Composição botânica, estrutura e produção do campo nativo em resposta a diferentes estratégias de manejo em sistema de pastoreio intermitente

Abstract

The experiment was conducted at Sítio Flor da Costa, located at Cerrito, Rio Grande do Sul (RS) – Brazil (31º 51' 23" S and 52º 48' 46" W, 50m of height), an area of native grassland, in the period of 01/10/2017 to 01/05/2019. The aim of the work was evaluate the effect of different intensity and frequency of defoliation in the botanical composition and in the productivity of native forage in intermittent grazing system. Two factors were tested during two years of evaluations with randomized block design: intensity of grazing (two levels: I - residue low or reduction of 75% of the grazed stratum; II - high residue or reduction of 50% of the grazed stratum); and Frequency of grazing (three levels: periods between grazing that were necessary for complete expansion of (i) 2 leaves of Paspalum notatum, (ii) 3 leaves, and (iii) 4 leaves). In each year of evaluation were two repetitions of area, Therefore, through the block design, there was 4 blocks per treatment (2 blocks in the first year + 2 blocks in the second year). The imposition of different management strategies, in an intermittent grazing system, during 5 months in spring and summer, resulted in similar production of native forage, however, the management strategies altered the botanical composition, the structure of the species that make up the forage mass. Periods between grazing necessary for the complete expansion of 2 and 3 leaves of Paspalum notatum, as well as the imposition of the lowest residue, were more favorable under the forage aspect, mainly, due to the higher production of high quality native forages such as Paspalum notatum and Desmodium incanum.