Home Composting
9/11/2013
Home Composting By: Brooke McMinn Burlington County Horticulturist
What is Soil? • A complex mixture of minerals, water, air, organic detritus, and living organisms. • Natural soils have important properties in common. – Physical, Chemical, and Biological
1
9/11/2013
What is Soil? • In nature, the five soil-forming factors are: 1. 2. 3. 4. 5.
Parent material Climate Living organisms Landscape position Time
Soil Profile • Layers in the soil are called ‘horizons’ – ‘topsoil’ = upper layer – ‘subsoil’ = middle layer – ‘parent material’ or ‘bedrock’ = found below these
2
9/11/2013
Soil Profile
Soil Characteristics • Physical • Biological • Chemical
3
9/11/2013
Physical Characteristics • Soils are comprised of: – Solids • Mineral component • Organic component – Liquids • water – Gases • ex. O2, CO2
45-50%
05%
Physical Characteristics: Texture • Texture – Refers to the relative amounts of different sized particles in the soil – Fineness or coarseness of the soil – There are 3 soil particles, classified by size, that determine the soil texture • Sand – 2 mm to 0.05 mm in diameter
• Silt – 0.05 mm to 0.002 mm in diameter
• Clay – 0.002 mm or less in diameter
4
9/11/2013
Physical Characteristics: Texture
Sand
Clay
Silt
Physical Characteristics: Texture 12 Textural Classes
5
9/11/2013
Physical Characteristics: Texture Feel Method
Falls apart = sand Stays together, extend far beyond fingers = clay Some form but crumbles = silt
Rough = sand Slick, greasy when wet = clay Smooth when dry = silt
Ribbon Method
Physical Characteristics: Texture • What is your definition of top soil? – Loose unconsolidated material overlying rock – The upper 2-3 feet of earth. – Dark colored soil – The 8 -12 inch Ap Soil horizon
6
9/11/2013
Physical Characteristics: Texture • Organic matter is: – Organic fraction of the soil that includes: • Plant and animal residues at various stages of decomposition • Food for the soil microbial population • Cells and tissues of soil organisms
– – – –
‚Glue‛ that helps to hold soil particles together Soil acidity reservoir Nutrient storehouse Difficult to significantly increase
Physical Characteristics: Texture • Organic matter comes from: – Plants, animals, microorganisms – Living, dead, decaying matter – Humus • Complex, dark colored reactive
7
9/11/2013
Physical Characteristics: Tilth • Tilth or Structure – The way that soil particles are held and grouped together into larger particles • • • •
Clusters Crumbs Aggregates Peds
Physical Characteristics: Tilth • Tilth or structure is affected by several factors, including: – Organic matter, limestone, biological activity • All increase aggregation or flocculation of particles
– Sodium • Decreases aggregation or dispersion of particles
• Tilth is primarily a ‘by-product’ of biological activity
8
9/11/2013
Physical Characteristics: Tilth
Physical Characteristics: Tilth
9
9/11/2013
Physical Characteristics: Tilth
Physical Characteristics: Water • Movement in Soil – Infiltration • Downward movement of water into the soil surface
– Percolation • Downward movement of water through the soil
10
9/11/2013
Physical Characteristics: Water • Infiltration – Movement of water into the soil surface
SAND
CLAY
SILT
Physical Characteristics: Water • Water Holding Capacity – Soil’s ability to hold internal moisture – Can be increased by raising organic matter levels
sand < silt < clay
11
9/11/2013
Physical Characteristics: Bulk Density • Bulk Density – The weight of dry soil per unit volume including air space – Practical Application • Compaction • Physical pressure due to weight on soil squeezes out the air space, making the soil more compact
Biological Characteristics • In one teaspoon of ‚healthy‛ soil there should be: – – – –
600 million bacteria three miles of fungal hyphae 10,000 protozoa 20 to 30 beneficial nematodes in a teaspoon of soil Dr. Elaine R. Ingham, Soil Food Web
12
9/11/2013
Biological Characteristics
Chemical Characteristics Fertility vs. Nutrition • Fertility: capacity of soil to supply nutrients to plants in adequate amounts. • Nutrition: processes by which a living organism assimilates food and uses it for growth and replacement of tissue. • Historically, plant growth was thought of in terms of soil fertility or how much fertilizer to add. • Plant Nutrition takes into account the interrelationships of mineral elements in the soil as well as their role in plant growth. • Many people confuse plant nutrition with plant fertilization.
13
9/11/2013
Chemical Characteristics Fertility vs. Nutrition • Nutrient supply from the soil has usually been studied by the soil scientist. • Root growth and absorption of nutrients by the root usually have been studied by the botanist and plant physiologist.
• An understanding of the plant root system and the mechanisms of nutrient and water absorption from the soil is important for determining why plant growth may be poor.
Chemical Characteristics Cation Exchange Capacity (CEC) • Cations: positively charged nutrient ions and molecules: – – – – – – –
calcium (Ca++) magnesium (Mg++) potassium (K+) sodium (Na+) hydrogen (H+) ammonium (NH4+) and aluminum (Al+++)
• Clay Particles: negatively charged constituents of soil. Organic matter particles also have a negative charge. Sand Particles carry little or no charge and do not react. • Cation Exchange Capacity: soil’s capacity to hold and exchange ions.
14
9/11/2013
Chemical Characteristics
Cation Exchange Capacity (CEC)
NEGATIVE
Clay and Organic Matter Particles Carry a Negative Charge
Chemical Characteristics Cation Exchange Capacity (CEC)
POSITIVE
CATIONS ( NH4, K, Ca, Mg) Carry a Positive Charge
15
9/11/2013
Chemical Characteristics
Cation Exchange Capacity (CEC)
Unlikes Attract
+ + -
+
+
-
Likes Repel -
Chemical Characteristics Cation Exchange Capacity (CEC) Ca++ NH4+ H+ K+
Cations are held on Clay and Organic Matter particles by magnetic attraction.
16
9/11/2013
Chemical Characteristics Cation Exchange Capacity (CEC) CEC…So What? CEC 11-50 Range
CEC 1- 10 Range
• Higher Clay Content
• Higher Sand Content
• More lime required to correct a given pH
• Nitrogen and Potassium leaching more likely
• Greater capacity to hold nutrients
• Less lime required to correct a given pH
• High water holding capacity
• Low water holding capacity
Chemical Characteristics The Nitrogen Cycle
17
9/11/2013
What is Compost? • A dark, crumbly, earthy smelling soil conditioner • Improves soil – Structure – Moisture retention – Drainage
• Provides nutrients needed by plants for growth • A living ecosystem of microorganisms! – Air – Water – Nutrients
What is Composting?
• Natural process • Organic materials decompose • Results in compost • Nothing new • Without it, life would cease to exist!
18
9/11/2013
Why Should I Compost? • Save $! • Reduce the volume of garbage going to landfills, transfer stations and incinerators • Avoid garbage collection and landfill fees • Reduce fertilizer use • Reduce water use
• Reduce runoff pollution • Improve soil structure and texture • Increase aeration and water retention of soil • Promote soil fertility • Improve plant health • Prevent erosion • It’s easy!
What Should I Compost? Do Compost:
Do Not Compost:
X X X X
Vegetable food scraps Grass clippings (in moderation) Leaves, flowers, weeds Rinsed egg shells Sawdust and wood ash Chopped twigs/branches Coffee grounds w/ filters Tea bags (staple removed) Shredded paper Dryer lint
X X X X X
Meat/fish scraps or bones Sauces Dairy products Food with oil or grease residue Food with soap residue Disease/insect infested plants Poisonous plants Weeds with seeds Dog or cat feces
19
9/11/2013
Compost Composition • Organisms – Living ecosystem – Will find a pile on the ground – Starter soil for elevated piles – Need water, air and nutrients for life
Food web of the compost pile (NRC, 1981a)
Compost Composition
• Water – Not too wet – Not too dry – Think wrung out sponge
20
9/11/2013
Compost Composition • Air – Turning the pile • Pitch fork • Minimum once/month
– Layering the pile • Cover greens with browns (every time) • Provides air space • Keeps away gnats, unwanted critters
Compost Composition • Size matters! – > surface area (smaller pieces) = faster decomposition – < surface area (larger pieces) = slower decomposition – Pile size • At least 3’x3’ (to hold heat) • No larger than 5’x5’ (air can’t reach center)
Washington State University
21
9/11/2013
Compost Composition • Nutrients – C:N ratio (~ 1:2) – C = ‚browns‛
– N = ‚greens‛
• Usually dry • Leaves, dried plant material, sawdust, chipped twigs and branches, shredded paper • Excess brown = slow decomposition
• Usually moist • Often, but not always green • Grass clippings, weeds, flowers, vegetable scraps, coffee grinds with filter, tea bags, egg shells, agricultural manures or meals • Excess green = odor
Compost Composition Material
% N by Weight
C:N Ratio
Sawdust
.1
500
Wood chips
.1
640
Paper
.25
170
Composted leaves
.5-1
40-80
Cow Manure
1-1.5
20
Eggshells
1-2
10
Fruit wastes
1.5
35
Coffee grounds
1.5-2
20
Grass clippings
2-4
25
Horse manure
1-5
25
Poultry manure
3-5
15
Vegetable scraps
None
15
22
9/11/2013
Composting Methods
Open pile
Composting Methods
Three-bin
Single bin
Commercial bin
23
9/11/2013
Montgomery County Division of Solid Waste Services Department of Environmental Protection
Composting Methods • Vermicomposting – Materials • Bin – – –
5 gallon bucket old dresser drawer ~2x2x8 wooden box (no cedar!)
• Bedding material – – – –
Shredded, moist Newspaper Cardboard Leaf compost
• Watering can or spray bottle • Red worms (Eisenia foetida) – – –
1 lb Flowerfield Enterprises, 10332 Shaver Rd, Kalamazoo, MI 49002 Lower East Side Ecological Center, P.O. Box 20488, New York, NY 10009
24
9/11/2013
Composting Methods • Vermicomposting – Procedure 1. 2. 3. 4.
Shred and moisten bedding material and place it loosely in the bin. Add 1 lb. of red worms. Place compostable material under the bedding. Keep the bin covered loosely with plastic or newspaper to retain moisture. Check every day or two and ad water when surface or edges begin to dry. 5. Keep above freezing and below 95° (indoors in winter, in shade in summer)
Composting Methods • Vermicomposting – To separate finished compost 1. 2. 3. 4. 5. 6.
Stop feeding for several days or weeks. Place compost and worms on table under lights. Worms will go the bottom of the pile. Remove top portion of compost and screen. Separate out surplus worms for new box Give the new box to a friend!
25
9/11/2013
Troubleshooting Symptom
Cause
Solution
Rotten odor
Insufficient air
Turn pile or layer greens with browns
Ammonia odor
Too many greens
Add browns
Dryness
Insufficient water/excess browns
Turn pile and moisten/add fresh greens
Low temperature
Pile is too small
Add more material
Insufficient moisture
Add water
Insufficient air
Turn pile/layer
Lack of N
Add greens
Cold weather
Insulate pile with layer of straw or cover with a tarp
Finished Compost • Temperature will have decreased to slightly above air temp. • Material will be dark, rich and crumbly in texture • When composting is complete, remove finished product from bin, screen out partially decomposed material and start over! • Best management = finished compost in 5-15 weeks. • Minimal attention = finished compost in 12-18 months.
26
9/11/2013
Using Compost • Mulch – – – – – –
Flower/vegetable plantings Trees & shrubs Exposed slopes Smothers weeds Retains moisture Prevents erosion
• Soil conditioner – Mix 1-3‛ into beds before planting – Improves organic matter, nutrient availability
• Potting mix – Make sure compost is fully decomposed and screened – 1: 1 compost/sand or soil – 1:1:1 compost/ sand or soil/perlite
Additional Resources •
Rutgers University: – – – – –
•
Home Composting http://njaes.rutgers.edu/pubs/publication.asp?pid=FS811 Minimizing Waste Disposal: Grass Clippings http://njaes.rutgers.edu/pubs/publication.asp?pid=FS389 Backyard Leaf Compost http://njaes.rutgers.edu/pubs/publication.asp?pid=FS074 Using Leaf Compost http://njaes.rutgers.edu/pubs/publication.asp?pid=FS117 Vermicompositng (Worm Composting) http://njaes.rutgers.edu/pubs/publication.asp?pid=FS805
NC State University: –
Building your Own Composting Bin: Designs for Your Community https://www.bae.ncsu.edu/bae/topic/composting/pubs/build-bin.pdf
– –
Community Backyard Composting Programs Can Reduce Waste and Save Money https://www.bae.ncsu.edu/bae/topic/composting/pubs/ag-599-backyard-composting.pdf Composting: ‘Microbe Farming’ https://www.bae.ncsu.edu/bae/topic/composting/pubs/composting-microorganisms.pdf
27
9/11/2013
28
Home Composting By: Brooke McMinn Burlington County Horticulturist
What is Soil? • A complex mixture of minerals, water, air, organic detritus, and living organisms. • Natural soils have important properties in common. – Physical, Chemical, and Biological
1
9/11/2013
What is Soil? • In nature, the five soil-forming factors are: 1. 2. 3. 4. 5.
Parent material Climate Living organisms Landscape position Time
Soil Profile • Layers in the soil are called ‘horizons’ – ‘topsoil’ = upper layer – ‘subsoil’ = middle layer – ‘parent material’ or ‘bedrock’ = found below these
2
9/11/2013
Soil Profile
Soil Characteristics • Physical • Biological • Chemical
3
9/11/2013
Physical Characteristics • Soils are comprised of: – Solids • Mineral component • Organic component – Liquids • water – Gases • ex. O2, CO2
45-50%
05%
Physical Characteristics: Texture • Texture – Refers to the relative amounts of different sized particles in the soil – Fineness or coarseness of the soil – There are 3 soil particles, classified by size, that determine the soil texture • Sand – 2 mm to 0.05 mm in diameter
• Silt – 0.05 mm to 0.002 mm in diameter
• Clay – 0.002 mm or less in diameter
4
9/11/2013
Physical Characteristics: Texture
Sand
Clay
Silt
Physical Characteristics: Texture 12 Textural Classes
5
9/11/2013
Physical Characteristics: Texture Feel Method
Falls apart = sand Stays together, extend far beyond fingers = clay Some form but crumbles = silt
Rough = sand Slick, greasy when wet = clay Smooth when dry = silt
Ribbon Method
Physical Characteristics: Texture • What is your definition of top soil? – Loose unconsolidated material overlying rock – The upper 2-3 feet of earth. – Dark colored soil – The 8 -12 inch Ap Soil horizon
6
9/11/2013
Physical Characteristics: Texture • Organic matter is: – Organic fraction of the soil that includes: • Plant and animal residues at various stages of decomposition • Food for the soil microbial population • Cells and tissues of soil organisms
– – – –
‚Glue‛ that helps to hold soil particles together Soil acidity reservoir Nutrient storehouse Difficult to significantly increase
Physical Characteristics: Texture • Organic matter comes from: – Plants, animals, microorganisms – Living, dead, decaying matter – Humus • Complex, dark colored reactive
7
9/11/2013
Physical Characteristics: Tilth • Tilth or Structure – The way that soil particles are held and grouped together into larger particles • • • •
Clusters Crumbs Aggregates Peds
Physical Characteristics: Tilth • Tilth or structure is affected by several factors, including: – Organic matter, limestone, biological activity • All increase aggregation or flocculation of particles
– Sodium • Decreases aggregation or dispersion of particles
• Tilth is primarily a ‘by-product’ of biological activity
8
9/11/2013
Physical Characteristics: Tilth
Physical Characteristics: Tilth
9
9/11/2013
Physical Characteristics: Tilth
Physical Characteristics: Water • Movement in Soil – Infiltration • Downward movement of water into the soil surface
– Percolation • Downward movement of water through the soil
10
9/11/2013
Physical Characteristics: Water • Infiltration – Movement of water into the soil surface
SAND
CLAY
SILT
Physical Characteristics: Water • Water Holding Capacity – Soil’s ability to hold internal moisture – Can be increased by raising organic matter levels
sand < silt < clay
11
9/11/2013
Physical Characteristics: Bulk Density • Bulk Density – The weight of dry soil per unit volume including air space – Practical Application • Compaction • Physical pressure due to weight on soil squeezes out the air space, making the soil more compact
Biological Characteristics • In one teaspoon of ‚healthy‛ soil there should be: – – – –
600 million bacteria three miles of fungal hyphae 10,000 protozoa 20 to 30 beneficial nematodes in a teaspoon of soil Dr. Elaine R. Ingham, Soil Food Web
12
9/11/2013
Biological Characteristics
Chemical Characteristics Fertility vs. Nutrition • Fertility: capacity of soil to supply nutrients to plants in adequate amounts. • Nutrition: processes by which a living organism assimilates food and uses it for growth and replacement of tissue. • Historically, plant growth was thought of in terms of soil fertility or how much fertilizer to add. • Plant Nutrition takes into account the interrelationships of mineral elements in the soil as well as their role in plant growth. • Many people confuse plant nutrition with plant fertilization.
13
9/11/2013
Chemical Characteristics Fertility vs. Nutrition • Nutrient supply from the soil has usually been studied by the soil scientist. • Root growth and absorption of nutrients by the root usually have been studied by the botanist and plant physiologist.
• An understanding of the plant root system and the mechanisms of nutrient and water absorption from the soil is important for determining why plant growth may be poor.
Chemical Characteristics Cation Exchange Capacity (CEC) • Cations: positively charged nutrient ions and molecules: – – – – – – –
calcium (Ca++) magnesium (Mg++) potassium (K+) sodium (Na+) hydrogen (H+) ammonium (NH4+) and aluminum (Al+++)
• Clay Particles: negatively charged constituents of soil. Organic matter particles also have a negative charge. Sand Particles carry little or no charge and do not react. • Cation Exchange Capacity: soil’s capacity to hold and exchange ions.
14
9/11/2013
Chemical Characteristics
Cation Exchange Capacity (CEC)
NEGATIVE
Clay and Organic Matter Particles Carry a Negative Charge
Chemical Characteristics Cation Exchange Capacity (CEC)
POSITIVE
CATIONS ( NH4, K, Ca, Mg) Carry a Positive Charge
15
9/11/2013
Chemical Characteristics
Cation Exchange Capacity (CEC)
Unlikes Attract
+ + -
+
+
-
Likes Repel -
Chemical Characteristics Cation Exchange Capacity (CEC) Ca++ NH4+ H+ K+
Cations are held on Clay and Organic Matter particles by magnetic attraction.
16
9/11/2013
Chemical Characteristics Cation Exchange Capacity (CEC) CEC…So What? CEC 11-50 Range
CEC 1- 10 Range
• Higher Clay Content
• Higher Sand Content
• More lime required to correct a given pH
• Nitrogen and Potassium leaching more likely
• Greater capacity to hold nutrients
• Less lime required to correct a given pH
• High water holding capacity
• Low water holding capacity
Chemical Characteristics The Nitrogen Cycle
17
9/11/2013
What is Compost? • A dark, crumbly, earthy smelling soil conditioner • Improves soil – Structure – Moisture retention – Drainage
• Provides nutrients needed by plants for growth • A living ecosystem of microorganisms! – Air – Water – Nutrients
What is Composting?
• Natural process • Organic materials decompose • Results in compost • Nothing new • Without it, life would cease to exist!
18
9/11/2013
Why Should I Compost? • Save $! • Reduce the volume of garbage going to landfills, transfer stations and incinerators • Avoid garbage collection and landfill fees • Reduce fertilizer use • Reduce water use
• Reduce runoff pollution • Improve soil structure and texture • Increase aeration and water retention of soil • Promote soil fertility • Improve plant health • Prevent erosion • It’s easy!
What Should I Compost? Do Compost:
Do Not Compost:
X X X X
Vegetable food scraps Grass clippings (in moderation) Leaves, flowers, weeds Rinsed egg shells Sawdust and wood ash Chopped twigs/branches Coffee grounds w/ filters Tea bags (staple removed) Shredded paper Dryer lint
X X X X X
Meat/fish scraps or bones Sauces Dairy products Food with oil or grease residue Food with soap residue Disease/insect infested plants Poisonous plants Weeds with seeds Dog or cat feces
19
9/11/2013
Compost Composition • Organisms – Living ecosystem – Will find a pile on the ground – Starter soil for elevated piles – Need water, air and nutrients for life
Food web of the compost pile (NRC, 1981a)
Compost Composition
• Water – Not too wet – Not too dry – Think wrung out sponge
20
9/11/2013
Compost Composition • Air – Turning the pile • Pitch fork • Minimum once/month
– Layering the pile • Cover greens with browns (every time) • Provides air space • Keeps away gnats, unwanted critters
Compost Composition • Size matters! – > surface area (smaller pieces) = faster decomposition – < surface area (larger pieces) = slower decomposition – Pile size • At least 3’x3’ (to hold heat) • No larger than 5’x5’ (air can’t reach center)
Washington State University
21
9/11/2013
Compost Composition • Nutrients – C:N ratio (~ 1:2) – C = ‚browns‛
– N = ‚greens‛
• Usually dry • Leaves, dried plant material, sawdust, chipped twigs and branches, shredded paper • Excess brown = slow decomposition
• Usually moist • Often, but not always green • Grass clippings, weeds, flowers, vegetable scraps, coffee grinds with filter, tea bags, egg shells, agricultural manures or meals • Excess green = odor
Compost Composition Material
% N by Weight
C:N Ratio
Sawdust
.1
500
Wood chips
.1
640
Paper
.25
170
Composted leaves
.5-1
40-80
Cow Manure
1-1.5
20
Eggshells
1-2
10
Fruit wastes
1.5
35
Coffee grounds
1.5-2
20
Grass clippings
2-4
25
Horse manure
1-5
25
Poultry manure
3-5
15
Vegetable scraps
None
15
22
9/11/2013
Composting Methods
Open pile
Composting Methods
Three-bin
Single bin
Commercial bin
23
9/11/2013
Montgomery County Division of Solid Waste Services Department of Environmental Protection
Composting Methods • Vermicomposting – Materials • Bin – – –
5 gallon bucket old dresser drawer ~2x2x8 wooden box (no cedar!)
• Bedding material – – – –
Shredded, moist Newspaper Cardboard Leaf compost
• Watering can or spray bottle • Red worms (Eisenia foetida) – – –
1 lb Flowerfield Enterprises, 10332 Shaver Rd, Kalamazoo, MI 49002 Lower East Side Ecological Center, P.O. Box 20488, New York, NY 10009
24
9/11/2013
Composting Methods • Vermicomposting – Procedure 1. 2. 3. 4.
Shred and moisten bedding material and place it loosely in the bin. Add 1 lb. of red worms. Place compostable material under the bedding. Keep the bin covered loosely with plastic or newspaper to retain moisture. Check every day or two and ad water when surface or edges begin to dry. 5. Keep above freezing and below 95° (indoors in winter, in shade in summer)
Composting Methods • Vermicomposting – To separate finished compost 1. 2. 3. 4. 5. 6.
Stop feeding for several days or weeks. Place compost and worms on table under lights. Worms will go the bottom of the pile. Remove top portion of compost and screen. Separate out surplus worms for new box Give the new box to a friend!
25
9/11/2013
Troubleshooting Symptom
Cause
Solution
Rotten odor
Insufficient air
Turn pile or layer greens with browns
Ammonia odor
Too many greens
Add browns
Dryness
Insufficient water/excess browns
Turn pile and moisten/add fresh greens
Low temperature
Pile is too small
Add more material
Insufficient moisture
Add water
Insufficient air
Turn pile/layer
Lack of N
Add greens
Cold weather
Insulate pile with layer of straw or cover with a tarp
Finished Compost • Temperature will have decreased to slightly above air temp. • Material will be dark, rich and crumbly in texture • When composting is complete, remove finished product from bin, screen out partially decomposed material and start over! • Best management = finished compost in 5-15 weeks. • Minimal attention = finished compost in 12-18 months.
26
9/11/2013
Using Compost • Mulch – – – – – –
Flower/vegetable plantings Trees & shrubs Exposed slopes Smothers weeds Retains moisture Prevents erosion
• Soil conditioner – Mix 1-3‛ into beds before planting – Improves organic matter, nutrient availability
• Potting mix – Make sure compost is fully decomposed and screened – 1: 1 compost/sand or soil – 1:1:1 compost/ sand or soil/perlite
Additional Resources •
Rutgers University: – – – – –
•
Home Composting http://njaes.rutgers.edu/pubs/publication.asp?pid=FS811 Minimizing Waste Disposal: Grass Clippings http://njaes.rutgers.edu/pubs/publication.asp?pid=FS389 Backyard Leaf Compost http://njaes.rutgers.edu/pubs/publication.asp?pid=FS074 Using Leaf Compost http://njaes.rutgers.edu/pubs/publication.asp?pid=FS117 Vermicompositng (Worm Composting) http://njaes.rutgers.edu/pubs/publication.asp?pid=FS805
NC State University: –
Building your Own Composting Bin: Designs for Your Community https://www.bae.ncsu.edu/bae/topic/composting/pubs/build-bin.pdf
– –
Community Backyard Composting Programs Can Reduce Waste and Save Money https://www.bae.ncsu.edu/bae/topic/composting/pubs/ag-599-backyard-composting.pdf Composting: ‘Microbe Farming’ https://www.bae.ncsu.edu/bae/topic/composting/pubs/composting-microorganisms.pdf
27
9/11/2013
28
