Assessing and improving sustainability of Camelina sativa through rhizobacterial inoculants and soil enzymatic activity

Abstract

Camelina sativa is an oilseed crop with potential to be used in biofuel production as an alternative to contemporary fossil fuels. To ensure biofuels are a more sustainable alternative , considerations and improvements must be made regarding the inputs and land-use needs of producing biofuel feedstocks. This research assessed the beneficial effects of inoculating C. sativa plant growth-promoting rhizobacteria candidates in greenhouse trials. Additionally, we explored agronomic responses of C. sativa and bulk soil enzymes in field trials across Montana to nitrogen and sulfur fertilizer treatments applied as pelleted urea and gypsum respectively. Co- inoculations of Pseudomonas putida ATCC 12633 and Bacillus thuringiensis ATCC 33679 were associated with seed yield increases of 60% relative to the uninoculated control. Co-inoculations of Pseudomonas brassicacearum 36D4 and B. thuringiensis ATCC 33679 were associated with significantly shortened root lengths of early seedlings but did not reduce total biomass. Field trials found a strong seed yield response to nitrogen treatments, with yields increasing with each treatment up to 168 kg N/ha. No significant yield response to sulfur treatments was observed. Additionally, fertilizer treatments did not have any significant effects on the activities of arylsulfatase, beta-glucosaminidase, beta-glucosidase, or urease in soils sampled at crop flowering. Rhizobacterial inoculants have potential to improve crop yields without additional inputs and should be tested on C. sativa in field settings. Urea applications can be used to improve C. sativa yields without any short term effects on soil enzymatic activity, but longer-term studies are needed to accurately determine the effects of the crop and its inputs on soil properties.