Brassica carinata biomass, yield, and seed chemical composition response to nitrogen rates and timing on southern Coastal Plain soils in the United States

Abstract

Brassica carinata (carinata), a non‐food oilseed feedstock mainly used for biofuel, is a relatively new alternative winter crop in the southeastern (SE) United States (US). However, there are limited N rate and N application timing data available at the regional scale. These data are needed to expand production in the SE US. An N rate study was conducted during the winter–spring growing seasons during 2017–2018 and 2018–2019 in Florida, US, and at three locations during 2018–2019 in Georgia, US, to quantify the effects of N rate (0, 45, 90, 134, and 179 kg N ha−1) on carinata nutrient uptake, biomass, seed yield, and seed chemical composition. Seed yield showed a linear response up to 134 kg N ha−1. Seed protein and glucosinolate concentrations decreased from 0 to 90 kg N ha−1, then increased from 90 to 179 kg N ha−1. Seed oil concentration was inversely related to seed protein concentration. A two‐factor N application timing study (4 N application timing: at‐plant, pre‐bolting, at‐plant + pre‐bolting, at‐plant + pre‐bolting + bolting × 4 N rates: 0, 45, 90, and 134 kg N ha−1) was conducted in Georgia, US, over three site‐years to quantify the effect of N application timing on yield and agronomic and economic optimum N rates (AONR and EONR, respectively). All split applications increased AONR by at least 10 kg N ha−1 compared to a single at‐plant application. A two‐split N application was more profitable than either a single N application or a three‐split N application based on marginal return. A two‐way split application (at‐plant + pre‐bolting) at 134 kg N ha−1 is recommended to optimize yield and economical production. Based on uncertainty analyses, the 50% credible interval of EONR occurred between 116 and 152 kg N ha−1, with a median estimate at 130 kg N ha−1.

Life Cycle Greenhouse Gas Emissions of Biodiesel and Renewable Diesel Production in the United States

“…In northern states, carinata is typically planted as a scavenger crop to recover excessive nitrogen content. On the other hand, recent field experiments , in the southeast U.S. suggest that the fertilizer rate could be much higher if the objective maximizes biomass yield. Using recommended fertilizer rates from trials conducted in the southeast U.S. would double carinata feedstock production GHG emissions.…”

“…On the other hand, recent field experiments , in the southeast U.S. suggest that the fertilizer rate could be much higher if the objective maximizes biomass yield. Using recommended fertilizer rates from trials conducted in the southeast U.S. would double carinata feedstock production GHG emissions. In this case, life-cycle GHG emissions of carinata BD and RD would increase by 11 g of CO 2 e/MJ (Figure S1), but still more than 50% lower than petroleum diesel.…”

Modeling Yield, Biogenic Emissions, and Carbon Sequestration in Southeastern Cropping Systems With Winter Carinata

“…Following model calibration, seed yield data from multiple subsequent carinata field trials were used for independent model validation. Plot-scale, machine-harvested carinata yield data was collected during the 2017/2018 and 2018/2019 winter seasons under a single N fertilizer treatment at Quincy, Florida, and under a range of N application rates at the University of Florida West Florida Research and Education Center in Jay, Florida (Bashyal et al, 2021;Boote et al, 2021). Other aspects of the experimental design were consistent with the 2015/2016 Quincy experiment.…”

“…While cover-cropping generally increases SOC levels, carinata may require additional tillage operations for establishment (Iboyi et al, 2021) that could undermine this effect due to soil disturbance and SOC destabilization (Bailey et al, 2019). Similarly, economically viable carinata seed production requires the application of substantial amounts of N fertilizer during the winter (Seepaul et al, 2019a;Bashyal et al, 2021) which may increase N 2 O emissions (Crutzen et al, 2008;Roth et al, 2015).…”

Economics of Crop Rotations With and Without Carinata for Sustainable Aviation Fuel Production in the SE United States

“…The DayCent model (Parton et al, 1998) was calibrated using data on aboveground biomass, root biomass, and tissue carbon: nitrogen ratios for carinata grown at the University of Florida North Florida Research and Education Center in Quincy, Florida for one season (winter 2015-2016) at four different nitrogen (N) fertilizer application rates (Seepaul et al, 2019). The resulting model was validated against data collected during subsequent field trials at Quincy as well as the University of Florida West Florida Research and Education Center in Jay, Florida (Bashyal et al, 2021;Boote et al, 2021), and five private farms across southern Georgia collected between 2016 and 2019. In this independent validation, DayCent reproduced 34% of the observed variability in carinata seed yield across sites and years, with a normalized root mean square error of 0.26 (Field et al, 2022).…”