Composting Livestock Manure
Introduction: Understanding manure
The benefits of manure are widely misunderstood. Many gardeners value it only as a fertilizer. As a source of primary nutrients, though, manure offers much less pound for pound than a bag of inorganic fertilizer. So what are its benefits?
First, manure does contain the primary nutrients - nitrogen, phosphate, and potash - but in small amounts. For example, you would need 8 times as much horse manure as 5-10-10 fertilizer to supply a given amount of nitrogen. If you rely on manure to supply primary nutrients, you'll need a pile, literally. Most gardeners supplement manure with other fertilizers.
Primary nutrients don't supply all of a plant's needs, though. Secondary elements;sulphur, calcium, and magnesium,are required in substantial amounts. Micronutrients;including zinc, boron, iron, and copper, are also needed in minute quantities. Manures are usually an excellent source of these elements.
Not only does manure supply nutrients, it helps hold them in the soil. Particles of humus derived from manure carry a negative electrical charge which allows them to combine with many plant nutrients that carry a positive electrical charge. Sand is electrically neutral, which explains why it doesn't hold nutrients well. Adding manure to sandy soil greatly enhances that soil's ability to catch and store nutrients.
The most important benefit of manure is as a soil conditioner. Mixing manure into a sandy soil is like introducing thousands of tiny sponges that help retain moisture. Manure also helps loosen and aerify a compacted clay soil.
Manures also transport useful microbial hitchhikers. These living components of organic matter manufacture glues that cement soil particles into crumbs. Crumbly soil is ideal as far as most plants are concerned because its structure allows it to hold both air and water.
Once dissolved in water, most inorganic fertilizers are quickly available to plants. But slow release fertilizers like manure are also beneficial because they provide small amounts of nutrients over several years. If you apply some manure each year, you'll maintain a small reserve of nutrients plants can draw on throughout their growing period.
Manure does have some drawbacks though. When fresh, it may contain weed seeds. You can minimize the problem by rapid composting. The heat generated in a quick pile will destroy most of weed seeds.
Some manure, such as chicken, can generate penetrating, nasty odors, but by applying them in winter or early spring they'll be less volatile.
Do not put manure from dogs, cats, and pigs in your food garden. They can carry disease organisms and parasites that can be transmitted to humans. Other precautions must also be taken to use livestock manure safely. Finally, it may be difficult to locate a cheap source of manure and transport it to your garden.
If you have access to a plentiful source, fresh manure can be applied at a rate of about 450 pounds per 1,000 square feet in the fall or winter. Composted manure can be applied anytime in a layer 1" to 2" deep and tilled into the soil. Use half these rates for poultry, rabbit, and sheep manures, which are more potent. You still may need to add phosphate and potash fertilizers since most manures don't provide sufficient amounts of all nutrients. A soil test will indicate if these are needed.
Gardeners interested in building a superior soil and stocking it
with slow release nutrients would do well to prospect for "brown
This site provides information from Conservation Districts on how to build and use a manure composting system. This system is designed for a small farm with 1 to 5 large animals. You can tailor your composting system to meet your needs depending on the number of livestock you have, the amount and type of bedding material you use, and how you plan to use the finished product. If you have a large farm or stable, or have any specific questions on setting up your composting system, please contact your local County Conservation District office.
How to Compost Manure
More information about this topic is available through your local WSU Extension Office
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