The response of late storage cabbage and broccoli to applications of sulphur and calcium

Abstract

Sulphur may become deficient in intensive vegetable production systems that rely on chemical fertilizers. Yield of cole crops in response to sulphur fertilization has not been evaluated under Ontario conditions. Since calcium is linked to clubroot disease and tipburn, the sulphur fertilizer source is an important consideration. Rates of sulphur and calcium were compared for effects on yield using Novacal (a prilled calcium sulphate product), calcium nitrate and potassium sulphate for 3 yr for cabbage and 2 yr for broccoli on both sand and loam soils. There appeared to be no difference in yield from fertilizer source of sulphur or calcium. Applications of sulphur increased yield of Huron late storage cabbage averaged over years and soil with a mathematical maximum occurring at 55 kg S ha-1. Soil tests indicated levels of approximately 13–19 µg g-1 for sulphur prior to treatment. Yield of cabbage increased proportionately to calcium application averaged over 3 yr. No effect of treatment was observed on broccoli. Thus, soil levels of sulphur were probably limiting for late cabbage but not for broccoli. Sulphur shortage or deficiency appears to exist for late storage cabbage grown in Ontario. Lack of response of broccoli and no calibrated soil test for either element suggest that crops have to be evaluated individually under field conditions for sulphur fertilizer requirements. Key words: Cabbage, broccoli, calcium, sulphur, nutrition, yield