Abstract  Products from waste streams can reduce the amount of materials going to landfills or being incinerated. Brown grease captured from grease traps or wastewater facilities is produced at approximately 1,500,000 metric tons annually in the United States. Two brown grease samples were characterized from a local collector. Raw brown grease was fermented using Clostridium butyricum to produce butyric acid, achieving a yield of 0.55 butyric acid/g sugars indicating that glycerol and lactic acid were also converted. Hexane extraction of the fermentation broth gave an 81.3% recovery of lipids. Techno-economic analysis calculated a minimum fuel selling price of $1.81 per gallon gasoline equivalent (GGE) for a facility based on a city the size of Denver and a brown grease delivery price of $100 per dry metric ton. Exploiting waste streams as feedstocks can significantly reduce costs to produce fuels and can be brought to scale more rapidly due to their ready availability.

Abstract  Neonicotinoid insecticides are of environmental concern, but little is known about their occurrence in surface water. An area of intense corn and soybean production in the Midwestern United States was chosen to study this issue because of the high agricultural use of neonicotinoids via both seed treatments and other forms of application. Water samples were collected from nine stream sites during the 2013 growing season. The results for the 79 water samples documented similar patterns among sites for both frequency of detection and concentration (maximum:median) with clothianidin (75%, 257 ng/L:8.2 ng/L) > thiamethoxam (47%, 185 ng/L:<2 ng/L) > imidacloprid (23%, 42.7 ng/L: <2 ng/L). Neonicotinoids were detected at all nine sites sampled even though the basin areas spanned four orders of magnitude. Temporal patterns in concentrations reveal pulses of neonicotinoids associated with rainfall events during crop planting, suggesting seed treatments as their likely source.

Abstract  This study identifies practices and regulatory standards that pertain to the handling and disposal of wet waste materials in the United States, and summarizes these practices for the following resources: (1) food waste, (2) fats, oils and greases, (3) sewage sludge, and (4) animal manure. It outlines the standards promulgated for the wet waste materials considered herein and how these standards influence the materials' feasibility for use in waste-to-energy processes. Waste-handling standards in the United States are also briefly contrasted with disposal practices in other countries and regions. This study finds that the environment for each of the four materials is extremely variable across geographic areas not only in the United States, but also across other countries and regions. Waste markets are in various stages of development worldwide, partially due to differences in waste management standards and practices, and differences in the adoption and effectiveness of overall waste management systems. Except for several types of fats, oils, and greases, all of the resources considered here are conventionally viewed and handled as waste resources rather than commodities. However, with maturation of conversion technologies that can fully utilize these materials in advanced waste-to-energy processes, the market value of these wastes could increase. In the developing waste-to-energy industry, there could be a synergy of regulatory programs and developing markets contributing to how the wastes are managed. Where these materials are currently used in mature waste-to-energy technologies (e.g., anaerobic digestion and incineration), there exists a demonstrated example of how the materials’ energy potential can be further realized while operating within the existing framework of disposal standards.

Abstract  Recent studies have shown that the CROPGRO-Soybean model does not predict soil temperature very well in Iowa. This typically gives errors in predicted emergence date, which translates to errors in timing of development and biomass accumulation during the remainder of the season. In order to improve the model, an energy balance-based soil temperature model was integrated into the soybean model and compared to the original soil temperature model, which was driven primarily by air temperature. In the new model, temperature at the soil surface is estimated from the basic energy balance equation at the air-soil interface and the soil temperature profile is calculated using the one-dimensional heat flow equation. The model was calibrated using five years of bare-soil temperature data measured at an experimental farm in Ames, Iowa. Validation of the new model using five additional years of bare-soil temperature data from the same location gave slightly better predictions of soil temperature in the top 5 cm (RMSE = 3.0, R 2 = 0.86 for validation years), and responded better to surface perturbations than the original model (RMSE = 3.2, R 2 = 0.80 for validation years). Under bare soil conditions, the new model generally gave lower RMSE and higher R 2 values compared to the old model at all soil depths. The models were also compared for accuracy in predicting emergence date. Experimental data on soil temperature and emergence for soybeans planted on weekly intervals over an eight-week period were used to test the models. The new model gave excellent predictions of emergence, with an average error of 0.6 day for the eight weekly experiments. The old model had an average error of one day. Under cool conditions, the new model gave more accurate predictions of emergence dates. However, under warm periods, both models typically gave the same accuracy, and were within about one day of the measured emergence date.

Abstract  Glyphosate [N-(phosphonomethyl)-glycine]-resistant soybean [Glycine max (L.) Merr.] production in the Mid-Atlantic occurs under full-season and double-crop production systems. Row-spacing and seeding rate manipulation affects the yield of soybean. This study evaluated the effects upon yield caused by reductions in seeding rate from current standards for these two systems. During 2000–2002, row spacing (19 and 38 cm) and seeding rates (current standard, 20 and 40% less, and 20% greater than the standard) were tested using four glyphosate-resistant cultivars representative of the maturity groups for the region. Tests were conducted for both full-season and double-crop systems at two Maryland locations for each per year on coastal plain soils. During the 3 yr, only 1 out of 48 total cultivar × row spacing comparisons for the two production systems had better yield with 38-cm rows. At best, 38-cm row spacing produced equivalent to the 19-cm rows. A 20% seeding rate reduction (345800 seeds ha−1 for full-season and 444600 seeds ha−1 for double-crop production) was generally found to not yield significantly different than the standard seeding rates for both systems. A 40% reduction consistently had yield significantly less than the standards in both systems. These results indicate a 20% seeding rate reduction can be a cost-saving practice for glyphosate-resistant soybean production in the Mid-Atlantic. With no yield loss at a 20% reduced seeding rate, additional profit ranging from $14.30 to $27.72 ha−1 can be realized.

Abstract  Corn (Zea mays L.) seeding rates have increased because new hybrids lodge less, have improved drought tolerance, and may respond to higher rates in narrow rows. Farmer–researcher partnerships were formed to evaluate two hybrids at two 0.76-m-row sites and a twin-row site at four seeding rates (61,750, 74,100, 86,450, and 98,800 kernels ha−1) and a narrow-row site (0.51- m rows at ∼5000 more kernels ha−1 across seeding rates) in field-scale studies in 2011 and 2012 in New York. Partial budget analyses were conducted to aid in future seeding rate decisions based on 2011–2012 market grain prices (US$265.76 Mg−1) in New York and grower seed (US$225 per 80,000 kernels) costs, in addition to drying and hauling costs. Yields averaged 11.8 Mg ha−1 in 2011 and 10.5 Mg ha−1 in 2012, but yield and relative profit responded inconsistently to seeding rates across sites, between hybrids, and between years at the narrow-row site. Maximum relative profit exceeded the recommended seeding rate of 74,100 kernels ha−1 at the twin-row site (76,000 kernels ha−1), at the narrow-row site in 1 yr (85,000–95,000 kernels ha−1) but not at 0.76-m-row sites. Lack of consistent responses to seeding rates is probably related to dry July conditions in both years, contributing to decreases of 4 to 5 kernels plant−1 and 0.5 to 1 mg in kernel weight for each 1000 kernel ha−1 seeding rate increase at most sites. Based on these field-scale studies, recommended seeding rates in New York will not change.

Abstract  A series of different mechanical mixtures of a narrow-pore Co/c-Al2O3 catalyst and a Cu-based WGS-catalyst has been investigated in the low-temperature Fischer-Tropsch synthesis (483 K, 20 bar) with a model bio-syngas (H-2/CO = 1.0) in a fixed-bed reactor. The higher the fraction of WGS-catalyst in the mixture, the lower is the Co-catalyst-time yield to hydrocarbons. This is ascribed to a strong positive kinetic effect of water on the Fischer-Tropsch rate of the Co-catalyst, showing the importance of the indigenously produced water, especially in fixed-bed reactors where the partial pressure of water is zero at the reactor inlet. A preliminary kinetic modeling suggests that the reaction order in P-H2O is 0.3 for the Co/c-Al2O3 catalyst in the range of the studied reactor-average partial pressures of water (i.e., 0.04-1.2 bar).

Abstract  Agricultural management practices which promote soil organic carbon (SOO sequestration can contribute to the long-term productivity of soils, thus research must quantify and predict SOC dynamics in response to crop management. Using long-term (1967-2009) data from 10 cropping systems on a Brown Chernozem (Arid ic Haploboroll) in the Canadian semiarid prairies at Swift Current, Saskatchewan, we assessed the effect of fertilizer, cropping frequency, and crop type on SOC dynamics in the 0- to 15-cm depth. Three models: Campbell, introductory carbon balance model (ICBM), and DayCent were evaluated, all of which produced fairly accurate predictions of SOC content and sequestration rates (R-2 of 0.64-0.82); however, DayCent had the highest correlation and lowest errors of prediction and was deemed superior. Residue inputs of 0.87 to 1.13 Mg C ha(-1) yr(-1) maintained the SOC level, and SOC content was directly related to factors which increased C inputs. The SOC content and sequestration rates were lowest for wheat (Triiicum aestivum L.)-based rotations which were frequently fallowed and included flax (Linurn usiiaiissimum L.), but highest for systems which were frequently cropped, well-fertilized, and included rye (Secale cereale L.) or pulse crops in rotation. For systems with high C input, DayCent projected SOC gains of 12 Mg C ha(-1) from 2009 to 2100, indicating that the soil at Swift Current had not reached maximum C capacity. This study was the first to rigorously test and demonstrate the strength of the DayCent for simulating SOC under different cropping systems on the Canadian prairies.

Abstract  With their application as seed coatings, the use of neonicotinoid insecticides increased dramatically during the last decade. They are now frequently detected in aquatic ecosystems at concentrations susceptible to harm aquatic invertebrates at individual and population levels. This study intent was to document surface runoff and subsurface tile drain losses of two common neonicotinoids (thiamethoxam and clothianidin) compared to those of companion herbicides (atrazine, glyphosate, S-metolachlor and mesotrione) at the edge of a 22.5-ha field under a corn-soybean rotation. A total of 14 surface runoff and tile drain discharge events were sampled over two years. Events and annual unit mass losses were computed using flow-weighted concentrations and total surface runoff and tile drain flow volumes. Detection frequencies close to 100% in edge-of-field surface runoff and tile drain water samples were observed for thiamethoxam and clothianidin even though only thiamethoxam had been applied in the first year. In 2014, thiamethoxam median concentrations in surface runoff and tile drain samples were respectively 0.46 and 0.16 μg/L, while respective maximum concentrations of 2.20 and 0.44 μg/L were measured in surface runoff and tile drain samples during the first post-seeding storm event. For clothianidin, median concentrations in surface runoff and tile drain samples were 0.02 and 0.01, μg/L, and respective maximum concentrations were 0.07 μg/L and 0.05 μg/L. Surface runoff and tile drain discharge were key transport mechanisms with similar contributions of 53 and 47% of measured mass losses, respectively. Even if thiamethoxam was applied at a relatively low rate and had a low mass exportation value (0.3%), the relative toxicity was one to two orders of magnitude higher than those of the other chemicals applied in 2014 and 2015. Companion herbicides, except glyphosate in tile drains, exceeded their water quality guideline during one sampling campaign after application but rapidly resumed below these limits.