After collating data and crunching numbers from last season’s crop production research, its time again for land preparation, seed weighing, and a myriad of activities related to planting as we enter the second quarter of year 3. Some of our northern sites already have site relevant studies in the ground. Among several focus areas in this growing season, one particular area is to tailor best management practices to different locations within the SE, especially with respect to optimum planting dates. Our modelers and on-the-ground data gatherers continue to brainstorm most relevant scenarios to model from the perspective of applicability for multiple SPARC stakeholders. The Freight and Transportation Optimization Tool (FTOT) originally developed by US DOTs Volpe is now being optimized for carinata production and logistics. The tool helps identify, optimum routes depending on existing infrastructure and subsequently, sites for future infrastructure development depending on production hubs and end user destinations. All these capabilities within SPARC allows us to furnish relevant information to decision makers as we move along on our mission to commercialize carinata. During this process, the importance of data users (modelers) fully understanding the method of data gathering cannot be overemphasized. So let’s keep at it and produce outstanding science to elevate (our knowledge), extend, and educate.

This summer, I took part in an 8-week internship with the ARA fuels team in conjunction with the SPARC project. I performed various tasks, both directly, and indirectly, advancing the progress of the SPARC project. This work included operation of the Hydrothermal Cleanup (HCU) and Catalytic Hydrothermolysis (CH) units, continued exploration and integration of SPARC coproducts, development of process flow diagrams, and research into brown grease suppliers.

A direct contribution made to the SPARC project was research into viable coproducts. Last summer, I was assigned the task of identifying the most viable coproducts by analyzing many different factors such as market demand, price, and profitability. The coproducts found to be most profitable were Erucic acid (a 22-carbon unsaturated fatty acid) and its derivatives.

Continuing this research, my work on coproduct development this summer was focused on actual production of C22 coproducts using ARA’s processes. A valuable erucic acid derivative is behenyl alcohol (a saturated 22-carbon alcohol), and we predict the most efficient way to produce it is from fatty acid methyl esters. I was tasked with identifying the most favorable conditions and catalyst for producing fatty alcohols from FAME. This research is related to the goal of producing FAME from carinata, then distilling the product to obtain the 22-carbon FAME, which is the precursor for behenyl alcohol. I also prepared samples of n-Docosane (C22 renewable paraffin wax) which was produced from carinata oil.

Another of my responsibilities during this internship was to identify where most brown grease is being collected and treated, then to contact these facilities to inquire about obtaining samples or consistent supply. I found that most wastewater treatments no longer accept brown grease. Instead, most brown grease is collected and processed by independent environmental companies. Once these companies were identified, I began conversations about their potential of becoming brown grease suppliers for ARA’s renewable fuels.

Weeds are the main cause of yield loss only second to drought worldwide, so they represent one of the most critical challenges for developing a new crop. It is for this reason that the efforts of the Southeast Partnership for Advanced Renewables from Carinata (SPARC) to make Brassica carinata a sustainable feedstock include identifying existing and developing new weed control tools.

Most weed control tools, especially herbicides, are developed for crops with large acreage such as corn, soybean, and cotton. Therefore, specialty and new crops depend on the existing control options that have been commercialized for conventional crops. During the last three years, SPARC has been screening the safety of multiple herbicides used in major conventional crops and some vegetable crops on B. carinata to identify those that can provide acceptable weed control without reducing yield due to herbicide injury. This has proven challenging because, as other crops from the Brassicaceae family, B. carinata is very sensitive to many herbicides. Thus, most herbicides that at the label rate provide acceptable weed control, also could cause yield reductions or even plant mortality in B. carinata. It is important to highlight that this situation is a similar to other crops such as canola/oilseed rape, radish, broccoli, cabbage, etc. The good news is that SPARC has identified several herbicides that are commercially available that can be used to provide effective weed control of many winter weeds without negatively affecting B. carinata growth and production. Those herbicides include pendimethalin and S-metolachlor for preemergence weed control and clopyralid and fluazifop-P-butyl for postemergence control of broadleaved and grass weeds, respectively. Although this is a small number of herbicides, they are a basic set of tools that when complemented with adequate cultural practices (planting and fertilization strategies) allow the implementation of effective integrated management strategies.

Research is currently underway to identify other herbicides that can be safely used in B. carinata. Promising preliminary results suggest that there are potential herbicides with other mechanisms of action that could be used to increase the spectrum of weed control in this crop (Fig. 1).

Fig. 1. Herbicide tolerance experiments in Salisbury, NC. The yellow frame indicates areas treated with herbicides that were lethal to Brassica carinata. Plants outside the yellow frame were tolerant to different herbicides.

Wild radish is perhaps the most challenging weed to control in B. carinata fields. Because this weed is closely related to B. carinata, it exhibits similar levels of tolerance to those herbicides that are safe for this crop. This means that although we can control many other weed species with the aforementioned herbicides, wild radish control is limited. In order to overcome this problem, SPARC researchers, mainly through Agrisoma breeding program, have been developing B. carinata germplasm with increased herbicide tolerance, which will allow using rates that are lethal to wild radish and safe to this crop (Fig. 2). An advantage of this approach is that the gain in herbicide tolerance also reduces the risk of injury due to carry-over of herbicides applied in previous crops. In this way, growers will have more flexibility for include B. carinata in diverse crop rotations.

Fig. 2. Identification of Brassica carinata genotypes with increased herbicide tolerance. Plants within the red frame were able to tolerate herbicides better than the ones outside the frame.

As part of the process of immersing agriculture in the digital era, SPARC is also generating tools to help B. carinata growers to automate decision-making based on weather networks and weed growth requirements. For example, a model was developed for wild radish, which allows using georeferenced data from the National Oceanic and Atmospheric Agency (NOAA) or local automated weather stations to predict the timing of wild radish emergence and when it reaches different growth stages. In this way, growers will know when to conduct activities such as crop planting, herbicide applications, and cultivation to maximize wild radish control. Similar predictive models are being developed for other winter weeds that can interfere with B. carinata growth.
Days after soil preparation
Growing-Degree Days with Daylength Restriction
Days after soil preparation
Growing-Degree Days with Daylength Restriction

Fig. 3. Predictive model for wild radish flowering time probability (orange dots). Wild radish exhibits large variability in flowering time (upper panel; blue dots indicate real observations), but using a thermal-time model with daylength restrictions allowed to explain most of the flowering time of this weed (lower panel).

Ensuring that B. carinata production will fit within existing crop rotations without affecting production and ecological process is very important. Therefore, we are studying whether the population dynamics of winter and summer annual weeds systems are affected by introducing B. carinata as a new component of the crop rotation. The premise is that a new crop should either have a null or positive, but definitively not a negative impact effect on the productivity and management of the existing crops. After completing a full cycle of rotation, the results suggest that B. carinata is not only compatible with existing summer crops in the Southeastern region, but could help reduce the populations of several weed species, although more research is needed to confirm these preliminary findings.

SPARC has implemented a unique and diverse strategy to develop options that will help B. carinata growers manage weeds in a cost-effective and integrated fashion. Furthermore, this strategy will progressively generate more control tools ensuring growers have the necessary flexibility to implement a weed management in accordance with their needs and preferences.