Nitrogen requirements of Ethiopian mustard for biofuel feedstock in South Dakota

Abstract

Ethiopian mustard (Brassica carinata A. Braun) is a non-food oilseed crop that has received attention for its potential as a low-input biofuel feedstock suitable for production in the semiarid regions of the Northern Great Plains (NGP). Because B. carinata is a new crop to the NGP, the best management practices have yet to be developed. The objective of the study was to evaluate the effects of N fertilizer rate on seed yield, seed oil concentration, and oil yield of B. carinata and to determine the economic optimum N fertilizer rates. Field studies were conducted at two locations in South Dakota to evaluate the response of two B. carinata varieties to five N fertilizer rates (0, 28, 56, 84, and 140 kg N ha–1) during the 2015 and 2016 growing seasons. Increasing N fertilizer rate increased seed yield and oil yield, each reaching a peak at 84 kg ha–1 N and then slowly decreasing following a quadratic model. On the other hand, increasing N rate linearly decreased seed oil concentration. The economic optimum N rate ranged from 60 to 81 kg N ha–1 depending on cost of N fertilizer and the price of carinata seed. These results show that the N requirement for B. carinata is lower than that for many crops grown in the NGP, including corn and small grains. These findings confirm that B. carinata requires low N fertility and has the potential for incorporation into cropping systems in the semiarid regions of the NGP.