Monday, November 13, 2006

Sowing Method and Crop Residue Effects on Overseeded Annual Ryegrass.

Paul Bartholomew and Robert Williams. USDA-ARS, Langston Univ, P O Box 1730, Langston, OK 73050

Overseeding of annual ryegrass (Lolium multiflorum Lam.) can provide valuable cool-season forage in the southern Great Plains. However, time and equipment constraints for ground preparation and sowing may limit the capacity of small and resource-limited livestock producers to take advantage of the potential of this crop. Experiments were undertaken to evaluate reduced-input overseeding of annual ryegrass into mixed native warm-season pasture. Annual ryegrass (cv Marshall) was sown by no-till drill, or broadcast, in fall of 2004 and 2005 into dormant or nearly-dormant warm-season pasture trimmed to stubble heights of 7 or 22 cm, with standing residue biomass (SRB) of 1000 or 2400 kg ha-1, or into a 22cm stubble thinned to an SRB of 1800 kg ha-1. In two years of experiments the number of established seedlings was reduced by broadcasting rather than drilling seed, however, tiller populations in mid-March or early April were not significantly different between sowing methods. On average, increased pasture residue did not have a significant effect on seedling establishment or tiller number. However, there was a significant interaction between sowing method and residue amount that was expressed in a reduced plant establishment on broadcast treatments sown on 7 cm stubble and on drilled treatments sown on 22 cm stubble. Forage yield of ryegrass was least when drilled into closely trimmed warm-season pasture. The amount of warm-season pasture residue had a marked impact on the temperature environment over winter around establishing seedlings, and in both years, diurnal temperature range and the incidence of below-freezing temperature at the soil surface were decreased with greater amounts of SRB. Annual ryegrass can be successfully oversown by broadcasting on dormant mixed native pasture without a need for close-trimming of residues prior to planting.