Forage peanut as a sustainable alternative to nitrogen fertilization for maintaining pasture productivity after recovery

ABSTRACT The objective of this study was to investigate the influence of nitrogen (N) input via fertilizer or through the inclusion of an N-fixing legume mixed with grass on canopy structural characteristics, forage production, and stocking rate in grazing systems. Three pastures type (PT), with Marandu palisadegrass (U. brizantha), were assessed: i) monoculture without N fertilizer application (Unfertilized); ii) monoculture fertilized with 150 kg N ha⁻1 year⁻1 (N-fertilized); iii) and mixed pasture with forage peanut (A. pintoi), without N fertilizer (Mixed). The treatments were managed under mob stocking with variable stocking rate. The canopy height target was between 25 and 30 cm (pre-grazing), and 15 cm (post-grazing). Beef cow-calf pairs were used (529 ± 49 kg cows and 80 ± 29 kg calves) for grazing. The pre-grazing total herbage mass was not influence for the PTs (P = 0.111), which averaged 7,234 kg ha⁻1. The greatest and lowest pre-grazing herbage mass were recorded for the N-fertilized and Unfertilized. The N-fertilized and Mixed had the greatest post-grazing herbage mass (P = 0.012). The legume proportion in the Mixed was on average 30.5%. The N-fertilized and Mixed showed the greatest herbage accumulation rate. The lowest herbage accumulation rate was recorded in the Unfertilized. Stocking rate was reduced by 35.7 and 78.5% in the Mixed and Unfertilized, respectively, compared with the N-fertilized pasture, with the Unfertilized averaging 0.9 AU ha⁻1. Overall, N-input is crucial for maintaining and supporting adequate carrying capacity in pasture ecosystems. Thus, forage peanut legume provides a way to add N with lower economic and environmental costs.