Mainly it's a matter of better animal performance. Livestock just 'do-better' on the mixture than they do on straight grass. Also when legumes are added to grass, the production distribution is better throughout the spring, summer and fall grazing months than grass alone. Pasture renovation improves conception rates as well as cattle gains. And, the calves from these mixed pastures weighed an average 50 pounds more at weaning.
Renovation also produces more milk.
In a Tennessee study, milk production increased 6 pounds per day or 1,800 pounds in a 305 day lactation period when grazing a clover-grass mix versus grass and nitrogen. A study by Purdue University researchers puts the entire picture together when it comes to the beef cow-calf herd. Over a three-year period using 100 cows, the renovated pastures produced 20 more calves each year. All of the calves in the herd on the clover-grass pastures weighed 85 pounds heavier than the matched calves on pastures with grass and nitrogen. When the 20 more calves saved are added to the increased weights for all of the calves, that's an additional 15,000 pounds more beef.