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Papers by Raghunath Subedi

Research paper thumbnail of Field assessment of ammonia emissions after soil application of cattle slurry amended with additives

Research paper thumbnail of Agronomic benefits and detriments of using biochar

Research paper thumbnail of Biochar, fattori che influenzano la sua qualità ammendante

Research paper thumbnail of Biochar: factors influencing its quality

Research paper thumbnail of Biochar, fattori che influenzano la sua qualità ammendante

Research paper thumbnail of Effects of biochar on soil phosphorus and interaction with phosphate solubilizing bacteria

Research paper thumbnail of Recovery and Use of Nutrients, Energy and Organic Matter from Animal Waste–Rethinking Manure Recycling

Research paper thumbnail of Chemically and biologically-mediated fertilizing value of manure-derived biochar

Science of The Total Environment, 2016

This study evaluates the potential of manure-derived biochars in promoting plant growth and enhan... more This study evaluates the potential of manure-derived biochars in promoting plant growth and enhancing soil chemical and biological properties during a 150day pot experiment. Biochars from pyrolysis of poultry litter (PL) and swine manure (SM) at 400 and 600°C, and a commonly available wood chip (WC) biochar produced at high temperature (1000°C) were incorporated to silt-loam (SL) and sandy (SY) soils on a 2% dry soil weight basis. Ryegrass was sown and moisture was adjusted to 60% water filled pore space (WFPS). The PL400 and SM400 biochars significantly increased (p<0.05) shoot dry matter (DM) yields (SL soil) and enhanced nitrogen (N), phosphorus (P) and potassium (K) uptake by the plants in both soils, compared to the Control. All biochars significantly increased the soil carbon (C) contents compared to the Control. Total N contents were significantly greater for PL400 and PL600 treatments in both soils. The dehydrogenase activity (DA) significantly increased for PL400 and SM400 treatments and was positively correlated with the volatile matter (VM) contents of the biochars, while β-glucosidase activity (GA) decreased for the same treatments in both soils. All biochars significantly shifted (p≤0.05) the bacterial community structure compared to the Control. This study suggests that pyrolysis of animal manures can produce a biochar that acts as both soil amendment and an organic fertilizer as proven by increased NPK uptake, positive liming effect and high soil nutrient availability, while WC biochar could work only in combination with fertilizers (organic as well as mineral).

Research paper thumbnail of Crop response to soils amended with biochar: expected benefits and unintended risks

Italian Journal of Agronomy

Biochar (BC) from biomass waste pyrolysis has been widely studied due to its ability to increase ... more Biochar (BC) from biomass waste pyrolysis has been widely studied due to its ability to increase carbon (C) sequestration, reduce greenhouse gas (GHG) emissions, and enhance both crop growth and soil quality. This review summarizes the current knowledge of BC production, characterization, and types, with a focus on its positive effects on crop yield and soil properties versus the unintended risks associated with these effects. Biochar-amended soils enhance crop growth and yield via several mechanisms: expanded plant nutrient and water availability through increased use efficiencies, improved soil quality, and suppression of soil and plant diseases. Yield response to BC has been shown to be more evident in acidic and sandy soils than in alkaline and fine-textured soils. Biochar composition and properties vary considerably with feedstock and pyrolysis conditions so much that its concentrations of toxic compounds and heavy metals can negatively impact crop and soil health. Consequently...

Research paper thumbnail of Gaseous emissions and modification of slurry composition during storage and after field application: Effect of slurry additives and mechanical separation

Journal of environmental management, Jan 10, 2017

The aim of the study was to evaluate the impact of slurry treatment by additives (EU200(®) (EU200... more The aim of the study was to evaluate the impact of slurry treatment by additives (EU200(®) (EU200), Bio-buster(®) (BB), JASS(®) and sulphuric acid (H2SO4)) and mechanical separation on the physical-chemical characteristics, gaseous emissions (NH3, CH4, CO2 and N2O) during anaerobic storage at ∼20 °C (experiment 1) and NH3 losses after field application (experiment 2). The treatments studied in experiment 1 were: whole slurry (WS), WS+H2SO4 to a pH of 6.0, WS+EU200 and WS+BB. Treatments for experiment 2 were: WS, slurry liquid fraction (LF), composted solid fraction (CSF), LFs treated with BB (LFB), JASS(®) (LFJ), H2SO4 to a pH of 5.5 (LFA) and soil only (control). The results showed an inhibition of the degradation of organic materials (cellulose, hemicellulose, dry matter organic matter and total carbon) in the WS+H2SO4 relative to the WS. When compared to the WS, the WS+H2SO4 increased electrical conductivity, ammonium (NH4(+)) and sulphur (S) concentrations whilst reducing slurry...

Research paper thumbnail of Short-Term Carbon Dioxide and Nitrous Oxide Emissions and Changes in Physico-Chemical Properties from Soils Amended with Different Biochars

Research paper thumbnail of Manure-derived biochars behave also as fertilizer

Research paper thumbnail of Greenhouse gas emissions and soil properties following amendment with manure-derived biochars: Influence of pyrolysis temperature and feedstock type

Journal of environmental management, Jan 17, 2015

Manure-derived biochars can offer a potential option for the stabilization of manure, while mitig... more Manure-derived biochars can offer a potential option for the stabilization of manure, while mitigating climate change through carbon sequestration and the attenuation of nitrous oxide emission. A laboratory incubation study was conducted to assess the effects of four different manure-derived biochars produced from different feedstocks (poultry litter and swine manure) at different temperatures (400 or 600 °C). A commonly available standard wood chip biochar, produced at a greater temperature (1000 °C), and non-amended treatments were used as references. Two different soils (sandy and silt-loam) were amended with 2% (w/w) biochar on a dry soil weight basis (corresponding to 20 Mg ha(-1)), with the soil moisture being adjusted to 75% saturation level. After a pre-incubation period (21 days), 170 kg N ha(-1) of NH4NO3 fertilizer was added. Measurements of CO2, N2O, CH4 emissions and soil N mineralisation were carried out on different days during the 85 days of incubation. The net C min...

Research paper thumbnail of Does soil amended with biochar and hydrochar reduce ammonia emissions following the application of pig slurry?

European Journal of Soil Science, 2015

Research paper thumbnail of Biochar, fattori che influenzano la sua qualità ammendante

Research paper thumbnail of Manure-derived biochars behave also as fertilizer

Research paper thumbnail of Use of biochar and hydrochar to reduce ammonia emissions from soils fertilized with pig slurry

Ammonia (NH 3 ) volatilization caused by animal manure application to agricultural soils leads to... more Ammonia (NH 3 ) volatilization caused by animal manure application to agricultural soils leads to high amounts of nitrogen (N) losses. The use of biochar and hydrochar by-products as soil amendments modifies the dynamic of N in soil and may also influence NH 3 emissions and nitrates leaching. The present study assessed the potential NH 3 emissions after surface application of pig slurry on soils amended with a biochar (from pyrolysis) and a hydrochar (from hydrothermal carbonization) of Miscanthus sp. in a laboratory experiment. The experiment was carried out in a dynamic chambers coupled with a photo-acoustic trace gas analyzer in a controlled environment for 48 hours. Statistical results showed significant differences among treatments. Total emissions of NH 3 and total inorganic N concentrations in the soil extracts were related to type of soil amendment and not to soil type.

Research paper thumbnail of Chemically and biologically-mediated fertilizing value of manure-derived biochar

Research paper thumbnail of Field assessment of ammonia emissions after soil application of cattle slurry amended with additives

Research paper thumbnail of Agronomic benefits and detriments of using biochar

Research paper thumbnail of Biochar, fattori che influenzano la sua qualità ammendante

Research paper thumbnail of Biochar: factors influencing its quality

Research paper thumbnail of Biochar, fattori che influenzano la sua qualità ammendante

Research paper thumbnail of Effects of biochar on soil phosphorus and interaction with phosphate solubilizing bacteria

Research paper thumbnail of Recovery and Use of Nutrients, Energy and Organic Matter from Animal Waste–Rethinking Manure Recycling

Research paper thumbnail of Chemically and biologically-mediated fertilizing value of manure-derived biochar

Science of The Total Environment, 2016

This study evaluates the potential of manure-derived biochars in promoting plant growth and enhan... more This study evaluates the potential of manure-derived biochars in promoting plant growth and enhancing soil chemical and biological properties during a 150day pot experiment. Biochars from pyrolysis of poultry litter (PL) and swine manure (SM) at 400 and 600°C, and a commonly available wood chip (WC) biochar produced at high temperature (1000°C) were incorporated to silt-loam (SL) and sandy (SY) soils on a 2% dry soil weight basis. Ryegrass was sown and moisture was adjusted to 60% water filled pore space (WFPS). The PL400 and SM400 biochars significantly increased (p<0.05) shoot dry matter (DM) yields (SL soil) and enhanced nitrogen (N), phosphorus (P) and potassium (K) uptake by the plants in both soils, compared to the Control. All biochars significantly increased the soil carbon (C) contents compared to the Control. Total N contents were significantly greater for PL400 and PL600 treatments in both soils. The dehydrogenase activity (DA) significantly increased for PL400 and SM400 treatments and was positively correlated with the volatile matter (VM) contents of the biochars, while β-glucosidase activity (GA) decreased for the same treatments in both soils. All biochars significantly shifted (p≤0.05) the bacterial community structure compared to the Control. This study suggests that pyrolysis of animal manures can produce a biochar that acts as both soil amendment and an organic fertilizer as proven by increased NPK uptake, positive liming effect and high soil nutrient availability, while WC biochar could work only in combination with fertilizers (organic as well as mineral).

Research paper thumbnail of Crop response to soils amended with biochar: expected benefits and unintended risks

Italian Journal of Agronomy

Biochar (BC) from biomass waste pyrolysis has been widely studied due to its ability to increase ... more Biochar (BC) from biomass waste pyrolysis has been widely studied due to its ability to increase carbon (C) sequestration, reduce greenhouse gas (GHG) emissions, and enhance both crop growth and soil quality. This review summarizes the current knowledge of BC production, characterization, and types, with a focus on its positive effects on crop yield and soil properties versus the unintended risks associated with these effects. Biochar-amended soils enhance crop growth and yield via several mechanisms: expanded plant nutrient and water availability through increased use efficiencies, improved soil quality, and suppression of soil and plant diseases. Yield response to BC has been shown to be more evident in acidic and sandy soils than in alkaline and fine-textured soils. Biochar composition and properties vary considerably with feedstock and pyrolysis conditions so much that its concentrations of toxic compounds and heavy metals can negatively impact crop and soil health. Consequently...

Research paper thumbnail of Gaseous emissions and modification of slurry composition during storage and after field application: Effect of slurry additives and mechanical separation

Journal of environmental management, Jan 10, 2017

The aim of the study was to evaluate the impact of slurry treatment by additives (EU200(®) (EU200... more The aim of the study was to evaluate the impact of slurry treatment by additives (EU200(®) (EU200), Bio-buster(®) (BB), JASS(®) and sulphuric acid (H2SO4)) and mechanical separation on the physical-chemical characteristics, gaseous emissions (NH3, CH4, CO2 and N2O) during anaerobic storage at ∼20 °C (experiment 1) and NH3 losses after field application (experiment 2). The treatments studied in experiment 1 were: whole slurry (WS), WS+H2SO4 to a pH of 6.0, WS+EU200 and WS+BB. Treatments for experiment 2 were: WS, slurry liquid fraction (LF), composted solid fraction (CSF), LFs treated with BB (LFB), JASS(®) (LFJ), H2SO4 to a pH of 5.5 (LFA) and soil only (control). The results showed an inhibition of the degradation of organic materials (cellulose, hemicellulose, dry matter organic matter and total carbon) in the WS+H2SO4 relative to the WS. When compared to the WS, the WS+H2SO4 increased electrical conductivity, ammonium (NH4(+)) and sulphur (S) concentrations whilst reducing slurry...

Research paper thumbnail of Short-Term Carbon Dioxide and Nitrous Oxide Emissions and Changes in Physico-Chemical Properties from Soils Amended with Different Biochars

Research paper thumbnail of Manure-derived biochars behave also as fertilizer

Research paper thumbnail of Greenhouse gas emissions and soil properties following amendment with manure-derived biochars: Influence of pyrolysis temperature and feedstock type

Journal of environmental management, Jan 17, 2015

Manure-derived biochars can offer a potential option for the stabilization of manure, while mitig... more Manure-derived biochars can offer a potential option for the stabilization of manure, while mitigating climate change through carbon sequestration and the attenuation of nitrous oxide emission. A laboratory incubation study was conducted to assess the effects of four different manure-derived biochars produced from different feedstocks (poultry litter and swine manure) at different temperatures (400 or 600 °C). A commonly available standard wood chip biochar, produced at a greater temperature (1000 °C), and non-amended treatments were used as references. Two different soils (sandy and silt-loam) were amended with 2% (w/w) biochar on a dry soil weight basis (corresponding to 20 Mg ha(-1)), with the soil moisture being adjusted to 75% saturation level. After a pre-incubation period (21 days), 170 kg N ha(-1) of NH4NO3 fertilizer was added. Measurements of CO2, N2O, CH4 emissions and soil N mineralisation were carried out on different days during the 85 days of incubation. The net C min...

Research paper thumbnail of Does soil amended with biochar and hydrochar reduce ammonia emissions following the application of pig slurry?

European Journal of Soil Science, 2015

Research paper thumbnail of Biochar, fattori che influenzano la sua qualità ammendante

Research paper thumbnail of Manure-derived biochars behave also as fertilizer

Research paper thumbnail of Use of biochar and hydrochar to reduce ammonia emissions from soils fertilized with pig slurry

Ammonia (NH 3 ) volatilization caused by animal manure application to agricultural soils leads to... more Ammonia (NH 3 ) volatilization caused by animal manure application to agricultural soils leads to high amounts of nitrogen (N) losses. The use of biochar and hydrochar by-products as soil amendments modifies the dynamic of N in soil and may also influence NH 3 emissions and nitrates leaching. The present study assessed the potential NH 3 emissions after surface application of pig slurry on soils amended with a biochar (from pyrolysis) and a hydrochar (from hydrothermal carbonization) of Miscanthus sp. in a laboratory experiment. The experiment was carried out in a dynamic chambers coupled with a photo-acoustic trace gas analyzer in a controlled environment for 48 hours. Statistical results showed significant differences among treatments. Total emissions of NH 3 and total inorganic N concentrations in the soil extracts were related to type of soil amendment and not to soil type.

Research paper thumbnail of Chemically and biologically-mediated fertilizing value of manure-derived biochar