(Compost Basics by Jessica Walliser, page 3 of 5)
Biosolids (human sewage sludge) are never found on a list of acceptable compost ingredients for organic farming.
Biosolids may contain heavy metals, human pathogens and chemicals of all sorts; it has no place in organic or home food production.
If using commercially produced composts, it’s exceedingly important to question the producer about the potential use of biosolids and avoid any products containing them.
Here’s what not to add to your compost pile and why:
- Meat, bones and fish: may cause odor and attract animals
- Dairy products: may cause odor and attract animals
- Dog, cat, pig or reptile feces: may carry pathogens and parasites
- Oils: slow to decompose and may cause odor
- Diseased plant material: may spread disease back to your garden
- Dryer lint: may contain synthetic fibers that will not break down
- Vacuum bag contents: contains synthetic carpet fibers and chemicals
- Glossy, colored newspaper inserts: ink contains heavy metals
- Treated grass clippings: any chemicals present may cause damage to soil, flora and fauna
- Kitty litter: may contain pathogens and chemicals
The Scoop on Poop
Animal manures are listed as one possible nitrogen provider, including manures from cows, horses, sheep, goats, chickens, rabbits, ducks and geese (avoid manures from meat eaters like pigs, dogs or cats).
Don’t Play the Pied Piper
One common misconception about compost is that it attracts rodents.
While the occasional field mouse may find a home in the pile (you can’t blame them—it’s warm in there all winter long!), the pile should not attract rats, raccoons, opossums or any other critters.
To ensure they won’t show up, bury kitchen scraps under straw, leaves or other “brown” material, and never add meat or dairy products.
If adding eggshells to the pile (a great source of calcium), wash and crush well before tossing them in.
If you have the right C:N ratio, the pile will get good and hot—160 degrees F is just too hot for even the toughest rat. Yet another great reason to do it right!
Manure can form an important part of the soil fertility program on an organic farm.
It’s important to note, however, that manure can be a source of E. coli and other human pathogens, and should be handled with care.
Well-composted and processed manures are generally safer than raw manures, but all require special consideration.
Uncomposted, raw manure can be used on fields not growing edible crops.
It can also be added directly to fields if a few rules are followed.
- Raw manure must be worked into the soil at least 120 days before the harvest of crops contacting the soil (potatoes and other root crops, or any crops that may get splashed with soil).
- A 90-day wait period is required for crops that must be peeled or that do not come in contact with the soil.
- And just because manure sat in a pile for years doesn’t mean it isn’t raw and fits the definition of “composted.” It still needs to meet application requirements or be properly composted as described below.
Well-composted manure can be used anytime, though the definition of “well-composted” should be strictly monitored.
The manure, along with the other compost ingredients, must heat to 160 degrees F for a minimum of 15 consecutive days to be considered fully composted; it must be turned at least five times during that period.
This temperature, sustained for this time period, kills any potential pathogens—and it’s a very important step in safe, organic food production.
Processed manures (heated to 150+ degrees F for one hour or more, frozen or dried) are acceptable because they are pathogen-free and are not in a raw state; therefore they don’t have a waiting period and there is no need to incorporate them into the soil before planting.
The difference in manure usage between conventional and organic farms: Organic farmers must apply either well-composted manures or apply the manure a minimum number of days before harvest.
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