Garden lime is a common soil amendment used to adjust garden and lawn conditions. Backyard chicken keepers often consider using this product in coops or runs for hygiene and odor control. Whether garden lime is safe for poultry depends entirely on the specific chemical composition of the product. Understanding the difference between the available types of lime is the most important step a chicken owner must take before application. Failing to identify the correct product can lead to a highly toxic environment for the flock.
The Critical Distinction Between Types of Lime
The term “lime” is a broad category encompassing several compounds with vastly different properties and safety profiles for use around animals.
The first major type is agricultural lime, also known as calcitic or garden lime, which is crushed limestone composed primarily of calcium carbonate. A closely related form is dolomitic lime, a mixture of calcium carbonate and magnesium carbonate. These two forms are generally considered non-caustic and are the products referred to as “safe” lime for soil.
The second and highly dangerous category includes hydrated lime, also called slaked lime, which is chemically calcium hydroxide. Quicklime, or burnt lime, is another highly reactive form, composed of calcium oxide. Both hydrated lime and quicklime are produced by intense heating of limestone, making them highly alkaline and caustic. These caustic forms of lime are not suitable for direct contact with chickens or their living environment.
Safety and Use of Non-Caustic Garden Lime
Non-caustic garden lime, including calcitic and dolomitic varieties, can be used safely in a chicken run, primarily to correct acidic soil conditions. Chicken waste is naturally high in nitrogen, which lowers the soil’s pH over time, especially in high-traffic areas. Applying agricultural lime helps neutralize this acidity, creating a healthier substrate for the flock.
This type of lime also helps with moisture management in the run, promoting a drier environment that is less favorable for the growth of mold and harmful bacteria. Application should involve lightly scattering the product over the run surface, not creating deep layers. Because it is non-caustic, small amounts accidentally ingested by chickens while foraging are not a cause for concern.
The application rate should always be moderate, as overuse can push the soil pH too high, which may still be detrimental to the birds’ health. It is often most effective when raked into the top layer of the soil or used to treat underlying earth rather than being mixed directly into the coop bedding.
Why Caustic Lime is Highly Dangerous to Poultry
Hydrated lime is highly caustic and poses severe, immediate risks to poultry, making it completely unsuitable for use in coops or runs where birds are present. Calcium hydroxide is a strong alkali that reacts violently with moisture. This reaction can cause chemical burns on the sensitive tissues of the bird, including their feet, eyes, and beaks.
If a chicken walks on hydrated lime, moisture can activate the caustic properties, leading to painful foot burns. Inhaling the fine dust from caustic lime is also extremely dangerous, as it can severely burn the mucous membranes and respiratory system. Such exposure can lead to respiratory distress and long-term health issues.
If this caustic lime is accidentally consumed, it will burn the bird’s mouth, esophagus, and digestive tract, leading to severe internal injury and possible death. Any product labeled as hydrated lime, slaked lime, or calcium hydroxide must be kept strictly away from all poultry living spaces.
Management Options Beyond Lime
Many chicken keepers seek out lime for odor control, parasite management, or mineral supplementation, but several safer alternatives are available.
Odor and Moisture Control
For controlling strong ammonia odors and moisture in the coop, specialized products containing zeolite are highly effective. Zeolite is a naturally occurring mineral that works by trapping and neutralizing the nitrogen compounds in waste that lead to ammonia production, significantly improving air quality.
Parasite Management
For managing external parasites such as mites and lice, food-grade diatomaceous earth (DE) is a popular and safer choice. DE is a fine powder made from the fossilized remains of algae that works by physically drying out the pests’ exoskeletons. It can be safely added to dust bath areas where chickens naturally attempt to cleanse themselves.
Calcium Supplementation
For ensuring a source of supplemental calcium for strong eggshells and general health, the best approach is providing crushed oyster shells or commercial grit. These materials deliver the necessary minerals without the risks associated with applying any type of lime to the chicken’s living quarters.