Manure: Spring is in the Air

By Master Gardener Sue Kowalchuk

While the appearance of robins is often cited as the harbinger of spring, I would argue that the application of manure on the farm fields is the true indication that spring is around the corner.  During this year’s unrelenting cold and snowy winter in eastern Pa, it was the sight of brown on the white, rolling fields that comforted me that winter was coming to end. 

Although manure is a commonly used soil amendment, the type used, the amount, and the timing of the application are critical factors in ensuring that it will be effective and safe.  Both fresh and composted cattle, poultry, and horse manure are typically utilized on farms and/or in home gardens. Application can improve soil health and structure, as well as provide nitrogen (N), phosphorus (P) and potassium (K); essential nutrients for plant growth. The amount of N, P, and K contained in each type of manure varies.  The best type to use will depend upon availability, percent of each nutrient in the specific manure and nutrient needs of the plants being grown. Consequently, soil testing to determine deficiencies and manure testing to determine nutrient content are good practices to guarantee success.  The amount applied is also important. Too little will result in insufficient nutrients, too much could leach into the groundwater, rivers, or streams and/or negatively impact plant growth.

Fresh manure of all types has a higher nitrogen content, with poultry having the highest. Some caution, however, is advised if choosing to apply fresh manure.  Not only can fresh manure contain weed seeds (horse manure is the worse offender), but pathogens, such as e.coli, or salmonella can be present.  In addition, the higher nitrogen levels can burn or kill plants. For these reasons, it is recommended that it be applied no later than 3 months before planting, and up to 4 months for crops that come in contact with the soil. For the home gardener, the safest practice is to apply in the fall, or consider composted manure.

Composted manure has been aged for several months and could also be mixed with other organic materials such as animal bedding. The overall levels of some nutrients are lower, but the heat generated in the compost pile and length of time exposed greatly reduces the likelihood of weed seed and pathogens.  This makes it a good choice for use later in the spring.

Using manure is a good way to improve soil health and increase plant yields while simultaneously “ recycling” animal waste.  Paying attention to type, amount and timing will provide you with the desired results and enable you to enjoy a bountiful harvest. That is, as long as the bugs, fungus, etc. are under control, but that is another story for another blog.

If you happen to notice the appearance of brown on the white snow or muddy fields, or a less than pleasant odor while driving past the farms, remember that it is a sign of spring and local fresh fruits and vegetables are almost around the corner.

Resources

http://cru.cahe.wsu.edu/CEPublications/pnw0533/pnw0533.pdf

http://web.extension.illinois.edu/cfiv/homeowners/000513.html

http://www.extension.umn.edu/garden/fruit-vegetable/using-manure-and-compost/

http://www.ext.colostate.edu/mg/gardennotes/242.html