Effects of Rice Husk Biochar Produced under Slow Pyrolysis on ...

National Pingtung University <strong>of</strong> Science and Technology
Pingtung, Taiwan.
Odette Varela Milla
Wu-Jang Huang PhD.

Contents:
• Objectives
• Introduction
• Characteristics <strong>of</strong> carbonized rice residues
• <strong>Biochar</strong> preparation and characterization
• Scanning electron microscopy analysis
• Water spinach
• Worm avoidance test
• Soil
• Application <strong>of</strong> rice husk biochar and wood
biochar to soil
• Results
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Objectives:
• Realize an investigation <strong>of</strong> the short-term effects
related to slow pyrolysis biochar effects in plant
growth.
• Furthermore it is planned to determine biochar
characteristics such as biodegradability, porosity and
cation exchange capacity, produced from agricultural
waste.
3

Organic waste as feedstock for biochar production
• Many different materials have been proposed as biomass
feedstocks for biochar, including wood, grain husks, nut
shells, manure and crop residues, (Lua et al., 2004, Martinez et
al., 2006, Gonzaléz et al., 2009).
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• The use <strong>of</strong> rice straw and rice husk has been practiced for a long
time (Ponamperuma, 1982; Eagle et al., 2000; Singh et al., 2008;
Kaewpradit et al., 2009).
• Karmakar et al., (2009) studied the effect <strong>of</strong> application <strong>of</strong> fly ash
and rice husk ash, the study showed that the application <strong>of</strong> these
type <strong>of</strong> waste improved soil properties by decreasing soil bulk density
and increasing soil pH, organic carbon, available nutrients, and crops
yield.
5

• The total amount <strong>of</strong> crop residues produced each year in rice-based
systems <strong>of</strong> Asia can be roughly estimated at about 112 million tons <strong>of</strong>
rice husks (based on 2005 production and a husk/paddy ratio <strong>of</strong> 0.2).
(Pandey 1998)
Asia and China <strong>Rice</strong> Production 2008
Source: http://www.fao.org/corp/statistics/en/
• Residue burning is widely practiced and causes air pollution, human
health problems, and considerable nutrient losses.
6

Taiwan’s cultivated land area
250000
0.14%
Hectares
200000
150000
100000
50000
0.64%
0.34%
99.36% 99.66% 99.86%
0.54%
99.46%
0
<strong>Rice</strong> Vegetable Fruits Tea Others
s
crops
Organic (ha) 949.44 518.43 295.52 139.84 453.1
96.66%
No organic (ha) 147081.56 151573.57 215067.48 25647.16 13107.9
3.34%
Source: Organization <strong>of</strong> certification Agriculture and Food Agency ,Council <strong>of</strong> Agriculture. 2009

Characteristics <strong>of</strong> Carbonized <strong>Rice</strong> Residues
• Carbonized rice husks are a very light material with a
microporous structure and a bulk density <strong>of</strong> about 0.150 g cm−3
(Nakajima 1986).
• The structure <strong>of</strong> rice husks is preserved in the carbonization
process but carbonized husks break easily, especially if
carbonized at high temperatures.
8

<strong>Biochar</strong> preparation and characterization
• <strong>Biochar</strong> was found to be alkaline in nature (pH 8.2). <strong>Rice</strong> husk biochar
produced <strong>under</strong> temperatures between 500 and 600 ℃, showed a
noticeable increment in silicon, calcium, potassium and magnesium
content.
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Scanning electron microscope analysis
• The EDS point analysis <strong>of</strong> rice husk indicated that the biochar
particles consisted <strong>of</strong> high silicon mineral agglomerates on lower
carbon content fibers with structures typical <strong>of</strong> its biomass
origin
10

• Wood biochar EDS point analysis, indicated that the biochar
particles consisted <strong>of</strong> high potassium, chlorine, and calcium.
• Mineral agglomerates also showed high carbon content
12

To investigate and quantify effects <strong>of</strong> rice husk-based
biochar and wood-based biochar on the growth <strong>of</strong> water
spinach, a field experiment was carried out <strong>under</strong> different
treatments, consisting <strong>of</strong>:
•(1) control soil and fertilizer,
•(2) soil with rice husk biochar and fertilizer in five
different quantities,
•(3) and soil with wood biochar and fertilizer in five
different quantities.
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From the literature, the recommends amount <strong>of</strong> rice husk biochar
that should be applied is: 10 ton per hectare (<strong>Biochar</strong> and Carbon
Sequestration, a regional perspective, 2009).
1.10 m
1.94 m

Water spinach
• Water convolvulus has been widely grown throughout the world. It is
found in South and Southeast Asia, Tropical Africa, South
America, and Oceania (Wenfang, 1997). However, it is only in south
and Southeast Asia that it is an important leafy vegetable.
http://waynesword.palomar.edu/ww0804.htm
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Worm avoidance test
• A toxicity test was conducted before starting the biochar
experiment. Following the guidelines from “A guide to
conducting biochar trials” (Major. J., 2009) we realized a
worm avoidance test
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• We made our trial with 50 worms that were purchased in a fish
shop
• The container was prepared with rice husk biochar and soil from
the experimental field. We had as a result that most <strong>of</strong> the
worms shown an acceptance for rice husk biochar
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Soil
• The experiment was
conducted on an
uncultivated clayey Ultisol
soil, which are strongly
leached, acid forest soils
with relatively low native
fertility.
http://eusoils.jrc.ec.europa.eu/esdb_archive/eudasm/asia/maps/TW3000_1SO.htm
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• Germination comparison between Soil field with <strong>Biochar</strong> and
soil field without biochar
• Soil with biochar shows the best germination
20

Application <strong>of</strong> rice husk biochar and wood
biochar to soil
• Soil preparation
21

• <strong>Biochar</strong>s were weighted and later added to each one <strong>of</strong> the
plots
22

• Top soil mixing technique (Major, 2009)
• Before transplanting was necessary to irrigate for 10 minutes
• Following the literature recommendations, plants were transplanted
in a distance <strong>of</strong> 15cm between them.
• Each plot had 22 plants
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Morphology
• Leaf number
• Leaf length and wide
• Stem size
• Stem number
• Root size
• Weight
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Results:
• Water spinach plants for all <strong>of</strong> the considered treatments were
harvested after 8 weeks.
25

Effect <strong>of</strong> rice husk biochar and wood biochar on plant
root growth
• All water spinach plants were measured before harvesting;
carefully plants and roots were removed from soil.
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Statistical analysis
• Both biochar treatments where compared using least
significant difference (LSD), for their main effects
on plant growth properties (SAS 9.1, 2004).
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Leaf wide (mm)
Leaf number
Leaf length (mm)
Leaf length (mm)
<strong>Rice</strong> husk
Wood
40
30
20
20
15
10
5
0
10
0 1 2 3 4 5
Treatments
0
0 1 2 160 3 4 5
Treatments 140
<strong>Rice</strong> husk
Wood
120
100
80
60
40
20
0
160
140
120
100
<strong>Rice</strong> husk
Wood
80
0 1 2 3 4 5
60
Treatments
40
20
0
0 1 2 3 4 5
Treatments
<strong>Rice</strong> husk
Wood
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Stem number
Stem size (mm)
<strong>Rice</strong> husk
Wood
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0 1 2 3 4 5
Treatments
200
<strong>Rice</strong> husk
Wood
150
100
50
0
0 1 2 3 4 5
Treatments
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• Randomly we choose water spinach plants from each
treatment, T1, T2, T3, T4, T5, treated with each one <strong>of</strong> the biochars.
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Root size (mm)
<strong>Rice</strong> <strong>Husk</strong>
Wood
150
100
50
0
0 1 2 3 4 5
Treatments
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Effect <strong>of</strong> rice husk biochar and wood biochar on
plant fresh weight
• From each treatment, plants were collected
• All plants were classified by treatment
• Plants were weighted
35

Weight (kg)
0.6
<strong>Rice</strong> <strong>Husk</strong>
Wood
0.5
0.4
0.3
0.2
0.1
0.0
0 1 2 3 4 5
Treatments
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Conclusions
•<strong>Rice</strong> husk biochar showed better holding capacity than wood
based biochar, due to the differences in their particle size, rice
husk biochar was able to integrate better into soil making the
distribution more uniform.
•Water spinach requires plenty <strong>of</strong> water because <strong>of</strong> its high
succulence, regardless <strong>of</strong> this information, we irrigated the
plants every 2 days for only 10 minutes.
•The plants were able to absorb the water that biochar was
retaining, being not affected by the lack <strong>of</strong> water.
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