The power of citizen science to contribute to both science and society is gaining increased recognition, particularly in physics and biology. Although there is a long history of public engagement in agriculture and food science, the term ‘citizen science’ has rarely been applied to these efforts. Similarly, in the emerging field of citizen science, most new citizen science projects do not focus on food or agriculture. Here, we convened thought leaders from a broad range of fields related to citizen science, agriculture, and food science to highlight key opportunities for bridging these overlapping yet disconnected communities/fields and identify ways to leverage their respective strengths. Specifically, we show that (i) citizen science projects are addressing many grand challenges facing our food systems, as outlined by the United States National Institute of Food and Agriculture, as well as broader Sustainable Development Goals set by the United Nations Development Programme, (ii) there exist emerging opportunities and unique challenges for citizen science in agriculture/food research, and (iii) the greatest opportunities for the development of citizen science projects in agriculture and food science will be gained by using the existing infrastructure and tools of Extension programmes and through the engagement of urban communities. Further, we argue there is no better time to foster greater collaboration between these fields given the trend of shrinking Extension programmes, the increasing need to apply innovative solutions to address rising demands on agricultural systems, and the exponential growth of the field of citizen science.

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Manganese (Mn) contamination of well water is recognized as an environmental health concern. In the southeastern Piedmont region of the United States, well water Mn concentrations can be >2 orders of magnitude above health limits, but the specific sources and causes of elevated Mn in groundwater are generally unknown. Here, using field, laboratory, spectroscopic, and geospatial analyses, we propose that natural pedogenetic and hydrogeochemical processes couple to export Mn from the near-surface to fractured-bedrock aquifers within the Piedmont. Dissolved Mn concentrations are greatest just below the water table and decrease with depth. Solid-phase concentration, chemical extraction, and X-ray absorption spectroscopy data show that secondary Mn oxides accumulate near the water table within the chemically weathering saprolite, whereas less-reactive, primary Mn-bearing minerals dominate Mn speciation within the physically weathered transition zone and bedrock. Mass-balance calculations indicate soil weathering has depleted over 40% of the original solid-phase Mn from the near-surface, and hydrologic gradients provide a driving force for downward delivery of Mn. Overall, we estimate that >1 million people in the southeastern Piedmont consume well water containing Mn at concentrations exceeding recommended standards, and collectively, these results suggest that integrated soil-bedrock-system analyses are needed to predict and manage Mn in drinking-water wells.

Environmental impacts of potentially toxic trace elements from coal fly ash are controlled in part by the mineralogy of the ash matrix and the chemical speciation of the trace elements. Our objective was to characterize the chemical and mineralogical composition of fly ash samples that are pertinent to the 2008 release of coal ash from a containment area at the Tennessee Valley Authority (TVA) Kingston fossil plant, which left 4 to 500 t of trace elements in adjoining river systems. Three fly ash samples were analyzed for elemental composition by digestion or neutron activation analysis, mineralogy and macroelement speciation by conventional and synchrotron-based X-ray diffraction (XRD and SXRD) and X-ray absorption spectroscopy (XAS), and for spatial associations of elements by electron probe microanalysis (EPMA). Ash samples were mainly composed of Si (20−27% w/w), Al (10−14% w/w), Fe (4−6% w/w), and Ca (4−6% w/w). Concentrations of selected trace elements ranged from 8 to 1480 mg kg −1 , with the following general trend: Sr > Mn ≈ Zn ≈ Cu ≈ Cr > As ≈ Pb > Se ≈ U. XRD and EPMA analyses indicated that fly ash matrices were heterogeneous mixtures of minerals and aluminosilicate glass containing Fe, Ca, Ti, Mg, Na, and K. XAS fitting analyses suggested that Fe was mostly in a poorly ordered, polymerized hydroxyl-Fe(III) phase, with minor proportions of magnetite, and hematite or maghemite. Consistent with XRD data, fits to Ca XAS data included standards of glass, anhydrite, lime, and calcite; and fits to S XAS data included anhydrite and reduced organic S forms. Electron microprobe analysis showed frequent correlations among Ca, Si, and Al (and with Sr), consistent with the glass and mineral phases identified. Ash composition and mineralogy help to define a geochemical basis for projecting the long-term fate of trace elements in residual ash left in sediments following cleanup operations at the TVA-Kingston site.

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Core Ideas Fertilizer additives to decrease N losses did not provide consistent yield advantages. Plots treated with N‐loss products did not increase N use efficiency or N uptake. Agronomic optimum N rates observed in the field aligned with North Carolina recommendations. To reduce environmental losses of N and increase crop use, it is critical to optimize N fertilization rates and determine if N‐loss prevention amendments increase yields. Research objectives were to: (i) determine N‐release patterns of three N‐loss amendments (urea ammonium nitrate [UAN] treated with NBPT+DCD, nitrapyrin, or an organo‐Ca) and UAN through a laboratory incubation; (ii) determine effectiveness of these four products for maize (Zea mays L.) and winter wheat (Triticum aestivum L.) produced in two to three regions of North Carolina; and (iii) determine agronomic optimum N rate for wheat and corn compared to state‐recommended rates. Nitrogen release was measured in three soils (coastal plain, piedmont, and mountains) during the incubation experiment. Field experiments were randomized complete block designs (four replications of six maize N rates and five wheat N rates), with each rate applied as one of four product treatments (UAN and UAN+ one of three N‐loss prevention amendments). In the incubation experiment, soils treated with UAN+nitrapyrin or UAN+NBPT+DCD delayed nitrification longer than soils treated with UAN or UAN+organo‐Ca. There was no significant effect of product on maize grain yield (coastal plain and mountains) and wheat yield (coastal plain and piedmont). A year × product interaction occurred for maize grain yield in the piedmont. Agronomic optimum N rates mostly aligned with current North Carolina N fertilizer recommendations. Despite positive laboratory results, N‐loss amendments did not have a significant effect on yield in 9 of 10 site‐years, indicating that proper N rates are a more effective nutrient management strategy.

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