Resumen

URBANO, Diannelis; CASTRO, Fernando  y  DAVILA, Ciro. Grazing pressure and NPK fertilization effects on botanical composition of kikuyu grass - perennial peanut association in highlands of Mérida state. Zootecnia Trop. [online]. 2005, vol.23, n.4, pp.333-344. ISSN 0798-7269.

To obtain the best combination of the grazing pressure and fertilization with nitrogen, phosphorus, and potassium that allow a good balance in the species kikuyu grass-perennial peanut association, a field grazing experiment was conducted in Jají, Mérida state, Venezuela. A complete randomized block design was used, with three replications. The treatments were a factorial in a split plot arrangement. Two grazing pressures were applied to main plots (HGP: 800 and LGP: 1600 kg residual DM/ha) and two levels of nitrogen (0 and 200 kg N/ha), three of phosphorus (0, 150, and 300 kg P₂O₅), and two of potassium (0 and 200 kg K₂O/ha) were applied to sub-plots. Botanical composition was estimated at the beginning and the end of the trial. Percent of kikuyu grass in the mixture decreased 11%, while perennial peanut increased in 9%. Also, dead material and the grass Cynodon sp decreased 3 and 0.79%, respectively. The grazing pressure factor and its interactions were not significant, but the tendency for the components of the association was that kikuyu grass decreased 13.1% in the LGP and 8.1% in HGP, but perennial peanut increased in both systems 12.8% and 6.1%, respectively. Nitrogen application and N x K interaction were significant (P<0.05) in the percent of kikuyu grass in the mixture, but in the legume component, the macro elements NPK did not affect its proportions, but the N x K interaction was significant (P<0.05). N application increased kikuyu grass, from 27.8 to 36.2%, broad leaf weeds decreased from 7.3 to 2.9% (P<0.05), but perennial peanut decrease from 45.6 to 43.5%. The kikuyu grass- perennial peanut association, in the tested conditions, had a high proportion of legume on offer that may be controlled with N fertilization.

Palabras clave : Pennisetum clandestinum; Arachis pintoi; botanical composition; grazing pressure; NPK fertilization.