Enhanced efficiency nitrogen fertilizer effect on camelina production under conventional and conservation tillage practices

Camelina (Camelina sativa) is a promising biofuel feedstock to fill the fallow period in dryland wheat (Triticum aestivum) −fallow cropping system of the U.S Northern Great Plains (NGP). Responses of camelina to tillage system (conventional tillage [CT] and no-till [NT]), nitrogen (N) rate (0, 45, 90 kg ha−1), and nitrogen source (urea and an enhanced efficiency nitrogen fertilizer [EENF] containing urease and nitrification inhibitors) were evaluated in a 2-yr (2013-2014) field experiment in a dryland farming system of central Montana. Grain yield, biomass, oil content, and oil yield of camelina displayed significant first-order effects of tillage, N rate, and N source when averaged across each of the other factors, but interaction effects were not significant. Camelina tended to yield greater in CT than NT by about 26%. Application of EENF significantly increased grain yield when compared with U, which was more pronounced under CT. Dose response of camelina grain yield, biomass, and grain protein to N rate in the range of 0 to 90 kg ha−1 was linear, whereas N fertilization showed a detrimental effect on oil accumulation in seeds. Although oil content declined in response to N application, oil yield (kg ha−1), which is the most important criterionin seedoil derived biofeedstock, positively responded to N application. Our results clearly demonstrated the need for further research to optimize management strategies for successful camelina production under NT system. Our results also indicated the potential of EENF in enhancing the yield of camelina, especially under CT system. Irrespective of tillage system and source of N, application of 90 kg N ha−1 (minus soil mineral N) led to the highest yield of camelina in this environment, but yield gain in response to N application greater than 45 kg ha−1 was very small.