Browsing by Subject "double cropping"

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    Winter Camelina Response to Nitrogen for Double Cropping with Maize and Soybean in the Upper Midwest
    (2021-09) Gregg, Stephen
    Winter camelina [Camelina sativa (L.) Crantz] is a potential third crop that could be used to intensify maize [Zea mays L.]-soybean [Glycine max (L.) Merr.] rotations. It is considered a low-input crop, but previous studies have shown that it responds to added N. Yet, no formal fertilization studies have been conducted to determine optimum N levels for conditions in the upper Midwest. A study on camelina response to fertilizer N was conducted from fall 2018 to fall 2020 at three locations in Minnesota. The objectives were to: (i) determine the response of winter camelina to N and (ii) assess the effects of N fertilization strategy (fall-spring split or spring only application) on the productivity and quality of winter camelina. Data collected included grain yield, biomass, grain quality, and yield components. Grain yield and biomass were both affected by N in all locations and years, and both were higher in 2019 compared to 2020; among N rates, grain yield was significantly different, while no differences were found for biomass. Both, oil and protein content in grain were affected by N, with oil content generally declining with N rates increasing beyond 67 or 100 kg N ha-1, depending on location and year. Among yield components, branches and silicles per plant were significantly different among N rates; the former, along with the seed:shell ratio were significantly different in all years and locations. Based on the results of this study, a fertilization rate of 97 kg N ha-1 was found to maximize grain and oil yield of winter camelina in southwest Minnesota. Maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] in the upper Midwest are productive, but decades of these monocultures with winter fallow and late spring planting are in part responsible for loss in agroecological functioning as well as nitrogen (N) pollution in the agricultural communities and downstream. Winter camelina [Camelina sativa (L.) Crantz] is a third crop that could grow during this fallow period, but the environmental impacts of its N requirements are not well known. A study was conducted at three locations in Minnesota to determine the response of winter camelina do N. Five N rates (0, 33, 67, 100, 135 kg N ha-1) and two application timings (spring, and fall-spring split) were used to assess the N use efficiency (NUE) and residual N in winter camelina grown for grain yield from fall 2018 to fall 2020. Results showed higher NUE for fall-spring split application compared to spring only application. The agronomic efficiency (AE), internal efficiency (IE), and nitrogen recovery efficiency (NRE) tended to decrease with increasing N rates; AE generally decreased beyond 67 kg N ha-1 in most instances. Total N uptake ranged from 34 to 176 kg ha-1 across N rates. Residual soil N increased with increasing N rates, especially at the 15 cm depth. Based on declining NUE and increasing residual soil N with increasing N rates, an N rate between 33 to 67 kg N ha-1 could balance an efficient use of fertilizer with less environmental risk of higher N rates. Double cropping with winter camelina is a diversification option for the typical maize-soybean rotation in the upper Midwest, a strategy that promises environmental and economic benefits. Studies on double-cropping maize and soybean with non-fertilized- (Study 1) and nitrogen (N)-fertilized (Study 2) winter camelina were compared to assess the growth and yield, N, water use (WU), and water productivity (WP) of winter camelina in two locations in Minnesota. Study 1 was conducted from 2015–2017 in one location and the Study 2 was conducted from 2018–2020 in two locations, both studies in Minnesota. Yield of winter camelina was as much as six times higher in Study 2 compared to Study 1; averaged across treatments, Study 2 yielded 1157 kg ha-1 compared to 556 kg ha-1 from Study 2. In Study 1, oil and protein content ranged from 26.4 to 27.2% and 19.4 to 27.1% respectively. In Study 2, oil and protein content ranged from 31.7 to 35.9% and 14.9 to 20.8% respectively. Water use tended to follow similar trends between studies. Winter camelina average WU across cropping systems was similar between Study 1 and Study 2 (165 compared to 168 mm). Camelina WP was higher in Study 2 compared to Study 1, and ranged from 0.60 to 0.84 and 0.20 to 0.42 respectively. Fertilizer N was generally found to increase biomass, yield, WU, WP, and residual soil N in winter camelina double cropped with maize and soybean.