Influence Of Biochar Amendments Research Articles

Influence of biochar amendment on removal of heavy metal from soils using phytoremediation by Catharanthus roseus L. and Chrysopogon zizanioides L.

Advances in sustainable toxic heavy metal treatment technologies are crucial to meet our needs for safer land to develop an urban resilient future. The heavy metals bioaccumulate in the food chain due to their persistence in the soil, which poses a serious challenge to its removal and control. Utilisation of hyperaccumulators to reduce the mobility, accumulation and toxic impact of heavy metals is a promising and ecologically safe technique. Amendments such as biochar and chelates have been shown to enhance the phytoremediation efficiency. However, the potential soil improvement is influenced by the properties of the amendment, plant and metal heterogeneities. In this study, an organic sugarcane bagasse biochar amendment for the 60-day pot experiment using Catharanthus roseus L. (NT) and Chrysopogon zizanioides L. (VT) in a heavy metal-contaminated soil was applied. The influence of biochar on the phytoremediation of lead (Pb), zinc (Zn) and cadmium (Cd) from the soil was explored. The plant survival rate enhanced to 100% with biochar amendment, and the biomass increased from 5.83 to 15g in Zn-contaminated samples. Nutrients such as potassium concentration are directly correlated to the amendment rates, whereas phosphate decreases beyond the 2% biochar amendment rate in both plants. High heavy metal accumulation capacities with improved growth with biochar indicate the sustainability of the process. The translocation factor (TF) > 1 for Zn in NT represents the phytoextraction efficiencies whereas VT indicates high BCF values in the range of 0.5-3.53 for the amended Zn-contaminated soils. The findings indicate that the amendment rate of 2% improves nutrient cycling, plant biomass and heavy metal removal efficiencies. The insights from this study establish that the synergy between biochar amendment and the selected medicinal plants improved the phytoremediation efficiency.

A review on influence of biochar amendment on soil processes and environmental remediation

ABSTRACT Biochar is the thermal degradation product of biomass generated in an oxygen-limited environment under different pyrolysis conditions. Biochar characteristics are functions of the feedstock material and pyrolysis temperature. Depending on pyrolysis conditions biochar concentrates varying quantities of recalcitrant and labile carbon along with nutrients which in turn affect soil physiochemical properties and microbial processes. Biochar in soil balances carbon content encourages nitrogen fixation and solubilize phosphorus along with enhancing soil enzyme activity. It serves as a microhabitat for microorganisms present in soil thus influences the diversity, composition, and distribution of soil microbial communities by affecting their intra- and interspecific communication. This review provides an overview of the current knowledge about biochar characteristics, its interactions with soil, and associated biota and its role in soil remediation. In addition, this paper also discussed the factors affecting the capacity of biochar to adsorb organic pollutants following different mechanisms. Being an effective adsorbent due its high specific surface area, large porosity, and numerous surface functional groups biochar has been explored extensively in field of environment to remediate contaminated soils.

Influence of biochar amendments on the soil quality indicators of sandy loam soils under cassava–peanut cropping sequence in the semi-arid tropics of Northern Lombok, Indonesia

Low nutrient retention and soil organic matter depletion are the major challenges of the cropping system in the sandy loam soils of Northern Lombok, Indonesia. A field experiment was conducted to evaluate the influence of biochar-based organic amendments on the soil quality of sandy loam soils under cassava (Manihot Esculenta, Crants)–peanut (Arachis Hypogeae L.) cropping sequence. The treatments were as follows: biochar (10 ton ha<sup>-1</sup>) and rice straw (3 ton ha<sup>-1</sup>) (B1); biochar (10 ton ha<sup>-1</sup>), cattle manure (10 ton ha<sup>-1</sup>), and rice straw (3 ton ha<sup>-1</sup>) (B2); biochar (10 ton ha<sup>-1</sup>) and cattle manure (10 ton ha<sup>-1</sup>) (B3); biochar (10 ton ha<sup>-1</sup>) and cattle manure (10 ton ha<sup>-1</sup>) plus rice straw mulch (3 ton ha<sup>-1</sup>) applied on surface soils (B4), and without organic amendments (B0) as control. Results showed that the biochar-based organic amendments significantly improved several soil quality indicators such as SOC, total N, available P, Ca, cation-exchange capacity (CEC), and aggregate stability but had no significant effect on pH, K, and Mg. Improvement in soil quality was strongly indicated by an increase in the growth and yield of cassava and peanuts. Treatments B1, B2, B3, and B4 generally had a comparable effect on soil parameters and tended to improve the growth and yield of cassava and peanuts. Cassava was responsive to treatments B2 (biochar, cattle manure, and rice straw) and B3 (biochar and cattle manure) with its actual yield of 27 tons ha<sup>−1</sup>, which is a 40% increase compared with that in the control. As a secondary crop growing after cassava, peanuts also exhibited higher yields in all amended plots compared with that in the control. The highest yield was obtained in B2 (1.38 ton ha<sup>−1</sup>), followed by B4 (1.36 ton ha<sup>−1</sup>), B1 (1.33 ton ha<sup>−1</sup>), and B3 (1.25 ton ha<sup>−1</sup>). In conclusion, the incorporation of biochar, cattle manure, and crop residues (rice straw) into soils is a promising option to maintain soil quality and sustainably produce cassava and peanuts in the sandy loam soils of the semi-arid tropics of Lombok, Indonesia.

Biochar addition regulates soil and earthworm gut microbiome and multifunctionality

The earthworm gut bacterial community and enzyme activities play a key role in many soil ecosystem functions, but how the addition of different types of biochar (used to improve soil quality) regulates soil and earthworm gut bacterial communities and associated enzyme activities is scarcely understood. An experiment was conducted using soil microcosms and seven treatments: no biochar application as control, and two types of biochar (maize straw and cow dung biochar, hereafter SB and CB treatments, respectively) with three biochar application rates (20, 50, and 100 g/kg soil). Eight enzymatic activities related to C-, N- and P-cycling (used to compute a “multifunctionality” index) and the abundance and composition of bacterial communities were assessed in both the soil and earthworm guts. Our results show that earthworm gut content, characterized by lower bacterial abundance but higher enzymatic activities than soil, was strongly influenced by biochar addition. Increasing biochar application rates significantly increased the nutrient content, bacterial abundance, and multifunctionality in the earthworm guts. Owing to the difference in physicochemical properties between SB and CB, the increased gut multifunctionality was linked to the significantly modified gut bacterial community composition in CB treatments but not in SB treatments. Structural equation modeling further revealed that the changed gut multifunctionalities in both biochar treatments were mostly related to the soil and gut physicochemical properties, especially in CB treatments, while the impacts of gut microbial variables on soil multifunctionality were higher in the SB than CB treatments. These results demonstrate that the influence of biochar amendment on earthworm gut microbiome and multifunctionality depends on the type of biochar, which also regulates the contributions of earthworm gut biochemical processes to soil ecosystem functions.

Vertical SOC distribution and aromatic carbon in centuries old charcoal‐rich Technosols

AbstractCharcoal‐rich Technosols on century‐old relict charcoal hearths (RCHs) are the subject of ongoing research regarding potential legacy effects that result from historic charcoal production and subsequent charcoal amendments on forest soil properties and forest ecosystems today. RCHs consist mostly of Auh horizons that are substantially enriched in soil organic carbon (SOC), of which the largest part seems to be of pyrogenic origin (PyC). However, the reported range of SOC and PyC contents in RCH soil also suggests that they are enriched in nonpyrogenic SOC. RCH soils are discussed as potential benchmarks for the long‐term influence of biochar amendment and the post‐wildfire influences on soil properties. In this study, we utilised a large soil sample dataset (n = 1245) from 52 RCH sites in north‐western Connecticut, USA, to quantify SOC contents by total element analysis. The contents of condensed highly aromatic carbon as a proxy for black carbon (BC) were predicted by using a modified benzene polycarboxylated acid (BPCA) marker method in combination with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy‐based partial least square regression (r2 = 0.89). A high vertical spatial sampling resolution allowed the identification of soil organic matter (SOM) enrichment and translocation processes. The results show an average 75% and 1862% increase in TOC and BPCA‐derived carbon, respectively, for technogenic Auh horizons compared to reference soils. In addition to an increase in aromatic properties, increased carboxylic properties of the RCH SOC suggest self‐humification effects of degrading charcoal and thereby the continuing formation of leachable aromatic carbon compounds, which could have effects on pedogenic processes in buried soils. Indeed, we show BPCA‐derived carbon concentrations in intermediate technogenic Cu horizons and buried top/subsoils that suggest vertical translocation of highly aromatic carbon originating in RCH Auh horizons. Topmost Auh horizons showed a gradual decrease in total organic carbon (TOC) contents with increasing depth, suggesting accumulation of recent, non‐pyrogenic SOM. Lower aliphatic absorptions in RCH soil spectra suggest different SOM turnover dynamics compared to reference soils. Furthermore, studied RCH soils featured additional TOC enrichment, which cannot be fully explained now.Highlights BC to TOC ratio and high resolution vertical SOC distribution in 52 RCH sites were studied. RCH soils non‐BC pool was potentially different to reference soils. RCH soils feature TOC accumulation in the topmost horizon. There is BC translocation into buried soils on RCH sites.

Biochar reduces the toxicity of silver to barley (Hordeum vulgare) and springtails (Folsomia candida) in a natural soil.

The use of biochar in soil remediation is a promising method to deal with metal contamination. In the present study, the influence of biochar amendment on the toxicity of silver (as AgNO3) to terrestrial organisms was assessed. For this, toxicity tests were conducted with terrestrial plant barley (Hordeum vulgare) and invertebrate springtails (Folsomia candida) in the standard natural Lufa soil amended or not with a wood-derived biochar at 5% (w/w). Biochar addition increased root length and mass in barley, compared to unamended soil. However, the effects of Ag on barley growth were masked by a great variation among replicates in biochar-amended soil. Photosynthetic pigment contents (total chlorophyll and carotenoids) were lower in plants exposed to Ag in Lufa soil, but not in biochar-amended soil. Moreover, Ag drastically decreased dehydrogenase activity in Lufa soil. For springtails, the addition of biochar clearly decreased the toxicity of Ag. The LC50 was 320mg Ag/kg in Lufa soil, while no mortality was observed up to 500mg Ag/kg in biochar-amended soil. The EC50 for effects on reproduction was significantly higher in biochar-amended soil compared to unamended Lufa soil (315 and 215mg Ag/kg, respectively). The wood-derived biochar used in this study has shown a potential for remediation of contaminated soils, as a decrease in Ag toxicity was observed in most endpoints analysed in barley and springtails.

Influence of biochar amendment on stormwater management in green roofs: experiment with numerical investigation

Influence of biochar amendment on stormwater management in green roofs: experiment with numerical investigation

Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.g. suction and water retention) of soil. However, variations in densities alter the properties of the soil–biochar mix. Such density variations are observed in agriculture (loosely compacted) and engineering (densely compacted) applications. The influence of biochar amendment on gas permeability of soil has been barely investigated, especially for soil with different densities. The major objective of this study is to investigate the water retention capacity, and gas permeability of biochar-amended soil (BAS) with different biochar contents under varying degree of compaction (DOC) conditions. In-house produced novel biochar was mixed with the soil at different amendment rates (i.e. biochar contents of 0%, 5% and 10%). All BAS samples were compacted at three DOCs (65%, 80% and 95%) in polyvinyl chloride (PVC) tubes. Each soil column was subjected to drying–wetting cycles, during which soil suction, water content, and gas permeability were measured. A simplified theoretical framework for estimating the void ratio of BAS was proposed. The experimental results reveal that the addition of biochar significantly decreased gas permeability k g as compared with that of bare soil (BS). However, the addition of 5% biochar is found to be optimum in decreasing k g with an increase of DOC (i.e. k g,65% > k g,80% > k g,95% ) at a relatively low suction range (< 200 kPa) because both biochar and compaction treatment reduce the connected pores.

Swelling behaviour and microstructure of biochar bentonite

Biochar bentonite is a potential candidate as a porous layer for nuclear waste repositories. It would provide an ideal niche for bacteria that could feed on sulfate from the host rock and hydrogen from the corroding canisters. In this study, the influence of biochar amendment on the swelling properties of bentonite at different densities has been examined through swelling experiments. Scanning electron microscopy (SEM) images were used to study the surface microscopic morphology of biochar bentonite samples. On the basis of the SEM results, the fractal dimension representing the microstructure of biochar bentonite was determined. The relationship between fractal dimension and the maximum swelling pressure was discussed to reveal the correlation between the microstructure and the variation of mechanical properties for biochar bentonite.

Influence of Biochar Amendment on Soil Denitrifying Microorganisms in Double Rice Cropping System

At present, it is not explicit how biochar regulates the microbial process of denitrification in paddy fields. Therefore, a field experiment was carried out in a double rice cropping system with three wheat straw biochar treatments:no biochar treatment (CK), added 24 t·hm-2 biochar (LC), and added 48 t·hm-2 biochar (HC). Real time PCR (qPCR) and terminal-restricted fragment length polymorphism (T-RFLP) technology were adopted to analyze the abundances and microbial community structures of denitrification functional genes (narG, nirK and nosZ) in the fallow season and rice season. Due to its alkalinity, biochar amendment increased soil pH by 0.2-0.8. Biochar amendment also increased soil NH4+-N and NO3--N contents by 21.1%-32.5% and 63.0%-176.0% in the fallow season due to the presence of soluble N. Nevertheless, it reduced NH4+-N content by 48.8%-60.1% in the rice season due to the adsorption of biochar. The amendment increased soil MBN content in the fallow season, which may be a result of the large surface of biochar supplying nutrients and a suitable survival environment for the microorganisms. In the fallow season, compared to CK treatment, the increased soil NH4+-N and NO3--N with biochar amendment promoted the conversion of NH4+-N to NO3--N, and thus increased the abundances of narG and nosZ (P<0.05). The higher soil pH with biochar addition increased the abundances of nosZ and altered the community structures of narG and nosZ in the fallow season. Biochar amendment altered the denitrification process, but it did not change N2O emissions in the fallow season, which might reduce NO3--N leaching losses. In the rice season, biochar amendment increased nosZ abundance (P<0.05). HC increased the nirK gene abundance, which contributed to increased N2O emission in the rice season (P<0.05). Biochar converted the community structures of nirK and nosZ by decreasing the NH4+-N content in the rice season. The changes of the narG community structure with HC treatment contributed to the increased N2O emission. In conclusion, biochar amendment can influence the microbes involved in soil denitrification by changing the soil properties, and thus impact the N2O emissions and NO3--N leaching.

Influence of biochar amendment and foliar application of iron oxide nanoparticles on growth, photosynthesis, and cadmium accumulation in rice biomass

The majority studies used the biochar or nanoparticles alone in metal-contaminated soils while less is known about the combined use of these amendments in metal-contaminated soils. We aimed to explore the efficiency of iron oxide nanoparticles (Fe NPs) and biochar on cadmium (Cd) uptake in rice in pot trial. An experiment was performed under ambient environmental conditions in a Cd-contaminated soil with and without biochar addition (1.0% w/w), and different Fe NP concentrations (0, 10, 20, 30 mg/L) were foliar sprayed at different time intervals (at 3rd, 4th, and 5th weeks of nursery transplantation in the pots) during the plant growth. After harvesting, rice growth, photosynthesis, Cd and Fe contents in rice tissues, and soil bioavailable Cd and soil pH were measured. Iron NPs enhanced the dry weights of rice tissues, chlorophyll concentrations, and gas exchange characteristics and the impact of NPs was further increased when the biochar was applied along with NPs. Iron NPs significantly decreased the intake of Cd in rice shoots by 31 and 42% and in rice roots by 26 and 39% with the foliar spray of Fe NPs (30 mg/L) without and with biochar, respectively. Foliar spray of Fe NPs reduced the total Cd accumulation by shoots, whereas the total Cd accumulation in the roots increased. The co-presence of Fe NPs and Cd enhanced the Fe concentrations in shoots of rice by 52 and 33% and in roots of rice by 32 and 21% when 30 mg/L Fe NPs were supplied with and without biochar, respectively. The effects of Fe NPs were higher with biochar application than without biochar except Fe concentrations in rice seedlings where the opposite trend was observed. The increase in biomass, Fe concentrations in tissues, and decrease in Cd levels in plants clearly demonstrate that Fe NPs + biochar could be a promising technique for the utilization of Cd-contaminated soils in the future.

Influence of biochar amendment on herb growth in a green roof substrate

The objectives of this research were: 1) to assess the effect of biochar incorporation on the growth of basil (Ocimum basilicum ‘Genovese Compact, Improved’) and peppermint (Mentha × piperita) and, 2) to determine the physical characteristic differences in heat-expanded clay (HEC) substrate following incorporations of biochar at 5%, 10%, or 15% (by volume). A commercially-available green roof substrate, Rooflite Intensive Ag (IA) substrate, was included for comparison. The IA substrate had the highest total porosity (TP), container capacity (CC), and air-filled porosity (AP). The HEC substrate showed a linear increase in TP and CC and a linear decrease in dry bulk density with increasing amounts of biochar. The commercially available IA substrate had the highest water retention (CC = 25.0%). Overall, there was a maximum increase of peppermint shoot dry weight (g/shoot) response in the HEC substrate using 15% biochar. Coverage area measurements indicated that peppermint benefited more than basil from the incorporation of biochar. Biochar alone did not influence stomatal conductance, although basil or peppermint grown in the IA substrate had higher stomatal conductance than plants grown on HEC with all three biochar incorporation rates at 3 and 4 d after irrigation, probably due to the lower aboveground biomass of the IA-grown plants. In conclusion, the addition of biochar amendment to HEC substrate had a minor influence on peppermint growth and no influence on stomatal conductance of either basil or peppermint.

Influence of Biochar Amendment on Soil Water Characteristics and Crop Growth Enhancement Under Salinity Stress

Salinity is an important environmental constraint to crop productivity in arid and semi-arid regions of the world. Most crop plants, including tomato (Lycopersicon esculentum Mill), are sensitive to salinity throughout the ontogeny of the plant. Biochar was used in the present study to improve the available water content (AWC), growth, yield and irrigation water use efficiency of tomato plant under saline soil condition. The biochar was applied at the rates of, 0%, 2% and 4% w/w and expressed as Ck (control), T1 and T2, respectively. The experiment was conducted in the pots inside the greenhouse. The results showed that soil bulk density, field capacity, permanent wilting point, AWC, and soil organic matter were improved significantly as biochar application rate increased. Biochar application also enhanced plant height, stem diameter, plant fresh and dry weights and yield components of tomato plant. It was found that biochar application at T2 treatment in the whole growing period was best to improve tomato plant growth and yield, providing a biochar amendment recommendation for tomato production in field. Moreover, biochar application improved the irrigation water use efficiency. Therefore, biochar amendment could be an effective option to improve saline soil which affected croplands.

Biochar amendment to soils impairs developmental and reproductive performances of a major rice pest Nilaparvata lugens (Homopera: Delphacidae)

AbstractBiochar amendments to soils had aroused much interest for having potential for greenhouse gas mitigation, soil improvement and increased crop productivity. However, little attention had been focused on the influence of biochar amendments on herbivorous insect pests. This study investigated whether a biochar amendment affected developmental and reproductive performances of the rice brown planthopper (Nilaparvata lugens) feeding on rice plants. The biochar from the pyrolysis of wheat straw was used for treatments of soils (from a fallow rice field), and the treated soils were applied to grow rice seedlings in small vials, in which N. lugens life history was observed. The nymphal development time was delayed and nymph‐to‐adult survival decreased with a high level of 200 g/kg biochar application. Herbivore lifetime fecundity decreased with increasing amounts of biochar, from 256 eggs under the control down to 69 eggs under the high level (200 g/kg) of biochar application. Egg‐hatching rate significantly decreased at the highest biochar level (200 g/kg), compared to the other lower biochar levels. Our results suggest that biochar amendment to rice fields may have negative impacts on the rice brown planthoppers when applied at level of 200 g/kg of soil.

Transport of , , and microspheres in biochar-amended soils with different textures.

The incorporation of biochar into soils has been proposed as a means to sequester carbon from the atmosphere. An added environmental benefit is that biochar has been shown to increase soil retention of agrochemicals, and recent research has indicated that biochar may be effective in increasing soil retention of bacteria. In this study we investigate the transport behavior of O157:H7, serovar Typhimurium, and carboxylated polystyrene microspheres in water-saturated column experiments for two soils (fine sand and sandy loam) amended with 2% poultry litter or pine chip biochars pyrolyzed at 350 and 700°C. Adding poultry litter biochar pyrolyzed at 350°C did not improve soil retention of either bacteria in fine sand and even facilitated their transport in sandy loam. Addition of either biochar pyrolyzed at 700°C generally improved retention of bacteria in fine sand, with the pine chip biochars being more effective in limiting their transport. Results from the column studies and auxiliary batch studies suggest that changes in cell retention after biochar amendments were likely due to changes in bacterial attachment in the column and not to physical straining or changes in survivability. We also found that changes in bacterial hydrophobicity after biochar amendments were generally correlated with changes in bacterial retention. The influence of biochar amendment in increasing retention of both bacteria was generally more pronounced in fine sand and indicates that soil texture affects the transport behavior of bacteria through biochar-amended soils.

Influence of biochar amendments on the sorption–desorption of aminocyclopyrachlor, bentazone and pyraclostrobin pesticides to an agricultural soil

The many advantageous properties of biochar have led to the recent interest in the use of this carbonaceous material as a soil amendment. However, there are limited studies dealing with the effect of biochar on the behavior of pesticides applied to crops. The objective of this work was to determine the effect of various biochars on the sorption–desorption of the herbicides aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropyl-4-pyrimidinacarboxylic acid) and bentazone (3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide) and the fungicide pyraclostrobin (methyl 2-[1-(4-chlorophenyl) pyrazol-3-yloxymethil]-N-methoxycarbanilate) to a silt loam soil. Aminocyclopyrachlor and bentazone were almost completely sorbed by the soils amended with the biochars produced from wood pellets. However, lower sorption of the herbicides was observed in the soils amended with the biochar made from macadamia nut shells as compared to the unamended soil, which was attributed to the competition between dissolved organic carbon (DOC) from the biochar and the herbicides for sorption sites. Our results showed that pyraclostrobin is highly sorbed to soil, and the addition of biochars to soil did not further increase its sorption. Thus, addition of biochars to increase the retention of low mobility pesticides in soil appears to not be necessary. On the other hand, biochars with high surface areas and low DOC contents can increase the sorption of highly mobile pesticides in soil.

Biochars improve aggregate stability, water retention, and pore‐space properties of clayey soil

AbstractThe influence of biochar amendments on the physical quality of a clayey soil (Vertisol) was evaluated by aggregate‐size distribution and stability, water retention, and pore‐space structure of biochar‐amended soils. Clayey soil was treated with three kinds of biochars (straw biochar, woodchips biochar, and wastewater‐sludge biochar) at the rate of 0, 20, 40, and 60 g biochar (kg soil)–1 and incubated for 180 d in glasshouse. The application of straw biochar (SB) and wastewater‐sludge biochar (WSB) significantly enhanced the formation of 5–2 and 0.25–0.5 mm macroaggregates in the clayey soil relative to the control treatment, while the &lt; 0.25‐cm microaggregate decreased with biochar additions. However, woodchips biochar (WCB) had no obvious effect on the formation of macroaggregate. The application of SB and WSB increased the mean weight diameter (MWD) and geometric mean diameter (GMD) of clayey soil, implying that biochar increased the aggregate stability. They improved the aggregate stability through an enhanced resistance to slaking and increased interparticular cohesion. The SB‐amended soils exhibited significant increases in the available water contents of soils. The application of SB significantly increased pore volume in the macropore (&gt; 75 μm) and mesopore (30–75 μm) ranges, which may be the result of the reorganization of pore‐size distribution and aggregation processes induced by the addition of biochar. Results indicated that biochar had the potential to improve the physical quality and pore‐space status of clayey soil. It is suggested that biochar may be considered as a soil amendment for improving poor physical characteristics of clayey soil.