RESUMO

Biochar can enhance the phytoremediation of copper-contaminated soils by improving soil quality and increasing plant growth. However, the impact of biochar varies with the biomass feedstock and soil condition. Our study investigated the effect of biochar from orange bagasse-OBB and coconut husk-CHB and two copper concentrations (0.17 mg kg-1-CLS soil; 100 mg kg-1- CTS soil) on plant growth, copper uptake, and physiological response of Brassica juncea. The low- and high-Cu soils were also tested without biochar. We evaluated plant biomass, plant Cu, N and P, chlorophyll content, and chlorophyll's transient fluorescence. Plant growth was meager without biochar, indicating that the high Cu concentration was not the only limiting factor. Biochar (OBB and CHB) increased shoot mass by 300-574% and root mass by 50-2900%, and improved chlorophyll content and photosynthetic activity by 6-16%. Both biochars were efficient in the low-Cu soil as they increased plant biomass, shoot copper concentration, and translocation factor. In the high-Cu soil, both biochars increased plant biomass and copper uptake and reduced shoot copper concentration and translocation factor. The CHB and OBB removed 342% and 783% more Cu from the contaminated soil than the Control; therefore, the OBB was proven to be the best choice for phytoremediation.Novelty statement Our study showed that the orange bagasse biochar can be successfully applied for the phytoremediation of copper-contaminated soils using Brassica juncea. The orange bagasse biochar was effective regardless of the copper level in the soil, removing twice as much copper as the coconut biochar; therefore, it can speed up the process and reduce the time needed to clean up the site. HighlightsBiochar significantly improved the plant's physiological responseBiochar increased plant growth and copper uptake in the contaminated soilTranslocation factor was increased in the clean soil and reduced in the contaminated soilBiochar from orange bagasse is more effective than coconut husk for phytoremediation.

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RESUMO

Biochar has shown much potential to be used as soil amendment and conditioner as well as an effective alternative to waste disposal. However, the effect of biochar on soil organic matter varies according to the type of feedstock. This study aimed to evaluate the influence of different types and rates of application of biochar on soil microbial activity and on soil carbon priming effect. The incubation experiment was set up as a completely randomized design in a 2 x 5 factorial scheme, with two types of biochar (coconut husk and orange bagasse) and five rates of application (0, 5, 10, 15 and 30 t ha-1), with three replications. Soil microbial activity was evaluated through the concentration of CO2 released from the soil during a period of 130 days. Carbon priming effect was determined based on the CO2 respired in the biochar treated soil and in the control soil. Both biochars increased the total oxidizable carbon in the soil when they were applied at 30 t ha-1, however, the orange bagasse biochar was more effective than the coconut biochar. Coconut biochar increased the cumulative soil microbial respiration at all rates of application during the incubation period, therefore, it contributed to a positive carbon priming effect and should be applied with caution to avoid excessive loss of carbon from the soil. Orange bagasse biochar had little influence on the cumulative CO2 emission, except at 15 t ha-1, which increased soil microbial activity.

O biocarvão tem mostrado grande potencial para uso como insumo e condicionador de solo, assim como uma alternativa eficiente para a disposição de resíduos. Contudo, o efeito do biocarvão sobre a matéria orgânica do solo varia de acordo com o tipo de biomassa. O presente estudo objetivou avaliar a influência de diferentes tipos e doses de biocarvão na atividade microbiana e no efeito priming do carbono do solo. O experimento de incubação foi desenvolvido em desenho inteiramente casualizado, em esquema factorial 2 x 5, com dois tipos de biocarvão (casca de coco seco e bagaço de laranja) e cinco doses (0, 5, 10, 15 and 30 t ha-1), com três repetições. A atividade microbiana do solo foi avaliada por meio da concentração de CO2 liberado durante 130 dias. O efeito priming do carbono foi determinado com base no CO2 respirado do solo tratado com biocarvão e do controle. Os dois biocarvões aumentaram a concentração de carbono total oxidável no solo quando aplicados na dose de 30 t ha-1; contudo, o biocarvão de bagaço de laranja foi mais eficiente do que o biocarvão de coco. O biocarvão de coco aumentou a concentração de carbono respirado acumulado em todas as taxas de aplicação durante o period de incubação, portanto, contribuiu para o efeito priming positivo e deve ser aplicado com cuidado para evitar perdas excessivas de carbono do solo. O biocarvão de laranja influenciou o carbono respirado acumulado apenas na dose de 15 t ha-1.

Assuntos

RESUMO

Biochar has shown much potential to be used as soil amendment and conditioner as well as an effective alternative to waste disposal. However, the effect of biochar on soil organic matter varies according to the type of feedstock. This study aimed to evaluate the influence of different types and rates of application of biochar on soil microbial activity and on soil carbon priming effect. The incubation experiment was set up as a completely randomized design in a 2 x 5 factorial scheme, with two types of biochar (coconut husk and orange bagasse) and five rates of application (0, 5, 10, 15 and 30 t ha-1), with three replications. Soil microbial activity was evaluated through the concentration of CO2 released from the soil during a period of 130 days. Carbon priming effect was determined based on the CO2 respired in the biochar treated soil and in the control soil. Both biochars increased the total oxidizable carbon in the soil when they were applied at 30 t ha-1, however, the orange bagasse biochar was more effective than the coconut biochar. Coconut biochar increased the cumulative soil microbial respiration at all rates of application during the incubation period, therefore, it contributed to a positive carbon priming effect and should be applied with caution to avoid excessive loss of carbon from the soil. Orange bagasse biochar had little influence on the cumulative CO2 emission, except at 15 t ha-1, which increased soil microbial activity.(AU)

O biocarvão tem mostrado grande potencial para uso como insumo e condicionador de solo, assim como uma alternativa eficiente para a disposição de resíduos. Contudo, o efeito do biocarvão sobre a matéria orgânica do solo varia de acordo com o tipo de biomassa. O presente estudo objetivou avaliar a influência de diferentes tipos e doses de biocarvão na atividade microbiana e no efeito priming do carbono do solo. O experimento de incubação foi desenvolvido em desenho inteiramente casualizado, em esquema factorial 2 x 5, com dois tipos de biocarvão (casca de coco seco e bagaço de laranja) e cinco doses (0, 5, 10, 15 and 30 t ha-1), com três repetições. A atividade microbiana do solo foi avaliada por meio da concentração de CO2 liberado durante 130 dias. O efeito priming do carbono foi determinado com base no CO2 respirado do solo tratado com biocarvão e do controle. Os dois biocarvões aumentaram a concentração de carbono total oxidável no solo quando aplicados na dose de 30 t ha-1; contudo, o biocarvão de bagaço de laranja foi mais eficiente do que o biocarvão de coco. O biocarvão de coco aumentou a concentração de carbono respirado acumulado em todas as taxas de aplicação durante o period de incubação, portanto, contribuiu para o efeito priming positivo e deve ser aplicado com cuidado para evitar perdas excessivas de carbono do solo. O biocarvão de laranja influenciou o carbono respirado acumulado apenas na dose de 15 t ha-1.(AU)

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