The purpose of this short communication is to demonstrate the importance of numerical analysis and wavelength increment selection when characterizing fluorescent dissolved organic matter (FDOM) using fluorescence excitation-emission matrix (EEM) regional integration. A variety of water samples, representing a landscape gradient and different types of FDOM, were analyzed for their percentage distribution of five operationally defined FDOM fractions (aromatic protein I, aromatic protein II, fulvic acid-like, soluble microbial byproduct-like, and humic acid-like) using three numerical methods in integrating volume under the surface of the fluorescence EEMs: Riemann summation, composite trapezoidal rule, and composite Simpson's rule. The influence of wavelength increment was also examined for the precision of the percentage distribution of each fraction. Our results show that the FDOM fraction estimated by Riemann summation with a 10- or 5-nm excitation wavelength can cause >40% or >5% errors, respectively, when compared with the best estimated values obtained by averaging results from composite trapezoidal rule and composite Simpson's rule with 1-nm excitation wavelength at the same emission increment. Also, our experiments show that fluorescence matrix regional integration could underestimate the two aromatic protein fractions but could overestimate the soluble microbial byproduct-like and humic acid-like fractions if improper increment and integral methods are used. The error can be reduced if a smaller wavelength increment is used. The smallest increment in a spectrofluorometer and composite Simpson's rule should be used for scanning fluorescence EEMs and calculating the percentage distribution of each FDOM fraction. Alternatively, 5-nm wavelength increments with composite Simpson's rule could be cost effective, and the error of each FDOM fraction commonly falls within 5% compared with those estimated by 1-nm increments.

In the western United States, sugar beet processing for sugar recovery generates a lime-based waste product (∼250,000 Mg yr) that has little liming value in the region's calcareous soils. This area has recently experienced an increase in dairy production, with dairies using copper (Cu)-based hoof baths to prevent hoof diseases. A concern exists regarding soil Cu accumulation because spent hoof baths may be disposed of in waste ponds, with pond waters being used for irrigation. The objective of this preliminary study was to evaluate the ability of lime waste to sorb Cu. Lime waste was mixed with increasing Cu-containing solutions (up to 100,000 mg Cu kg lime waste) at various buffered pH values (pH 6, 7, 8, and 9) and shaken over various time periods (up to 30 d). Copper sorption phenomenon was quantified using sorption maximum fitting, and the sorption mechanism was investigated using X-ray absorption spectroscopy. Results showed that sorption onto lime waste increased with decreasing pH and that the maximum Cu sorption of ∼45,000 mg kg occurred at pH 6. X-ray absorption spectroscopy indicated that Cu(OH) was the probable species present, although the precipitate existed as small multinuclear precipitates on the surface of the lime waste. Such structures may be precursors for larger surface precipitates that develop over longer incubation times. Findings suggest that sugar beet processing lime waste can viably sorb Cu from liquid waste streams, and thus it may have the ability to remove Cu from spent hoof baths.

Common management practices, such as the application of green waste compost, soil moisture manipulation, and nitrogen fertilization, affect nitrous oxide (NO) emissions from agricultural soils. To expand our understanding of how soils interact with these controls, we studied their effects in 10 agricultural soils. Application of compost slightly increased NO emissions in soils with low initial levels of inorganic N and low background emission. For soils in which compost caused a decrease in emission, this decrease was larger than any of the observed increases in the other soils. The five most important factors driving emission across all soils, in order of increasing importance, were native dissolved organic carbon (DOC), treatment-induced change in DOC, native inorganic N, change in pH, and soil iron (Fe). Notable was the prominence of Fe as a regulator of NO emission. In general, compost is a viable amendment, considering the agronomic benefits it provides against the risk of producing a small increase in NO emissions. However, if soil properties and conditions are taken into account, management can recognize the potential effect of compost and thereby reduce NO emissions from susceptible soils, particularly by avoiding application of compost under wet conditions and together with ammonium fertilizer.

Activated carbons are a byproduct from pyrolysis and have value as a purifying agent. The effectiveness of activated carbons is dependent on feedstock selection and pyrolysis conditions that modify their surface properties. Therefore, pecan shell-based activated carbons (PSACs) were prepared by soaking shells in 50% (v/v) HPO or 25 to 50% of KOH-NaHCO followed by pyrolysis at 400 to 700°C under a N atmosphere. Physically activated PSACs were produced by pyrolysis at 700°C under N followed by activation with steam or CO at 700 to 900°C. Physicochemical, surface, and adsorption properties of the PSACs were compared with two commercially available activated carbons. The average mass yield of PSACs with respect to the initial mass of the biomass was about 20 and 34% for physically activated and chemically activated carbons, respectively. Acid-activated carbons exhibited higher surface area, higher bulk density, and lower ash content compared with steam- or CO-activated carbons and the two commercial products. Base activation led to the development of biochar with moderate to high surface area with surface charges suitable for adsorption of anionic species. Regardless of the activation method, PSACs had high total surface area ranging from 400 to 1000 m g, better pore size distribution, and more surface charges than commercial samples. Our results also showed that PSACs were effective in removing inorganic contaminants such as Cu and NO as well as organic contaminants such as atrazine and metolachlor. This study showed that pyrolysis conditions and activation had a large influence on the PSAC's surface characteristics, which can limit its effectiveness as a custom sorbent for targeted water contaminants.

Large amounts of livestock manure solids are expected to become available in the near future due to the development of technologies for the separation of the solid fraction of animal effluents. The charring of manure solids for biochar (BC) production represents an opportunity for recycling organic matter (OM) of high nutrient value. The objectives of this study were to evaluate the suitability of BC from swine solids (SS) to improve soil fertility through nutrient supply and decomposition of the OM incorporated into soil and to verify a possible interaction effect on soil nutrient dynamics between digestate application and soil amendment with BC. We monitored at laboratory scale the soil mineral nitrogen (N) and Olsen phosphorus (P) content, and the cumulative carbon dioxide (CO-C) release in treatments with or without a supply of digestate obtained from a biogas plant. The experiment was performed in laboratory microcosms during a 3-mo incubation period. Compared treatments were soil amendments with SS, BC from SS, wood chip, BC from wood chip, and soil with no amendment, each of them with and without incorporation of digestate (10 treatments in total). Soil N levels were unaffected by BC amendments and only increased temporarily when digestate was applied to soil amended with SS or BC from SS. For the same N content, the BC from SS supplied much more P than the nontreated OM. The amount of cumulative CO-C released from soil with BC with or without digestate did not differ from that in the unamended control soil and was lower than that in the soils with noncharred amendments. Soil amendment with BC from SS does not modify soil N availability, whereas it increases the content of P available for crops and reduces the release of CO-C from digestate applied to soil for agricultural purposes.

This study investigated the potential for controlled tile drainage (CD) to reduce bacteria and nutrient loading to surface water and groundwater from fall-season liquid manure application (LMA) on four macroporous clay loam plots, of which two had CD and two had free-draining (FD) tiles. Rhodamine WT (RWT) was mixed into the manure and monitored in the tile water and groundwater following LMA. Tile water and groundwater quality were influenced by drainage management. Following LMA on the FD plots, RWT, nutrients, and bacteria moved rapidly via tiles to surface water; at the CD plots, tiles did not flow until the first post-LMA rainfall, so the immediate risk of LMA-induced contamination of surface water was abated. During the 36-d monitoring period, flow-weighted average specific conductance, redox potential, and turbidity, as well as total Kjeldahl N (TKN), total P (TP), NH-N, reactive P, and RWT concentrations, were higher in the CD tile effluent; however, because of lower tile discharge from the CD plots, there was no significant ( ≤ 0.05) difference in surface water nutrient and RWT loading between the CD and FD plots when all tiles were flowing. The TKN, TP, and RWT concentrations in groundwater also tended to be higher at the CD plots. Bacteria behaved differently than nutrients and RWT, with no significant difference in total coliform, , fecal coliform, fecal streptococcus, and concentrations between the CD and FD tile effluent; however, for all but , hourly loading was higher from the FD plots. Results indicate that CD has potential for mitigating bacteria movement to surface water.

Research is limited for cow-calf operations as a potential nonpoint source of P within Florida's central highlands region (CHR). The study was conducted in a bahiagrass ( Flügge) pasture. The soil is an excessively drained 'Candler' sand. In dung-designated plots, 2 kg of fresh cattle dung was deposited across the surface of a 15-cm-radius circular zone (Zone 1 [Z1]) centered within 3 × 3 m plots. In urine plots, 1 L of urine was deposited on Z1 and 1 L on Zone 2 (Z2), an area extending outward from Z1 to 30 cm from plot center. In dung and urine plots, Zone 3 (Z3) extended from Z2 to 45 cm from plot center and Zone 4 (Z4) from Z3 to 60 cm. Excreta deposition frequencies (DFs) were 0, 1, 2, and 3 times per year during 2006 and 2007. Total apparent remaining P (ARP = [fertilizer P + excreta P] - forage P removal) for Z1 of dung plots was 21, 447, 905, and 1249 kg ha for DF0, DF1, DF2, and DF3, respectively. In 2008, soil was incrementally sampled to a depth of 120 cm in all zones. Urine deposition did not increase soil P. Soil P levels and the degree of P saturation percentages increased with DF but only in the upper 10 cm of topsoil beneath Z1 of dung plots. Our results suggest that the risk of dung P reaching groundwater is low due to a considerable P retention capacity within the rooting zone of the Candler soil.

Inorganic fertilizers are widely used for crop production, but their long-term impacts on soil organic carbon (SOC) pools and soil physical attributes are not fully understood. We studied how half a century of N application at 0, 45, 90, 134, 179, and 224 kg ha and P application at 0, 20, and 40 kg ha (since 1992) affected SOC pools and soil structural and hydraulic parameters in irrigated continuous corn ( L.) under conventional till on an Aridic Haplustoll in the central Great Plains. Application of 45, 90, 134, 179, and 224 kg N ha increased the SOC pool by 4.6, 6.8, 7.6, 7.9, and 9.7 Mg ha, respectively, relative to nonfertilized plots in the 0- to 45-cm depth. Application of 20 kg P ha increased the SOC pool by 2.9 Mg ha in the 0- to 30-cm depth. The highest N rate increased the SOC pool by 195 kg ha yr. The C gains may be, however, offset by the C hidden costs of N fertilization. Application of >45 kg N ha reduced the proportion of soil macroaggregates (>0.25 mm) in the 7.5- to 30-cm depth. Fertilization did not affect hydraulic properties, but application of ≥90 kg N ha slightly increased aggregate water repellency. An increase in SOC concentration did not increase the mean weight diameter of wet aggregates ( = 0.1; > 0.10), but it slightly increased aggregate water repellency ( = 0.5; 0.005). Overall, long-term inorganic fertilization to irrigated corn can increase SOC pool, but it may reduce soil structural stability.