Use of forage legumes in bahiagrass (Paspalum notatum Flüggé) pastures for animal performance, nutrient cycling and nitrate leaching in North Florida

Abstract

Animal production in pasture systems is the predominant way of raising ruminants in the world, due to its low cost, practicality and food safety. According to the United States Department of Agriculture, the world herd of cattle concentrates around 1 billion animals. Aiming to optimize the production of pastures and animal gain, the insertion of forage legumes in the system is extremely important. Producers in the southeastern United States (USA) often opt out of applying N fertilizers due to high economic costs and the decreasing N utilization in pastures has led to increased instances of degraded pasturelands because of depletion of N in the soil. Planting forage legumes (C3) into warm-season grass (C4) swords is a management tool that may potentially reduce reliance on N fertilizer inputs. Therefore, the objective of this work is to substitute N fertilizer with biological N2 fixing forage legumes and assessing the effect on nitrate leaching, nutrient cycling and livestock productivity in exclusive pastures and mixed with Bahiagrass and forage peanut. The study is already established at the North Florida Research and Education Center (NFREC), Marianna (30°52'N, 85°11'W, 35m altitude). Currently, paddocks contain nine drain lysimeters (one per experimental unit; and replicated three times) and 18 porous cup lysimeters (two per experimental unit; and replicated three times). Treatments are assigned in a complete randomized block design, with three replications. The treatments are 112.09 kg N/ha during the warm season on bahiagrass; unfertilized bahiagrass during the warm-season; unfertilized bahiagrass/perennial peanuts during the warm-season and cattle performance will be determined every 21 days after the 16-h fasting period. Data will be analyzed using PROC MIXED in SAS . For the trial, fixed effects are grazing systems, year, and sampling date. The blocks will be the random effect. Means will be compared using LSMEANS procedure adjusted for Tukey's test (P d 0.05). The repeated measures procedure will be used for repeated measurement variables. Differences will be considered significant at P d 0.05. (AU)