PHOTO: iStock/Thinkstock
Maurice Pitesky
March 31, 2017

Backyard chicken keeping has many benefits aside from farm-fresh eggs. If you garden, chicken manure is black gold when composted and applied appropriately, returning nutrients to the soil and helping produce better plants, fruits and vegetables for you and your family.

In a 2014 survey conducted by UC Davis Animal Science Master’s student Carine Elkhoraibi and her adviser, Dr. Joy Mench, more than 1,400 backyard chicken-keepers responded. When asked the major reasons they kept backyard chickens, 95 percent of the respondents mentioned food for home use followed by 63 percent who listed their chickens as gardening partners: Think pest control and manure as a fertilizer. While this suggests that composting is common, we need to be careful how we handle, compost and apply compost in order to avoid contamination of the fruits and vegetables we are growing in our gardens.

Manure Macronutrients

Aside from macronutrients nitrogen, phosphorus and potassium, which are essential for plant growth, chicken manure also contains calcium, magnesium and sulfur, which are not found in synthetic fertilizers. In its raw form, however, poultry manure also has high concentrations of bacteria, including pathogenic salmonella, meaning that you should never apply raw poultry manure to your edible garden. The bacteria can come into contact with your growing produce and either stick to the surface or move inside the plant’s cells, making cleaning impossible.

In addition, if you apply raw, noncomposted manure to your plants, they may very well die due to excessive available nitrogen and salts. The best way to dispose of the manure is to first compost it and then use it correctly and safely.

Step 1: Collect Materials

Think bedding material, such as rice hulls and wood shavings, and put it in a composting bin. You’re aiming for approximately 25 percent manure and 75 percent other materials, which can include the aforementioned bedding material, leaves, plant material or kitchen scraps, and lawn clippings. You should have at least 1 cubic foot of material to allow the composting process to heat the pile up to an internal temperature of 140 to 160 degrees F, which will kill pathogenic bacteria.

Step 2: Add Water

You’re looking for the pile to match the texture of a wet sponge.

Step 3: Monitor Temperature

Do this daily with a composting thermometer, which you can find online or at a home-improvement store, and keep a temperature log to refer to. Your goal is to reach a temperature between 140 to 160 degrees F and maintain that temperature for three days.

The temperature is key: Submitting compost samples to a lab for detection of pathogens is not practical or effective. However, temperatures of 160 degrees F or higher will kill salmonella and common bacterial pathogens found in poultry manure. If you don’t achieve that temperature, the chances of pathogen survival for an extended period of time will increase.

Step 4: Repeat

While the internal part of your pile is treated, the outside is not. Therefore, repeat the process at least two more times to make sure all parts of the pile have been treated.

Step 5: Cure

Put the compost in a covered pile for at least 80 days. This waiting period helps to ensure that the pathogenic bacteria have been killed.

How To Use It

On commercial farms, farmers match the nutrient requirements of the crop with the application rate, which helps mitigate any issues related to nitrogen leaching into groundwater. This approach is not practical for backyard gardeners, but it’s important to recognize that more is not always better and the timing of application is important.

In general, always apply compost as near as possible to planting time and apply it between 1 and 2 inches deep to your garden crops or 1/2 inch deep to your lawn. If you want your compost samples analyzed for macronutrients, such as nitrogen, phosphorus and potassium, and E. coli and salmonella levels, you can collect a sample and send it to a private diagnostic lab.

Here are a few other items of note:

  • Do not add dog, cat or human feces to your compost pile, as they can’t be safely composted.
  • You shouldn’t smell ammonia associated with manure inside the coop; aside from being bad for our lungs, it can cause ulcers in the chickens’ corneas. If you do, you need more bedding material. Straw, though commonly used, isn’t the best choice for bedding, as it’s relatively nonabsorbent compared to wood shavings or rice hulls, and can contribute to that strong ammonia smell. Clean your coop as needed, but ideally, if you have the right density of birds and the correct amount of bedding material, you shouldn’t need to clean your coop more than once every couple of months. (The birds often will “till” their manure with their bedding as part of their normal scratching behavior.)
  • Remember that after you compost the material can still contain low levels of salmonella, E. coli and other pathogens, which is fine. This is a numbers game in that your starting material had millions of these bacteria per gram of manure. Very low levels of these bacteria will not cause disease if you have a normal immune system. It’s still recommended to always wash freshly picked fruits and vegetables.

Compost is a safe and ideal fertilizer for your home garden—if processed correctly. Aside from providing nutrients to your plants, the manure adds organic matter to the soil and increases the water-holding capacity and the beneficial bacteria present in the soil, but processing it properly is paramount.

This article is written by Pramod Pandey and Maurice Pitesky, faculty members at the UC Davis School of Veterinary Medicine at the University of California, Davis, and the University of California Cooperative Extension. Dr. Pandey’s research focus is on composting and microbial waste management, and Dr. Pitesky’s research focus is on poultry health and food safety epidemiology.

This article appeared in the March/April 2017 issue of Chickens.


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