Mixing clovers with grasses reduces the risks of a disease or insect devastating a stand of grass. Legumes complement grasses in many ways and having a mixed sward of grass and clovers constitutes a lower risk situation than having a pure grass sward. Clover in forage can reduce animal disorders caused by forage grasses alone. Grass tetany is another animal disorder reduced or eliminated by clovers in animals' diets. They furnish pollen and nectar for honeybees and tend to increase populations of beneficial predatory insects.
Clovers also provide food for wildlife including deer, rabbits and game birds.
Another reason given in the pamphlet, though this is stretching it a bit, is that pastures with clover are more interesting and attractive. Clovers are said to be more colorful and attractive than grasses to humans and, given their palatability, to grazing animals as well. Clovers in rotations or pastures can increase profits. The use of clovers can have an enormous impact on the economics of pasturing grazing animals. Nutrition is generally recognized as the primary limiting factor on most livestock farms, and legumes usually provide higher nutrition levels than grasses.