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| Chickens foraging on the ground. Photo: UMN Extension |
If you have backyard chickens, you’re probably well aware of
the benefits of using chicken litter (manure plus bedding) in the garden.
Poultry litter contains nitrogen, phosphorus, potassium and a variety of other
nutrients that plants need for ideal growth.
The combination of manure, feathers, feed waste, plus straw, wood shavings, or other bedding material provides an excellent source of organic materials to feed soil microbes that help keep your soil and plants healthy.
Fall is a great time to apply poultry litter to your garden – particularly if you grow edible crops.
The combination of manure, feathers, feed waste, plus straw, wood shavings, or other bedding material provides an excellent source of organic materials to feed soil microbes that help keep your soil and plants healthy.
Fall is a great time to apply poultry litter to your garden – particularly if you grow edible crops.
Why add chicken litter?
Composting backyard chicken manure can help stabilize
nutrients, lower salt levels, and decrease harmful human pathogens (germs, such
as Salmonella bacteria) that can make
people very sick if ingested on raw produce, such as lettuce, cantaloupe, or
tomatoes.
You won’t know whether or not your chickens carry these bad germs – chickens are natural carriers of many bacteria that can make people really sick, so it’s important to consider that all chicken manure can be a source of pathogens.
You won’t know whether or not your chickens carry these bad germs – chickens are natural carriers of many bacteria that can make people really sick, so it’s important to consider that all chicken manure can be a source of pathogens.
And while the composting process can greatly decrease nasty
germs, not all backyard compost piles are able to achieve the temperature,
time, and turning requirements that can significantly reduce these harmful
pathogens, however.
How to use chicken litter
The good news is that even if you’re not an expert composter, you can still use chicken litter in the garden. Let’s explore the options.Option A: The "fully composted" pile
For chicken litter to be fully composted - or treated - to
ensure a substantial reduction in harmful pathogens, the compost pile needs to
reach certain temperature, time, and turning thresholds. This can be
challenging – but certainly not impossible – to achieve in a backyard setting.
These specific time, temperature, and turning requirements for safety are from the National Organic Program standards for manure use in organic fruit and vegetable production. If you buy certified organic produce from the grocery store or farmers’ market, and they’ve used composted manure, the compost will have met these same requirements for safety.
So, what are those requirements?
These specific time, temperature, and turning requirements for safety are from the National Organic Program standards for manure use in organic fruit and vegetable production. If you buy certified organic produce from the grocery store or farmers’ market, and they’ve used composted manure, the compost will have met these same requirements for safety.
So, what are those requirements?
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| Fully composted chicken litter. Photo: University of Kentucky Extension |
Temperature and time: First of all, high temperatures are needed to kill harmful pathogens.
Temperatures of at least 131°F must be observed for at least fifteen days, although
those days do not need to be consecutive.
What this means is that your pile must be large enough to allow for microbes to really get going with the decomposition so the pile can heat up on the inside.
You’ll need a compost thermometer – a thermometer with a long stem that can reach well into the pile (see photo below) – to check the temperature. Note that if your pile gets too hot, generally >160°F, the beneficial, heat-loving microbes can also be killed.
What this means is that your pile must be large enough to allow for microbes to really get going with the decomposition so the pile can heat up on the inside.
You’ll need a compost thermometer – a thermometer with a long stem that can reach well into the pile (see photo below) – to check the temperature. Note that if your pile gets too hot, generally >160°F, the beneficial, heat-loving microbes can also be killed.
Turning: Next, the pile must be turned at least five times during the
heating period. Turning ensures that all parts of the pile can be adequately
decomposed by providing oxygen and new material from the edges to the center of
the pile.
Incorporating edge material provides more food for microbes and allows the pile to reheat after turning. Turning also ensures that all of the litter will be exposed to the high temps needed to kill pathogens.
Incorporating edge material provides more food for microbes and allows the pile to reheat after turning. Turning also ensures that all of the litter will be exposed to the high temps needed to kill pathogens.
Curing: Finally, the pile must be allowed to “cure” for a period of
time afterwards. Generally, the curing stage can last a few weeks to months,
allowing the pile to cool down and the nutrients to be stabilized before being
incorporated into the soil.
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| Long-stem compost thermometer. Photo: Chryseis Modderman |
If all of these requirements are met – at least 131°F for 15
days with 5 turns followed by curing – the compost is considered to be low
risk for pathogens. This means that you can apply this type of compost
anytime during the year – even in the spring, before planting.
It's still a good idea to minimize direct contact between crops and composted manure whenever possible – composting greatly reduces harmful pathogens, but it may not completely eliminate them.
It's still a good idea to minimize direct contact between crops and composted manure whenever possible – composting greatly reduces harmful pathogens, but it may not completely eliminate them.
One thing to note, however, is that care must be taken to
store and handle fully treated compost to ensure that it doesn’t become
recontaminated.
Compost can get recontaminated when animals such as rats or mice build nests in the compost (their feces contains lots of nasty germs) or when tools used to turn raw compost are then used to turn or move partially-composted or finished compost.
Compost can get recontaminated when animals such as rats or mice build nests in the compost (their feces contains lots of nasty germs) or when tools used to turn raw compost are then used to turn or move partially-composted or finished compost.
Option B: The "aged" pile (or the "lazy composter" pile)
Lots of backyard chicken owners will have a pile where they put litter to “age”, thinking that if it’s left out there long enough, it’ll decompose and be safe for use in the garden. The truth is that un-managed, “aged” manure is really no different than raw manure.While some parts of the pile may get hot, not all parts of the pile are exposed to the conditions needed to kill pathogens. Even if the pile is occasionally turned, if you’re not measuring temperature, you won’t know whether or not the temperatures are high enough to adequately kill the bad germs.
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| "Aged" chicken litter, approximately two years old. Photo: Anne Sawyer |
Fear not – you can still use “aged” manure in your garden!
Basically, you just need to use it in the same way that you’d use raw manure.
Raw manure can be applied to a garden with edible produce provided that there’s adequate time between applying the manure and harvesting the crop.
An adequate application-to-harvest time window helps ensure that the pathogen populations are significantly reduced by other organisms in the soil, through exposure to UV radiation from the sun, or from other environmental factors that can kill them.
Raw manure can be applied to a garden with edible produce provided that there’s adequate time between applying the manure and harvesting the crop.
An adequate application-to-harvest time window helps ensure that the pathogen populations are significantly reduced by other organisms in the soil, through exposure to UV radiation from the sun, or from other environmental factors that can kill them.
Once again, the National Organic Program has standards for
the safe use of raw (or “aged”) manure when growing produce. The minimum amount
of time between applying manure and harvesting crops that don’t touch the soil
(such as trellised tomatoes or snap peas) is 90 days. For crops that do contact the soil (such as root
veggies, melons, or even bush green beans), the minimum amount of time between
applying manure and harvesting these crops is 120 days.
Because we have such a short growing season in Minnesota,
this generally means that “aged” manure should be applied to gardens in the fall.
So, that pile of chicken litter that’s been sitting in the back corner of the
yard for a couple of years? Put it on the garden now!
You can spread about 1-2” on the surface of the garden. Turning or tilling the compost into the soil will help ensure that nutrients are retained and not lost to runoff and that pathogens are forced to compete with native soil microbes – a battle that they generally lose.
You can spread about 1-2” on the surface of the garden. Turning or tilling the compost into the soil will help ensure that nutrients are retained and not lost to runoff and that pathogens are forced to compete with native soil microbes – a battle that they generally lose.
Option C: The "raw" stuff
The standards for raw manure are - as you may have guessed -
exactly the same as for “aged” manure, because “aged” manure is no different
than raw manure. So, if you want to apply what's fresh from the coop, apply it in the fall for use on edible crops.
Raw poultry manure also can contain high levels of ammonia-nitrogen and salts that can damage plants if applied in the spring, so don’t apply raw manure to any garden immediately prior to planting.
Raw poultry manure also can contain high levels of ammonia-nitrogen and salts that can damage plants if applied in the spring, so don’t apply raw manure to any garden immediately prior to planting.
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| Chicken litter in the coop. Photo: University of Wisconsin Extension |
What about chickens IN the garden?
Chickens in the garden can
provide excellent pest control and fertility at the same time! However,
chickens – and their manure – are primary sources of germs that can make people
very sick, as we’ve already discussed. Not only can pathogens be present in
chicken droppings, but they can also be present in saliva, on their feathers,
and certainly on their feet.
If you allow your chickens to free-range in your garden, do so only in the fall after all edible crops have been harvested for the year. Chickens in the garden are spreading raw manure, so the guidelines for raw manure stated above apply to free-ranging fowl.
If you allow your chickens to free-range in your garden, do so only in the fall after all edible crops have been harvested for the year. Chickens in the garden are spreading raw manure, so the guidelines for raw manure stated above apply to free-ranging fowl.
So yes, chickens and gardens can be a great
combination – but only when best practices for food safety are used. And of course, remember to wear gloves, a mask and/or other personal protective equipment when handling poultry litter and ALWAYS wash your hands after handling litter or compost.
To
learn more about composting manure and the National Organic Program standards,
see this USDA fact sheet. To learn more about other garden food safety
practices, visit Extension’s GAPs (Good Agricultural Practices) Education page
at z.umn.edu/growsafefood.
Author: Anne Sawyer, PhD
Author: Anne Sawyer, PhD
Extension Educator, On-Farm Food Safety
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