Sowing date and nitrogen supply determine the outcome of competition between dallisgrass (Paspalum dilatatum Poir.) and tall fescue (Festuca arundinacea Schreb.) in the Pampas region of Argentina

Abstract

The effects of sowing date and nitrogen (N) fertilizer on the inter-specific competition between dallisgrass (Paspalum dilatatum Poir.) and tall fescue (Festuca arundinacea Schreb.) in the humid Pampas of Argentina were investigated in two pot experiments where a constant soil moisture content was maintained. Tall fescue and dallisgrass seeds were sown either in the spring (October 2000) or in the autumn (March 2001) in mixed and mono-specific stands with 0 or 100 kg N ha )1 . In the spring, competition from tall fescue depressed drymatter (DM) yield of dallisgrass from 1AE53 to 0AE36 g DM per plant and tiller number from 9AE4 to 3AE7 tillers per plant in mixed and in mono-specific stands, respectively, while tall fescue had 3-4 times higher DM yields in mixed stands. Leaf extension rate (LER) of tall fescue was higher (1AE3 mm d )1 ) than that of dallisgrass (0AE53 mm d )1 ). In the autumn, inter-specific competition did not affect DM yield of dallisgrass and N fertilizer increased DM yield from 0AE53 to 2AE07 g DM per plant, tiller number from 6AE8 to 14AE2 tillers per plant and LER at the beginning of autumn from 1AE2 to 2AE12 mm d )1 in both species. As temperature decreased, LER was reduced in both species to 0AE31 mm d )1 by late autumn. The number of leaves per tiller was not affected by treatment. Nitrogen fertilizer increased N concentration of above-ground tissues of both species (18 g kg )1 DM in autumn and 20 g kg )1 DM in spring). It was concluded that a productive mixed pasture of dallisgrass and tall fescue can be obtained by sowing early in the autumn. The application of N fertilizer in this season is essential to ensure a high herbage yield and quality.

Forage biomass, soil cover, stability and competition in perennial grass–legume pastures with different Paspalum species

“…However, the higher tall fescue soil cover in the mixture with P. dilatatum maintained a high mixture cover, similar to that of the conventional pasture. This compatibility between P. dilatatum and tall fescue had been previously documented in the region in pot experiments (Jacobo et al ., ) suggesting that a productive mixture of P. dilatatum and tall fescue can be obtained when sowing both species together in the autumn. The lower mixture soil cover of CP + Pn can be explained by the low tall fescue cover.…”