In regard to mowing, fertilizing and weed control what is the best method to maintain a horse pasture.
Oakland County Michigan
Mowing - when mowing and/or clipping the pasture do not mow the forage less than 4 inches. This will help in maintaining a good stand of grass that may out compete weeds.
Fertilizing - conduct a soil test. These are relatively inexpensive (less than $20). The fall season is an excellent time frame to conduct of soil test. This will tell you what the nutrient levels are in the soil and also give you recommendations on what the soil may need and when to apply fertilizer, if needed. Otherwise, everything else is pretty much a guess and can be an expensive waste of resources.
Weed control - the best defense for maintaining a horse pasture against weed invasion is to not overgraze the pasture. When forage is grazed down to a height of 3 - 4 inches, remove the horses from the pasture to give the grass a chance to regrow. Below are the titles to a few bulletins that may be of interest. You can easily find these by typing in the name of the bulletin into your search engine.
1. Growing Hay and Pasture for Michigan Horses
2. Rotational Grazing for Michigan Horses