Effect of sowing rate, grass competition and cutting frequency on persistence and productivity of two lucerne (Medicago sativa) cultivars at Biloela, Queensland

Abstract

Persistence and production of lucerne (Medicago sativa) cvv. Hunter River and Siro Peruvian were studied on alluvial soil under raingrown conditions in a factorial experiment examining effects of lucerne sowing rates (1.1 and 4.4 kg ha-1), competition from buffel grass (Cenchrus ciliaris cv. Biloela) and 3,6 and 9-weekly cutting frequencies. Lucerne populations at establishment from 1.1 and 4.4 kg ha-1seed averaged 18 and 60 plants m-2, which reduced to 4 and 7 plants m-2 respectively after three years. Population initially declined rapidly at the higher sowing rate and the presence of buffel grass accentuated this decline. Persistence of Siro Peruvian was inferior to that of Hunter River. Cutting frequency did not affect lucerne persistence. Sowing pure lucerne and cutting every six weeks produced highest lucerne yield, but total yield was greatest from the lucerne/buffel grass mixture cut either 6- or 9-weekly. Increasing lucerne sowing rate increased lucerne yield only slightly and lucerne cultivar had no effect on total lucerne yield.