Effects of Manure and Fertilizer Applications on Canola Oil Content and Fatty Acid Composition

Increasing fertilizer costs have resulted in more growers evaluating the use of alternative nutrient sources such as manure. Coin- cidentally, the questions about fertilizer eff ects on oil yield and oil fatty acid composition have been a concern. A 2-yr study was conducted to investigate nutrient source (fertilizer urea plus S and manure) and N level (0, 84, and 168 kg N ha -1 ) eff ects on canola seed yield, total oil content, and oil composition at East Lansing and Chatham, MI. Results indicated nutrient applica- tions were not necessary to increase canola yield (865-1991 kg ha -1 ) in fertile fi elds. However, N fertilizer appeared to reduce total oil content (444−536 mL kg -1 ), and at similar N levels, total oil content in canola with fertilizer was sometimes lower than that with manure application. Compared with the no nutrient control treatment, fertilizer application sometimes decreased lin- olenic acid (LN) content, and increased palmitic acid (P) and arachidic acid (A) at Chatham, while it appeared to decrease oleic acid (O) and increase P, linoleic (L) and A at East Lansing. Fertilizer applications oft en increased canola total saturated fatty acid content (6.80-8.32%) and decreased ratio of O/(L+LN) (2.04-2.52). Manure application had milder eff ects on oil composition than fertilizer application. Compared with less N (84 kg N ha -1 ) applications, greater N level (168 kg N ha -1 ) tended to lower oil quality by increasing total saturated fatty acid content and decreasing the O/(L+LN) ratio.