The canola plant has a relatively high demand for sulfur (Franzen, 1997). Since fertilizer applications frequently lack this element, deficiencies in the field are not uncommon. This experiment was conducted on a low-S soil to evaluate the response of canola (Hyola 401) to 20 and 40 pounds S/acre in combination with 120 or 220 pounds total soil N/acre. Fertilizer formulations of S were also compared.

The application of 20 pounds S significantly increased test weight and yield, but no additional response was observed at the 40-pound rate (Table 1). Increasing the

N rate from 120 to 220 pounds/acre extended the bloom duration and days to physiological maturity, but did not influence yield or grain quality (Table 2). Neither S nor N significantly affected days to beginning bloom, height, or lodging (data not shown).

Applying S in a readily available form (ammonium sulfate) consistently improved yield compared to the control (Table 2). Commercial S fertilizers varied in effectiveness, with Kmag equal to ammonium sulfate, Tiger 90 less effective, and Sulfur 95 intermediate. Less soluble, elemental sulfur products (e.g. Tiger 90 and Sulfur 95) are useful for longer-term treatment. However, the response during the first season after application will likely be less than from formulations containing sulfur in a more readily available form for plant uptake.

The application of 20 pounds S/acre in a readily available form is recommended for canola fields where an S deficiency is anticipated.

Table 1. Mean responses of canola to sulfur (S) and nitrogen (N) treatments, 1998.