For many gardeners, showy packages of chemical fertilizers have no appeal as they prefer natural, organic methods. Manure not only breaks down into useful nutrients which can feed your plants, it is cheap and it improves the structure of the surrounding soil.
Contact local race tracks, farmers or horse stables; introduce yourself and explain that you'd like to get some horse manure for your garden. Typically such places will give you as much manure as you like at no cost.
Schedule a mutually convenient time for a manure pick up. You'll have to shovel and haul the stuff away yourself, so be sure your vehicle is adequately prepared for the venture.
Combine the manure with an equal measure of leaves or straw and then pile the mixture in a sunny location. This effectively creates a manure compost pile. Horse manure must be composted prior to application; in raw form it is the perfect growth medium for weeds, pests and pathogens. Composting removes these unhealthy elements, rendering the manure harmless.
Turn the contents of the compost pile at least once a week. Use a shovel to recombine the pile, moving the middle portions to the top, the top to the bottom and the bottom to the middle. This allows air to reach all of the components of the pile and reduces the required composting time.
Add water as needed to keep the compost damp, but not soaking wet. Check the moisture content when turning the pile, mixing the water into the drier areas.
Wait six to nine months for the manure to be ready for your garden. The compost is ready to use when a handful retains the clumped shape after squeezing.
Apply horse manure compost to your plants once a year, spreading a one inch layer evenly across the garden or mixing it into the first few inches of top soil.