Horse manure compost is a source of NPK. Manure solids contain nitrogen (0.7%), potassium (02%) and potash (0.7%). Many gardeners who try thus compost become true believers in its green growing power.
It is ready for use after it has been aged. Once aged, it is no longer hot.
Before you buy horse manure compost ask how long it was aged. You do not want to apply hot manure to your garden. It will burn your plants roots and can cause havoc in your garden.
The Compost Aging Process
Generally, horse manure is piled up with decomposing horse bedding like straw and sawdust mixed. After it has been aged, it maybe mixed with other organic materials such as soil, worms, and beneficial fungi.
For best results, during the aging process the compost is kept moist and at temperatures between 140 and 150 degrees. This heat kills harmful pathogens and weed; however, at these temperatures, beneficial bacteria stay alive. The entire process can take as long as a year.
Applying the Compost to New Flower Beds
The best time to apply is in early spring. If your soil is dense (e.g. clay) or low in organic matter and nutrients (sandy), consider adding as much as 40% to new rose beds. When you are done incorporating it into your bed you will have a fluffy 40/60% (your soil) ratio.
For those of you with healthy soil, you can give your garden a boost by applying about 2 inches on your tops soil. With a pitchfork, work the compost into the tops 6 inches of your soil.
Applying Aged Manure Compost in an Established Garden
You can work the compost into the soil around your roses but stay away from the bud union so you do not burn your rose (in case the compost is still generating some heat).
Work it into the top 2 inches of the soil that is near and around the perimeter of the rose’s drip line.
drip line perimeter shown here