the to study was recently published in GCB Bioenergy. According to research, bioenergetic sorghum hybrids capture and sequester significant amounts of atmospheric carbon dioxide in the soil. Cropping can improve soil fertility and potentially earn carbon credits to offset greenhouse gas emissions.
In addition, the study shows that the unusually deep root system of bioenergetic sorghum can reach water and nutrient sources untapped by other annual crops. These results suggest that cultivation can help manage fertilizer runoff from other annuals in a crop rotation.
Mullet is an expert in genomics, genetics and genetic regulatory networks in bioenergy crops. Rooney has spearheaded the development of bioenergetic sorghum hybrids for the past 20 years. Over the past 15 years, Rooney and Mullet have worked together to develop bioenergetic sorghum.
In fact, Mullet and Rooney have worked to improve bioenergetic sorghum varieties to produce an ideal annual bioenergetic crop. The hybrid used in the recent study creates high yields of biomass for the production of fuel, electricity and bioproducts. The crop also has excellent drought resistance, good nitrogen use efficiency and a deep root system.
“The most sustainable bioenergy crops are assumed to be perennial because they require fewer inputs and can sequester more biomass than annuals,” Rooney said. “These statements are true, but American agriculture still needs varieties and annual growing options.”
New benchmark for modeling carbon credits, soil fertility
The study shows that one acre planted with a bioenergetic sorghum hybrid accumulates about 3.1 tonnes of dry root biomass during the crop’s 155-day growing season. Bioenergetic sorghum roots have also reached a depth of over 6.5 feet during their growing season.
These new measurements make it easier to predict the amount of atmospheric carbon dioxide that could be captured inside the roots. The numbers can also shed light on how many carbon credits a planted field could earn.
“Frankly, the numbers are pretty favorable,” Rooney said.
The numbers are also important in understanding the potential of the crop to improve soil fertility and water holding capacity by replenishing soil organic carbon. However, previous research has shown that in the United States, soil organic carbon levels have declined by 50% over the past 100 years in land planted with annual crops.
This drop in soil carbon levels could be due to cultural practices, microbial activity and changes in land use, Rooney said. These complex factors mean that predicting how long it will take to replenish the lost carbon requires sophisticated modeling. The restoration process will likely take several decades.
“For modeling, they have to have a realistic number to start with,” Rooney said. “Historically, we haven’t had enough information to do this, but this study provides a benchmark for scientists and policy makers.
Need further research
In this study, Rooney and his team managed the field trials and assisted with the phenotyping. Mullet and his team characterized the root system and the genes expressed within.
Over several years, the study took an in-depth look at how a bioenergetic sorghum hybrid interacts with two types of soil, Rooney said. He insisted on the need for further research.
“In this study, we did not sample the genetic diversity of bioenergetic sorghum at all, except for one standard type,” Rooney said. “And it’s critical to look at multiple environments and expand the range of environments we’re evaluating. “
Bioenergetic sorghum as part of a sustainable bioenergy production system
Modeling studies estimate that millions of acres of abandoned and marginal cropland in the United States are available for planting. Many of these acres are found in the Gulf Coast region. The region is ideal for bioenergy sorghum production due to the abundant rainfall, long growing seasons and low competition with cereal crops, Mullet said. Additionally, the harvest has improved over the years in terms of productivity, resilience and composition, thanks to the efforts of Mullet and Rooney.
“Recently, I decided that the most important thing we can do is to continue research into optimizing the bioenergy of sorghum, but also to help design and build biorefineries that will process the materials from the sorghum. crop optimally, ”Mullet said.
Carbon captured in biofuels and bioproducts in biorefineries and by bioenergetic sorghum roots could generate carbon credits, which could benefit producers and industry.
Yet despite the Gulf Coast’s excellent biofuel production potential, there are no bioenergy research centers and very few biorefineries in the region, Mullet said.
Therefore, Mullet is now working to attract funding from industry and government to help build the next generation of biorefineries designed to use bioenergetic sorghum biomass for the production of biofuels, bioproducts and bioenergy.
“The project has expanded not only to the production of biofuels and bioproducts, but also to direct carbon capture and sequestration,” he said.