Forage Yield of Megathyrsus maximus Cultivars Managed with Two Fertilization Rates in a Sequential Cropping System

In the oilseed–cereal–forage system, information on the performance of grasses of the genus Megathyrsus maximus and on the optimal fertilization levels for forage production is still scarce. Therefore, this study aimed to evaluate forage yield (FY) of pastures established in crop succession systems and subjected to two fertilization regimes during the 2020 and 2021 growing seasons, in the municipality of Rio Verde, Brazil. The experiment evaluated four M. maximus cultivars (Paredão, Zuri, Quênia, and Tamani) under two fertilization rates: maintenance (50, 50, 20, and 3.2 kg ha−1 year−1 of N, K, S, and micronutrients, respectively) and enhanced (150, 150, 40, and 6.4 kg ha−1 year−1, respectively). The Zuri cultivar showed a higher daily forage accumulation rate and greater forage leaf mass compared with the other cultivars. In addition, the Zuri and Paredão cultivars achieved the highest FY, reaching 12.80 and 12.10 Mg ha−1, respectively. The Tamani cultivar exhibited a lower neutral detergent fiber concentration and a higher total digestible nutrient concentration, indicating its potential for systems that prioritize higher forage nutritive value. Zuri and Paredão maximize forage yield in crop succession systems, while enhanced fertilization increases yield by 15%, with adoption dependent on economic feasibility.