Manure in the Garden

manure in the garden

Using manure in the garden is an old gardening treat that may turn out to be more trick. There are hazards and problems that may create more problems than the manure can correct.

Manure has been used as a soil amendment in gardens and on farms for as far back as human agriculture can be established.  The use of manure continues to this day in many places.  Even human excrement is used in some countries as it has been for centuries.

It is a practice almost as old as agriculture.  However, there are problems with the use of raw manure in home gardens and even in larger agricultural production.  Before anyone applies raw manure to their garden or landscape, there are things that you should know and understand.

Raw vs. Composted

Raw manure, the stuff that hits the ground directly from the source, is a different commodity than composted manure.  Many people have access to manure that has been sitting idle for months.  They often refer to this as “aged manure” and consider it the same as composted manure.  Nothing could be further from the truth.

Disadvantages

Raw manure has several disadvantages and some dangers that should be considered before it is used in a garden, especially an urban garden.

The most noticeable is the smell.  Raw manure can be odiferous.  It may become an issue with neighbors, especially if used I large quantities.  This can be especially true if it rains soon after the manure is applied. 

Raw manure is also rich in nitrogen and ammonia.  The addition of too much of these compounds in the soil can lead to problems with your plants. 

manure in the garden - foliage burning from excess nitrogen
  • High concentrations of nitrogen in the soil can cause plants to overgrow, producing massive amounts of foliage and few blooms.  
  • An overabundance of nitrogen can also stunt root growth, and when the readily available nitrogen is gone, the plants stress without a proper root ball to sustain growth. 
  • Too much nitrogen will burn the foliage, causing the leaves to turn brown on the edges and eventually curl, resulting in plant death.

Other risks

There are other risks, as well.  Unless you can be certain that the manure you source is free of pesticides and herbicides, you risk the possibility of bringing those contaminants into your garden as well.  There is research as well as anecdotal evidence that some pesticides and herbicides applied to feed products can be passed through the animal and into the manure.   One interesting anecdotal report concerns the transmittal of an herbicide into manure that was transported into a garden and the damage and death of a large number of plants in the landscape.  (What’s In Your Manure, http://nwdistrict.ifas.ufl.edu/hort/2016/05/24/whats-in-your-manure/)

Last but not least, some weed seeds can pass through an animal’s digestive system unharmed and be dormant until they land in your garden.  A fresh batch of raw manure can bring an unwanted host of new weeds into your garden.

Contamination

There is also some concern that biological contamination in raw manure may be transmitted to humans.  The USDA has issued recommendations to only apply raw manure to vegetable garden areas at least 120 days before vegetables are planted.  Root vegetables may also be subject to surface contamination and should be washed thoroughly or peeled before using.  Some research shows pathogens such as salmonella, listeria, and E. coli, as well as parasites such as roundworms and flatworms,  can be transported to humans through raw manure.

Aged Manure

What some people call “aged manure” is nothing but manure that has been left unattended for a length of time.  It has not been composted, and its nothing more than old, perhaps dried out raw manure.  It can contain the same pathogens and transmit the same problems as raw manure.  It will generate foul odors as soon as it is wet.

Composted Manure

manure in the garden - manure compost

Properly composted manure is a process that first mixes the raw manure with other organic substances.  This mixture is then placed in piles and carefully monitored for temperature, pH, and moisture content.  These parameters are regulated to insure that the compost reaches a temperature sufficient enough to kill the majority of the pathogens and weed seeds in the manure.  There is some debate on whether composting will mediate the presence of pesticides and herbicides.

Using Raw Manure

It can’t be denied that manure has been used almost as long as humans have been engaged in agriculture.  It will work if properly used. 

Our recommendation is to use products that are safer and offer the same sorts of benefits.  Compost of any kind is our preference.  Compost, your own or commercially available bag products, eliminate the vast majority of the problems associated with raw manure.  In an urban garden environment, it just makes sense to avoid the problems with odor and possible pathogen transmittal.

Some Suggestions

If you still wish to use raw manure in your garden, there are some tricks to doing it too avoid many of the problems.

  • Never apply raw manure to your garden after your plants have been put into the soil.  This is especially true of vegetable plants.  The USDA recommends that raw manure not be applied to any vegetable garden within 120 days of harvest.  This holds for all vegetables including root crops.
  • The bests way to use raw manure in the garden is to use it as a soil amendment in the fall.  To do this safely, you would need to till the manure into the soil.  The downside to this is the damage you do to your soil biome by tilling.  Any advantage you may gain from the manure is more than likely offset or even negatively affected by destroying the bacteria and fungi in otherwise healthy soil.
  • If you are sourcing your manure locally, inquire from the source about any pesticides or herbicides that may have been used on the feed crops for the animals involved.  If the source cannot provide information about the source of the feed, you face a possible contamination hazard for your garden
manure in the garden - tool hygiene
  • Practice good hygiene.   Clean and wash your garden tools after using them with manure.  Soaking in hydrogen peroxide or a bleach solution is a good habit.  Wash your hands thoroughly, paying attention to your nails.  Raw manure can harbor pathogens and parasites that can be transmitted to humans.

Recommendations

Our recommendation for urban gardeners is to avoid using raw manure in the garden.  While it does have benefits for your soil, the possible problems and dangers far outweigh the benefits in our estimation.  Good quality compost offers almost the same set of benefits without the drawbacks and possible damage to your soil, your plants, and your health.

Links and Resources

For more information about organic gardening, lifestyles, and living, visit our website at West Texas Organic Gardening.

If you found the information here helpful, you might also find these articles on our website of interest.

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