Why do farmers use a combination of manures and fertilizers in their fields?

Manure is an organic matter in which many nutrients packed into a tremendously interconnected structure. Generally, if only a required nutrient is applied as fertilizer to the plants, then there is a possible risk of it being leached away or lost due to fixation. This results in insufficient supply of nutrients to the plant, but if fertilizer is applied long with manure, then it remains in the soil structure without getting leached and is made available for the plants.