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Bio slurry
PPRE Oldenburg University
April 26-28, 2011
Biogas Practice Area
Soil fertility
Biogas Practice Area
Cultivation:
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Soil air:
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Air / water critical
Respiration: roots &
micro organisms
Crop rotation
Slash & burn
Fallowing
Population pressure!
Mineral matter:
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Clay: < 0.002 mm
Silt: 0.002 – 2mm
Stone: > 2mm
Biological population:
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Climate:
Worms,insects,spiders
Fungi, bacteria, algae
20% SOM
Physical & decomp
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Soil water:
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Held by clay & humus
Transport nutrients
Micro-organism activity
Mineral weathering
Temp: chemical
reaction for weathering
Rainfall: washing out
weathering products
Organic matter:
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Larger organisms:
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Vegetation, animals
Tropical soils: low Ccontent
Decomposing organisms
Humus, back (C) jelly, in
mineral matrix
Biogas Practice Area
Nutrient depletion in Africa
Biogas Practice Area
• Water & wind erosion = 16
- 300 x soil development
through weathering
• Nutrient export by product
export
Plant growth
Biogas Practice Area
O2
CO2
Nutrient levels:
• Deficient: Severely limited growth
and yield
• Critical: Growth and yield below
average, good response on
added nutrients
• Sufficient: Added nutrients result
in added nutrient in produce
rather then increased yields
• Excessive: Reducing yields,
causing nutrient imbalances, toxic
N-P-K
H2O
Mg, Cu, Fe ….
Plant nutrients
Biogas Practice Area
Macronutrients (0.2 - 4% DW)
• Primary: nitrogen (N), phosphorus (P), potassium (K)
• Secondary: calcium (Ca), magnesium (Mg), sulphur (S)
• Silicon (Si)
Micronutrients (trace elements, 5 – 200 ppm)
• boron (B), copper (Cu), iron (Fe), chlorine (Cl), manganese
(Mn), molybdenum (Mo), zinc (Zn)
Non-Mineral Nutrients
• hydrogen (H), oxygen (O), carbon (C)
Macro nutrients
Biogas Practice Area
Nitrogen (N)
Phosphorus (P)
Potassium (K)
Increases growth and
development of all living
tissues.
Helps in early maturing by
stimulating flowering
Enhances the plant's
ability to resist diseases
Improves the quality of
leafy vegetables and
fodder and the protein
content of the food grains
and makes them green.
Helps in seed and fruit
development.
Assists carbohydrate
translocation and water
utilization by stomatal
regulation.
Helps uptake of
phosphorus, potash and
micronutrients.
Helps for the growth and
development of root of the
plant
Resist from wilting and
lodging of plants
Soil Organic Matter
Small fraction of soils: < 2 % (in tropics)
OM:
• Living organisms: roots,
fungi, earthworms, etc.
• Dead material: plant
residues, fym, compost,
humus, etc
Positive effects:
• Soil structure (roots, air)
• Water retention capacity
• Soil fertility (CEC = cation exchange capacity)
• Buffers soil pH
• Resistance to erosion
Biogas Practice Area
Fertilizers
Organic fertilizer:
– Broad range of nutrients
– Low in N-P-K
– Long term effect (indirect)
– High soil organic matter content
Chemical fertilizers:
– Short term effect (direct)
– High in N, P or K
Integrated Soil Fertility Management:
– Optimal combination of organic and chemical fertilizers
Biogas Practice Area
Sustainable agriculture
Biogas Practice Area
Ecologically sound, economically feasible, socially acceptable
Origins
Characteristics
Farm yard manure
Partly decomposed mix of
dung and urine with
bedding material
High NPK and OM
content, handling is critical
to prevent nutrient losses
Animal manure
Droppings and urine of
animals
Free ranging: nutrient loss
through evaporation and
washing
Compost
Aerobically decomposed
organic material
High carbon content
(humus)
Bio-slurry
Anaerobic decomposed
organic material
Lower OM component,
high available N
Anaerobic Digestion Process
Biogas Practice Area
Acid Production
Liquefaction
Liquefying
Bacteria
Acid-Forming
Bacteria
Liquefied
soluble organic
compounds
Manure
Insoluble
Compounds
(organic,
inorganic,
water)
Biogas
Production
Methane-Forming
Bacteria
Simple
organic
acids
End
Products
Biogas
(Methane,
CO2, misc.)
Effluent
Bio-slurry characteristics
Biogas Practice Area
An example of Nutrient contents of slurry at different situations/practices
(Gurung, 1997)
Situation/practice
Fresh wet slurry
Sun dried slurry
Over dried slurry
FYM
Nitrogen
1.03
1.0
0.97
0.6
Average value (%)
Phosphorus
Potash
0.82
1.07
0.23
0.84
0.24
0.97
0.25
0.55
Factors affecting nutrient content
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Species, age, and condition
of the animal from which the
dung is drawn
Nutrition - composition of
diets
Environmental factors
The way the slurry is stored,
treated and applied to the
field
Biogas Practice Area
Farm system
Biogas Practice Area
Crop
production
system
Bio slurry
Biogas plant
Household
system
Animal
production
system
Economic benefits of slurry
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Higher yield kg/ha
Better quality, higher price/kg
Savings chemical fertilizer
Savings on pesticides
Financial benefits of bioslurry is far greater
than that of biogas!
(Vietnam, India, China)
Biogas Practice Area
Effect of biogas slurry
Biogas Practice Area
Dry and wet slurry on wheat
Treatment
Grain yield
(kg/ha)
Avg over 3 yrs
Increment over
control (kg/ha)
Control
1288
Bio-slurry dry
1450
162
Bio-slurry wet
1842
554
50% dry slurry + 50% CF
2706
1418
75% dry slurry + 25% CF
1744
456
Chemical fertilizer
3503
2215
Source: Maskey, 1978 in Gurung, 1997
Slurry application methods
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Slurry as a ready-made manure
Application of slurry with irrigation water
Slurry used as dried dust
Use after composting
Biogas Practice Area
Other applications
• Soil conditioning
• Starter for composting
• Enriched with organic fertilizer (urea, super
phosphate)
• Feed (fish culture, animal husbandry)
• Pesticide application
• Seed pelleting
• Mushroom cultivation
• Earthworm rearing
Biogas Practice Area
Wet Storage
Biogas Practice Area
Shading
Biogas Practice Area
(semi) Dry Storage
Biogas Practice Area
Slurry hut
Biogas Practice Area
Wet application
Biogas Practice Area
Wet application II
Biogas Practice Area
Dry Application
Biogas Practice Area
Challenges of Bio-slurry utilization
Biogas Practice Area
• Storage has significant deterioration effect on the
slurry quality
• It is expensive and labor intensive to transport
composted slurry, particularly, to fields far away from
homesteads
• Determining specific plant requirement and soil test is
required
• Determining optimum time and season for slurry
application
– Lack of knowledge and skill in the value and use of
the slurry
Thank you
Biogas Practice Area