; 51 (4):977-982 - 33.
Fru BS, Francis NA, Angwafo TE, Precillia TN. Waterleaf ( Talinum triangulare ) response to biochar application in a humid-tropical forest soil. Journal of Soil Science and Environmental Management. 2017;8 (5):95-103 - 34.
Kammann C, Ratering S, Eckchard C, Muller C. Biochar and hydrochar effects on greenhouse gas fluxes from soils. Journal of Environmental Quality. 2015; 41 :1052-1066 - 35.
Bamboo Biochar—Bio-organic Fertilizer. Biochar. 2019. Available from: https://biochar.co.nz/component/jce/?view=popup&tmpl=component&img=images/BIOCHAR-FILES/BBP-NO.2-Diagram.jpg&title=Process_Diagram&width=500 [Accessed: 22 April 2019] - 36.
Subedi R, Kammann C, Pelissetti S, Taupe N, Bertora C, Monaco S, et al. Does soil amended with biochar and hydrochar reduce ammonia emissions following the application of pig slurry? European Journal of Soil Science. 2015; 66 :1044-1053 - 37.
Raghunath S, Chiara B, Laura Z, Carlo G. Crop response to soils amended with biochar: Expected benefits and unintended risks. Italian Journal of Agronomy. 2017; 12 :161-173 - 38.
Tariq MI, Afzal S, Hussain I, Sultana N. Pesticides exposure in Pakistan: A review. Environment International. 2007; 33 :1107-1122 - 39.
Atreya K. Health costs from short-term exposure to pesticides in Nepal. Social Science & Medicine. 2008; 67 :511-519 - 40.
Bale JS, van Lenteren JC, Bigler F. Biological control and sustainable food production. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 2008; 363 (1492):761-776 - 41.
Egamberdieva D, Wirth S, Behrendt U, Abd Allah EF, Berg G. Biochar treatment resulted in a combined effect on soybean growth promotion and a shift in plant growth promoting rhizobacteria. Frontiers in Microbiology. 2016; 7 :209. DOI: 10.3389/fmicb.2016.00209 - 42.
Berg G. Plant-microbe interactions promoting plant growth and health: Perspectives for controlled use of microorganisms in agriculture. Applied Microbiology and Biotechnology. 2009; 84 (1):11-18 - 43.
Abiala MA, Popoola OO, Olawuyi OJ, Oyelude JO, Akanmu AO, Killani AS, et al. A review: Harnessing the potentials of vesicular arbuscular mycorrhizal (VAM) fungi to plant growth. International Journal of Pure and Applied Sciences and Technology. 2013; 14 (2):61-79 - 44.
Olawuyi OJ, Odebode AC, Olakojo SA, Popoola OO, Akanmu AO, Izenegu JO. Host-pathogen interaction of maize ( Zea mays L.) andAspergillus niger as influenced byArbuscular mycorrhizal fungi (Glomus deserticola ). Archives of Agronomy and Soil Science. 2014;60 (11):1577-1591 - 45.
Chukwuka KS, Okechukwu RU, Umukoro BO, Obiakara MC. Arbuscular mycorrhiza fungi, NPK (15,15,15) and cow dung interaction in sustainable cassava production and food security. Advances in Plants & Agricultural Research. 2017;7 (4):00262 - 46.
Akanmu AO, Popoola AR, Adebare G, Abiala MA, Odebode AC, Adeoye GO. Effectiveness of some plant extracts in the management of tomato pith necrosis caused by Pseudomonas corrugata . International Journal of Organic Agriculture Research and Development. 2012;5 :127-140 - 47.
Akanmu AO, Abiala AM, Aiyelaagbe OO, Olaoluwa OO, Odebode AC. Inhibition of Fusarium pathogens in millet by extracts ofJatropha curcas andMangifera indica . International Journal of Plant Biology & Research. 2014;2 (1):1007 - 48.
Akanmu AO, Olawuyi OJ, Bello OB, Akinbode OA, Aroge T, Oyewole B, et al. Genotypic variations in the inhibitory potentials of four combined botanicals on mycelia growth of Macrophomina phaseolina of cowpea [Vigna unguiculata (L) Walp.]. Tropical Plant Research. 2015;2 (3):257-263 - 49.
Wuddivira MN, Stone RJ, Ekwue EI. Structure stability of humid tropical soils as influenced by manure incorporation and incubation duration. Soil Science Society of America Journal. 2009; 73 :1353-1360 - 50.
Smith P, Gregory PJ, Van Vuuren D, Obersteiner M, Havlik P, Rounsevell M, et al. Competition for land. Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 2010; 365 :2941-2957 - 51.
Atkinson CJ, Fitzgerald JD, Hipps NA. Potential mechanisms for achieving agricultural benefits from biochar application to temperate soils: A review. Plant and Soil. 2010; 337 :1-18 - 52.
Noguera D, Rondon M, Laossi KR, Hoyos V, Lavelle P, Cruz de Carvalho MH, et al. Contrasted effect of biochar and earthworms on rice growth and resource allocation in different soils. Soil Biology and Biochemistry. 2010; 42 :1017-1027 - 53.
Van Der Heijden MG, Bardgett RD, Van Straalen NM. The unseen majority: Soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems. Ecological Letters. 2008; 11 :296-310 - 54.
Birk JJ, Steiner C, Teixeira WC, Zech W, Glaser B. Microbial response to charcoal amendments and fertilization of a highly weathered tropical soil. In: Woods WI, Teixeira WG, Lehmann J, Steiner C, Winkler Prins AMGA, Rebellato L, editors. Amazonian Dark Earths: Wim Sombroek’s Vision. Berlin: Springer; 2009. pp. 309-324 - 55.
Schnee LS, Knauth S, Hapca S, Otten W, Eickhorst T. Analysis of physical pore space characteristics of two pyrolytic biochars and potential as microhabitat. Plant and Soil. 2016; 408 (1-2):357-368. DOI: 10.1007/s11104-016-2935-9 - 56.
Verheijen FGA, Jeffery S, Bastos AC, van der Velde M, Diafas I. Biochar Application to Soils - A Critical Scientific Review of Effects on Soil Properties, Processes and Functions. EUR 24099 EN. Luxembourg: Office for the Official Publications of the European Communities; 2009. pp. 149 - 57.
Shackley S, Ruysschaert G, Zwart K, Glaser B. Biochar in European Soils and Agriculture Science and Practice. Routledge; 2016. 302 pages|95 B/W Illus. pp. 90-94 - 58.
Rouquerol J, Avnir D, Fairbridge CW, Everett DH, Haynes JM, Pernicone N, et al. Recommendations for the characterization of porous solids (technical report). Pure and Applied Chemistry. 1994; 66 (8):1739-1758 - 59.
Gray M, Johnson MG, Dragila MI, Kleber M. Water uptake in biochars: The roles of porosity and hydrophobicity. Biomass and Bioenergy. 2014; 61 :196-205 - 60.
Novak JM, Busscher WJ, Watts DW, Amonette JE, Ippolito JA, Lima IM, et al. Biochars impact on soil-moisture storage in an ultisol and two aridisols. Soil Science. 2012; 177 :310-320 - 61.
Barnes RT, Gallagher ME, Masiello CA, Liu Z, Dugan B. Biochar-induced changes in soil hydraulic conductivity and dissolved nutrient fluxes constrained by laboratory experiments. PLoS One. 2014; 9 (9):e108340 - 62.
Hille M, Den Ouden J. Charcoal and activated carbon as adsorbate of phytotoxic compounds—A comparative study. Oikos. 2005; 108 :202-207 - 63.
Chen B, Zhou D, Zhu L. Transitional adsorption and partition of non-polar and polar aromatic contaminants by biochars of pine needles with different pyrolytic temperatures. Environmental Science & Technology. 2008; 42 :5137-5143 - 64.
Downie A, Crosky A, Munroe P. Physical properties of biochar. In: Lehmann J, Joseph S, editors. Biochar for Environmental Management: Science and Technology. London, UK: Earthscan; 2009. pp. 13-32 - 65.
Ahmad M, Rajapaksha AU, Lim JE, Zhang M, Bolan N, Mohan D, et al. Biochar as a sorbent for contaminant management in soil and water: A review. Chemosphere. 2014; 99 :19-33 - 66.
Thies J, Rilling M, Graber ER. Biochar effects on the abundance, activity and diversity of the soil biota. In: Lehmann J, Joseph S, editors. Biochar for Environmental Management: Science and Technology. 2nd ed. London, UK: Earthscan; 2015 - 67.
Warnock DD, Lehmann J, Kuyper TW, Rilling MC. Mycorrhizal responses to biochar in soil—Concepts and mechanisms. Plant and Soil. 2007; 300 :9-20 - 68.
Graber ER, Harel YM, Kolton M, Cytryn E, Silber A, David DR, et al. Biochar impact on development and productivity of pepper and tomato grown in fertigated soilless media. Plant and Soil. 2010; 337 :481-496 - 69.
Kolton M, Harel YM, Pasternak Z, Graber ER, Elad Y, Cytryn E. Impact of biochar application to soil on the root-associated bacterial community structure of fully developed greenhouse pepper plants. Applied and Environmental Microbiology. 2011; 14 :4924-4930 - 70.
Fischer D, Glaser B. Synergisms between compost and biochar for sustainable soil amelioration. In: Sunil K, Bharti A, editors. Management of Organic Waste. Rijeka, Croatia: In Tech; 2012. pp. 167-198. DOI: 10.5772/31200 - 71.
Schulz H, Dunst G, Glaser B. Positive effects of composted biochar on plant growth and soil fertility. Agronomy for Sustainable Development. 2013; 33 (4):817-827 - 72.
Burketova L, Trda L, Ott PG, Valentova O. Bio-based resistance inducers for sustainable plant protection against pathogens. Biotechnology Advances. 2015; 33 (6), (Part 2):994-1004 - 73.
Matsubara YI, Hasegawa N, Fukui H. Incidence of Fusarium root rot inAsparagus seedlings infected withArbuscular mycorrhizal fungus as affected by several soil amendments. Journal of the Japanese Society for Horticultural Science. 2002;71 :370-374 - 74.
De Tender CA, Debode J, Vandecasteele B, D’Hose T, Cremelie P. Biological, physicochemical and plant health responses in lettuce and strawberry in soil or peat amended with biochar. Applied Soil Ecology. 2016; 107 :1-12. DOI: 10.1016/j.apsoil.2016.05.001 - 75.
Yao Q , Liu J, Yu Z, Li Y, Jin J, Liu X, et al. Three years of biochar amendment alters soil physiochemical properties and fungal community composition in a black soil of Northeast China. Soil Biology and Biochemistry. 2017; 110 :56-67. DOI: 10.1016/j.soilbio - 76.
Akiyama K, Matsuzaki KI, Hayashi H. Plant sesquiterpenes induce hyphal branching in Arbuscular mycorrhizal fungi. Nature. 2005;435 :824-827 - 77.
IPCC. Climate Change 2007: Synthesis Report. In: Core Writing Team, Pachauri RK, Reisinger A, editors. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Geneva, Switzerland: IPCC; 2007. 104 pp - 78.
Mukome FND, Six J, Parikh SJ. The effects of walnut shell and wood feedstock biochar amendments on greenhouse gas emissions from a fertile soil. Geoderma. 2013; 200-201 :90-98 - 79.
Hanson PJ, Edwards NT, Garten CT, Andrews JA. Separating root and soil microbial contributions to soil respiration: A review of methods and observations. Biogeochemistry. 2000; 48 (1):115-146. DOI: 10.1023/a:1006244819642 - 80.
Zimmerman AR, Gao B, Ahn MY. Positive and negative carbon mineralization priming effects among a variety of biochar-amended soils. Soil Biology and Biochemistry. 2011; 43 :1169-1179 - 81.
Joseph SD, Camps-Arbestain M, Lin Y, Munroe P, Chia CH, Hook J, et al. An investigation into the reactions of biochar in soil. Australian Journal of Soil Research. 2010; 48 :501-515 - 82.
Wang J, Chen Z, Xiong Z, Chen C, Xu X, Zhou Q , et al. Effects of biochar amendment on greenhouse gas emissions, net ecosystem carbon budget and properties of an acidic soil under intensive vegetable production. Soil Use and Management. 2015; 31 :375-383 - 83.
Gillam KM, Zebarth BJ, Burton DL. Nitrous oxide emissions from denitrification and the partitioning of gaseous losses as affected by nitrate and carbon addition and soil aeration. Canadian Journal of Soil Science. 2008; 88 :133-143 - 84.
Yanai Y, Toyota K, Okazaki M. Effect of charcoal addition on N2O emissions from soil resulting from rewetting air-dried soil in short-term laboratory experiments. Soil Science & Plant Nutrition. 2007; 53 :181-188 - 85.
Stewart CE, Zheng J, Botte J, Cotrufo MF. Co-generated fast pyrolysis biochar mitigates green-house gas emissions and increases carbon sequestration in temperate soils. GCB Bioenergy. 2013; 5 :153-164 - 86.
Spokas K, Novak J, Venterea R. Biochar’s role as an alternative N-fertilizer: Ammonia capture. Plant and Soil. 2012; 350 :35-42 - 87.
Jones DL, Rousk J, Edwards-Jones G, DeLuca TH, Murphy DV. Biochar-mediated changes in soil quality and plant growth in a three year field trial. Soil Biology and Biochemistry. 2012; 45 :113-124 - 88.
Karhu K, Mattila T, Bergstrom L, Regina K. Biochar addition to agricultural soil increased CH4 uptake and water holding capacity—Results from a short-term pilot field study. Agriculture, Ecosystems and Environment. 2011; 140 :309-313 - 89.
Van Zwieten L, Kimber S, Morris S, Chan K, Downie A, Rust J, et al. Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soil fertility. Plant and Soil. 2010; 327 :235-246 - 90.
Bruun EW, Petersen CT, Hansen E, Holm JK, Hauggaard-Nielsen H. Biochar amendment to coarse sandy subsoil improves root growth and increases water retention. Soil Use and Management. 2014; 30 :109-118 - 91.
Quilliam RS, Rangecroft S, Emmett BA, Deluca TH, Jones DL. Is biochar a source or sink for polycyclic aromatic hydrocarbon (PAH) compounds in agricultural soils? GCB Bioenergy. 2012; 5 :96-103 - 92.
Rondon M, Ramirez JA, Lehmann J.. Charcoal additions reduce net emissions of greenhouse gases to the atmosphere. Volume 208. In: Proceedings of the 3rd USDA Symposium on Greenhouse Gases and Carbon Sequestration in Agriculture and Forestry; Maryland, USA; 2005 - 93.
Zhang A, Cui L, Pan G, Li L, Hussain Q , Zhang X, et al. Effect of biochar amendment on yield and methane and nitrous oxide emissions from a rice paddy from Tai Lake plain, China. Agriculture, Ecosystems and Environment. 2010; 139 :469-475 - 94.
Zhang A, Liu Y, Pan G, Hussain Q , Li L, Zheng J, et al. Effect of biochar amendment on maize yield and greenhouse emissions from a soil organic carbon poor calcareous loamy soil from Central China plain. Plant and Soil. 2012; 351 :263-275 - 95.
Cayuela ML, Jeffery S, van Zwieten L. The molar H: Corg ration of biochar is a key factor in mitigating N2O emissions from soil. Agriculture, Ecosystems and Environment. 2015; 202 :135-138 - 96.
Fan C, Hao C, Bo L, Zhengqin X. Biochar reduces yield-scaled emissions of reactive nitrogen gases from vegetable soils across China. Biogeosciences. 2017; 14 :2851-2863 - 97.
Le Mer J, Roger P. Production, oxidation, emission and consumption of methane by soils: A review. European Journal of Soil Biology. 2001; 37 :25-50 - 98.
Topp E, Pattey E. Soils as sources and sinks for atmospheric methane. Canadian Journal of Soil Science. 1997; 77 :167-178 - 99.
Castro MS, Steudler PA, Melillo JM. Factors controlling atmospheric methane consumption by temperate forest soils. Global Biogeochemical Cycles. 1995; 9 :1-10 - 100.
Wang J, Pan X, Liu Y, Zhang X, Xiong Z. Effects of biochar amendment in two soils on greenhouse gas emissions and crop production. Plant and Soil. 2012; 360 :287-298 - 101.
Knoblauch C, Maarifat AA, Pfeiffer EM, Haefele SM. Degradability of black carbon and its impact on trace gas fluxes and carbon turnover in paddy soils. Soil Biochem. 2011; 43 :1768-1778 - 102.
Castaldi A. Impact of biochar application to a Mediterranean wheat crop on soil microbial activity and greenhouse gas fluxes. Chemosphere. 2011; 85 :1464-1471 - 103.
Scheer C, Grace P, Rowlings D, Kimber S, Van Zwieten L. Effect of biochar amendment on the soil-atmosphere exchange of greenhouse gases from an intensive subtropical pasture in northern New South Wales, Australia. Plant and Soil. 2011; 345 :47-58 - 104.
Liu Y, Yang M, Wu Y, Wang H, Chen Y, Wu W. Reducing CH4 and CO2 emissions from waterlogged paddy soil with biochar. Journal of Soils and Sediments. 2011; 11 :930-939 - 105.
Ameloot N, De Neve S, Jegajeevagan K, Yildiz G, Buchan D, Funkuin YN. Short-term CO2 and N2O emissions and microbial properties of biochar amended sandy loam soils. Soil Biology and Biochemistry. 2013; 57 :401-410 - 106.
Van Zwieten L, Kimber S, Morris S, Chan KY, Downie A, Rust J, et al. Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soilfertility. Plant and Soil. 2010; 327 :235-246 - 107.
Laine MM, Jùrgensen KS. Effective and safe composting of chlorophenol-contaminated soil in pilot scale. Environmental Science & Technology. 1997; 31 :371-378 - 108.
Joyce JF, Sato C, Cardenas R, Surampalli RY. Composting of polycyclic aromatic hydrocarbons in simulated municipal solid waste. Water Environment Research. 1998; 70 :356-361 - 109.
Wei S, Zhu J, Zhou QX, Zhan J. Fertilizer amendment for improving the phytoextraction of cadmium by a hyperaccumulator Rorippa globosa (Turcz.) Thell. Journal of Soils and Sediments. 2011;11 :915-922 - 110.
Wang T, Camps Arbestain M, Hedley M, Bishop P. Chemical and bioassay characterisation of nitrogen availability in biochar produced from diary manure and biosolids. Organic Geochemistry. 2012; 51 :45-54 - 111.
Asemoloye MD, Jonathan SG, Jayeola AA, Ahmad R. Mediational influence of spent mushroom compost on phytoremediation of black-oil hydrocarbon polluted soil and response of Megathyrsus maximus Jacq. Journal of Environmental Management. 2017;200 :253-262 - 112.
Asemoloye MD, Ahmad R, Jonathan SG. Synergistic action of rhizospheric fungi with Megathyrsus maximus root speeds up hydrocarbon degradation kinetics in oil polluted soil. Chemosphere. 2017;184 :1-12 - 113.
Ji L, Wan Y, Zheng S, Zhu D. Adsorption of tetracycline and sulfamethoxazole on crop residue-derived ashes: Implication for the relative importance of black carbon to soil sorption. Environmental Science & Technology. 2011; 45 :5580-5586 - 114.
Uchimiya M, Lima IM, Klasson KT, Wartelle LH. Contaminant immobilization and nutrient release by biochar soil amendment: Roles of natural organic matter. Chemosphere. 2010; 80 :935-940 - 115.
Singh B, Singh BP, Cowie A. Characterization and evaluation of biochars for their application as a soil amendment. Australian Journal of Soil Research. 2010; 48 :516-525 - 116.
Mukherjee A, Lal R, Zimmerman AR. Effects of biochar and other amendments on the physical properties and greenhouse gas emissions of an artificially degraded soil. Science of The Total Environment. 2014; 487 :26-36 - 117.
Barrow CJ. Biochar: Potential for countering land degradation and for improving agriculture. Applied Geography. 2012; 34 :21-28 - 118.
Cayuela ML, Van Zwieten L, Singh BP, Jeffery S, Roig A, Sánchez-Monedero MA. Biochar’s role in mitigating soil nitrous oxide emissions: A review and meta-analysis. Agriculture, Ecosystems and Environment. 2014; 191 :5-16 - 119.
Lin Y, Munroe P, Joseph S, Henderson R, Ziolkowski A. Water extractable organic carbon in untreated and chemical treated bio-chars. Chemosphere. 2012; 87 :151-157. DOI: 10.1016/j.chemosphere.2011.12.007 - 120.
Ameloot N, Graber ER, Verheijen FGA, De Neve S. Interactions between biochar stability and organisms: Review and research needs. European Journal of Soil Science. 2013; 64 :379-390 - 121.
Ameloot N, Maenhout P, De Neve S, Sleutel S. Biochar induced N2O emission reductions after field incorporation in a loam soil. Geoderma. 2016; 267 :10-16 - 122.
Li J, Dai J, Liu G, Zhang H, Gao Z, Fu J, et al. Biochar from microwave pyrolysis of biomass: A review. Biomass and Bioenergy. 2016; 94 :228-244 - 123.
Windeatt JH, Ross AB, Williams PT, Forster PM, Nahil MA, Singh S. Characteristics of biochars from crop residues: Potential for carbon sequestration and soil amendment. Journal of Environmental Management. 2014; 15 :189-197 - 124.
Novak JM, Ro K, Ok YS, Sigua G, Spokas K, Uchimiya S, et al. Biochars multifunctional role as a novel technology in the agricultural, environmental, and industrial sectors. Chemosphere. 2016; 142 :1-3 - 125.
Karami N, Clemente R, Moreno-Jiménez E, Lepp N, Beesley L. Efficiency of green waste compost and biochar soil amendments for reducing lead and copper mobility and uptake to ryegrass ( Lolium perenne ). Journal of Hazardous Materials. 2011;191 :41-48 - 126.
Wenzel W. Rhizosphere processes and management in plant-assisted bioremediation (phytoremediation) of soils. Plant and Soil. 2009; 321 :385-408. DOI: 10.1007/s11104-008-9686-1 - 127.
Clemente R, Walker DJ, Pardo T, Martínez-Fernández D, Bernal MP. The use of a halophytic plant species and organic amendments for the remediation of a trace elements-contaminated soil under semi-arid conditions. Journal of Hazardous Materials. 2012; 223-224 :63-71. DOI: 10.1016/j.jhazmat - 128.
Beesley L, Moreno-Jiménez E, Gomez-Eyles JL, Harris E, Robinson B, Sizmur T. A review of biochars’ potential role in the remediation, revegetation and restoration of contaminated soils. Environmental Pollution. 2011; 159 :3269-3282. DOI: 10.1016/j.envpol - 129.
Prendergaast-Miller MT, Duvall M, Sohi SP. Localisation of nitrate in the rhizosphere of biochar-amended soils. Soil Biology and Biochemistry. 2011; 43 :2243-2246 - 130.
Prendergast-Miller MT, Duvall M, Sohi SP. Biochar-root interactions are mediated by biochar nutrient content and impacts on soil nutrient availability. European Journal of Soil Science. 2014; 65 :173-185. DOI: 10.1111/ejss.12079 - 131.
Camps-Arbestain M, Saggar S, Leifeld J. Environmental benefits and risks of biochar application to soil. Agriculture, Ecosystems and Environment. 2014; 191 :1-4 - 132.
Nelissen V, Saha BK, Ruysschaert G, Boeckx P. Effect of different biochar and fertilizer types on N2O and NO emissions. Soil Biology and Biochemistry. 2014; 70 :244-255. DOI: 10.1016/j.soilbio.2013.12.026 - 133.
Gul S, Whalen JK, Thomas BW, Sachdeva V. Physico-chemical properties and microbial responses in biochar-amended soils: Mechanisms and future directions. Agriculture, Ecosystems and Environment. 2015; 206 :46-49 - 134.
Harel YM, Elad Y, Rav-David D, Borenstein M, Shulchani R, Lew B, et al. Biochar mediates systemic response of strawberry to foliar fungal pathogens. Plant and Soil. 2012; 357 :245-257 - 135.
George C, Kohler J, Rillig MC. Biochars reduce infection rates of the root-lesion nematode Pratylenchus penetrans and associated biomass loss in carrot. Soil Biology and Biochemistry. 2016;95 :11-18 - 136.
DeLuca TH, Gundale MJ, Mac Kenzie MD, Jones DL. Biochar effects on soil nutrient transformations (chapter 15). In: Lehmann J, Joseph S, editors. Biochar for Environmental Management: Science, Technology and Implementation. 2nd ed. Abingdon, UK: Routledge; 2015. pp. 421-455 - 137.
Subedi R, Taupe N, Ikoyi I, Bertora C, Zavattaro L, Schmalenberger A, et al. Chemically and biologically-mediated fertilizing value of manure-derived biochar. Science of The Total Environment. 2016; 550 :924-933 - 138.
Subedi R, Taupe N, Pelissetti S, Petruzzelli L, Bertora C, Leahy JJ, et al. Greenhouse gas emissions and soil properties following amendment with manure-derived biochars: Influence of pyrolysis temperature and feedstock type. Journal of Environmental Management. 2016; 166 :73-83 - 139.
Drake JA, Cavagnaro TR, Cunningham SC, Jackson WR, Patti AF. Does biochar improve establishment of tree seedlings insaline sodic soils? Land Degradation and Development. 2016; 27 :52-59 - 140.
Cheng CH, Lehmann J. Ageing of black carbon along a temperature gradient. Chemosphere. 2009; 75 :1021-1027 - 141.
Hartley W, Dickinson NM, Riby P, Lepp NW. Arsenic mobility in brown field soils amended with green waste compost or biochar and planted with Miscanthus . Environmental Pollution. 2009;157 :2654-2662 - 142.
Fellet G, Marmiroli M, Marchiol L. Elements uptake by metal accumulator species grown on mine tailings amended with three types of biochar. Science of the Total Environment Volumes. 2014; 468-469 :598-608 - 143.
Houben D, Evrard L, Sonnet P. Beneficial effects of biochar application to contaminated soils on the bioavailability of Cd, Pb and Zn and the biomass production of rapeseed ( Brassica napus L.). Biomass and Bioenergy. 2013;57 :196-204 - 144.
Ippolito JA, Laird DA, Busscher WJ. Environmental benefits of biochar. Journal of Environl Quality. 2012; 41 :967-972 - 145.
Ippolito JA, Spokas KA, Novak JM, Lentz RD, Cantrell KB. Biochar elemental composition and factors influencing nutrient retention. In: Lehmann J, Joseph S, editors. Biochar for Environmental Management: Science, Technology and Implementation. 2nd ed. Abingdon, UK: Routledge; 2015. pp. 139-163 - 146.
Kuppusamy S, Thavamani P, Megharaj M, Venkateswarlu K, Naidu R. Agronomic and remedial benefits and risks of applying biochar to soil: Current knowledge and future research directions. Environment International. 2016; 87 :1-12 - 147.
Liang B, Lehmann J, Sohi SP, Thies JE, O’Neill B, Trujillo L, et al. Black carbon affects the cycling of non-black carbon in soil. Organic Geochemistry. 2010; 41 :206-213 - 148.
Chintala R, Schumacher TE, Kumar S, Malo DD, Rice J, Bleakley B, et al. Molecular characterization of biochar materials and their influence on microbiological properties of soil. Journal of Hazardous Materials. 2014; 279 :244-256 - 149.
Thies EJ, Rilling MC. Characteristics of biochar: Biological properties. In: Lehmann J, Joseph S, editors. Biochar for Environmental Management: Science and Technology. London: Earthscan; 2009. pp. 85-102 - 150.
Steinbeiss S, Gleixner G, Antonietti M. Effect of biochar amendment on soil carbon balance and soil microbial activity. Soil Biology and Biochemistry. 2009; 41 :1301-1310. DOI: 10.1016/j.soilbio.2009.03.016 - 151.
Anderson CR, Condron LM, Clough TJ, Fiers M, Stewart A, Hill RA. Biochar induced soil microbial community change: Implications for biogeochemical cycling of carbon, nitrogen and phosphorus. Pedobiologia. 2011; 54 :309-320 - 152.
Jha P, Biswas AK, Lakaria BL, Rao AS. Biochar in agriculture—Prospects and related implications. Current Science. 2010; 99 :1218-1225 - 153.
Cross A, Sohi SP. The priming potential of biochar products in relation to labile carbon contents and soil organic matter status. Soil Biology and Biochemistry. 2011; 43 :2127-2134 - 154.
Swaine M, Obrike R, Clark JM, Shaw LJ. Biochar alteration of the sorption of substrates and products in soil enzyme assays. Applied and Environmental Soil Science. Article ID 968682. 2013. DOI: 10.1155/2013/968682 - 155.
Asemoloye MD, Ahmad R, Jonathan SG. Synergistic rhizosphere degradation of γ-hexachlorocyclohexane (Lindane) through the combinatorial plant-fungal action. PLoS One. 2017; 12 (7):e-0183373 - 156.
Schmalenberger A, Fox A. Bacterial mobilization of nutrients from biochar amended soils. Advances in Applied Microbiology. 2016; 94 :109-109