Corn and wheat residue management effects on greenhouse gas emissions in the Mid-Atlantic USA

Greenhouse gas (GHG) emissions from crop residue management have been studied extensively, yet the effects of harvesting more than one crop residue in a rotation have not been reported. Here, we measured the short-term changes in methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) emissions in response to residue removal from continuous corn (Zea mays L.) (CC) and corn-wheat (Triticum aestivum L.)-soybean (Glycine max L. Merr.) (CWS) rotations in the Mid-Atlantic USA. A first experiment retained five corn stover rates (0, 3.33, 6.66, 10, and 20 Mg ha-1) in a continuous corn (CC) in Blacksburg, VA, in 2016 and 2017. Two other experiments, initiated during the wheat and corn phases of the CWS rotation in New Kent, VA, utilized a factorial combination of retained corn (0, 3.33, 6.66, and 10.0 Mg ha-1) and wheat residue (0, 1, 2, and 3 Mg ha-1). Soybean residue was not varied. Different crop retention rates did not affect CO2 fluxes in any of the field studies. In Blacksburg, retaining 5 Mg ha-1 stover or more increased CH4 and N2O emissions by ~25%. Maximum CH4 and N2O fluxes (4.16 and 5.94 mg m-2 day-1) occurred with 200% (20 Mg ha-1) retention. Two cycles of stover management in Blacksburg, and one cycle of corn or wheat residue management in New Kent did not affect GHG fluxes. This study is the first to investigate the effects of crop residue on GHG emissions in a multi-crop system in humid temperate zones. Longer-term studies are warranted to understand crop residue management effects on GHG emissions in these systems

Utilization of Coal and Biomass Ash

Sustainable utilization of the ash generated from the combustion of coal or biomass is a big challenge for the power industry. Huge quantities of ash are generated and, in general, they are disposed-off in ash ponds. However, recent regulatory requirements demand 100% utilization of ash. So many new areas of ash utilization are being explored by the researchers and ash managers. Bulk utilization sectors are cement industry, construction, bricks, landfill, mine back filling, and soil amendment for growing plants. Efforts to enhance the use in value-added low-volume sectors like fertilizer, cenosphere, catalyst support, zeolites, aerogels, and so on are continuously evolving. The heterogeneity of the ash properties is one of the main challenges for advocating a generalized utilization pattern of the ash. Biomass has some typical properties that limit its use for some sectors. However, beneficiation of both coal and biomass ash and use of other additives could improve the suitability of the ashes to multifarious uses