The effect of nitrogen and sulphur on the agronomical and water use efficiencies of canola (Brassica napus L.) grown in selected localities of the Western Cape province, South Africa
The grain yield per unit of plant-available nitrogen (N) and sulphur (S) nutrients in the soil is usually low in most crops, including canola. Besides the ability of different crops in utilising nutrients, soil and climatic conditions can also influence uptake and use of major plant nutrients. Hence, to determine the effect of soil and climatic differences on canola agronomic efficiency response to N and S application, a factorial split-plot experiment consisting of three S (0, 15 and 30 kg S ha−1) and five N (0, 30, 60, 90 and 120 kg N ha−1) rates was conducted at selected localities (Altona, Elsenburg, Langgewens, Roodebloem and Welgevallen) in the Western Cape province during the 2009 to 2011 growing seasons. Agronomic efficiencies of N applications were improved if 15 kg S ha−1 was applied, but not with applications of 30 kg S ha−1. Sulphur use efficiency also improved when high N (120 kg N ha−1) was applied. The application of both N and S resulted in higher water use efficiencies at some localities.
Keywords: agronomic use efficiency, canola, water use efficiency