Responses of soil surface greenhouse gas emissions to nitrogen and sulfur fertilizer rates to Brassica carinata grown as a bio-jet fuel

Abstract

Carinata (Brassica carinata A. Braun), a non-food oilseed crop and an alternative bio-jet fuel feedstock, has received attention for its potential as a low-input option for production in the semi-arid region of the Northern Great Plains of the United States. Research addressing the impacts of nitrogen (N) and sulfur (S) fertilizers on soils and greenhouse gas (GHG; CO2, N2O, and CH4) emissions from carinata production are limited. Thus, objective of this study was to evaluate the impact of different rates of N and S fertilizers applied to carinata on soil properties and GHG emissions. Field experiments were conducted in 2017 and 2018 to assess the response of carinata to four N (56, 84, 112, and 140 kg N ha−1) and three S (0, 22, and 45 kg S ha−1) rates. Soil samples were collected at crop harvest to measure soil properties; however, soil surface GHG fluxes were measured during 2017 and 2018 growing seasons using static chamber method. Data showed that application of N fertilizer increased soil EC, soil organic carbon (SOC), stable C, and labile N. However, sulfur fertilizer decreased SOC, labile N, and soil inorganic N contents. Results from GHG fluxes showed that higher rates of N fertilizer application increased the soil CO2 and N2O emissions, whereas the S fertilizer did not impact these fluxes. This study concludes that S and N fertilizers application to carinata crop affected soil properties, and higher rates of N fertilizer increased the GHG emissions. Therefore, N fertilizer application rate needs to be optimized to mitigate GHG emission for carinata production.