Diferimento de pastagem com Urochloa brizantha cv. Marandu em sistema silvipastoril

Abstract

The objective of this study was to evaluate the agronomic, structural, chemical and mineral characteristics of Urochloa brizantha cv. Marandu using four periods of deferral (60, 90, 120 and 150 days), under three types of systems: full sun (FS) and silvopastoral (SPS) in two structural arrangements, 12m x 2m (SPS12) and 18m x 2m (SPS12 ) among the rows of Eucalyptus urophylla trees. The experimental design adopted was completely randomized (CR) in a factorial arrangement (3 x 4), with 3 repetitions each. There was no interaction effect between the factors (P> 0.05). There was an effect of deferral (P <0.05) for tiller population density (TPD), leaf dry mass (LDM), dry mass of dead material (DMDM), dry stem mass (DSM), leaf / stem ratio (L / S), total dry mass (TDM), green dry mass (GDM), Plant height. TPD and F / C had a decreasing effect with the increase in deferral. Already MSF, MSC, plant height and MSV increased as the deferment progressed, followed by a decrease. The maximum production of LDM occurred at approximately 88 days of sealing reaching 0.63 Mg ha 1; for DSM it occurred at 105 days with 0.45 Mg ha-1; GDM reached 94 days at 1.11 Mg ha-1 and the highest plant height (90 cm) occurred around 114 days of deferral. DMDM and TDM increased with the increase in deferral.The CP content decreased linearly with the advance in the deferral period, but up to 75 days it met the suggested demand for ruminants. Conversely, the concentration of NDF and ADF increased with the increase in sealing. The levels of P and K decreased with increasing deferral, but were able to supply the reference values for cattle, P throughout the period and K only up to 80 days. The concentration of Mg and Ca did not differ under deferral, but in relation to the evaluated systems there was a difference only for Mg, which was higher in PS and SPS12, differing from SPS18. The SPS with 12 and 18m between the rows of trees can be adopted because it does not give negative effects to the forage. To reconcile production, good morphological composition and nutritional value, pasture can remain deferred from 75 to 94 days from March using marandu grass in an SSP in the cerrado region of Tocantins.