Here at Gardening Know How we get lots of questions, and our goal is to provide answers to those inquiries to the best of our knowledge. Fertilizing gardens with manure is an age old practice. However, if not done properly manure fertilizers can actually be more harmful than helpful. The following information includes the 10 most commonly asked questions about using manure as fertilizer.
Animal manures are an inexpensive, natural way to fertilize plants. However, cow manure can be very high in nitrogen, which can ultimately burn plants if over used. It is recommended that cow manure be added to hot compost bins and mixed with the proper carbon to nitrogen ratio before being spread in the garden to prevent fertilizer burn. Straw or sawdust can provide the carbon to neutralize the high levels of nitrogen in cow manure. Hot composting cow manure before using it as a fertilizer also kills off potentially harmful pests and diseases in the manure.
Raw manures can be so nutrient rich that they actually burn plants, causing extensive damage or even plant death. It is recommended that you compost raw chicken manure before spreading it in the garden. Composting chicken manure breaks down the high levels of nitrogen and other nutrients so that plants are more able to absorb them safely. Raw chicken manure should be composted for at least six months before using it in the garden.
Using 25-40 lbs. of composted manure per every 100 square feet is usually a sufficient amount. However, plants or garden beds that may need extra nutrients can be mixed with up to 60lbs/100 sq. ft. Composted manure is usually tilled into garden beds in fall or early spring. It can also be lightly spread on lawns, garden beds or around plants as a nutrient rich top dressing. Many gardeners also make manure tea as a fertilizer for gardens.
Composted manure tea is an excellent liquid fertilizer for the garden. The proper mixing ratio of manure tea is the same as compost tea, one part composted manure for every five parts water. Our experts at Gardening Know How recommend placing the composted manure in a pillowcase or large burlap bag to be used as a tea bag. Steep this composted manure tea bag in the proper amount of water for a week or two, swishing or stirring around the tea bag at least once a day to mix.
It is recommended that only manures from animals with vegetarian diets be used as garden fertilizer. Pigs are omnivorous and are sometimes fed meat. The meat in their diet can cause pests and diseases to be present in their manure. Hot composting can kill off these pests and diseases, though. Like all manure, pig manure would need to be composted before being used in the garden. Pig manure should be composted for at least six months before using as fertilizer.
Sheep manure is actually lower in nitrogen than other animal manures, so it is less likely to cause fertilizer burn to plants. Yet, it is still rich in potassium and phosphorus. It is still recommended that sheep fertilizer be composted before using as a fertilizer. Sheep fertilizer also has less odor than other manures, so it is more pleasant to use. Composted sheep manure can be tilled in to garden beds, used as a top dressing or made in to manure tea to provide a boost of nutrients to the garden.
Horse manure is slightly higher in nutrients than cow manure; therefore, after it is properly composted for at least two to three months, it makes an excellent fertilizer for flowers and other garden plants. Horse manure can also contain more weed seeds than other animal manures. Hot composting is recommended to kill weed seeds and pathogens which may be found in raw horse manure.
Because bat guano has such high concentrates of nutrients, it is normally used less frequently and in smaller doses than other manures. It can also be expensive or hard to come by in certain locations. Bat guano is usually used as a soil conditioner for new gardens in the spring only. However, bat guano fertilizer tea can be made by mixing one cup of bat guano for every one gallon of water. This bat guano tea can be used as a fertilizer throughout the growing season.
It is not recommended to use cat feces or dog waste in compost. Cat and dog wastes can contain many harmful parasites and bacteria. To kill off these parasites, the temperature of a hot compost pile would have to remain at 165 F. (73 C.) for over five days. If you do choose to compost pet waste, it is especially important to never use this compost on edible plants.
Using manure as fertilizer in the garden can be beneficial but care needs to be taken with fresh manure. Raw manure can be mixed directly in to the garden in fall, so that it will have the winter months to sit and cure. Raw manure is very high in nutrients that can actually burn and even kill plants, so it either needs adequate time to cure or needs to be composted before using around plants. Composting times for manure usually range between two to six months depending on the animal the manure is sourced from.
We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer. We’re always here to help.