Effects of nitrogen fertiliser on canola production in north central Victoria

Abstract

Effects of nitrogen (N) fertiliser at sowing and at bud stage (terminal bud enlarged) on canola seed yield and oil and protein concentrations were studied at 6 sites in north-central Victoria during 1988-90. Rates of application (kg/ha) of nitrogen fertiliser were 0, 25, 50, and 100 at sowing, and 0, 25, 50, 100, and 200 topdressed at bud stage. Canola seed yields responded to N fertiliser applied at either sowing or bud stage, generally increasing with increased N. There was significant variation between years and sites. Maximum seed yields at any of the sites varied from 0.8 t/ha in 1990 to 2.66 t/ha at Charlton in 1989. No combination of N fertiliser treatments produced the highest yield at more than 2 sites. Percentage oil in seed generally decreased with increasing N. Oil concentrations were lowest in 1990, in response to a generally drier season, especially the spring. Maximum oil concentrations in 1988-89 ranged from 42.4 to 45.0%. Nitrogen fertiliser increased total seed protein by increasing seed yield and percentage protein in seeds. Highest seed protein was always obtained with highest application of N.