Xaraés palisadegrass remains productive after the disappearance of stylo in tropical legume-grass pasture

Rodrigo Carvalho Menezes,Eveline Bueno Alves,Thiago Fernandes Bernardes,Antônio Ricardo Evangelista,Daniel Rume Casagrande,Márcio André Stefanelli Lara

doi:10.1590/0103-9016-2015-0039

Rodrigo Carvalho Menezes, Eveline Bueno Alves + Show 4 more

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https://doi.org/10.1590/0103-9016-2015-0039

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Journal: Scientia Agricola	Publication Date: Dec 1, 2015
Citations: 4	License type: cc-by

Affiliation: Universidade Federal de Lavras

Abstract

Gradual reduction of legumes in mixed tropical pastures requires periodic oversowing. Exploiting the carrying capacity of grass for an extra year after the disappearance of legumes can be economically advantageous to the farmer. This study aimed to evaluate the productivity of Xaraes palisadegrass (Brachiaria brizantha) pastures in response to its historical association with stylo (Stylosanthes guianensis) under two canopy heights to determine whether different grazing management conditions affect the defoliation pattern left by grazing animals. The split-plot experimental design was used, with the historical botanical composition (HBC) (24, 34, 45 and 52 % legume composition) corresponding to the main plots and the canopy frequency of defoliation determined at heights of 30 and 45 cm for Xaraes palisadegrass corresponding to the subplots with two replicates (500 m2) grazed by Tabapua cows. Pastures with over 34 % stylo in the botanical composition remained productive for one year after legume disappearance, accumulating more than 8 mg ha−1 of forage per year. Xaraes palisadegrass pastures at a height of 30 cm provided better canopy structure, with 64 % less stem production and 43 % less dead material. The 30-cm pre-grazing canopy height provided a grazing environment conducive to forage intake by animals that resulted in efficient use of the pasture. In response to the improved canopy structure, the cows grazed an average of 60 fewer minutes. A HBC greater than 34 % of legumes in the pastures allows for the postponement of legume oversowing until the next growing season.

Highlights

Using legumes mixed with grasses allows the nitrogen fertilizers to be replaced by biological nitrogen fixation (Ledgard and Steele, 1992)
This study aimed to evaluate the productivity of Xaraés palisadegrass (Brachiaria brizantha) pastures in response to its historical association with stylo (Stylosanthes guianensis) under two canopy heights to determine whether different grazing management conditions affect the defoliation pattern left by grazing animals
The forage accumulation rate (FAR) was higher in the canopies of HBC34, HBC45 and HBC52 during the third study period

Summary

Introduction

Using legumes mixed with grasses allows the nitrogen fertilizers to be replaced by biological nitrogen fixation (Ledgard and Steele, 1992). The greatest obstacle to adopting this technique is the complex management of mixed pastures (Lascano, 2000) due to difficulties in the establishment, productivity and persistence of legumes (Nyfeler et al, 2009), especially in warm regions (Muir et al, 2014). The persistence of legumes is related to grazing tolerance and natural reseeding capacity (Hodgson, 1990). The Mineirão stylo (Stylosanthes guianensis) is considered a perennial legume and can be associated with grasses, but when this legume is subjected to frequent and intense grazing, the population density reduces dramatically within three to four years due to low seed production capacity, lowering the potential plant propagation and, its maintenance (Paciullo et al, 2014). The use of nutrients derived from the decomposition of legume residues (i.e., litter, roots and nodules) can ensure pasture productivity for an extra rainy season

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