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Influence of nitrogen rate on winter canola production in the southeastern United States

Yaru Lin, Dexter B. Watts, H. Allen Torbert, Julie A. Howe
Agronomy 2020 v.112 no.4 pp. 2978-2987
Brassica napus var. napus, biomass production, canola, double cropping, fertilizer rates, humid subtropical climates, loamy sand soils, nitrogen fertilizers, nutrient uptake, plant growth, plant height, sandy loam soils, seed yield, soil fertility, soil-plant interactions, winter, Alabama
Canola (Brassica napins L.) has the potential for being used in a double‐cropping system (two crops grown in 1 yr) as a winter crop in the humid subtropical southeastern U.S. climate, but little information is known about its nitrogen (N) management when grown in this region. Thus, a field study was conducted at two locations (Shorter, AL: Compass loamy sand; Prattville, AL: Lucedale fine sandy loam) in 2016 to determine the effect of different rates of N fertilizer on plant growth, seed yield, and N uptake of canola. The experimental design was a randomized complete block with four replications. The N rates included were 0, 68, 135, 180, 202, and 270 kg N ha⁻¹. Linear‐plateau regression was used to evaluate the response of plant growth, seed yield, and N uptake to N rate. Overall, canola growth, yield, and N uptake were highly dependent on N fertility. Applying 180 kg N ha⁻¹ or more for canola production significantly increased plant height, plant biomass accumulation, seed yield, and N uptake compared with the unfertilized control at both locations. The linear‐plateau regression model indicated that the optimal N rate was 197–232 kg N ha⁻¹ for these southeastern U.S. soils. This study suggests that winter canola grown in a humid subtropical region of the United States can be a successful winter crop for a double‐crop production system and provide seed yields comparable to yields from major winter canola production areas.