Safe CompostingHeidi Kratsch

Area Horticulture Specialist

History of composting Started with use of manure

in Mesopotamia References in Bible and

Talmud New England farmers: “10

parts muck to 1 part fish” Early 20th century: Plant

nutrients were discovered – chemical fertilizers replaced composting

Sir Albert Howard wrote An Agriculture Testament in 1943

J.I. Rodale – popularized organic farming in the U.S.

Mesopotamia

Composting is an extension of the natural process of decomposition.

Aerobic bacteria (require O2)◦Psychrophilic – active between 55 and 70 F

◦Mesophilic – 70 to 100 F◦Thermophilic – 113 to 160F

Composting and microbes

Pile heatsup

Temperature peaks

Pile shrinks

160 F

Turn the pile

Actinomycetes – ◦Higher-form bacteria◦Responsible for earthy smell◦Decompose tough materials (lignin, cellulose)

◦Populations rise during the later stages

Other compost actors

Prefer cooler temperatures (70-75 F)Prevalent during the late stages of composting

Fungi

Earthworms and Arthropods

Food – carbon and nitrogenAir - oxygenMoisture – keep moist, not wet

Good drainage

Keeping them alive

Carbon for energy◦ Dry and brown such as leaves, straw, and wood

chips◦ Decompose slowly

Nitrogen for growth and reproduction◦ Wet and green such as fresh grass clippings and

food waste◦ Decompose quickly

Carbon and Nitrogen

2 parts carbon-rich to 1 part nitrogen-rich

Air flow through compost

40 to 65% moisture Too dry – process is

slowed Too wet – leads to

anaerobic (low oxygen) conditions

Keeping it moist

Temperature – hot composting occurs between 110 and 160 F

Particle size – 1/8 to 2 inches Volume – 3 x 3 x 3 feet is optimal

Things to monitor

Appropriate length to reach the center of your compost pile

Clear, easy to read display

Made of stainless steel or other non-rusting material

Temperature range from 0-200 degrees Fahrenheit

Display is hermetically sealed, preventing fogging

Composting thermometers

Fresh and colorful (“green”) materials◦Fresh lawn/garden waste◦Animal manure (from herbivores only)

◦Non-animal-based kitchen wastes◦Garden and canning waste◦Fruits and vegetables

What to Compost

Dry or woody (“Brown”) materials◦Dry leaves, cornstalks◦Wood chips (chipped fine)◦Weed-free hay or straw◦Sawdust◦Shredded paper

What to compost

Meat or fishBonesFats, grease, lard or oilsLarge branchesDairy productsSynthetic productsPlasticsPet wastes

What not to compost

Creating your compost pile

Nitrogen source

% Nitrogen Cups to apply

Urea 46 4Ammonium nitrate 33 6Calcium nitrate 15 13Dried blood meal 12 16Fish meal 10 20

Provides 1 lb. N per cubic yard

Source: Backyard Composting in Utah, Utah State University

How do I know when it’s done?

Dark brown and crumbly (fluffy) with an earthy odor.

Original materials should not be recognizable.

Temperature same or a bit higher than outside air.

Should not reheat. May see earthworms and

insects. Should not be hot, moldy or

smell like ammonia!

Leave finished compost in a pile for up to one month.

Decomposition of larger hidden particles may continue

Compost “stabilizes” Ensures the process is complete before you apply to planted areas.

Curing your compost

Steaming during the curing phase is not uncommon.

Problem Possible cause

Smells bad Compacted;Too much moisture

Pile damp but won’t heat Not enough N;Materials too wet

Dry and not composting Not enough water

Ammonia odor Too much nitrogen

Pile temperature too high Pile too large;Insufficient ventilation

Pile temperature too low Pile too small; not enough moisture; poor aeration; lack of nitrogen

Trouble-shooting

Screen compost

Apply compost deeply

Double-digging

Making compost safe for pets

Tremorgenic mycotoxin is produced by a mold that causes tremors.

Tremorgenic mycotoxin poisoning◦Agitation◦Lack of coordination◦Panting◦Drooling◦Vomiting◦Tremors◦Seizures◦Untreated = death

Keep pets (and other critters) safe

Fence off composting areas

What about compost tea?

Compost tea is not the dark-colored solution that leaks from the bottom of the compost pile (do not spray this on food crops!)

Compost tea is the extract of compost made suspending compost in a barrel of water (aerated or unaerated) for a short period of time (up to a week).

What is compost tea?

Provides nutrients (amounts and types depend upon ingredients used to make the compost)

Disease suppression (maybe?)◦ 50% less powdery mildew on grapes◦ Slight reduction of gray mold◦ INCREASE in downy mildew

Rodale Institute and Pennsylvania State University, recent unpublished work

What does compost tea do?

What compost tea does NOT do:

Improve soil structure

Help retain nutrients Help retain moisture Improve soil aeration Lower soil pH

Compost does all of these things!

Use only potable water. Sanitize all equipment. Use only compost that has maintained a

temp of 131 F for 3 days (use hot composting method).

Avoid additives (esp. simple sugars like molasses)

Must be used within 24 hours of making it.

If you decide to make compost tea:

Questions?