Beneficial Utilization of Coal Fly Ash with Organic Amendments to Enhance Biofuel Feedstock Production of Indiangrass (Sorgastrum nutans) in Armour Silt Loam Soils

Waste to energy conversions are emerging as one of the creative strategies with the current focus on energy security and environmental sustainability. With the increasing costs of effective management of coal fly ash (CFA) and the emerging focus on bioenergy crops for biofuel feedstock production, the current thesis project investigated biofuel feedstock production of indiangrass (IG), a warm season perennial grass (WSPG) grown in Armour silt loam soils (ASL) that was amended with CFA and organic amendments such as poultry litter (PL) and vermicompost (VC). Two experiments were conducted in the greenhouse; preliminary and the main experiment, to assess biomass productivity of IG in ASL soils whose pH was adjusted to initial levels of 4.5 representing acid impacted soils that account for 30% of the world\u27s arable cropland and 6.5 representing soil `agronomic\u27 conditions. In the first experiment, addition of CFA alone at 5% caused a reduction of shoot biomass production by IG. However, there were no significant differences in total biomass production between ASL control, treatments with PL alone or with combination of CFA+PL. Similarly, there were no significant differences between any of the treatments at pH=6.5 In addition to CFA and PL amendments, the second experiment also evaluated biomass productivities of ASL together with vermicompost (VC) alone or in combination with other treatments. At pH=4.5 in this experiment, only treatments with CFA alone or combination CFA+PL+VC showed lower biomass production. At pH=6.5, all treatments consisting of CFA, PL or VC alone, or in combinations showed significant total biomass enhancement compared to unamended ASL soils. Biomass productivities of switchgrass (SG), the model bioenergy feedstock showed no influence of pH or soil amendment on biomass productivity. In the preliminary experiment, biomass production by SG was practically identical at both pHs. In the final experiment, only selected SG treatments were evaluated (ASL control and 10% CFA+PL+VC) with similar results. These assessments support further investigation of IG as biofuel feedstock that could be grown on CFA-amended soils in the presence of appropriate organic amendment at least in agronomic soils

Planting date and dicamba‐based herbicide programs influence soybean production in the Southern Great Plains

Abstract The interplay of management decisions involving soybean (Glycine max L.) planting date, herbicide programs, and herbicide application timings is critical to optimize soybean performance and weed control in Southern Great Plains soybean production systems. This research sought to evaluate soybean yield potential and the level of weed control as influenced by early‐, delayed‐, and late‐ planting dates and various combinations of preemergence (PRE), early‐postemergence (EPOST), and mid‐postemergence (MPOST) weed management programs. A field study was established in Bixby, OK in 2017 and 2018 under irrigated conditions and in Perkins, OK in 2017 under dryland conditions, consisting of three planting windows (early, delayed, and late) of XtendFlex soybean, with or without a PRE (chlorimuron + flumioxazin + pyroxasulfone + glyphosate + dicamba) combined with EPOST or EPOST + MPOST (glyphosate + dicamba) versus no in‐season applications. The gap in late‐planted soybean yield potential, compared to early‐planted soybean, was exacerbated in the dryland systems (1346 kg ha−1) versus an irrigated system (2311 kg ha−1). Use of PRE provided 60% weed control until MPOST and increased yields by 657 kg ha−1 and 457 kg ha−1 for delayed and late‐planted soybean, respectively. Late‐planted soybean with EPOST + MPOST provided up to 50% weed control, but lack of biomass production for cultural control reduced weed control by 29% compared to early‐ and delayed‐planted soybean. From an agronomic management standpoint, the time of soybean planting is influential on the success of weed control measures and soybean yields in double‐cropping system in the Southern Great Plains, particularly with late‐planted soybean

Root growth, architecture, and ion uptake of alfalfa and triticale irrigated with brackish groundwater and reverse osmosis concentrate

Abstract Soil salinity is a major environmental constraint for agricultural production, especially in arid and semiarid regions of the world. Salts in irrigation water and soil can potentially harm plant root growth. To date, more research has been devoted to aboveground biomass production. This study is aimed at determining the impacts of irrigating with brackish groundwater (BGW) and reverse osmosis (RO) concentrate on the root and shoot biomass, root/shoot ratio (R:S), and root system architecture (RSA) of alfalfa (Medicago sativa L.) and triticale (× Triticosecale Wittm. ex A. Camus). Two replicated experiments were conducted in the Fabian Garcia Science Center (FGSC) greenhouse from 7 Oct. 2017 to 7 Jan. 2018 in Las Cruces, NM, USA. After 90 d, roots were scanned using a WinRHIZO image analysis system and the data were analyzed. In both the species, RO and BGW + NaCl increased root Na+ and Cl– concentrations. Triticale behaved more like a root Na‐retaining species than alfalfa but with an associated decrease in total root biomass. Irrigation with BGW in alfalfa increased root length and the number of forks and crossings, whereas RO irrigation increased root length density (RLD). Unlike alfalfa, triticale root architectural parameters were largely unaffected by salinity. However, RO and BGW + NaCl waters promoted significantly (p ≤ .05) higher shoot biomass in triticale than the control and BGW alone. Our findings recommend BGW for alfalfa irrigation, and triticale as a potential future forage crop for dry and saline conditions

Per- and Polyfluoroalkyl Substances (PFAS) in Integrated Crop–Livestock Systems: Environmental Exposure and Human Health Risks

Per- and polyfluoroalkyl substances (PFAS) are highly persistent synthetic organic contaminants that can cause serious human health concerns such as obesity, liver damage, kidney cancer, hypertension, immunotoxicity and other human health issues. Integrated crop–livestock systems combine agricultural crop production with milk and/or meat production and processing. Key sources of PFAS in these systems include firefighting foams near military bases, wastewater sludge and industrial discharge. Per- and polyfluoroalkyl substances regularly move from soils to nearby surface water and/or groundwater because of their high mobility and persistence. Irrigating crops or managing livestock for milk and meat production using adjacent waters can be detrimental to human health. The presence of PFAS in both groundwater and milk have been reported in dairy production states (e.g., Wisconsin and New Mexico) across the United States. Although there is a limit of 70 parts per trillion of PFAS in drinking water by the U.S. EPA, there are not yet regional screening guidelines for conducting risk assessments of livestock watering as well as the soil and plant matrix. This systematic review includes (i) the sources, impacts and challenges of PFAS in integrated crop–livestock systems, (ii) safety measures and protocols for sampling soil, water and plants for determining PFAS concentration in exposed integrated crop–livestock systems and (iii) the assessment, measurement and evaluation of human health risks related to PFAS exposure