Date of Award
Master of Science
Plant and Soil Science
TITLE: Canola Production as Influenced by Previous Crop and Tillage System MAJOR PROFESSORS: Dr. Michael Schmidt and Dr. Brian Klubek This study was conducted to compare the profitability of winter canola versus winter wheat following corn and soybean under a reduced till and no till regime. Yield of double crop soybean production behind canola vs. wheat was also studied. The experiment was designed as a complete factorial with a split-split-split plot arrangement using 4 replications. Corn/soybean served as the main effect. Tillage was the sub-plot, and winter canola/wheat served as the sub-sub-plot. Two varieties each of canola and wheat were tested as sub-sub-sub plot. Fall stand, seed yield, and double crop soybean yield were measured for all plots. Interactions between either pair of canola or wheat varieties with previous crop or tillage system were not detected either season. Canola produced a higher yield after a previous crop of corn than after a previous crop of soybean in 2005-2006. In 2007-2008, the yield of canola after soybean was higher however this difference was not significant. No influence of previous crop on wheat yield was detected either season. The influence of tillage on canola and wheat yield was inconsistent across seasons. Canola produced a higher yield under reduced till in 2007-2008, but not in 2005-2006. In 2005-2006, wheat produced a higher yield under no-till and a higher yield under reduced till in 2007-2008. In 2007-2008, a significant interaction between previous crop and tillage system was detected for both canola and wheat. Canola yield was significantly reduced by no-till after corn but not so by no-till after soybean. Wheat yield was significantly lower following corn no-till than following soybean no-till, however, there was no difference in wheat yield following corn or soybean under reduced till. The yield of double crop soybean did not differ following winter canola or winter wheat either season, however in 2005-2006, yield was higher following corn after either canola or wheat. The double crop soybean yield was 1,421 hg/ha in 2005-2006 and was 3,161 kg/ha in 2007-2008. The results herein indicate that canola and wheat can be profitably grown behind either corn or soybean and under either a reduced till or a no-till system. However, these results are inconclusive as to which combination of previous crop or tillage system should be recommended for either winter crop. It does appear that there is a greater concern establishing a canola stand under a no-till system. Canola provided greater gross revenue over that of wheat both seasons, even after considering the additional canola seed and nitrogen costs. When combined across seasons, canola had a mean yield of 3,838 kg/ha and a mean revenue of $1,236/ha. Wheat had a mean yield of 5,511kg/ha and a mean revenue of $939/ha. The seed and nitrogen cost differential was computed at $70. Thus, the canola crop provided revenue that was 25% higher per hectare than the wheat crop.
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