Palisadegrass pastures with or without nitrogen or mixed with forage peanut grazed to a similar target canopy height. 1. Effects on herbage mass, canopy structure and forage nutritive value

Abstract

Nitrogen (N) inputs to pasture systems coupled with grazing management strategies based on monitoring and control of canopy structure may provide conditions for greater productivity and enhanced forage nutritive value. This 2‐year study assessed canopy structure and nutritive value responses of three pasture treatments, namely, (1) mixed Marandu palisadegrass (Brachiaria brizantha [Hochst. ex A. Rich.] R.D. Webster [syn. Urochloa brizantha Stapf]) cv. Marandu and forage peanut (Arachis pintoi Krapov. & W.C. Greg.) cv. BRS Mandobi pastures without N fertilizer (GRASS + LEGUME); (2) monoculture Marandu palisadegrass pastures fertilized with 150 kg N/ha (GRASS + N); and (3) monoculture Marandu palisadegrass without N fertilizer (GRASS). Grazing management was similar across pasture treatments, using continuous stocking and a target canopy height of 20–25 cm. Herbage mass was greater in GRASS + N and GRASS + LEGUME pastures than in GRASS in summer and spring (p = .014). The leaf:stem ratio in the grass mass (p = .731) was similar between treatments. Grass crude protein (CP) and in vitro digestible dry matter (IVDDM) were greatest in the GRASS + N pasture (p < .001). Grass neutral detergent fibre (NDF) concentration was greater at GRASS and GRASS + LEGUME pastures than in GRASS + N (p < .001). Forage peanut had a greater IVDDM and CP concentration and a lower NDF concentration than Marandu palisadegrass. Nitrogen application or the presence of the legume increased green herbage mass and improved forage nutritive value in canopies with similar height.

Palisadegrass pastures with or without nitrogen or mixed with forage peanut grazed to a similar target canopy height. 2. Effects on animal performance, forage intake and digestion, and nitrogen metabolism

“…Detailed information on Marandu palisadegrass establishment and lime and fertilizer applications are described by Homem et al. (2021).…”

“…); for details on climate and soil, see Homem et al. (2021). Average air temperature and annual rainfall during experimental period were 21.0°C and 1,191 mm, respectively (Figure 1).…”

“…Detailed information on forage peanut establishment and management were described by Homem et al. (2021). Grazing management targets were imposed in March 2016, under continuous stocking.…”

“…Herbage mass was sampled at ground level every 30 days and botanical composition was measured in the samples of GRASS + LEGUME pastures as reported earlier (Homem et al., 2021). From December 2016 to January 2019, the proportion of grass and legume biomass was obtained for each of canopy layers (Homem et al., 2021).…”

“…Herbage mass was sampled at ground level every 30 days and botanical composition was measured in the samples of GRASS + LEGUME pastures as reported earlier (Homem et al., 2021). From December 2016 to January 2019, the proportion of grass and legume biomass was obtained for each of canopy layers (Homem et al., 2021). Herbage allowance was calculated as average herbage mass for a season divided by the average total weight of animals that grazed during the season (Sollenberger et al., 2005).…”