What Does Well Rotted Manure Mean?

Well rotted manure looks like soil/compost. It won't have any trace of straw or shavings and it will be crumbly and not smell of horse poo any more. If what you have collected is still steaming, it will possibly still be rotting down and might be too rich for plants.

What can I use instead of well rotted manure?

You could for example use grass clippings, silage, leaves and half-finished compost. The material will transform into great fertilizer with the help of the worms in the soil.

Can you plant directly into well rotted manure?

Sow into the surface layer as usual, even well rotted animal manure. This does not cause forking because it is not dug in (forking can occur when manure is dug into the soil, not an issue with no dig!) To harvest carrots, just pull out, or wiggle a trowel next to them to loosen before pulling.