Composting

Montgomery County

Master Gardeners

Amanda Laudwein

February 5, 2010

Things You Need to Know…

Questions We Hope to Answer:

What is compost and composting?

Why should I compost?

How is it made?

Is it hard to do or can I make

it myself?

What do I do with it?

What is Compost?

Decayed plant matter.

What is Composting?

The conversion of organic

matter into compost.

What is Humus?US EPA says

“Mature compost is a stable

material with a content called

humus that is dark brown or

black and has a soil-like,

earthy smell.”

Another definition:

A soft, rich substance on

the forest floor that is a

dark and relatively stable

residue resulting from the

decomposition of organic

material.…i.e. Compost!

How DOES it happen in nature?

In the forest:

– leaves and twigs fall from trees

– animals drop their wastes or die.

Meanwhile:

soil organisms decompose these organic

materials Bacteria

Termites

Worms

…into humus!

Why Compost?

It decreases the amount of green waste that enters landfills. 23-30% of the waste stream is yard and kitchen waste in the US

Provides a product that can be used to improve soil tilth.

Can provide a natural source of plant nutrients.

Free fertilizer!

From the US Environmental Protection Agency:

Did You Know That Compost Can...

Suppress plant diseases and pests.

Reduce or eliminate the need for chemical

fertilizers.

Promote higher yields of agricultural crops.

Facilitate reforestation, wetlands restoration,

and habitat revitalization efforts by amending

contaminated, compacted, and marginal soils.

Cost-effectively remediate soils contaminated

by hazardous waste.

How does it happen in

your back yard?

This is the little bit of science part!

Compost…

two ways to achieve it:

AEROBIC (with oxygen) decomposition of plant materials.

ANAEROBIC (without oxygen)

decomposition of plant

materials.

AEROBIC Composting

From the Greek word meaning AIR

Living organisms, which use oxygen, feed upon the organic matter.

When some of the organisms die, their stored nitrogen and carbon becomes available to other organisms.

AEROBIC Composting…

Generates a lot of heat while converting the

carbon and nitrogen inside the pile and

reducing the volume.

– Increased temperatures in the compost kills

many pathogens and weed seeds but not all.

ANAEROBIC Composting

(without oxygen)

Occurs in nature only where oxygen is not

available

And it stinks!

Caused by the hydrogen sulfide from the

decaying organic matter which contains

sulfur (smells like rotten eggs).

Starting a Compost

Aerobic or Anaerobic

First decide which type you want to do…

ANAEROBIC Composting

(Easy, easy, easy)

Have you ever come across this form of

composting? Grass clippings in a sealed garbage bag.

(Slow, slow, slow)

But the results are worth it!

Garbage bag composting…

one of the easiest…but slow!

What you need:

Black plastic garbage bag

– The bags should be 30 to 40 gallon in size and

at least 3 ml. in thickness. This size bag should

hold approximately 3 bushels of organic

materials.

…then add:

Grass clippings

One shovel full of soil

A little water

A handful of high

nitrogen fertilizer

A little lime

Close tightly.

Give the bag a shake.

Leave for 6 - 12 months.

Bags can be

concealed behind

shrubs.

But you CAN:

Periodically FLIP the bag over to redistribute the contents and incorporate a bit of air to speed things up a bit.

For best decomposition…

Set bags in a sunny spot where they can

absorb heat

In the winter, move bags to a heated garage

or basement

And remember…

Patience is a virtue!

AEROBIC Composting

What materials do I need?

What does compost need?

What can I compost?

What should NOT be composted?

What materials do I need? Compost Bins or Piles

– Can be simple homemade bins made out of

fence or wire.

– Garbage cans with holes punched through the

sides.

Compost Bins or Piles

– Wood or wood pallets

(not pressure treated)

– Purchased systems

Compost Bins or Piles

– Compost bins are even available from the county

Think compost

bins are ugly?

Check these out!

Compost Bins or Piles

– A multiple bin system allows for continual

addition of new material.

Compost Bins or Piles

– Piles can also be used ( some municipalities

require bins or structures)

Compost Bins or Piles

– Size can be a benefit.

– A pile three feet wide

and three feet deep

composts well.

– Make the pile size

something you can work

with and turn as needed.

– If you don’t want to turn

it, composting will still

happen, just more

slowly!

These are a bit large…

unless you have

a front-end loader!

Setting Up A Bin or Pile

First select a spot to set up your bin. It

should be out of the way but convenient to

reach with plenty of room to work around.

Setting Up A Bin or Pile

It is also a good idea to choose a location

near to a source of water.

And don’t forget a

shovel or pitch fork

for turning the pile!

A thermometer is

also useful

The Recipe

Brown stuff

Green stuff

Water

Air

What does compost need?Pretty much the same stuff as in the

ANAEROBIC Composting system…

Brown stuff

Green stuff

Water

Air… but

more of it

And a bit of

exercise!

Composting…

is like a Layer Cake It is easiest to build a compost bin in layers

of ingredients like a cake:

– Start with the

BROWN STUFF

– Add a thinner layer of

GREEN STUFF

– Add WATER.

– AIR is already there!

Particle Size has

an Impact

Grind leaves with the

lawn mower or grinder

Aeration is Important

Small particle

size speeds the

process but …

Coarse material

makes sure

oxygen can move

through the pile.

You need both!

What is the Stuff?

Brown stuff is dead, dried plant parts like leaves and pine needles. – Brown stuff is high in the element carbon.

Green stuff is fresh, living parts like grass clippings, kitchen vegetable scraps, weeds and other plants.– Green stuff is high in the element nitrogen.

Water that either nature or YOU provide.

Air that nature provides but YOU keep available.

The Brown Stuff and

The Green Stuff –

Your Carbon and Nitrogen Sources

The carbon-nitrogen ratio:

– The closer you keep to a 30:1 carbon:nitrogen ratio the

faster it will compost

More of this than this

HOWEVER

Any ratio will eventually fully

compost given enough time!

Some Common Carbon Sources

Dried leaves

Pine needles

Newspaper

Sawdust

Some Common Nitrogen Sources

Food Scraps

(no meat or dairy)

Grass clippings

Coffee grounds

Horse manure

(manure only -

no bedding)

Water Each layer gets a good

sprinkling of water to wet

the ingredients. It is

important to wet each

layer as you build it.

Later on

RAINFALLwill help out –

or your hose

will again!

Air

Repeat each of the

layers until the bin is

full and then.....

Do not pack it down!

HINT:

Don’t spend a lot of time trying to balance

the pile, it will balance itself.

(…OR SO)

Things NOT to Add:

Meat, milk products

– because pets and

other animals may

try to dig them up

out of your compost

bin.

Things NOT to Add:

Diseased garden plants.

Things NOT to Add:

Noxious weeds with seeds

or stolens.

Some More Things NOT to Add:

Cooking oils and grease

Bones

Cat manure

Dog manure

What Happens Next

At first organisms

which live at

temperatures

between 50o F and

115o F go to work.

Then...

As the temperature increases

these organisms die and become

food for other organisms that

thrive in warmer temperatures.

These organisms will work

between 120o

and 160o

F.

Oxidation takes place much

faster with this group of

organisms.

Later As the compost cools down, you

may see larger organisms

Compost is teeming

with living things!

Compost "Critters"

The

Compost

Cycle of

Life

Why Temperature and WATER

are Important!

Temperatures between 120o F and 160

oF kills

weed seeds and many pathogens, so...

The compost pile should heat

for one to five days, but not longer.

If temperatures get too high or moisture levels

drop too low, combustion may occur.

Turning the Pile is Important

If it smells,

turn it!

Turning the Pile

Turn the pile regularly, at least once per week.

How long does it take?

Until all the material is consumed.

How to tell when it’s done:

When it’s cool!

Still too hot! Just right!

From Maryland Department of the Environment’s website:

PROBLEMS SOLUTIONS

Odor

– Turn more frequently, add Browns if necessary

Pile too wet

– Turn more frequently, add Browns if necessary

Pile does not get hot

– Pile too small, Organics not degrading. Check

moisture, turn more frequently, add Greens,

fresh manure, blood meal or urea

PROBLEMS SOLUTIONS

Rodents

– Remove and stop adding food scraps, turn

more frequently and keep moist

Pets

– Bury food scraps under one foot of material and

put pallet on top as lid

Insects

– Keep moist and turn more frequently

Use the New Compost

The compost can be added to your garden.

Typical Compost Application Rates New grass establishment

– 1 - 2 inches

Lawn maintenance– 1/8 – ½ inch

Planting bed preparation– 1 - 2 inches

Planting trees– Mix 1/3 compost into backfill soil.

Mulching around trees and shrubs– 1 – 3 inches Apply out to drip line.

Why Use Compost?

Increases moisture holding capacity of a soil.

While not high in the essential nutrients

(N,P and K), it adds organic matter to the

soil increasing the soil’s ability to retain

those nutrients in a form available to plants.

May contain important micronutrients.

May suppress some diseases like crown gall

in grapes and roses.

But Remember...

Try not to use unfinished compost material

And...

Compost is an

important part of

gardening and

waste reduction.

Use it and enjoy

the benefits.

Things You Needed to Know…

Questions We Hope We Answered: What is compost and composting?

– A stable material that is dark brown or black and

smells earthy like soil

Why should I compost?

– Waste reduction

– Really good for my garden

How is it made?

– Little beasties eat it and die, other beasties eat

them and die and so on until everything they eat

is gone and it is ready for you to use in your

garden!

Things You Needed to Know…

Questions We Hope We Answered:

Is it hard to do or can I make it myself?

NOPE! And YEP!

– Pile it

– Turn it

– Wait a bit

What do I do with it?

– Use it!

Bonus!

Another recipe…

(not this kind!)

Compost Tea

Put finished compost in a burlap bag.

Soak the bag in a trash can filled with water.

Let soak for several days, stirring occasionally.

Dip out the “tea” colored liquid, which will initially be high in microbes and use to water your plants.

Some Web Resources:

University of Maryland Extension Home and

Garden Information Center http://hgic.umd.edu/content/onlinepublications.cfm

US Environmental Protection Service http://www.epa.gov/epawaste/conserve/rrr/compos

ting/index.htm

Maryland Department of the Environment http://www.mde.state.md.us/programs/landprogra

ms/recycling/education/compostinfo.asp

Questions

Contact Information

• Hotline: 301-590-9650

• Monday - Friday,

9 am -1 pm

(March -October)

• Monday-Wednesday,

10 am - 1 pm

(November -February)

• Web: http://montgomery.umd.edu/

• Hotline: 800-342-2507

• Monday - Friday, 8 a.m. - 1 p.m.

• Web: http://www.hgic.umd.edu/

Web: http://www.growit.umd.edu/

This program was brought to you by

Maryland Master Garden Program

Montgomery County

University of Maryland Extension

78

College of

Agriculture and Natural Resources