Dr. Munoo Prasad Formerly, Chief Scientist, Bord na … · Dr. Munoo Prasad Formerly, Chief Scientist, Bord na Mona. Now, Compost Research & Advisory, Naas. ... Ravi prasad Created

Composting Manure: Getting it Right

Dr. Munoo Prasad Formerly, Chief Scientist, Bord na Mona. Now, Compost Research & Advisory, Naas. [email protected]

Paper Content• Definition• Biology• Advantages of Manure Composting• Selection of ingredients. • Testing required.• Composting Technology• Common Problems Encountered in

Composting• Benefits of manure composting• Conclusion

Composting

• Definition: “..the biological decomposition and stabilisation of organic substrates under conditions that allow development of thermophilic temperatures as a result of biologically produced heat..”

• Aim: “..to produce a final product that is stable, free of pathogens and weed seeds.

Biology

• Microorganisms consume > 90% of the available organic matter.

• The organic matter is broken down into: CO2, H2O, heat and compost.

• The composting process proceeds through three phases:– Mesophilic 10-45°C– Thermophilic 45-70°C– maturation (curing)

Temperature Vs Oxygen during Composting

Advantages of Manure Composting

• Reduced moisture, weight, and volume of stored manure

• An efficient recycling method for crop residues• Reduced fly, weed and odour problems in

manure• More stable form of nitrogen and other nutrients

Advantages of manure composting

• For Soil Improvement –physical characteristics- Infiltration rate- Water holding capacity & tilth, soil aggregation- Increase population and diversity of soil microbial

community• For fertilizer - for specific nutrients e.g. nitrogen, phosphorus,

potassium and micronutrients• To increase humus content of soil

Manure Composting

• Ideally Composting and Manure Handling should be matched and adjusted. A large part of labour in composting involves handling and mixing manure and amendments

• Composting does not lock the farm into composting all the manure produced.

• Manure can and should be applied directly to cropland when conditions are right

• Manure application needs less labour than composting but still provides organic matter to soil but the quality of organic matter is not as good

• Release of nutrients is much faster, potential for pollution

Selection of Ingredients

Selection of Feedstock Ingredients

• Mixing raw materials for composting requires testing of compost feedstock.

• From the initial analysis it can be calculated what percentages of feedstock need to be added.

Criteria for Mixing Raw Material for Composting

• Total N• Ash (C:N Ratio)• pH• EC (Salinity)• Particle Size• Moisture Content• Bulk Density

C:N Ratio

• Correct C:N ratio required to ensure rapid decomposition and to conserve N in final product.

• If C:N ratio is >40, nitrogen will be a limiting factor in decomposition.

• If C:N ratio is < 20, nitrogen will be lost as ammonia.

Approx N and C/N Ratio of some Compostable Materials

N C/N• Poultry Manure 6.3 ---• Sheep / Pig Manure 3.75 ---• Horse Manure 2.3 ---• Cow Manure 1.7 ---• Wheat Straw 0.3 128• Sawdust 0.11 511• Grass Clippings 3-6 12-15• Vegetable Waste 2.5-4 11-12• Potato Tops 1.5 25• Leaves variable 30-80

CATTLE, PIG, SHEEP, DUCK OR HORSE SOLID MANURES – Total and available nutrientsNitrogen – Typical total nitrogen content (fresh weight basis)

‘Old’ FYM ex - storagea‘Fresh’ FYM b

Dry matter (%)

Total nitrogen (kg/t)

Readily availablenitrogen

% of total N

Readily availablenitrogen

(kg/t)

Cattle farmyard manure

25 6.0 10% 20%

Pig farmyard manure 25 7.0 14% 25%

Sheep farmyard manure

25 7.0 10% 20%

Duck farmyard manure

25 6.5 15% 25%

Horse farmyard manure

30 7.0 ND ND

ND = no data.a FYM that has been stored for 3 months or more. b FYM that is spread straight from the building.

Manure C:N Ratio

Structure/Porosity

Moisture

Degradability

Treatment Required

Caution

Poultry 10 poor Moist Good Bulking material

Odour

Cattle 20 medium medium Very good

Bulking material

-

Recommended Range for Active composting

Carbon: Nitrogen ratio 20:40

Moisture 40 – 60%

Particle size 12 – 40mm

Bulk Density 480 – 600 kg/m3

pH 5.5 – 8.5

Temperature 45 - 60

Oxygen Concentration >5%

Good Amendments for controlling moisture of manure for composting

1. Sawdust2. Straw3. Wood shavings4. Bark

Nitrate

• Nitrate levels can indicate compost maturity.

• As composting proceeds nitrification occurs.

• The Nitrate Strip Reader can be dispensed of if one needs only semi-quantitative results.

Moisture

• A simple ‘squeeze’ test can be employed for moisture determination.

• A small handful of sample is squeezed. • At suitable moisture content:

– no water escapes when sample is squeezed, – sample does not fall apart when hand is

opened, – breaks apart with light pressure

Moisture- ‘Squeeze Test’

• Top left – sample too dry• Top Right – sample too

wet• Bottom left – sample at

suitable moisture

Composting Technology

• Static Pile• Windrow• In-vessel Composting

Feedstock Preparation• Reducing the particle size.

• increases the surface area for microbial decomposition

• Decreases porosity• Increased O2 demand can exceed the capacity of

passive ventilation = anaerobic conditions.

• Particle size can be measured using handheld sieves.

Static Pile

Windrow

Dump Truck forming windrows

Windrow

Forming windrows using a manure spreader

Turning using attachment to a tractor

Screening

Common Problems in a Compost Pile

Common Problems in a Compost Pile

• High bulk density of initial mix• Compaction of pile• C:N ratio too high/low• Organic Matter too low.• Moisture too high/low• pH too high/low• Oils in feedstock-lead to odour

Odour

Effective management can minimise odourPrincipal Causes• Odorous raw material• Poor site conditions• Ammonia lost from high Nitrogen materials• Excessive anaerobic conditions in piles

Odour Management

• Provide extra carbon to nitrogen rich materials

• Process potentially odorous materials quickly

• Keep pH optimum• Provide proper site drainage• Maintain proper aeration, moisture,

temperature.

Benefits of Composting

Manure compost

• Improves aeration of heavy soil.• Improves water holding capacity of light

soil-can reduce flooding• Saving on agricultural chemicals – less

plant disease.• Saving on fertilizer application.

Fertilizer Substitute

• Reduces fertiliser usage particularly P and K

• Can eliminate need for chemical fertiliser dependant on feed stock – such as chicken manure.

• Rates have to be high.• Reduces ground water pollution.

Benefit: Horticulturist, cereal growers, potato growers.

C:N ratio in relation to potentially mineralisable N

(Wallace, 2006)

Compost C:N ratio % of total N estimated to be mineralised after application

In Year 1 Over 3 Years

10.0 12.5 25

12.5 8.05 17.5

15 5.0 10

17.5 2.5 5

20.0 0.0 <2

Proposed phosphorus availability from various composts made from different feedstock relative to

superphosphateType of Compost Relative availability when

superphosphate is 100%

Spent Mushroom Compost 100

Composted Manure 80 - 90

Biowaste 75

Greenwaste 60

Potassium

• Potassium from most composts have almost similar availability as conventional potassium fertilizer

Humus productionGreen Fertilisation <15%

Slurry/Straw 20 – 30%

Fresh compost 30 - 45%

Solid manure 35 – 45%

Stable compost >50%

Humus increased from an initial 2.5% to 4% over 12 years as a result of compost application

Benefits of Humic Substances

• Response of Plants to Humic SubstancesImproved germination and seedling growthBetter root initiation and growth

• Improved Uptake of Macronutrients• Improved Uptake of Micronutrients• Improved Uptake of Humic SubstancesBiochemical effect – Membrane permeability – Energy Metabolism

• Reduction of Active Levels of Toxic Substances• Enhancement of Microbial Populations

Composted Material Applications( an example)

• Benefit to Potato Crop• Higher yield but needs extra N• Higher dry matter• Less bruising• Tend towards reduction in disease

Conclusion• Composting is a very suitable and effective way

of managing manure.• It can be simple e.g.windrow static pile

composting or sophisticated e.g. in-vessel composting with automated controls.

• It can replace inorganic fertilizers and bring other quantifiable benefits

• Certain aids can be helpful in optimising the composting process and final analysis required for optimum use of the compost.

• It reduces pollution

THANK YOU FOR YOUR ATTENTION!