Green Waste Biochar Research Articles

Enhanced adsorption of anionic dyes onto NaOH modified green coffee waste biochar: characteristics and performance evaluation

Enhanced adsorption of anionic dyes onto NaOH modified green coffee waste biochar: characteristics and performance evaluation

A quantitative review of the effects of biochar application on the reduction of Cu concentration in plant: a meta-analysis.

Contamination and toxicity of copper (Cu) in soils are global issues, particularly in regions where Cu-based fungicides are utilized. Elevated Cu concentrations can lead to soil contamination and pose significant risks to the ecosystem, including plant life, wildlife, and human health. The application of biochar has been proposed as a viable strategy to mitigate Cu accumulation in plants. However, there is no quantitative and data-based consensus on the impact of biochar on plant Cu accumulation. In this meta-analysis, 624 data records from 65 published literature were collected and the effects of various factors, including biochar properties, experimental conditions, and soil properties on Cu accumulation in plants, were examined through meta-subgroup analysis and meta-regression models. The results obtained indicate a significant dose-dependent effect of biochar in decreasing Cu concentration in plants by an average of 23.45%. Soils with acidic pH values and medium textures were more conducive for biochar to mitigate Cu accumulation in plant tissues. In addition, manure biochar and green waste biochar were found to be more successful in decreasing Cu concentrations in plants compared to other biochar types. Biochar types with pyrolysis temperatures of > 600°C and pH values of ≥ 10 resulted in greater decreases in plant Cu concentration. Regarding biochar application, biochar minimum range of 1% in potting experiments and 20 t/ha in field experiments have been recommended to effectively decrease Cu concentration in plants. Overall, these findings provide valuable insights into Cu transfer mitigation through food chain to human bodies and for policymakers to take preventive measures.

Effectiveness of feeding different biochars on growth, digestibility, body composition, hematology and mineral status of the Nile tilapia, Oreochromis niloticus

Oreochromis niloticus fingerlings (5.15 ± 0.02 g; n = 315) were fed with different types of biochar (BC)-supplemented sunflower meal-based (SFM) diet to investigate the effects of various BC inclusions on their nutritional digestibility, body composition, hematology and mineral status for 60 days. Seven different diets were formulated based on the SFM based diet: one was a control (TD-I, CON) and the other six diets were supplemented with 2% BC derived from different sources. These BCs were derived from the following: cotton stick (CSBC, TD-II), wheat straw (WSBC, TD-III), corn cob (CCBC, TD-IV), house waste (HWBC, TD-V), grass waste (GWBC, TD-VI), and green waste (GwBC, TD-VII) biochar. There were three replicates for each test diet. Each tank had fifteen tilapia fingerlings, and they were fed with 5% of their live wet weight and twice daily. The outcomes showed that the supplementation of CCBC significantly elevated the growth, nutrient absorption, and body composition of the O. niloticus fingerlings (p < 0.05); with concomitant lowering of the quantity of nutrients released into the water bodies whereas HWBC gave negative impacts. The maximal mineral absorption efficiency (Ca, Na, K, Cu, Fe, P, and Zn) was achieved by the supplementation of 2% CCBC. All hematological parameters showed positive improvements (p < 0.05) with CCBC. Interestingly, CCBC significantly improved the growth, digestibility, body composition, hematology, and mineral status of O. niloticus.

Norfloxacin adsorption by urban green waste biochar: characterization, kinetics, and mechanisms.

Biochar, as a potential adsorbent, has been widely employed to remove pollutants from sewage. In this study, a lignin-based biochar (CB-800) was prepared by a simple high-temperature pyrolysis using urban green waste (Cinnamomum camphora leaves) as a feedstock to remove norfloxacin (NOR) from water. Batch adsorption test results indicated that CB-800 had a strong removal capacity for NOR at a wide range of pH values. The maximum adsorption achieved in the study was 50.90 ± 0.64mg/g at 298K. The pseudo-first and second-order kinetic models and the Dubinin-Radushkevich isotherm fitted the experimental data well, indicating that NOR adsorption by CB-800 was a complex process involving both physi-sorption and chemi-sorption. The physical properties of CB-800 were characterized by SEM and BET. The mesoporous structures were formed hierarchically on the surface of CB-800 (with an average pore size of 2.760nm), and the spatial structure of NOR molecules was more easily adsorbed by mesoporous structures. Combined with Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis, it was showed that the main NOR adsorption mechanisms by CB-800 included ion exchange, π-electron coordination, hydrogen bonding, and electrostatic adsorption. Meanwhile, the reduction of C = O and pyridine nitrogen, and the presence of C-F2, also indicated the occurrence of substitution, addition, and redox. This study not only determined the reaction mechanism between biochar and NOR, but also provides guidance to waste managers for the removal of NOR from water by biochar. It is envisaged that the results will broaden the utilization of urban green waste.

Stability and maturity indexes of organic fraction compost

Composting is an environmentally friendly way to turn wastes into useful product (compost). This study aimed to monitor various chemical,physical, and biological parameters over the course of the co-composting of three organic compounds. In this context, 55 kg (55%) ofgreen waste (GW) were co-composted with 40 kg (40%) of poultry manure at 40 kg (40%) and 5 kg (5%) green waste biochar (GWB).The monitoring of this experiment continues until the final product is stable. According to several previous studies, it was generallyagreed that it was better to employ a combination of multiple tests to be sure that the compost has really reached a state of maturityand stability. During this study, a series of tests were used to determine the maturity and stability of co-composting organic wastes forsafe use. Tests used during this follow-up include the pile temperature, pile moisture, pH, total nitrogen, total carbon, C/N ratio, microbialactivity (CO2 emission), germination index, and a scanning electron microscopy. According to the results of tests carried out during thisexperiment, the compost had attained maturity on the 54th day from the beginning of the composting.

Response of sunflower and soybean to infection with Sclerotinia sclerotiorum with addition of organic amendments

The addition of compost, green waste biochar, and wood biochar to a pathosystem consisting of Sclerotinia sclerotiorum (Lib.) de Bary and two susceptible host plants, sunflower (Helianthus annuus L.) and soybean (Glycine max L.), was investigated in a greenhouse study. Plant growth characteristics, disease incidence and the mycelial growth of S. sclerotiorum in root exudates of plants inoculated and not inoculated with this pathogen were determined. Both plants showed different responses in terms of shoot and root weight. Disease incidence in sunflower was lowest in the substrate consisting of green waste biochar and compost. The disease incidence in this substrate was approximately half that in the control treatment. In soybean, the highest disease suppression was achieved with this combined substrate too. Mycelial growth in sunflower root exudates from uninoculated plants was higher than that in sunflower plants inoculated with S. sclerotiorum. The substrate did not influence mycelial growth in root exudates. Soybean root exudates did not show this effect of the pathogen. This study proves that the addition of organic matter inputs such as biochar and compost can improve plant growth and can also have favorable effects against S. sclerotiorum infection. In addition, it is demonstrated that both the pathogen and host plant are instrumental in determining the mode of action of the supplemented organic material. The addition of the same organic material can lead to different responses in certain pathogens, such as S. sclerotiorum, depending on the host plant.

Effect of acidified biochar on soil phosphorus availability and fertilizer use efficiency of maize (Zea mays L.)

This study evaluated the impact of various biochars prepared from different sources and their acidified forms on soil phosphorus (P) availability and fertilizer use efficiency (FUE) of maize (Zea mays L.) crop. Plastic pots of 20 kg capacity (59 × 46 × 15 cm) were filled with 15 kg soil and seven seeds of hybrid maize (cv. Pioneer 30Y87) were sown in each pot. Various biochars and their acidified forms, including green waste biochar (GWB), acidified green waste biochar (AGWB), corncob biochar (CCB) and acidified corncob biochar (ACCB) were added in each pot t 90 g/pot before seed sowing. The control treatments were; T1 (C + 50% P), T2 (C + 75% P) and T3 (C + 100% P). The experimental treatments included T4 (CCB + 50% P), T5 (CCB + 75% P), T6 (CCB + 100% P), T7 (ACCB + 50% P), T8 (ACCB + 75% P), T9 (ACCB + 100%P), T10 (GWB + 50%P), T11 (GWB + 75%P), T12 (GWB + 100%P), T13 (AGWB + 50%P), T14 (AGWB + 75%P) and T15 (AGWB + 100%P). Results indicated that soil pH decreased (8.5 with AGWB compared to 8.76 with C), soil organic carbon (SOC) was significantly improved with all treatments. Soil electrical conductivity (EC) and cation exchange capacity (CEC) were also influenced by GWB (26 cmolckg−1) and ACCB (7.25 cmolckg−1). Bioavailability of P was highest (90 mg kg−1) with AGWB compared to control treatments. Similarly, addition of GWB and AGWB along with 50% P recorded significant improvement in plant height and fresh weight compared to control treatments. Therefore, it is suggested that among all the biochar types, AGWB is capable of improving chemical properties of the studied soil, growth, yield and nutrient uptake in maize crop compared to sole the application of P-fertilizers.

Biochar, compost and arbuscular mycorrhizal fungi: a tripartite approach to combat Sclerotinia sclerotiorum in soybean

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease in soybean in many parts of the world. Sustainable control measures to combat this pathogen can be better achieved by combining different available tools. One element to control fungal diseases could be changing biological activities by adding organic matter inputs, such as biochar and compost, to the soil. Other players are arbuscular mycorrhizal fungi (AMF); bioprotective effects have already been documented for them. In the present study, we assessed the effect of organic matter inputs, such as compost alone at the application rate of 20% of the total substrate (v/v) and/or green waste biochar at the application rate of 3% (v/v) in combination with or without arbuscular mycorrhizal fungi, against Sclerotinia sclerotiorum and their effect on plant growth characteristics in soybean. Substrates including compost resulted in a lower disease severity in both, plants inoculated and non-inoculated with AMF. The AMF root colonization was highest in plants grown in the control treatment and green waste biochar substrate inoculated with Sclerotinia sclerotiorum; the lowest colonization was found in plants grown in substrates containing compost. Soil substrates, especially compost, affected shoot dry matter production in soybean plants inoculated with Sclerotinia sclerotiorum and in non-inoculated plants; compost alone was superior in treatments with and without AMF. Root morphological traits were more strongly influenced by AMF than by the substrate. Our findings suggest that compost has a positive effect in terms of soybean growth and diseases suppression, which is more pronounced than that of biochar and AMF.

Immobilization of cadmium and lead using phosphorus-rich animal-derived and iron-modified plant-derived biochars under dynamic redox conditions in a paddy soil

Functionalized biochar has gained extensive interests as a sustainable amendment for an effective remediation of paddy soils contaminated with heavy metals (HMs). We examined the efficiency of pig carcass-derived biochar (P-rich biochar, total P=8.3%) and pristine (raw biochar, total Fe=0.76%) and Fe-modified (Fe-rich biochar, total Fe=5.5%) green waste-derived biochars for the immobilization of cadmium (Cd) and lead (Pb) in a paddy soil under pre-defined redox conditions (Eh, from -400 to+300mV). Average concentrations (μg L-1) of dissolved Cd increased under reducing conditions up to 10.9 in the control soil, and decreased under oxidizing conditions to below the detection limit (LDL=2.7) in the raw and Fe-rich biochar treated soils. Application of the raw biochar decreased the concentrations of dissolved Cd by 43-59% under Eh≤-100mV, compared to the non-treated control, which was more effective than the Fe-rich biochar (31-59%) and the P-rich biochar (8-19%). The immobilization of Cd under low Eh might be due to its precipitation with sulfide (S2-), whereas its immobilization under high Eh might be due to the associated increase of pH. Concentrations (μg L-1) of Pb ranged from 29.4 to 198.2 under reducing conditions, and decreased to LDL (12.5) under oxidizing conditions. The P-rich biochar was more effective in immobilizing Pb than the raw and Fe-rich biochars, particularly under Eh≤0mV (55-82%), which might be due to the retention of Pb by phosphates. The raw and Fe-rich biochars immobilized Pb under low Eh (≤ -300mV), but both biochars, particularly the Fe-rich biochar mobilized Pb under Eh higher than -200mV, especially at+100mV, due to the decrease of pH at this point (pH=6.0 to 6.5). These results improved our understanding of using P-rich and Fe-rich functionalized biochars for the immobilization of Cd and Pb in a paddy soil under stepwise redox changes. The amendment of P-rich pig carcass-derived biochar to paddy soils could be a promising approach for mitigating the risk of Pb for human health and the environment. The raw and Fe-rich green waste-derived biochars can be used for immobilizing Cd and mitigating its risk in paddy soils under both reducing and oxidizing conditions.

Molecular and biochemical insight into biochar and Bacillus subtilis induced defense in tomatoes against Alternaria solani

This study was aimed to elucidate the biochar induced resistance pathways in association with beneficial plant growth promoting rhizobacteria (PGPR) in the tomato (Solanum lycopersicum) – Alternaria solani pathosystem. To examine the impact of biochar on plant defense mechanisms at the molecular level, tomato plants were grown in two different biochars (wood and green waste biochar; 3 and 6% application level of each) both with and without Bacillus subtilis, (PGPR). Although, the reduction in disease index and disease incidence was significant in wood biochar amended soil but the resistant plant response against early blight was only recorded in the 6% green waste biochar amended treatment. Biochar application has induced the expression of defense associated genes including jasmonic acid related PI2, TomloxD, salicylic acid related PR1a, PR2 and ethylene responsive Pti4. Green waste biochar (6%) was more efficient in eliciting the expression level of TomloxD, PI2, PR1a and PR2 in tomatoes challenged by A. solani, while PGPR inoculation has enhanced the PR2 expression levels in comparison to tomatoes grown in wood biochar amended soil substrate. Moreover, phenolics, catalase and peroxidase production levels of plants grown in green waste biochar alone as well as in the presence of B. subtilis, contributed significantly in moderating infection induced damages.In conclusion, tomatoes response to invading A. solani was dependent on the type of biochar, while protection against early blight was better at higher application rate of biochar i.e. 6%. Different biochar types also differ with their ability to elicit the defense gene expression/signaling pathways. Our study revealed that biochar and PGPR induced protection against early blight of tomatoes involves both induced systemic resistance (ISR) and systemic acquired resistance (SAR) mechanisms.

Role of biochar, compost and plant growth promoting rhizobacteria in the management of tomato early blight disease

The individual role of biochar, compost and PGPR has been widely studied in increasing the productivity of plants by inducing resistance against phyto-pathogens. However, the knowledge on combined effect of biochar and PGPR on plant health and management of foliar pathogens is still at juvenile stage. The effect of green waste biochar (GWB) and wood biochar (WB), together with compost (Comp) and plant growth promoting rhizobacteria (PGPR; Bacillus subtilis) was examined on tomato (Solanum lycopersicum L.) physiology and Alternaria solani development both in vivo and in vitro. Tomato plants were raised in potting mixture modified with only compost (Comp) at application rate of 20% (v/v), and along with WB and GWB at application rate of 3 and 6% (v/v), each separately, in combination with or without B. subtilis. In comparison with WB amended soil substrate, percentage disease index was significantly reduced in GWB amended treatments (Comp + 6%GWB and Comp + 3%GWB; 48.21 and 35.6%, respectively). Whereas, in the presence of B. subtilis disease suppression was also maximum (up to 80%) in the substrate containing GWB. Tomato plant growth and physiological parameters were significantly higher in treatment containing GWB (6%) alone as well as in combination with PGPR. Alternaria solani mycelial growth inhibition was less than 50% in comp, WB and GWB amended growth media, whereas B. subtilis induced maximum inhibition (55.75%). Conclusively, the variable impact of WB, GWB and subsequently their concentrations in the soil substrate was evident on early blight development and plant physiology. To our knowledge, this is the first report implying biochar in synergism with PGPR to hinder the early blight development in tomatoes.

Pristine and iron-engineered animal- and plant-derived biochars enhanced bacterial abundance and immobilized arsenic and lead in a contaminated soil

In this study, typical animal- and plant-derived biochars derived from pig carcass (PB) and green waste (GWB), and their iron-engineered products (Fe-PB and Fe-GWB) were added at the dose of 3% (w/w) to an acidic (pH = 5.8) soil, and incubated to test their efficacy in improving soil quality and immobilizing arsenic (As = 141.3 mg kg−1) and lead (Pb = 736.2 mg kg−1). Soil properties, microbial activities, and the geochemical fractions and potential availabilities of As and Pb were determined in the non-treated (control) and biochar-treated soil. Modification of PB (pH = 10.6) and GWB (pH = 9.3) with Fe caused a decrease in their pH to 4.4 and 3.4, respectively. The application of PB and GWB significantly increased soil pH, while Fe-PB and Fe-GWB decreased soil pH, as compared to the control. Application of Fe-GWB and Fe-PB decreased the NH4H2PO4-extractable As by 32.8 and 35.9%, which was more effective than addition of GWB and PB. However, PB and GWB were more effective than Fe-PB and Fe-GWB in Pb immobilization. Compared to the control, the DTPA-extractable Pb decreased by 20.6 and 21.7%, respectively, following PB and GWB application. Both biochars, particularly PB significantly increased the 16S rRNA bacterial gene copy numbers, indicating that biochar amendments enhanced the bacterial abundance, implying an alleviation of As and Pb bio-toxicity to soil bacteria. The results demonstrated that pristine pig carcass and green waste biochars were more effective in immobilizing Pb, while their Fe-engineered biochars were more effective in As immobilization in co-contaminated soils.

Effects of Mesorhizobium ciceri and Biochar on the Growth, Nodulation and Antifungal Activity Against Root Pathogenic Fungi in Chickpea (Cicer arietinum L.)

This study was conducted to investigate the effects of the inoculation of Mesorhizobium ciceri on the nodulation, growth and antagonistic expression against soil-borne fungal pathogens (Phytophthora medicaginis, Fusarium oxysporum and Fusarium solani) on Cicer arietinum L. or commonly known as chickpea grown in vermiculite medium amended with 5% green waste (GW) biochar. The combination of M. ciceri and biochar showed significant effect to chickpea compared with other treatments and control plants in terms of nodulation. The chickpea inoculated with M. ciceri and amended with biochar produced the highest nodule number with an average value of 110 nodules per plant and with an average nodule fresh weight of 57.90 mg per plant at 60 days harvest. The other treatments (M. ciceri only and biochar only) and the positive control (2 mM nitrate-treated plants) produced an average of 55, 65 and 15 nodules per plant with the corresponding average nodule weight of 39.5, 46.5 and 35.6 mg per plant, respectively, 60 days after seed sowing. The combined M. ciceri and biochar also enhanced the shoot length, and fresh and dry weights of chickpea. However, it was observed that the primary root length was shorter than the control but clusters of feeder roots were observed. The combination of M. ciceri and biochar also completely inhibited the colony development of all root pathogenic fungi of chickpea after three days of inoculation. Therefore, the inoculation of M. ciceri in vermiculite medium amended with green waste biochar enhanced the nodulation and growth conditions in chickpea as well as inhibited the growth of root pathogenic fungi P. medicaginis, F. oxysporum and F. solani.

Tomato green waste biochars as sustainable trivalent chromium sorbents.

Chromium removal from aqueous solutions has gained attention due to its hazardous impact on life organisms. In the present study, sorption processes were performed to examine the opportunity to apply biochar derived from waste tomato leaves and stems for Cr(III) ion removal. Biochars were produced through pyrolysis in a wide range of temperature (250-800°C). The obtained biochars were investigated in detail by means of ultimate and proximate analyses, pH point of zero charge, FT-IR, scanning electron microscopy, and mercury porosimetry. Biochars are characterized by high amount of ash varying from 23 to 44% and as a result high pHpzc values of about 13. It was proven that increasing pyrolysis temperature positively affected sorption of Cr(III) ions. Mineral matter in the biochars plays a crucial role in the removal of Cr(III) ions from aqueous solution mainly due to their precipitation. The sorption capacity of biochar produced at 800°C was 169.5mgg-1, whereas at 250°C only 62.2mgg-1. It was found that biochar can be reused in sorption process after desorption using 0.1M HCl, while the sorption capacity decreased 4-fold.

Biochar bound urea boosts plant growth and reduces nitrogen leaching

Over use of N fertilizers, most commonly as urea, had been seriously concerned as a major source of radiative N (Nr) for severe environment impacts through leaching, volatilization, and N2O emission from fertilized croplands. It had been well known that biochar could enhance N retention and use efficiency by crops in amended croplands. In this study, a granular biochar-mineral urea composite (Bio-MUC) was obtained by blending urea with green waste biochar supplemented with clay minerals of bentonite and sepiolite. This Bio-MUC material was firstly characterized by microscopic analyses with FTIR, SEM-EDS and STEM, subsequently tested for N leaching in water in column experiment and for N supply for maize in pot culture, compared to conventional urea fertilizer (UF). Microscopic analyses indicated binding of urea N to particle surfaces of biochar and clay minerals in the Bio-MUC composite. In the leaching experiment over 30 days, cumulative N release as NH4+-N and of dissolved organic carbon (DOC) was significantly smaller by >70% and by 8% from the Bio-MUC than from UF. In pot culture with maize growing for 50 days, total fresh shoot was enhanced by 14% but fresh root by 25% under Bio-MUC compared to UF. This study suggested that N in the Bio-MUC was shown slow releasing in water but maize growth promoting in soil, relative to conventional urea. Such effect could be related mainly to N retention by binding to biochar/mineral surfaces and partly by carbon bonds of urea to biochar in the Bio-MUC. Therefore, biochar from agro-wastes could be used for blending urea as combined organo/mineral urea to replace mineral urea so as to reduce N use and impacts on global Nr. Of course, how such biochar combined urea would impact N process in soil-plant systems deserve further field studies.

Organic and chemical amendments positively modulate the bacterial proliferation for effective rhizoremediation of PCBs-contaminated soil

Polychlorinated Biphenyls (PCBs) are xenobiotic chlorinated aromatic compounds with high toxicity to both fauna and flora. PCBs can enter the environment through close interactions of multiple environmental matrices such as sediments, soils, water and food web. Biogeochemical cycle of PCBs can transport them far from their initial source of production. The present study aims to investigate the effects of organic and chemical amendments during rhizoremediation of PCBs in aged contaminated soil. Italian ryegrass (Lolium multiflorum) was grown in PCB-contaminated soil, whereas different combinations of two biochar (i.e., beech woodchip and green garden waste) and a surfactant (i.e., sodium dodecyl sulfate) were applied to assess the removal efficiency. The overall system’s performance was evaluated based on plant growth, PCBs degradation, and proliferation of PCBs degrading bacteria after 5-months of sowing of ryegrass. We found that PCBs removal was significantly high in the vegetated soils as compared to the un-vegetated soils. Maximum removal (85% of total PCBs load) was observed in the presence of green garden waste biochar whereas less removal was observed with the surfactant application. The observations on PCBs degrading bacteria and plant growth parameters were consistent with the degradation scheme, which suggest the potential role of bacteria in the overall degradation process. We conclude that appropriate combinations of vegetation, soil amendments, and PCB degrading bacteria can help to improve the degradation of PCBs impacted soils.

Relationship between greenhouse gas emissions and changes in soil gas diffusivity in a field experiment with biochar and lime

AbstractReducing greenhouse gas emissions from arable soil while maintaining productivity is a major challenge for agriculture. Biochar is known to reduce N2O emissions from soil, but the underlying mechanisms are unclear. This study examined the impact of green waste biochar (20 Mg ha−1) and lime (CaCO3; 2 Mg ha−1) application on soil gas transport properties and related changes in these to soil N2O and CO2emissions measured using automated chambers in a field experiment cropped with maize. In situ soil water content monitoring was combined with laboratory measurements of relative soil gas diffusion coefficient (Dp/D0) at different matric potentials, to determine changes inDp/D0over time. Cumulative N2O emissions were similar in the control and lime treatment, but much lower in the biochar treatment. Cumulative CO2emissions decreased in the order: lime treatment &gt; biochar treatment &gt; control soil. When N2O emissions were not driven by excess N supply shortly after fertilisation, they were associated withDp/D0changes, whereby decreases inDp/D0corresponded to N2O emissions peaks. No distinct pattern was observed between CO2emissions andDp/D0. Cumulative N2O emissions were positively related to number of days withDp/D0&lt; 0.02, a critical limit for soil aeration. These results indicate that improved soil gas diffusivity, and hence improved soil aeration, may explain the effect of biochar in reducing N2O emissions. They also suggest that knowledge ofDp/D0changes may be key to explaining N2O emissions.

Soil amendment with biochar: growth, physiology and fruit yield and quality of young ‘Fuji’ trees

Declining soil health in perennial fruit tree orchards is a concern due to long term lack of carbon inputs. The objective of this study was to investigate the effects of different soil amendments on the growth, physiology and fruit yield and quality of ‘Fuji’ apple trees on M.26 rootstock in a ‘replant’ soil. Treatments included application of a low-temperature-derived green-waste biochar at 47 t ha-1, compost application at 10 t ha-1, biochar plus compost application, and control. Trunk girth of trees in the biochar plus compost treatment was significantly greater than that of the control while the biochar or compost only treatments were intermediate. Leaf pre-dawn and midday water potentials were not significantly different between treatments as measured during the second cropping season. Lack of a significant difference in tree water- and nutrient-relations between treatments was attributed to the site receiving excess nutrients and irrigation such that potential effects of biochar and compost on increased water and nutrient availability were not realized. The increased trunk girth of trees in the biochar plus compost treatment was attributed in part to synergistic effect of biochar plus compost on soil microbial community in the context of this replant situation. Other effects of soil amendment with biochar may become evident on this site in dry seasons.

Evaluation of Green Waste and Popular Twigs Biochar Produced at Low and High Pyrolytic Temperature for Efficient Removal of Metals from Water

Biomass-derived biochar is considered as a promising heavy metal adsorbent, due to its favorable physicochemical properties, from aqueous solution as compared with other adsorbents. However, there is a limited number of studies on the effects of biochar produced from different feedstocks and pyrolytic temperatures on metal removal from metal-contaminated water. So in this study, the removal of the most prevalent heavy metals [(lead (Pb(II)), cadmium (Cd), and chromium (Cr)] by green waste biochar (GWB) and popular twigs biochar (PTB), produced at different pyrolytic temperatures, i.e., low 350 and high 650 °C, has been investigated, following the determination of physical and chemical properties of biochar. The efficiency of heavy metals removal of biochar was studied at different concentrations of heavy metals (10 and 100 μg mL−1), biochar types and treatment duration (3, 6, 9, and 12 h) at isothermic condition of aqueous solution. Results revealed that both feedstock type and pyrolytic temperature to produce biochar significantly affected its metal sorption capacity. The maximum sorption capacities of all three metals, i.e., Pb (II), Cd, and Cr were determined in the GWB produced at low pyrolytic temperature 350 °C after 9 h of treatment duration at both high and low metal concentrations. This highest sorption capacity of all metals by low pyrolytic temperature produced GWB was due to its better physicochemical properties especially high surface area, cation exchange capacity, and oxygen-containing functional groups as compared with woody feedstock based high pyrolytic temperature produced PTB. Conclusively, low pyrolytic temperature produced GWB was evaluated as a potential adsorbent to efficiently reduced heavy metal concentration in metal-contaminated water.

Erratum to: Potential of Fusarium wilt-inducing chlamydospores, in vitro behaviour in root exudates and physiology of tomato in biochar and compost amended soil

Biochars are recognised for their ability to improve soil functions and to stimulate plant defense mechanisms. We evaluated the response of Fusarium oxysporum f. sp. lycopersici chlamydospores to tomato plants grown in biochar and compost amended soil to get a deeper insight into the tomato-Fusarium pathosystem. Wood chips and green waste biochar in combination with compost (‘WCBcomp and GWBcomp’ respectively) were studied for their ability to suppress the Fusarium chlamydospores infectivity. Plant growth parameters and in vitro effects on chlamydospores were determined. The ‘GWBcomp’ soil amendment stimulated plants growth and gaseous exchange rates and had a suppressive effect on the chlamydospore infectivity in comparison with the ‘WCBcomp’ treatment and the treatment containing compost only. The germination rate of chlamydospores was unaffected by the source of root exudates, whereas the mycelial growth was significantly higher in root exudates from chlamydospore inoculated plants grown in ‘WCBcomp’ amended soil unlike to ‘GWBcomp’ amended soil. Overall, our findings indicate that both biochars had a variable effect on chlamydospores. We conclude that soil amendment with garden waste biochar and compost exhibit a great potential in suppressing Fusarium chlamydospore infectivity and alleviating pathogen–induced physiological stress in tomato plants.