2013 MGGNO Spring Symposium

1. Composting
Recycling Organic Matter
Dan Gill
LSU AgCenter
Consumer Horticulturist

2. For an outline of this
program, send a request to:
dgill@agcenter.lsu.edu

3. Organic Matter
• Material derived from plants
• May be used as is or in a decayed state or
processed
• Has many horticultural uses, including
bed preparation, mulching, potting mixes

4. Coming to Terms
• Compost, Compost, Composting,
Composted, Composter
• Amendment, Amend, Amended,
Amending
• Mulch, Mulch, Mulching, Mulched

5. Compost
• Organic matter that has gone through a
period of decomposition.
• Finished compost is a dark brown,
crumbly material with an earthy smell.
The original organic materials are no
longer recognizable.

6. Dark brown, crumbly

7. Amendments
• Materials added to the soil to improve it
in some way for plant growth.
• May be organic: compost, leaf mold,
composted manure, peat moss, soil
conditioner
• Or inorganic: lime, sulfur, green sand,
fertilizer, sand

8. Mulch
• Any material spread over the soil surface.
• May be organic or inorganic.
• Organic mulches provide many benefits:
Reduce weeds
Conserve soil moisture
Moderate soil temperature
Prevent compaction
Provide nutrients/encourage earthworms

9. COMPOST
HAPPENS

10. Why Compost?
• Recycling organic yard waste reduces
materials going into municipal waste
streams and landfills.
• Save money not purchasing organic
matter from nurseries.
• May be the best organic matter for bed
preparation.

12. A Natural Process of Decay
• Happens on the forest floor
• In lawn
• When organic mulch is used
• Prevents the world from being
overwhelmed by organic matter
• Carried out primarily by naturally
occurring fungi and bacteria

13. Controlled Composting
• Speeds up the process through
proper management.
• What is the most important thing to
understand about composting….?

15. It’s not a Pile – It’s a Pet
• The transformation of organic matter to
compost is carried out by living
organisms – mostly fungi and bacteria.
• Everything we do in composting caters to
the needs of these living organisms to
help them work more efficiently.

16. So, what do they need?
• Large surface areas
• Air/Oxygen
• Food
• Water

17. Large Surface Areas
• Chopping or grinding organic matter
greatly enhances the composting process.
• Smaller particles expose more surface
area to the action of the microorganisms.
• This allows the fungi and bacteria to
more rapidly decay the organic matter.

18. Air/Oxygen
• The microorganism we want to be active in
the process need oxygen to live. They are
aerobic organisms.
• We do not want microorganisms that live in
an oxygen-free environment – anaerobic
organisms. They stink.
• So, the compost pile should not be too dense
or stay too wet.

19. Air/Oxygen
• To ensure adequate oxygen, piles are
enclosed by ventilated sides.
• Piles may be turned.
• Maintain proper moisture.

20. Turning Compost

21. Food
• The organic matter in the pile is the food
the microorganisms eat.
• This is where the carbon:nitrogen ratio
comes into play: 30 to 1.
• Various organic materials have different
ratios of carbon to nitrogen they contain.
• Roughly divided into “brown” materials
and “green” materials.

22. Brown: High Carbon/Nitrogen Ratio
• Cardboard, shredded………...350:1
• Leaves……………………………..60:1
• Newspaper, shredded………..175:1
• Peanut shells…………………….35:1
• Pine needles……………………..80:1
• Sawdust……………………………325:1
• Straw……………………………….75:1
• Wood chips………………………400:1

23. Green: Low Carbon/Nitrogen Ratio
• Alfalfa……………………………..12:1
• Coffee grounds…………………20:1
• Garden waste…………………..30:1
• Grass clippings…………………20:1
• Hay…………………………………25:1
• Manures………………………….15:1
• Vegetable scraps……………….25:1
• Weeds……………………………..30:1

24. Diversity, Diversity, Diver sit y ,
Diversity
• The more different types of organic
matter you put into the compost,
generally the better.
• But, try to include some of the browns
and some of the greens as you build your
pile, whenever possible.

25. But…
• Be cautious about relying on recipes
• Gardens rarely generate organic
materials in proportions matching
recipes.
• It’s generally better to be flexible, but
mindful.

26. High Carbon/Nitrogen Ratio
• Add some nitrogen fertilizer –
commercial or organic (blood meal,
cotton seed meal)
• Or some low carbon/nitrogen ratio
material, such as manure.
• Should be composted before adding to
the garden.

27. Low Carbon/Nitrogen Ratio
• Add high carbon/nitrogen ratio
material, such as shredded
newspaper, shredded cardboard or
ground wood.
• Turn frequently.

28. Water
• Dry organic matter will not
decompose.
• Fungi and bacteria must have water
to decompose organic matter.
• You may need to water a pile
occasionally. Rain helps much of the
year.
• Not too wet.

29. Making Compost
• Enclose the pile, no need for expensive compost
bins, but you can use them.
• Chop organic matter.
• Add nitrogen if the organic matter is low in
nitrogen
• Keep the pile moist – not soggy.
• Turn the pile if possible.
• Harvest when the organic matter has turned
into a dark brown, crumbly material.

30. Some Like it Hot
• Well constructed and maintained
compost piles can achieve remarkably
high temperatures
• Around 140 to 16 0 degrees F
• Carried out by thermophilic organisms
• Temperatures this high can kill weed
seeds and disease organisms
• But, can’t always be relied on

31. Compost Starters
• Are they really necessary?
• They are certainly not critical to the
process, but feel free to give them a
try.
• Shovel of soil.

32. Safety Concerns
• Some issues with fresh manures and
bacteria, such as E. coli.
• Compost fresh manure. Incorporate it.
• Do not topdress with fresh manure.
• Leafy vegetables eaten raw. Wash.

33. Using Compost
• Outstanding amendment for bed
preparation.
• Great addition to potting mixes.
• Not a great mulch.
• Compost tea

34. Critters
• Worms
• Insects –
Roaches
• Mammals

35. Do you need a bin?

36. Location
• Sun or Shade
• Near a source of
water.
• Near gardens
where it will be
used.

43. My Compost Piles
Passive Composting

46. Green Manures and Cover Crops
• Add organic matter to the soil.
• Useful when beds are not being used to grow
crops.
• Different for different seasons.
• For winter, rye, wheat, green peas and crimson
clover are possible choices.
• Legumes may provide a net gain in nitrogen.
• Turn under while still young and tender, before
seeds form.

47. QUESTIONS?