Spring canola (Brassica napus L. var. napus) is becoming a significant oils
eed crop adapted to the western USA. Often N and S limit crop growth, Field
experiments were established to study the effects of N and S fertilization
on seed yield, oil content, and N, P, K, and S uptake of spring canola, Fo
ur N rates in combination with three S rates were evaluated on two irrigate
d and three rainfed locations in the western triangle area of Montana near
Conrad, Seed yields ranged from 0.1 to 3.8 Mg ha(-1). Seed yield and oil co
ntent N responses were closely related to available N (fertilizer N plus so
il NO3-N in 90 cm of soil). Seed oil content varied from 370 to 510 g kg(-1
) and was depressed by increasing N, Optimum seed and oil yield occurred at
about 200 kg N ha(-1). Two of the experimental sites responded to S, About
20 kg S ha(-1) was adequate for optimum seed and oil yields. At the optima
l N and S levels, total plant N, P, K, and S uptake averaged 140, 25, 170,
and 60 kg ha(-1), respectively. Of the total N, P, K, and S accumulation, a
bout 40% of the N, 30% of the P, and 85% of the K and S remained in the pos
tharvest residue.