If you have fresh manure add it under the top layer of soil. As it composts it will create some heat that will aid germination and as the plants grow and the roots get longer they will benefit from the nitrogen, somewhat weakened by composting. Generally cow or horse manure isn't too hot if mixed with soil but usually contains weed seeds. Chicken manure is excellent but must be composted first or it will burn anything that touches it. Rabbit manure is as good as chicken but will not burn your plants.
Look up the "The Encyclopedia of Organic Gardening" by Rodale Press. I have had my copy since 1980. All the info is still pertinent and they have probably added lots more since then.
My cloches are made with 2x4 fence wire. I cut it so I can fold it in half lengthwise to make a tent shape the length of the bed. It is the same size as the bed when folded. When temps drop I add clear plastic film to continue the growing season. I use the 2x4 wire so the rabbits don't get in.
The best soil you can use is soil you make your self. Top soil usually has too many weed seeds so I stay away from it. A mixture of soil, manure, lime, leaf mold and other organic materials works best. A soil test is a good idea. Last year I didn't till my garden(also promotes weed growth) but dug a hole for each plant and mixed in 30 year old dried manure we got from an old cattle barn. Boy did those plants jump!
Weed seeds like from crabgrass can stay underground for 60 years or more. As soon as you turn the soil and the light hits them, they will germinate.
