The application of biochar amendments to soil has been proposed as a strategy for mitigating global carbon (C) emissions and soil organic carbon (SOC) loss. Biochar can provide additional agronomic benefits to cropping systems, including improved crop yield, soil water holding capacity, seed germination, cation exchange capacity (CEC), and soil pH. To maximize the beneficial effects of biochar amendments towards the inventory, increase, and management of SOC pools, nondestructive analytical methods such as ground penetrating radar (GPR) are needed to identify and quantify belowground C. The use of GPR has been well characterized across geological, archaeological, engineering, and military applications. While GPR has been predominantly utilized to detect relatively large objects such as rocks, tree roots, land mines, and peat soils, the objective of this study was to quantify comparatively smaller, particulate sources of SOC. This research used three materials as C sources: biochar, graphite, and activated C. The C sources were mixed with sand—12 treatments in total—and scanned under three moisture levels: 0%, 10%, and 20% to simulate different soil conditions. GPR attribute analyses and Naïve Bayes predictive models were utilized in lieu of visualization methods because of the minute size of the C particles. Significant correlations between GPR attributes and both C content and moisture levels were detected. The accuracy of two predictive models using a Naïve Bayes classifier for C content was trivial but the accuracy for C structure was 56%. The analyses confirmed the ability of GPR to identify differences in both C content and C structure. Beneficial future applications could focus on applying GPR across more diverse soil conditions.

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Sorghum species provide a unique opportunity to develop perennial cropping systems due to their interspecific hybridization compatibility and phenotypic plasticity from annual to perennial life cycle. Sorghum bicolor (L.) Moench is a diploid (2n = 2x = 20) annual species that does not produce rhizomes, whereas Sorghum propinquum (Kunth) Hitchc. is a diploid (2n = 2x = 20) perennial, rhizomatous species native to Asia and is considered a wild relative of S. bicolor. Because of their relatively close taxonomic relationship, S. bicolor × S. propinquum hybrids offer both valuable insights between annuals and perennials, as well as hybridization opportunities for the introgression of perennialism into a major cereal crop. The objective of this study was to characterize a novel S. bicolor × S. propinquum F 2 population for height, tillering capacity, days to flowering, and overwintering capacity. Our research identified F 2 hybrids exhibiting transgressive segregation for height, whereas hybrids were intermediate between the parental extremes for days to mid-anthesis and tillering capacity. Fortuitous harsh winter conditions in 2018 applied strong natural selection pressure for overwintering capacity, allowing for the identification of F 2 hybrids with greater overwintering capacity than S. propinquum. The present results provide both novel perennial sorghum germplasm resources and insight towards developing effective breeding programs for perennial cereal cropping systems.

Nutrient management is vital for food, feed, fiber, and fuel production. However, excessive application and loss (volatilization, leaching, runoff , etc.) of inorganic and organic sources of nutrients have detrimental environmental impacts, while increasing prices for petroleum-based and mined fertilizers further limit opportunities for their utilization in developing nations. This study evaluated a novel, alternative type of nutrient source through pretreatment processes of torrefaction and pyrolysis by converting high-biomass feedstocks into renewable soil amendments. Napiergrass (Pennisetum purpureum Schumach., [cv. Merkeron]) and pearl millet-napiergrass (Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.) (PMN) were converted under atmospheric pressure with minimal oxygen at 250˚C and 400˚C, ground to 1 millimeter (mm) and 2 mm particle sizes, and compared to urea in a full-season field trial and short-season nursery trial growing maize (Zea mays L.) and PMN for fertility response. When compared to urea in the field trial, the torrefied biomass amendment (TBA) and biochar had similar responses despite lower nitrogen (N) application rates. The nursery trial also produced equivalent responses from urea and TBA regardless of lower N application with the exception being phosphorus (P). Finally, maize and PMN had higher P uptake with the TBA in both trials.

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