Determining Aluminum Tolerance and Critical Soil Ph For Winter Canola in the Southern Great Plains

Abstract

A growing interest in winter canola (Brassica napus L.) across the southern Great Plains has brought about many issues regarding production. One of the issues to be addressed is winter canola's tolerance of aluminum when growing on acid soils. The objectives of this study were to determine the maximum aluminum concentration and minimum pH for canola production. To evaluate this, a field experiment was conducted in north-central Oklahoma comparing 8 different winter canola cultivars over a natural occurring pH gradient (ranging from approximately 4-6.5). Yield will be measured in June of 2007 and 2008 and post harvest soil samples will be taken to determine the current year's aluminum concentration and pH. In the laboratory experiment 9 winter canola cultivars were selected and grown in Al concentrations of 0, 20, 40, 60, and 80 mg Al kg^-1. Canola grain yield decreased linearly below a soil pH of 5.8, which corresponded to a KCl exchangeable Al concentration of 15 and 11 mg Al kg^-1 for 2007 and 2008, respectively. Differences between cultivars were seen in the laboratory experiment with KS 3074 and DKW 13-69 showing less sensitivity to Al concentrations. Consideration will have to be given to the effects of soil acidity in order to optimize winter canola grain yield in the southern Great Plains