THE EFFECT OF SULPHUR ON MANGANESE AND COPPER NUTRITION OF CANOLA

Abstract

A growth chamber experiment was conducted to assess the Mn and Cu nutrition of canola (Brassica napus L. 'Westar') and whether S nutrition has an impact on the Mn and Cu nutrition of this crop. Three rates of Mn (0, 25, and 50 mg kg−1), three of Cu (0, 5, and 10 mg kg−1) and three rates of S (10, 20, and 30 mg kg−1) were applied in all combinations to canola grown on an organic soil. High Mn:Cu ratios (> 15) led to Cu deficiency, which, at 10 and 20 mg S kg−1, was alleviated by Cu additions. The Mn-induced Cu deficiency was self-corrected at the 30 mg S kg−1 application rate. This was attributed to the alleviation of a Cu × Mo antagonistic effect through addition of S. Key words: Canola, available soil Mn and Cu, Mn × Cu × S interaction, S × Mo interaction, Cu × Mo interaction