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Soil fumigation is commonly employed for pest control in potato production, although it can unintentionally harm non-target organisms in the soil. The presence of cover crops can significantly influence the abundance and composition of microorganisms. However, there is limited knowledge regarding the combined impact of soil fumigation and cover crops on soil health in potato fields. To address this knowledge gap, a field study was conducted at the Hermiston Agricultural Research and Extension Center, Oregon State University with a randomized split-plot design consisting of four fumigation treatments (no fumigation control, Telone, metam sodium, and co-applied Telone and metam sodium) as the main plots and five cover crop treatments [no cover crop, wheat (Triticum aestivum), mustard (Brassica nigra), radish (Raphanus sativus), and a mixture of winter pea (Pisum sativum) and faba bean (Vicia faba)] as the subplots. Compared to the control, microbial biomass carbon (MBC) in non-fumigated soils of pea+faba bean, wheat, and radish increased by 41 %, 37 %, and 31 %, respectively. In soils treated with metam sodium, pea+faba bean, wheat, radish, and mustard increased MBC by 30 %, 34 %, 41 %, and 40 % compared to the control. The results demonstrated the potential of cover crops to enhance MBC after fumigation. Both Fumigation and cover crop did not impact the total yield of potatoes, although fumigation increased the yield of tubers within 171-283 g size category compared to the control. However, the current data is not sufficient for making a conclusive remark. Further field studies should be conducted to understand the role of fumigation and cover crops on potato soil health and potato production.

Bioavailable organic-rich food waste (FW) is a promising feedstock for renewable hydrogen production. However, its highly suspended and complex nature presents substantial challenges for producing high-purity hydrogen in dual-chamber microbial electrolysis cells (MECs). This study examined the effects of pretreating FW through pre-fermentation and/or filtration on its microbial electrolysis. Both methods enhanced the exoelectrogenic utilization of FW, with pre-fermentation being especially effective by conditioning substrate composition, while filtration alone was less advantageous due to associated energy loss. The MECs fed with pre-fermented FW exhibited significantly higher performances, achieving the highest hydrogen yield of 1,029 mL/g chemical oxygen demand fed (39.1 % increase over raw FW) when pre-fermentation was followed by filtration. Bioanodes across all MECs were dominated by exoelectrogenic bacteria, mainly Geobacter and Desulfovibrio, with significantly greater abundance observed with pre-fermentation. These findings highlight the value of pretreatment, particularly pre-fermentation, and warrant further optimization research to maximize FW conversion into hydrogen.

ABSTRACTThe concept of “blue carbon” is, in this study, critically evaluated with respect to its definitions, measuring approaches, and time scales. Blue carbon deposited in ocean sediments can only counteract anthropogenic greenhouse gas (GHG) emissions if stored on a long‐term basis. The focus here is on the coastal blue carbon ecosystems (BCEs), mangrove forests, saltmarshes, and seagrass meadows due to their high primary production and large carbon stocks. Blue carbon sequestration in BCEs is typically estimated using either: 1. sediment carbon inventories combined with accretion rates or 2. carbon mass balance between input to and output from the sediment. The inventory approach is compromised by a lack of accurate accretion estimates over extended time periods. Hence, short‐term sedimentation assays cannot be reliably extrapolated to long timescales. The use of long‐term tracers like 210Pb, on the other hand, is invalid in most BCEs due to sediment mobility by bioturbation and other physical disturbances. While the mass balance approach provides reasonable short‐term (months) estimates, it often fails when extrapolated over longer time periods (> 100 years) due to climatic variations. Furthermore, many published budgets based on mass balance do not include all relevant carbon sources and sinks. Simulations of long‐term decomposition of mangrove, saltmarsh (Spartina sp.), and eelgrass (Zostera sp.) litter using a 3‐G exponential model indicate that current estimates of carbon sequestration based on the inventory and mass balance approaches are 3–18 times too high. Most published estimates of carbon sequestration in BCEs must therefore be considered overestimates. The climate mitigation potential of blue carbon in BCEs is also challenged by excess emissions of the GHG methane (CH4) and nitrous oxide (N2O) from biogenic structures in mangrove forests and saltmarsh sediments. Thus, in many cases, carbon sequestration into BCE sediments cannot keep pace with the simultaneous GHG emissions in CO2 equivalents.