Yield, oil and protein content of oilseed rape as affected by soil and fertilizer nitrogen and phosphorus

Abstract

The Zephyr cultivar of oilseed rape (Brassica napus) was grown on two sites at Wagga Wagga. Both sites had a wide range in levels of available phosphorus; one had a low and the other a high level of soil nitrogen. On both sites superphosphate applied prior to, and during, the current cropping phase caused significant increases in dry matter production, seed yield, oil and protein yields. Pod numbers increased significantly only on the high nitrogen site. On the high nitrogen site, seed, protein and oil yields (kg ha-1) were higher than on the low nitrogen site, even when the latter site was cropped using nitrogen fertilizer. Oil yields ranged from 237 to 1273 kg ha-1 on the high nitrogen site and from 229 to 91 6 kg ha-1 on the low nitrogen site. The rape crop responded to drilled superphosphate on sites with low to medium levels of 'available' phosphorus. Soil tests developed for wheat indicated sites with adequate soil nitrogen and phosphorus.