Compost mg notes for class 2011 jan 26 part 1

Compost 101Linn Benton Master Gardeners

Lecture notes Part 1

Teresa Matteson

January 26, 2011

Woody paths

Woody mulch

around

woody plants

Compost turf with high Nitrogen amendment

Cover

One year

(be careful with cotton seed meal)

Rate of decomposition depends on:

• Carbon to Nitrogen Ratio

• Air

• Water

• Size

• Time

C:N Ratio

• Ratio of carbon to nitrogen– Analogous to carbohydrates (carbon) and

protein (nitrogen) in our food

– High carbon materials are BROWN– High nitrogen materials are GREEN

C:N ratios• C always listed first,

grams C per gram N

25:1 or 25

• Lower C:N means

microbes need less N from soil

Critical Values of C:N

• C:N < 25:1, N release to plants

• C:N > 25:1, N taken from soil –microbes out compete higher plants every time

Organic material C/N

soil organic matter 10soil microbes 5-10alfalfa 13manure 20corn stover 57wheat straw 80sawdust 600

C:N ratio of different materials

Manure Comparison

Manure C:N Moisture

Chicken 10 37 - 69

Cattle 16 81

Horse 30 72 (seeds)

Sheep 16 69

Pig 14 80 (parasites)

C:N

Turn materials

Turn outside of pile to the center

so that all feedstocks

heat up

and smile!

AIR

Alternative to turning - Aeration pipes

AIR

Rule of thumb: 50% moisture

• Feels damp like a wrung-out sponge

• Should not drip when squeezed

WATER

COVER the pile to control moisture

WATER

Reduce sizeChopMowGrindChip

Increase

surface

areaSIZE

Minimum: 1 cubic yard - 3’ x 3’ x 3’

Maximum: <4 ft wide by <9 ft tall As long as you want

Pile size matters

SIZE

• It smells good, like the forest floor

• It is brown and crumbly

• The original materials cannot be identified

• It will pass through a ½” sieve toss overs back in the pile

When is your compost finished?4 criteria

TIME

•It is brown and crumbly

•The original materials cannot be identified

TIME

Make a ½ inch sieve that sits

on your wheelbarrow

Overs go back into the pile or

inoculate a new pile

Free-form pile

Build a hot pile

Build a hot pile

6 “ coarse brown

Build a hot pile

3” green

6” brown

Build a hot pile

6” brown

3” green

Add soil, amendments & MIX

Expensive

Holds moisture

Turning?