Manure offers a tremendous amount of benefits to your vegetable garden. For the sake of this article I am focusing in on animal manure, more specifically horse manure. If you want more information on "green manures" check out Cover Crops, Green Manures and Mulches.
I am writing this article on horse manure after receiving this question from fellow vegetable gardener Lynne Blackwell:
Manure Adds Nutrients to the Soil
Horse manure is a great source of nitrogen. Fresh horse manure contains about 50 percent
nitrogen (src: http://tinyurl.com/5d5n9f) of which a lot of it is soluble meaning it will be washed away in a good rain storm if you spread it out over a field.
However, before you start saying "what's the point then?", by composting your manure first, most of the nitrogen it contains will be stable and will slowly release into your soil, which is much better for your plants.
Composted horse manure will also release slowly over subsequent seasons, and that means if you add composted horse manure each season, your soil will always be rich and full of the nutrients your plants need.
Manure Increases Microbial Activity
First let us define what microbial activity is. Microbial activity, in its simplest definition means, that microorganisms are working hard in the soil to breakdown organic matter so that the finished result is usable by plants.
You can add horse manure to your soil, but it still has to be broken down to a level where the plants roots can absorb the nutrients. The beneficial bacteria and fungi will do that and that is microbial activity.
An Increase of microbial activity will:
- Help protect the roots of your vegetable plants.
- Reduce soil pathogens
- Build soil structure and tilth (cultivation of land; tillage)
- Soil will be more porous
- Helps balance your soil's pH level
Manure Helps Improve Drainage IssuesWhen you add composted horse manure to your soil, you will build a good soil structure. That in turn will help increase the amount of air and the amount of water that your soil can hold. This is important because, just like everything else, plants need air as well, and of course they certainly need water.
If your soil can retain more water, that is less watering you will have to do which comes in very handy in areas that may experience drought conditions.
To reiterate, because it is so important, horse manure is a great source of "fertilizer" for your garden, however, do not limit yourself to just horse manure.
If you have access to chicken manure, pig manure, or cow manure, the same information from above will apply as well.
Also be sure, that when you are composting your horse manure (or whichever manure you choose), to mix in other types of organic material, such as leaves, grass clippings, shredded paper, wood ash, and kitchen scraps. This will help balance out your compost pile.