Biochar and its importance in sustaining crop productivity & soil health

1. 25-10-20161

2. Course code:-RAWE
Course title:-Rural
Agriculture Work Experience
Credit hour:-(0+4)
B.Sc.(Ag.) 4th Yr., INSTITUTE OF AGRICULTURE SCIENCES, BHU 25-10-20162

3. Contents:
 Introduction
 What is Biochar?
 Important feedstocks for Biochar
 Charactertistics of Biochar
 Methods of biochar preparation
 Biochar application in soil
 Biochar impact on soil properties, soil water
hydaulics & soil biota
 Critical factors for maximizing the benefits of
biochar
 Conclusion 25-10-20163

4. INTRODUCTION:-
 Soil health is the foundation of a vigorous and sustainable
food system. As the land is farmed, the agricultural process
disturbs the natural soil systems including nutrient cycling
and the release and uptake of nutrients.
 Efficient use of biomass, available as crop residues and other
farm wastes, by converting it to a useful source of soil
amendment/nutrients is one way to manage soil health and
fertility.
 Biochar is a potential soil amendment and carbon
sequestration medium. It also reduces farm waste and
improve the soil quality. 25-10-20164

5. BIOCHAR
 Biochar is a fine-grained, carbon-rich, porous product
remaining after plant biomass has been subjected to thermo-
chemical conversion process (pyrolysis) at temperatures
(~350–600°C) in an environment with little or no oxygen.
 It is highly porous structure & is also very variable in quality,
depending on raw material, pyrolysis conditions, whether it is
enriched with other compounds and how finely it is ground.
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Amonette and Joseph, 2009.
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6. IMPORTANT FEEDSTOCKS FOR
BIOCHAR
 Feedstocks used at a commercial scale include wood waste,
crop residues (including straw, nut shells, and rice hulls),
switch grass, bagasse from the sugarcane industry, chicken
litter, dairy manure, sewage sludge and paper sludge.
 Types of feedstock- a) Nutrient rich feedstocks
b) Lignin rich plant biomass feedstocks
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7. 25-10-2016
Summary of common biochar feedstocks, typical products, applications and uses of these products.
Source: Sohi et al. 2009.
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8. CHARACTERISTICS OF BIOCHAR
 Physical characterization
Pyrolysis temperature is the main regulating factor which
governs characterization of biochar.
 It also depends on the type of feedstock used.
Ex- bulk density of rice and wheat biochar prepared at 400ºC
was comparatively lower than the maize and pearl millet
biochar. 25-10-2016
Low temperature (400ºC & below.) High temperature (600 – 900ºC)
Surface area 120 sq. m/gm. Surface area 460 sq. m/gm.
Suitable for controlling release of nutrients. Material analogous to activated carbon.
Lower ash content. Higher ash content.
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9. • Chemical characterization
Low temperature (400ºC & below) High temperature (600 – 900ºC)
Lower carbon content. Higher carbon content.
Higher amount of N, S, K & P compounds. Lower amount of N, S, K & P compounds.
Lower pH, EC & extractable NO3-. Higher pH, EC & extractable NO3-.
Higher extractable P, NH4+, and phenols. Lower extractable P, NH4+, and phenols.
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• The biochar prepared from rice residues showed highest CEC.
• pH of maize & pearl millet biochar was higher than that in wheat & rice biochar.
• Maize biochar was richer in major (N, P, K), secondary (Ca, Mg) and
micronutrient (Fe, Mn, Zn and Cu) contents. Wheat biochar ranked second with
respect to all the above nutrients except sulphur for which it ranked first.
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10. 25-10-2016
Materials used for
producing biochar
pH C N C:N Ca Mg P K CEC
(%) (cmolp+/kg)
Paper mill waste1-
(waste wood chip)
9.4 52.0 0.48 104 6.2 1.20 - 0.22 9.00
Paper mill waste2-
(waste wood chip)
8.2 52.0 0.31 168 11.0 2.60 - 1.00 18.00
Green waste(grass
Clippings, cotton trash,
and plant prunings)
9.4 36.0 0.18 200 0.4 0.56 - 21.00 24.00
Eucalyptus biochar - 82.4 0.57 145 - - 1.87 - 4.69
Cooking biochar - 72.9 0.76 96 - - 0.42 - 11.19
Poultry litter (450oC) 9.9 38.0 2.0 19 - - 37.42 - -
Poultry litter (550oC) 13 33.0 0.85 39 - - 5.81 - -
Wood biochar 9.2 72.9 0.76 120 0.83 0.20 0.10 1.19 11.90
Hardwood sawdust - 66.5 0.3 221 - - - - -
Source: Jha et al. (2010)10

11. Methods Of Biochar Preparation
 Heap Method
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Traditional earth kiln.11

12. Drum Method
25-10-2016Cylindrical low cost kiln made from fire brick at IARI.12

13. Biochar Stove
 Types- a) Top-Lit Updraft Gasifier (TLUD)
b) Anila stove
 The TLUD operates as a gasifier by creating a stratified
pyrolysis regime with four basic zones: raw biomass, flaming
pyrolysis, gas combustion and charcoal combustion.
 Biomass fuel is placed between the two cylinders and a fire is
ignited in the centre. Heat from the central fire pyrolyzes the
concentric ring of fuel.
 The gases escape to the centre where they add to the cooking
flame as the ring of biomass turns to char.
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14. Anila stove
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15. BIOCHAR APPLICATION IN SOIL
 Methods of application
1. By hand
2. Using a tractor propelled lime spreader
3. Deep banding of biochar in rhizosphere
4. Mixing of biochar with composts & manures
5. Line trenching and backfilling
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16. • Rate of application
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Most studies back the field application rates to be 25 tons/ha
that increased crop productivity varying with crop type with
greater increases for legume crops (30%), vegetables (29%),
and grasses (14%) compared to cereal crops corn (8%), wheat
(11%), and rice (7%).
The yield gains were attributed to the combined effect of
increased nutrient availability (P and N) and improved soil
chemical conditions resulting from the bio-solid based
amendment.
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17. BIOCHAR IMPACT ON SOIL PROPERTIES
Some selected soil
properties
Findings References
Cation exchange capacity 50 % increase Glaser et al., 2002
Fertilizer use efficiency 10 – 30 % increase Gaunt and Cowie, 2009
Liming agent 1 unit pH increase
Lehman and Rondon, 2006Crop productivity 20 – 120% increase
Biological nitrogen fixation 50 – 72 % increase
Soil moisture retention Upto 18 % increase Tryon, 1948
Mycorrhizal fungi 40 % increase Warnock et al., 2007
Bulk density Soil dependent Laird, 2008
Methane emission 100% decrease Rondon et al, 200525-10-2016
Source: Srinivasarao et al. 2013)17

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19. Biochar Influence on Soil Water Hydraulics
 Biochar additions to soils had mixed results with regard to
modifying soil hydraulic conductivity (ksat ).
 Some experiments have reported improvements in ksat after
biochar additions to a silt and sandy loam-textured soil,
respectively.
 In contrast no significant change has been reported in ksat for
biochar applied to loam- and clay-textured soils, respectively.
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20. BIOCHAR INFLUENCE ON SOIL BIOTA
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 The chemical stability of a large fraction of a given biochar
material means that microbes will not be able to readily
utilize the C as an energy source or the N and possibly other
nutrients contained in the C structure.
 However, depending on the type of biochar, a fraction may
be readily leached and therefore mineralizable and in some
cases has been shown to stimulate microbial activity and
increase abundance.
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22. Critical factors for maximizing the
benefits from biochar
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 Quality of feedstock biomass
 Optimum temperature for biochar production
 Soil carbon level
 Soil types and soil moisture
 Soil pH and soil contamination
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23. CONCLUSION
 Biochar has been found to improve agriculturally significant soil
parameters such as soil pH, cation exchange capacity and soil
water holding capacity.
 It helps reduce GHG emissions and sustain carbon sequestration.
 Store recalcitrant form of carbon in soil.
 Helps overcome waste lands by reclamation of the soil.
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 Reduce the need for fertiliser/manure/compost as well as
costs of sewage & animal waste treatment and cut emissions.
 Nutrient affinity i.e. retention of plant nutrients, notably
retention of N on permeable soils under rainy conditions is
found higher with biochar application.
 In general, it has proved to be a soil health manager in a no.
of experiments.
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25. Welcome Queries…
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