How to Make Horse Manure Fertilizer

Build a manure pile that is 7-feet square and 3-feet high. This is a manageable size compost heap. Choose a site that is level, slightly elevated and is accessible to machinery like tractors. Try to put mostly horse manure in the pile and less bedding. Do this by only removing soiled bedding from the horses' stalls and using less bedding when cleaning them.

Turn the compost heap regularly to improve aeration and encourage decomposition. Use a tractor to turn the pile over or a pitch for for smaller piles. Turn the pile as often as possible or at least weekly. If you can't use a tractor on larger compost piles, drill holes in PVC pipe and insert the pipe into the pile. Air will travel down the pipe and out the holes, increasing aeration. Use pipes that are 5-feet long for 3-foot piles.

Water the compost pile when it gets too dry. Squeeze a handful of manure -- if it feels like a wrung-out sponge, it has enough water. If it is dry and crumbly, you need to water it. During rainy spells, cover the pile with a tarp to prevent it from getting water logged. Turn the pile after a heavy rain to dry out the top layer and spread moisture to the bottom layers.

Take the temperature of the pile using a long-stemmed compost thermometer. The pile will start out with a low temperature of 50 to 110 degrees Fahrenheit. As it starts to decompose, the temperature will increase to 160 degrees. Optimal decomposition occurs between 135 and 150 degrees Fahrenheit. Piles are cooler in the winter and warmer in the summer. A pile that is consistently above 160 degrees Fahrenheit should be broken into smaller piles.

Finish the compost by letting it cure for three weeks. Do this once the decomposition process is finished, the manure looks like dark, crumbly earth and the temperature drops to about 100 degrees Fahrenheit before stabilizing at the same outside temperature as the surroundings. Add to the garden at a ratio of 2 bushels per 100-square feet of garden.