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Surface inlets installed in agricultural closed depressions can transport sediment- and nutrient-laden runoff directly to receiving streams or water bodies. Replacing tile risers with blind inlets has the potential to decrease these sediment and nutrient loads, but adoption of blind inlets has been met with hesitation from producers who fear that changes to the surface inlet may result in additional water ponding, crop damage, or crop loss. The objectives of this study were to assess hydrologic performance of blind inlets over time, and to determine whether blind inlets influenced the hydrology of a closed depression compared to a tile riser. Hydrograph characteristics including flow duration, time to peak flow, peak flow rate, and cumulative flow were evaluated for 549 storm events over a 12-year period (2006 to 2017) for a pair of closed depressions in northeastern Indiana. Surface water could be drained in both depressional areas with either a tile riser or blind inlet. Results showed that blind inlet infiltration rates declined approximately linearly over time (1.4 cm h−1 y−1). While changes in infiltration were largely controlled by annual tillage practices at the study sites, findings suggest that blind inlets have an effective service life of 8 to 10 years under the study conditions. Surface water management practices significantly influenced depression hydrology; however, the practices functioned differently between fields. Blind inlets did not influence the frequency of discharge, but they may increase or decrease the duration of flow and cumulative flow compared to a tile riser depending on the extent of subsurface tile drainage within the closed depression. Findings from this study underscore the inherent connections between surface and subsurface hydrologic processes in drained closed depressions and how these connections may influence both water quantity and water quality.

Sequestration of anthropogenic antibiotics by biochars from waters may be a promising strategy to minimize environmental and human health risks of antibiotic resistance. This study investigated the long-term sequestration of lincomycin by 17 slow-pyrolysis biochars using batch sorption experiments during 365 days. Sorption kinetics were well fitted to the Weber-Morris intraparticle diffusion model for all tested biochars with the intraparticle diffusion rate constant (kid) of 25.3–166 μg g−1 day−0.5 and intercept constant (Cid) of 39.0–339 μg g−1, suggesting that the sorption kinetics were controlled by fast initial sorption and slow pore diffusion. The quasi-equilibrium sorption isotherms became more nonlinear with increasing equilibration time at 1, 7, 30, and 365 days, likely due to increasing abundance of heterogeneous sorption sites in biochars over time. Intriguingly, low-temperature (300 °C) and high-temperature (600 °C) biochars had faster sorption kinetics than intermediate-temperature (400–500 °C) biochars at the long term, which was attributed to greater specific surface area and pore volume of high-temperature biochars and the substantial and continuous release of dissolved organic carbon (DOC) from low-temperature biochars, respectively. DOC release enhanced lincomycin sorption by decreasing biochar particle size and/or increasing the accessibility of sorption sites and pores initially blocked by DOC. Additionally, a large fraction (>75%) of sorbed lincomycin in biochars after a 240-day equilibration could not be extracted by the acetonitrile/methanol extractant. The strong sorption and low extraction recovery demonstrated the great potential of biochars as soil amendments for long-term sequestration of antibiotics in-situ.

Drainage of tile-riser inlets allow direct discharge of surface water into tile drainage systems, effectively bypassing soil filtration processes and negatively affecting water quality. Blind inlet...

The establishment of long-term tillage and crop rotations studies helps to investigate the cumulative effect and the long-term effect of management practices on soil properties, including those affecting soil health and water quality. In this study, a suite of techniques was used to evaluate the impact of a 28-year long-term tillage and crop rotations on soil structural stability parameters including soil cohesion, aggregate stability, and sediment loss. Fluidized bed experiments to estimate soil cohesion and aggregate stability tests were performed on samples collected from plots managed under chisel tillage (CT) and no-till practice (NT) and four rotations (continuous corn [Zea mays], CC; continuous soybean [Glycine max], BB; corn-soybean, CB; and soybean-corn, BC). At the same site, rainfall simulation experiments were conducted and sediment loss was correlated to fluidized bed and aggregate stability measurements. No-till practice had a positive effect on soil cohesion in the 0–15 cm soil layer; average pressure drop at fluidization (ΔPf) values were 30.8 Pa for NT and 17.0 Pa for CT and a higher proportion of stable macroaggregates was present under NT practice (51.4% vs. 28.9%). In the 15–30 cm soil layer, aggregate stability measurements mimicked those of the surface layer for each tillage practice and crop rotation. In this study, we found no correlation between fluidized bed results and aggregate stability tests. The soil organic carbon content correlated to macroaggregates (R2 = 0.56) and magnitude of cohesion (R2 = 0.51). Corn residues were associated with improved aggregation in both surface and lower soil layers with respectively 18% and 13% more aggregates than soybean residues. Rainfall simulation experiments conducted on the sample sites revealed tillage effect on sediment loss patterns consistent with aggregate stability and fluidized bed measurement results. Chisel-tilled fields yielded 20 times more sediment loss than no-till fields. The effect of corn residue on aggregate stability resulted in 380 and 6.7 kg ha−1 less sediment loss under conventional and no-till practices, respectively.

Made available in DSpace on 2022-04-28T19:46:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Combining deep soil tillage systems with lime application is a potential strategy for improving the sugarcane production in acidic soils. The authors evaluated the influence of tillage systems and lime application on sugarcane performance and soil attributes, including acidity. A field study in a clayey-textured Rhodic Hapludox soil was conducted with sugarcane for two growing seasons utilizing a 3 × 2 factorial scheme comprising three soil tillage systems with and without lime: conventional soil tillage system (CT), deep strip-tillage system (DT) and modified deep strip-tillage system (MDT). The soil tillage systems differed in the depth of soil disturbance and/or lime positioning. In addition to sugarcane stalk and sugar yields, pH, potential acidity (Pac), soil organic carbon (SOC), solid-phase and soil-solution calcium (Ca) and magnesium (Mg), the percentage distribution of exchangeable (%Alex) and non-exchangeable aluminum (%Alne) in the solid phase, and total monomeric (%TM-Al) in soil water extracts were analyzed and determined. The positioning of lime by the different tillage systems influenced the distribution of the Al fractions. TM-Al existed exclusively as organic monomeric Al (OM-Al) and showed little influence from treatments. In contrast, the distribution of Alex and Alne were highly influenced by lime and tillage system and varied according to the tillage efficiency of soil amendment. Soil chemical attributes and yield parameters were also influenced by the treatments in both growing seasons, highlighting the residual effect of liming. The soil chemical attributes influenced the Al fractions. Soil pH and exchangeable and soluble calcium (Caex and Cas) and magnesium (Mgex and Mgs) explained the variation of %Alne. Pac correlated with %Alex, whereas SOC explained the variation of %TM-Al. In general, the sucrose concentration, total recoverable sugar and stalk and sugar yields were increased by lime addition in plant cane and by lime addition and tillage systems in second ratoon. The stalk yield was highest in MDT, whereas the sugar yield was highest in both deep tillage systems. São Paulo State University (UNESP) College of Agricultural Sciences Department of Crop Science, P. O. Box 237 National Soil Erosion Research United States Department of Agriculture São Paulo State University (UNESP) College of Agricultural Sciences Department of Crop Science, P. O. Box 237 FAPESP: 2014/20593-9

Growing demand for soybean [Glycine max (L.) Merr.] creates pressure to expand soybean production onto marginal lands and grow soybean continuously. Experiments comparing continuous soybean with soybean–corn (Zea mays L.) rotation, cereal rye [Secale cereale (L.)] cover crop with no cover crop, and flue‐gas desulfurization (FGD) gypsum surface‐applied at 0, 1.1, and 2.2 Mg ha−1 were conducted at Shorter, AL, Farmland, IN, Hoytville, OH, and Piketon, OH, for 5 yr. The objective was to evaluate soybean yield response to these practices across a range of soil types and climatic conditions. Response to continuous soybean and cover crop varied by site (soil drainage class) with no interaction effects. Continuous soybean reduced yield only on well‐ and moderately well‐drained soil types. Cover crop reduced yield on the very poorly drained soil type and increased yield on the well‐drained soil type. Crop production practices that promote soil health and sustainability may not provide yield improvement.

Crayfishes (Decapoda) are common inhabitants of agricultural headwater streams in the Midwestern USA that have been impacted by physical habitat degradation and contamination by agricultural pollutants. The frequency and severity of injuries within crayfish communities are indicators of crayfish aggression, which is influenced by physical, chemical, and biotic factors. Previous studies have not evaluated the relationships of the frequency and severity of crayfish injuries with physical habitat quality, water quality, and biotic factors within agricultural headwater streams. Understanding these relationships will assist with determining if crayfish injury variables can serve as an indicator of physical habitat quality or water quality in these small degraded streams. We sampled crayfishes, documented the frequency and type of injuries, and measured instream habitat and water chemistry in 2014 and 2015 within 12 agricultural headwater streams in Indiana, Michigan, and Ohio. We documented five native crayfish species from 1641 adult captures. The most abundant species were Faxonius rusticus, Faxonius immunis, and Faxonius propinquus. Linear mixed effect model analyses indicated that four crayfish injury response variables were positively correlated (p

The current increment of invasive fungal infections and the availability of new broad-spectrum antifungal agents has increased the use of these agents by non-expert practitioners, without an impact on mortality. To improve efficacy while minimizing prescription errors and to reduce the high monetary cost to the health systems, the principles of pharmacokinetics (PK) and pharmacodynamics (PD) are necessary. A systematic review of the PD of antifungals agents was performed aiming at the practicing physician without expertise in this field. The initial section of this review focuses on the general concepts of antimicrobial PD. In vitro studies, fungal susceptibility and antifungal serum concentrations are related with different doses and dosing schedules, determining the PD indices and the magnitude required to obtain a specific outcome. Herein the PD of the most used antifungal drug classes in Latin America (polyenes, azoles, and echinocandins) is discussed. Keywords: Antifungal agents, Pharmacology, Pharmacodynamics, Pharmacokinetics, Candidiasis, Aspergillosis

Phenolic plant secondary metabolites actively participate in a broad range of important reactions that affect livestock, plants and soil. In soil, phenolic compounds can affect nutrient dynamics and mobility of metals but their role in northern Great Plains agroecosystems is largely unknown. We evaluated the effects of three phenolic compounds on plant nutrient extractability in agricultural soil. Soil samples (0–10 cm) from pasture and cropped sites near Mandan, North Dakota, USA were treated with water (control) or aqueous solutions of increasingly complex compounds; benzoic acid (BA), gallic acid (GA), or β-1,2,3,4,6-penta-O-galloyl- d -glucose (PGG) at four concentrations (1.25, 2.5, 5 or 10 mg compound gram−1 soil). We measured extractable nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and manganese (Mn) in treatment supernatants and after a subsequent incubation in hot water (16 h, 80 °C). While significant quantities of nitrogen were extracted with water, each compound reduced N extracted in a concentration dependent manner with greatest response to BA (about 25%). However, PGG reduced the solubility of N only during the hot water incubation, suggesting its effects are mostly on organic forms of N. Unlike N, GA and PGG increased extraction of P, relative to water, while BA had less effect. Extraction of the major cations, K, Ca, and Mg, was strongly increased by BA and GA but unaffected by PGG. Extraction of Mn was increased most by treatments of GA but less so by BA. The effects of PGG on Mn were consistent with GA when expressed on a molar basis. These findings suggest plant secondary compounds affect nutrient dynamics in soil, and thus may be part of future management strategies to improve nutrient-use efficiency.

Agricultural land use leads to changes in physical and chemical characteristics of sediment that influence macroinvertebrate community diversity and abundance in streams. To the best of our knowledge the joint influence of sediment&rsquo, s physical and chemical characteristics on stream macroinvertebrates has not been assessed. We measured sediment&rsquo, s physical and chemical characteristics and sampled macroinvertebrates in eight agricultural headwater streams in Indiana, Michigan, and Ohio, United States, in 2017 and 2018 to determine the physical and chemical conditions of the sediment, to evaluate the relationships between physical and chemical characteristics of the sediment, and the relationship of macroinvertebrate communities with the sediment&rsquo, s physical and chemical characteristics. Sediments within most sites were dominated by sand or silt. pH was suitable for macroinvertebrates and nitrate, herbicide, and trace metal concentrations were below concentration levels anticipated to affect macroinvertebrate survival. Linear mixed effect model analysis results indicated that a physical gradient of percent small gravel and percent silt was positively correlated (p &lt, 0.05) with a chemical gradient of potassium concentrations, magnesium concentrations, and percent total nitrogen in the sediments. Our linear mixed effect model analysis results also indicated that Invertebrate Community Index scores were negatively correlated (p &lt, 0.05) with a chemical gradient of simazine and calcium concentrations and were negatively correlated (p &lt, 0.05) with physical gradient of grain size diversity and percent sand. Our results suggest that watershed management plans need to address physical and chemical degradation of sediment to improve macroinvertebrate biotic integrity within agricultural headwater streams in the Midwestern United States.

Annually in the USA, about 800,000 creosote-treated railroad ties (“ties”) may end up in landfills, presenting environmental concerns. Pyrolysis of ties to recover creosote and produce biochar may be an alternative to landfill disposal. In this study, ties were pyrolyzed under different conditions at 667 and 700 °C at two different facilities, and analyzed for residual creosote (as polyaromatic hydrocarbons, PAHs). Condensed gases from the 700 °C pyrolysis were collected. Toxicity and leachability tests were conducted on ties and biochars. Relative to the ties, both 667 and 700 °C pyrolysis reduced the extracted PAHs by 98.71 and 99.94%, respectively. Only the 700 °C pyrolysis biochar qualified as “basic” biochar for soil amendment according to the European Biochar Certificate PAHs requirements. The condensed gases generated a lower (high PAHs content) and upper (low PAHs content) layer. No trace metals of environmental concern were detected on the biochars using toxicity and leachability tests.

Objective To assess the true association between appropriate prescription of antibiotics and prognosis in patients with sepsis, a key issue in health care and quality improvement strategies. Methods Prospective cohort study in three university hospitals to determine whether the empirical prescription of antibiotics was adequate or inadequate, and to compare hospital death rates and length of stay according to different classifications of antibiotics prescription. Logistic regression models for risk estimation were fitted. Results A total of 705 patients with severe sepsis were included. No differences were found in positive-culture patients (n = 545) regarding the risk of death with insufficient spectrum antibiotics, compared to patients who received adequate spectrum antibiotics (OR = 0.90; 95% CI = 0.55-1.48). Delay in initiating antibiotics was not associated with the risk of death in patients with adequate spectrum of antibiotics, either with positive (OR = 1.04; 95% CI = 0.99-1.08) or negative cultures (OR = 0.98; 95% CI = 0.92-1.04). There were no differences in the length of hospital stay, according to the antibiotic prescription (median 11 days, IQR = 7-18 days for the whole cohort). Conclusions No associations were found between inadequate antibiotic prescription or delay to initiate therapy and mortality or length of stay.

An understanding of organic C dynamics in soils is necessary to develop management options to enhance soil organic C sequestration. The objective of this research was to study the distribution of newly formed humic materials into mineralogical distinct clay-size fractions of a silt loam soil. Oats (Avena sativa L), grown under simulated no-tillage conditions, were pulse labeled with "CO2. After senescence, the surface residue was removed and the labeled roots were allowed to decompose in the soil for 360 days. The soil clay fraction (

Purpose: To analyze the prognostic role of positive cultures in patients with sepsis. Methods: A prospective cohort study in a tertiary referral hospital in Medellín, Colombia. Adults older than 18 years of age with a bacterial infection diagnosis according to Centers for Disease Control criteria and sepsis (evidence of organ dysfunction) were included. A logistic regression model was used to determine the association between positive cultures and hospital mortality, and a Cox regression with a competing risk modeling approach was used to determine the association between positive cultures and hospital stay as well as secondary infections. Results: Overall, 408 patients had positive cultures, of which 257 were blood culture, and 153 had negative cultures. Patients with positive cultures had a lower risk of mortality (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.27-0.68), but this association was not maintained after adjusting for confounding factors (OR, 0.56; 95% CI, 0.31-1.01). No association was found with the hospital stay (adjusted subhazard ratio [SHR], 1.06; 95% CI, 0.83-1.35). There was no association between positive cultures and the presence of secondary infections (adjusted SHR, 0.99; 95% CI, 0.58-1.71). Conclusion: Positive cultures are not associated with prognosis in patients with sepsis.

In a 6-year study, we investigated the effectiveness of blind inlets as a conservation practice in reducing pesticide losses compared to tile risers from two closed farmed depressional areas (potholes) in the US Midwest under a 4-year cropping rotation. In two adjacent potholes within the same farm and having similar soils, a conventional tile riser and blind inlet were installed. Each draining practice could be operated independent of each other in order to drain and monitor each depression with either practice. Sampling events (runoff events) were collected from the potholes from 2008 to 2013 using autosamplers. The samples were analyzed for atrazine, metolachlor, 2,4-D, glyphosate, and deethylatrazine. The results of this study demonstrated that the blind inlet reduced analyzed pesticide losses; however, the level of reduction was compound dependent: atrazine (57 %), 2,4-D (58 %), metolachlor (53 %), and glyphosate (11 %). Results from this study corroborate previous research findings that blind inlets are an effective conservation practice to reduce discharge and pollutants, including pesticides from farmed pothole surface runoff in the US Midwest.

Surface inlets are installed in subsurface drainage systems to reduce ponding duration and surface runoff, but can contribute to water quality concerns by allowing water to directly enter buried drains. Blind inlets consist of perforated pipes covered with gravel and are separated from an overlying sand layer by a geotextile membrane and have been shown to be more effective in reducing losses of sediment, nutrients, and pesticides than typical tile line risers. In this study, we investigated whether the effectiveness of blind inlets to sorb pollutants, with emphasis on the herbicide atrazine, could be further improved by amended them with materials other than limestone. The media, shredded tires (tire chips), electric arc steel furnace slag (steel slag), and oak-derived biochar were chosen because they are readily available, inexpensive, and do not present environmental concerns. Kinetic sorption and isotherms were determined to ascertain atrazine sorption by these materials, in addition to testing for potential metal leaching using the Synthetic Precipitation Leaching Procedure (SPLP) and the Toxicity Characteristic Leaching Procedure (TCLP). The kinetic data were fitted using pseudo first- and second-order reaction equations and indicated that atrazine sorption rate was 38 times faster and equilibrium was reached 5 times earlier for biochar than tire chips. The 24-h sorption isotherm data were fitted to the Freundlich sorption equation. The sorption coefficient for biochar was higher than for tire chips, steel slag, and limestone. Per the SPLC and TLCP tests, there was no leaching of heavy metals at levels of environmental concern. Our results suggested that the effectiveness of blind inlets as well as other conservation practices that include filter media such as rain gardens and filter socks could be improved by incorporating more reactive materials than sand and gravel with biochar being a particularly effective alternative.

Negligible in vivo growth of enterococci and high-level dispersion of data have led to inaccurate estimations of antibiotic pharmacodynamics (PD). Here we improved an in vivo model apt for PD studies by optimizing the in vitro culture conditions for enterococci. The PD of vancomycin (VAN), ampicillin-sulbactam (SAM), and piperacillin-tazobactam (TZP) against enterococci were determined in vivo , comparing the following different conditions of inoculum preparation: aerobiosis, aerobiosis plus mucin, and anaerobiosis plus mucin. Drug exposure was expressed as the ratio of the area under the concentration-time curve for the free, unbound fraction of the drug to the MIC ( f AUC/MIC) (VAN) or the time in a 24-h period that the drug concentration for the free, unbound fraction exceeded the MIC under steady-state pharmacokinetic conditions ( fT >MIC ) (SAM and TZP) and linked to the change in log 10 CFU/thigh. Only anaerobiosis plus mucin enhanced the in vivo growth, yielding significant PD parameters with all antibiotics. In conclusion, robust in vivo growth of enterococci was crucial for better determining the PD of tested antibacterial agents, and this was achieved by optimizing the procedure for preparing the inoculum.

There is no effective natural alternative control for gastrointestinal nematodes (GIN) of small ruminants, with Haemonchus contortus being the most economically important GIN. Despite frequent reports of multidrug-resistant GIN, there is no new commercial anthelmintic to substitute failing ones. Although trematocidal activity of artemisinin analogs has been reported in sheep, neither artemisinin nor its plant source (Artemisia annua) has been evaluated for anthelmintic activity in ruminants. This study evaluated the anthelmintic activity of A. annua crude extracts in vitro and compared the most effective extract with artemisinin in sheep naturally infected with H. contortus. A. annua leaves extracted with water, aqueous 0.1% sodium bicarbonate, dichloromethane, and ethanol were evaluated in vitro by the egg hatch test (EHT) and with the bicarbonate extract only for the larval development test (LDT) using H. contortus. The A. annua water, sodium bicarbonate (SBE), ethanol, and dichloromethane extracts tested in vitro contained 0.3, 0.6, 4.4, and 9.8% of artemisinin, respectively. The sodium bicarbonate extract resulted in the lowest LC99 in the EHT (1.27 μg/mL) and in a LC99 of 23.8 μg/mL in the LDT. Following in vitro results, the SBE (2 g/kg body weight (BW)) and artemisinin (100 mg/kg BW) were evaluated as a single oral dose in naturally infected Santa Inês sheep. Speciation from stool cultures established that 84-91% of GIN were H. contortus, 8.4-15.6 % were Trichostrongylus sp., and 0.3-0.7% were Oesophagostomum sp. Packed-cell volume and eggs per gram (EPG) of feces were used to test treatment efficacy. The SBE tested in vivo contained no artemisinin, but had a high antioxidant capacity of 2,295 μmol of Trolox equivalents/g. Sheep dosed with artemisinin had maximum feces concentrations 24 h after treatment (126.5 μg/g artemisinin), which sharply decreased at 36 h. By day 15, only levamisole-treated sheep had a significant decrease of 97% in EPG. Artemisinin-treated and SBE-treated sheep had nonsignificant EPG reductions of 28 and 19%, respectively, while sheep in infected/untreated group had an average EPG increase of 95%. Sheep treated with artemisinin and A. annua SBE maintained blood hematocrits throughout the experiment, while untreated/infected controls had a significant reduction in hematocrit. This is the first time oral dose of artemisinin and an aqueous extract of A. annua are evaluated as anthelmintic in sheep. Although oral dose of artemisinin and SBE, at single doses, were ineffective natural anthelmintics, artemisinin analogs with better bioavailability than artemisinin should be tested in vivo, through different routes and in multiple doses. The maintenance of hematocrit provided by artemisinin and A. annua extract and the high antioxidant capacity of the latter suggest that they could be combined with commercial anthelmintics to improve the well-being of infected animals and to evaluate potential synergism.

Polyphenols including tannins comprise a large percentage of plant detritus such as leaf litter, and affect soil processes including metal dynamics. We tested the effects of tannins on soil metal mobilization by determining the binding stoichiometries of two model polyphenols to Al(III) and Fe(III) using micelle-mediated separation and inductively coupled plasma optical emission spectroscopy (ICP-OES). By fitting the data to the Langmuir model we found the higher molecular weight polyphenol (oenothein B) was able to bind more metal than the smaller polyphenol (epigallocatechin gallate, EGCg). For example, oenothein B bound 9.43 mol Fe mol(-1), while EGCg bound 4.41 mol of Fe mol(-1). Using the parameters from the binding model, we applied the Langmuir model for competitive binding to predict binding for mixtures of Al(III) and Fe(III). Using the parameters from the single metal experiments and information about polyphenol sorption to soils we built a model to predict metal mobilization from soils amended with polyphenols. We tested the model with three natural soils and found that it predicted mobilization of Fe and Al with r(2)=0.92 and r(2)=0.88, respectively. The amount of metal that was mobilized was directly proportional to the maximum amount of metal bound to the polyphenol. The secondary parameter in each model was the amount of weak organically chelated Fe or Al that was in the soil. This study provides the first compound-specific information about how natural polyphenols interact with metals in the environment. We propose a model that is applicable to developing phytochelation agents for metal detoxification, and we discuss how tannins may play a role in metal mobilization from soils.

Although tannin-rich forages are known to increase protein uptake and to reduce gastrointestinal nematode infections in grazing ruminants, most published research involves forages with condensed tannins (CT), while published literature lacks information on the anthelmintic capacity, nutritional benefits, and antioxidant capacity of alternative forages containing hydrolyzable tannins (HT). We evaluated the anthelmintic activity and the antioxidant capacity of plant extracts containing either mostly CT, mostly HT, or both CT and HT. Extracts were prepared with 70% acetone, lyophilized, redissolved to doses ranging from 1.0mg/mL to 25mg/mL, and tested against adult Caenorhabditis elegans as a test model. The extract concentrations that killed 50% (LC(50)) or 90% (LC(90)) of the nematodes in 24h were determined and compared to the veterinary anthelmintic levamisole (8 mg/mL). Extracts were quantified for CT by the acid butanol assay, for HT (based on gallic acid and ellagic acid) by high-performance liquid chromatography (HPLC) and total phenolics, and for their antioxidant activity by the oxygen radical absorbance capacity (ORAC) assay. Extracts with mostly CT were Lespedeza cuneata, Salix X sepulcralis, and Robinia pseudoacacia. Extracts rich in HT were Acer rubrum, Rosa multiflora, and Quercus alba, while Rhus typhina had both HT and CT. The extracts with the lowest LC(50) and LC(90) concentrations, respectively, in the C. elegans assay were Q. alba (0.75 and 1.06 mg/mL), R. typhina collected in 2007 (0.65 and 2.74 mg/mL), A. rubrum (1.03 and 5.54 mg/mL), and R. multiflora (2.14 and 8.70 mg/mL). At the doses of 20 and 25mg/mL, HT-rich, or both CT- and HT-rich, extracts were significantly more lethal to adult C. elegans than extracts containing only CT. All extracts were high in antioxidant capacity, with ORAC values ranging from 1800 μmoles to 4651 μmoles of trolox equivalents/g, but ORAC did not correlate with anthelmintic activity. The total phenolics test had a positive and highly significant (r=0.826, p ≤ 0.01) correlation with total hydrolyzable tannins. Plants used in this research are naturalized to the Appalachian edaphoclimatic conditions, but occur in temperate climate areas worldwide. They represent a rich, renewable, and unexplored source of tannins and antioxidants for grazing ruminants, whereas conventional CT-rich forages, such as L. cuneata, may be hard to establish and adapt to areas with temperate climate. Due to their high in vitro anthelmintic activity, antioxidant capacity, and their adaptability to non-arable lands, Q. alba, R. typhina, A. rubrum, and R. multiflora have a high potential to improve the health of grazing animals and must have their anthelmintic effects confirmed in vivo in both sheep and goats.

Artemisia annua is mostly known as the source of artemisinin, the raw material for the production of artemisinin-based combination therapy, used against drug-resistant Plasmodium falciparum where malaria is endemic. Artemisinin is also effective against helminthic and protozoan parasites that afflict both humans and livestock. Besides being the only commercial source of artemisinin, the plant contains a pleasantly aromatic essential oil valued in perfumery and cosmetics. However, multi-use of the leaf biomass for the production of artemisinin, essential oil, and antioxidants has never been investigated. The objectives of this research were to evaluate the effect of distillation time of A. annua biomass on essential oil yield, artemisinin concentration, and antioxidant capacity of the plant residue from distillation (PRD). Results demonstrated that leaf biomass can be explored for both essential oil and as a source of antioxidants, but the PRD is devoid of artemisinin. The high antioxidant capacity of the PRD (75% of the control samples) suggests that the industrial byproduct used to produce the essential oil is also a potential source of antioxidants for use as a livestock feed supplement or as a source of compounds for the nutraceuticals market.

Natural polyphenols may play an important role in aluminum detoxification in some plants. We examined the interaction between Al(3+) and the purified high molecular weight polyphenols pentagalloyl glucose (940 Da) and oenothein B (1568 Da), and the related compound methyl gallate (184 Da) at pH 4 and 6. We used spectrophotometric titration and chemometric modeling to determine stability constants and stoichiometries for the aluminum-phenol (AlL) complexes. The structures and spectral features of aluminum-methyl gallate complexes were evaluated with quantum chemical calculations. The high molecular weight polyphenols formed Al3L2 complexes with conditional stability constants (β) ∼ 1 × 10(23) at pH 6 and AlL complexes with β ∼ 1 × 10(5) at pH 4. Methyl gallate formed AlL complexes with β = 1 × 10(6) at pH 6 but did not complex aluminum at pH 4. At intermediate metal-to-polyphenol ratios, high molecular weight polyphenols formed insoluble Al complexes but methyl gallate complexes were soluble. The high molecular weight polyphenols have high affinities and solubility features that are favorable for a role in aluminum detoxification in the environment.

The presence of antibiotics in agroecosystems raises concerns about the proliferation of antibiotic-resistant bacteria and adverse effects to human health. Soil amendment with biochars pyrolized from manures may be a win-win strategy for novel manure management and antibiotics abatement. In this study, lincomycin sorption by manure-derived biochars was examined using batch sorption experiments. Lincomycin sorption was characterized by two-stage kinetics with fast sorption reaching quasi-equilibrium in the first 2 d, followed by slow sorption over 180 d. The fast sorption was primarily attributed to surface adsorption, whereas the long-term slow sorption was controlled by slow diffusion of lincomycin into biochar pore structures. Two-day sorption experiments were performed to explore effects of biochar particle size, solid/water ratio, solution pH, and ionic strength. Lincomycin sorption to biochars was greater at solution pH 6.0 to 7.5 below the dissociation constant of lincomycin (7.6) than at pH 9.9 to 10.4 above its dissociation constant. The enhanced lincomycin sorption at lower pH likely resulted from electrostatic attraction between the positively charged lincomycin and the negatively charged biochar surfaces. This was corroborated by the observation that lincomycin sorption decreased with increasing ionic strength at lower pH (6.7) but remained constant at higher pH (10). The long-term lincomycin sequestration by biochars was largely due to pore diffusion plausibly independent of solution pH and ionic composition. Therefore, manure-derived biochars had lasting lincomycin sequestration capacity, implying that biochar soil amendment could significantly affect the distribution, transport, and bioavailability of lincomycin in agroecosystems.

Acid weathered soils often require lime and fertilizer application to overcome nutrient deficiencies and metal toxicity to increase soil productivity. Slow-pyrolysis chicken manure biochars, produced at 350 and 700°C with and without subsequent steam activation, were evaluated in an incubation study as soil amendments for a representative acid and highly weathered soil from Appalachia. Biochars were mixed at 5, 10, 20, and 40 g kg into a Gilpin soil (fine-loamy, mixed, active, mesic Typic Hapludult) and incubated in a climate-controlled chamber for 8 wk, along with a nonamended control and soil amended with agronomic dolomitic lime (AgLime). At the end of the incubation, soil pH, nutrient availability (by Mehlich-3 and ammonium bicarbonate diethylene triamine pentaacetic acid [AB-DTPA] extractions), and soil leachate composition were evaluated. Biochar effect on soil pH was process- and rate-dependent. Biochar increased soil pH from 4.8 to 6.6 at the high application rate (40 g kg), but was less effective than AgLime. Biochar produced at 350°C without activation had the least effect on soil pH. Biochar increased soil Mehlich-3 extractable micro- and macronutrients. On the basis of unit element applied, increase in pyrolysis temperature and biochar activation decreased availability of K, P, and S compared to nonactivated biochar produced at 350°C. Activated biochars reduced AB-DTPA extractable Al and Cd more than AgLime. Biochar did not increase NO in leachate, but increased dissolved organic carbon, total N and P, PO, SO, and K at high application rate (40 g kg). Risks of elevated levels of dissolved P may limit chicken manure biochar application rate. Applied at low rates, these biochars provide added nutritional value with low adverse impact on leachate composition.

We investigated tannin–soil interactions by assessing the kinetics of sorption and sorption capacities, and their relationship to the chemical properties of six polyphenolic compounds and the textures of six soils. We developed a new extraction procedure for recovering tannins from soil samples by successive extraction with solvents of decreasing polarity. Sorption of polyphenolic compounds methyl gallate, catechin, oenothein B, pentagalloyl glucose, epigallocatechin gallate, and procyanidin dimer was determined using six soils with textures ranging from 7% silt–89% sand to 52% silt–22% sand. Sorption kinetics and capacity of the soils were determined using room temperature mixing with high performance liquid chromatography (HPLC) to determine polyphenol concentration. Tannins were extracted from soils loaded with known amounts of the model compounds using solvents with a range of polarities, and establishing recovery by HPLC. Multivariable regression was used to establish relationships between polyphenol properties and sorption, and between soil texture and sorption. Sorption of the polyphenols followed the Langmuir isotherm with unique binding capacity and kinetics of sorption for each compound. Tannin sorption was correlated to molecular weight and polarity. For an Ultisol pasture soil, up to 18.7 mg g−1 soil of the large, hydrophobic compound epigallocatechin gallate was bound compared to only 5.11 mg g−1 soil of the smaller, more polar compound methyl gallate. Kinetics of sorption also varied with sorption reaching equilibrium between 75 and 350 min. Silt and sand composition affected polyphenol sorption in a unique fashion for each polyphenol. Using sequential extraction with solvents ranging from polar (water) to non-polar (hexane), we extracted up to 42% of the material that had been loaded on the soil as a mixture of five polyphenols. This work demonstrates that the likely fate of tannins and related polyphenols from plant sources is rapid sorption, with little likelihood of release of unmodified tannins from the soil by leaching. Tight sorption impedes recovery and analysis of soil tannins, but better methods for extraction may improve our knowledge of tannins in the soil.

Retention of tannins, produced by plants, could be important for managing soil organic matter and nutrient cycling. However, we know little about the comparative retention of different classes of tannins and related compounds or if soils have a maximum storage capacity for them. To address these questions, forest, and pasture loam soils, collected at 0–5 cm (surface) and 10–20 cm (subsurface), were repeatedly treated with water (Control) or solutions containing condensed and hydrolyzable tannins or related phenolic subunits (10 mg g−1 soil). Treatments included a polymeric flavonoid-based procyanidin from sorghum, catechin, tannic acid, β-1,2,3,4,6-penta-O-galloyl- d -glucose (PGG), gallic acid, and methyl gallate. After each application, soluble-C in supernatants was determined by oxidative-combustion infrared analysis and retention of treatment-carbon by soil was calculated as the difference between added and recovered soluble-C. An interaction between soil depth and treatment was evident through all applications with highest retention of both hydrophobic (PGG) and hydrophilic (procyanidin) tannins, compared to other phenolic compounds. For all treatments except gallic acid and methyl gallate, higher sorption occurred in surface soil, which contained more organic matter than subsurface soil. With each successive application, less additional treatment-C was retained by soil and the amount of C remaining in supernatants was correlated with the presence of phenolic substances. Cumulative retention by surface soil was more than 10.3, 8.5 and 6.4 mg C g−1 soil for PGG, tannic acid, and procyanidin, several times higher than the other compounds. Soluble-C extracted from treated soil, with cool water (23 °C), was 1–2 orders of magnitude greater than Control samples and highly correlated with Prussian Blue (PB) phenolics, indicating some retained treatment-C was only weakly held on the soil. The final extraction, with hot water (80 °C), removed more soluble-C, particularly from surface samples, that contained fewer PB phenolics per unit soluble-C than cool water extracts. After all extractions more than 85% of sorbed procyanidin-C was retained by samples compared to 81% of methyl gallate, 79% of PGG, 74% of tannic acid, 50% of catechin, and 40% of the gallic acid. Total C, measured in soil after all extractions, was close to expected values, confirming tannins and phenolic compounds had remained in soil and were not otherwise lost. Cation exchange capacity was increased about 30% in subsurface and forest samples by PGG, a hydrolyzable tannin, but decreased by 30% and 35% in surface and pasture soil, respectively, by its monomer, gallic acid.

Some tannins, plant-derived polyphenolic compounds, can rapidly affix to soil and affect the solubility of labile soil-N but a more complete understanding of the nature and persistence of tannin-soil interactions is needed. Forest and pasture soils from two depths were treated for 1 h with cool (23 °C) water (Control) or solutions that added 10 mg g−1 soil tannic acid (TA), an imprecisely defined mixture of galloyl esters, gallic acid (GA), a phenol, or β-1,2,3,4,6-penta-O-galloyl- d -glucose (PGG), a hydrolyzable tannin. Soluble-C and N, in treatment supernatants, was measured to uncover evidence for sorption of treatments or effects on extraction of soil-N. Significant amounts of soluble-C, added with treatments, were not recovered in supernatants indicating sorption of nearly 90% of the PGG-C, about 75% of the TA-C but less than 25% of the GA-C in surface soil. Disappearance of soluble-C from treatment supernatants was accompanied by a corresponding reduction of total phenolic content. Treatments added a negligible amount of N to soil; but while PGG and TA reduced soluble-N, in extracts from surface soil, GA had little effect. Soluble-N in extracts was composed mainly of organic-N. Effects of tannins persisted in surface soil through 12 washings with hot water (80 °C), suggesting the formation of stable complexes with soil. The proportion of initial soil-C and N remaining after all extractions was higher in samples treated with PGG or TA than either the Control or GA treatment. We conclude PGG readily sorbs to soil and reduces the solubility of soil organic-N unlike GA, its simple monomeric constituent. These differences could be especially important near the surface where quantities of soil organic matter and biological activity are comparatively large and most easily affected by management.

Introduction Although high-performance liquid chromatography with ultraviolet detection (HPLC-PAD) is widely available, it has not been used for artemisinin (1) analysis because of the lack of UV absorption reported for this lactone. Increased Artemisia annua cultivation for production of 1 requires an affordable and reliable method to analyse 1 and its precursors dihydroartemisinic acid (2) and artemisinic acid (3) simultaneously from underivatized plant extracts. Objective To validate HPLC-PAD for the quantification of underivatized artemisinin from A. annua and artemisinin-based drugs. Methodology Dried A. annua leaves were extracted with petroleum ether, dried, reconstituted in acetonitrile, and analysed by HPLC-PAD at 192 nm using an isocratic mobile phase (60:40, acetonitrile:0.1% acetic acid). HPLC-PAD was evaluated through accuracy, precision, recovery and comparison with HPLC with evaporative light scattering detection (HPLC-ELSD). Results HPLC-PAD proved accurate, precise and reproducible for the direct quantification of 1 and related compounds, and was more sensitive than ELSD for most of the compounds tested. The limit of quantification of 1–3 from plants was 0.048, 0.024 and 0.008 g/100 g dry weight, respectively. Recoveries were over 98%, with good intra- and inter-day repeatability. HPLC-PAD correlated significantly (r2 = 0.99, p

Differences in soil properties between forests and pastures have been well documented in the literature, especially under coniferous forests. However, since nearly all of these reports have been time-point comparisons, utilizing long-term paired-sites, properties of transitional states and time of their appearance can only be inferred at present. In this study, a deciduous forest ecosystem was converted to a silvopasture ecosystem by tree thinning, fertilization, and sheep incorporation of seed and forest litter. After 2 years, topsoil (0–15 cm) physico-chemical properties, particularly P fractions, and phosphatases were monitored over the growing season in these ecosystems, and a nearby pasture ecosystem. Initially, before spring vegetative growth, differences were found for pH, exchangeable cations and soil moisture, most of which could be explained by management history. Compared to forest, organic-C (Co) and organic-N (No) concentrations were reduced in silvopasture by 17 and 9%, respectively, indicative of substantial litter decomposition. Most values for all these physico-chemical properties for silvopasture were intermediate between forest and pasture, and generally remained so throughout the growing season. Initial total P (TPt), organic-P (TPo) and inorganic-P (TPi) concentrations were generally as anticipated for the forest and pasture. Silvopasture, however, had 36 and 23% greater TPo than forest and pasture, respectively, presumably due to fertilizer-P immobilization induced by incorporation of forest litter. Total P components remained essentially constant over the growing season in all ecosystems, with the exception of pasture, likely due to high forage TPi uptake. Bray I-extractable-organic-P (BrPo) and bicarbonate-extractable-organic-P (BiPo) concentrations, although consistently highest in the forest and silvopasture soils, were not reflective of the increase in TPo under silvopasture. Acid phosphatase (PMEac) activities were highest in spring in all the ecosystems, then gradually declined to typically 25–50% initial activities. Alkaline phosphatase (PMEal) activities showed a broadly-similar pattern, with exception of forest and silvopasture soils, which exhibited low activities throughout the season. For the entire data set, PMEac and PMEal activities were poorly correlated with TPi, BrPi, and BiPi. These results demonstrate that conversion of forest to silvopasture results in soil changes indicative of its rapid transition to pasture and that an increased Po reservoir results that should be taken into account in fertilizer-P recommendations for temperate silvopastures.

Tannins are plant-derived polyphenolic compounds that precipitate proteins, bind to metals and complex with other compounds. Solutions of tannic acid, or other phenolic compounds, were added to soil samples to determine if they would affect recovery of soluble soil carbon (WSC) or –nitrogen (WSN) or influence the extraction and composition of Bradford-reactive soil protein (BRSP), associated with glomalin. Tannic acid-C added with water was not completely recovered from samples and the amount of total net WSC and WSN recovered was reduced, suggesting formation of insoluble complexes. By comparison, non-tannin phenolics like gallic acid, or methyl gallate, had little effect on extraction of WSC or WSN while a simple gallotannin derived from tannic acid, 1,2,3,4,6-penta- O -galloyl- d -glucose (PGG), inhibited extraction most. The C and N concentrations in BRSP increased when soil samples were treated with tannic acid or PGG before extraction, a procedure that includes autoclaving. Increases were greatest in the 10–20 cm compared to 0–5 cm depth. Accompanying these were declines in the ratio of absorbance at 465 and 665 nm ( E 4/ E 6 ratio) of BRSP extracts suggesting formation of larger or heavier molecules. In contrast, C and N composition in lyophilized BRSP was unaffected or even slightly reduced when tannic acid or PGG were added to the BRSP extract solution after the extraction process. We conclude that some tannins can reduce the solubility of labile soil C and N, at least temporarily and given unpredictability of response associated with phenolic substances, the Bradford assay should not be relied on to quantify pools or composition of soil proteins like glomalin.

Some generics of antibacterials fail therapeutic equivalence despite being pharmaceutical equivalents of their innovators, but data are scarce with antifungals. We used the neutropenic mice model of disseminated candidiasis to challenge the therapeutic equivalence of three generic products of fluconazole compared with the innovator in terms of concentration of the active pharmaceutical ingredient, analytical chemistry (liquid chromatography/mass spectrometry), in vitro susceptibility testing, single-dose serum pharmacokinetics in infected mice, and in vivo pharmacodynamics. Neutropenic, five week-old, murine pathogen free male mice of the strain Udea:ICR(CD-2) were injected in the tail vein with Candida albicans GRP-0144 (MIC = 0.25 mg/L) or Candida albicans CIB-19177 (MIC = 4 mg/L). Subcutaneous therapy with fluconazole (generics or innovator) and sterile saline (untreated controls) started 2 h after infection and ended 24 h later, with doses ranging from no effect to maximal effect (1 to 128 mg/kg per day) divided every 3 or 6 hours. The Hill's model was fitted to the data by nonlinear regression, and results from each group compared by curve fitting analysis. All products were identical in terms of concentration, chromatographic and spectrographic profiles, MICs, mouse pharmacokinetics, and in vivo pharmacodynamic parameters. In conclusion, the generic products studied were pharmaceutically and therapeutically equivalent to the innovator of fluconazole.

Bradford reactive soil protein (BRSP) is thought to correlate to glomalin, an important soil glycoprotein that promotes soil aggregate formation and may represent a significant pool of stable soil organic matter (SOM). However, more information is needed about its importance in Appalachian soils and its relationships with other soil properties. We measured BRSP in 0-20 cm soil from pastures, hayfields, cultivated fields or forest areas in southern West Virginia. Highest amounts of BRSP were found near the soil sur- face and decreased significantly with depth for all land uses except cultivated sites. Forest and pas- ture sites contained more BRSP than hayfields or cultivated fields but these differences occurred only in the 0-5 cm depth. Overall averages of C and N in BRSP represented about 4.0 and 6.5% of the total soil C and N respectively. During a 395 day soil incubation, we found CO2-C evolu- tion rates comparable to other studies but only small changes in BRSP ( < 10%) including some evidence for increases during incubation. Sodium citrate, sodium pyrophosphate, and sodium oxa- late recovered significantly more BRSP from soil than the other extractants we tested with highest extraction efficiencies observed for sodium citrate and pyrophosphate. Recovery of BRSP appears related to negative charge and buffering capacity of both the soil and extractant. Extractants with low negative charge had little buffering capacity and yielded little BRSP. Tannic acid appeared to increase extraction of BRSP but less soluble-N was recovered from tannin-treated samples than from untreated controls and E4/E6, the ratio of absorbance at 465 and 665 nm, decreased, evi- dence for the formation of larger or heavier molecules. Formation of dark-colored substances during extraction suggests the colorimetric Brad- ford assay may overestimate soil protein when tannins are present. Recovery of less soluble-N from soil extracts and lower E4/E6 ratios suggests tannins may bind with soil constituents them- selves or form non-extractable N-containing complexes.

The objective of this study was to determine whether smectites abiotically catalyze transformation of glucose under conditions relevant to soil organic matter (SOM) formation. Four smectites saturated with Na, Ca, Fe and Al were incubated under abiotic conditions with glucose solutions for 21 days at 37°C. After the incubations, soluble organic C recoveries ranged from 95 to 109.3%, relative to the amount of C added as glucose; however, glucose recoveries in the solutions ranged from 18.3 to 98.3%. The results indicate that a significant amount of the added glucose was abiotically transformed to soluble organic compounds other than glucose during the incubations. In general, glucose recoveries decreased with the acidic character of smectites: SWa-1 > Panther > Otay. Also, within clays, glucose recoveries decreased as the exchangeable cation became more acidic: Na > Ca > Al. Higher glucose recoveries were obtained for 'Fe-rich' smectites relative to 'Fe-poor' smectites, suggesting that Fe-oxyhydroxy coatings on smectite surfaces inhibit the transformation of glucose. High-pressure liquid chromatography analysis of the incubation solutions revealed small peaks for 5-(hydroxymethyl)-2-furaldehyde along with peaks for other unknown compounds. The results suggest that under conditions similar to those found in soils, smectites catalyze glucose dehydration to form furfural compounds. Polymerization of furfural compounds may be a major pathway leading to the formation of new humic materials in soils.

The polyphenol theory of humic-substance formation has been studied extensively; however, an alternative theory, that humic substances are formed through the condensation of amino acids and reducing sugars (Maillard reaction), has not been explored to the same extent. The general objectives of this study were to determine whether smectites and goethites catalyze the abiotic polymerization of arginine and glucose to form humic-like compounds. The effects of smectite type, saturating cation, and the degree of Al substitution in goethites on the polymerization reaction were also studied. Four cation-saturated smectites and four Al-substituted goethites were incubated abiotically with solutions containing a mixture of arginine + glucose for 21 days at 37°C. After the incubations, total C recovered ranged from 80.6 to 123.8% and from 100.5 to 105.1% for the smectite and goethite systems, respectively. At the end of the incubations, 21.4–50.3% of the added C and 16.5–90% of the added N were sorbed on the various smectites, and 6.2–9.0% of the added C and 2.3–4.6% of added N was sorbed on the goethites in a form that could not be desorbed by washing with 100 mM CaCl2. X-ray diffraction analysis indicated that some of the sorbed C was intercalated in the smectites and FTIR analysis provided evidence of new absorption bands at 1650 and 1668 cm−1, which are consistent with Maillard reaction products. Thus, it is concluded that smectites catalyze the condensation of arginine and glucose to form humic-like products. Goethites, however, have little or no ability to catalyze this reaction.

An understanding of organic C dynamics in soils is necessary to develop management options to enhance soil organic C sequestration. The objective of this research was to study the distribution of newly formed humic materials into mineralogically distinct clay-size fractions of a silt loam soil. Oats (Avena sativa L. cv. Ogle), grown under simulated no-tillage conditions, were pulse labeled with 14 CO 2 . After senescence, the labeled surface residue was removed and replaced with unlabeled residue and the labeled roots were allowed to decompose in the soil for 360 d. The soil clay fraction (

Nicosulfuron (2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide is a relatively new sulfonylurea promoted for weed control in corn (Zea mays L.). However, there are no published studies on its transport and mobility in soils. In this study, breakthrough curves (BTCs) were measured using soil columns for eight Iowa soils and four Oxisols from Brazil. Chloride (Cl ) and pentafluorobenzoic acid (PFBA) were used as nonreactive tracers. For the sandy Iowa soils and the Brazilian soils BTCs were symmetrical, while for the nonsandy Iowa soils BTCs were asymmetrical. Breakthrough curves were interpreted using convection-dispersion equation and equilibrium and nonequilibrium transport models. In Brazilian soils and sandy Iowa soils equilibrium models described the BTCs well. In nonsandy Iowa soils, where tailing was observed, the data were better described by a two-site/ two-region model, indicative of nonequilibrium processes. A comparison with the Cl and PFBA BTCs suggests that the nonequilibrium is not transport-related. This is also supported by the low correlation between the mass transfer parameters and the partition coefficients. It is proposed that the observed nonequilibrium in nonsandy Iowa soils is most likely due to nicosulfuron chemisorption on smectites. The results of this study indicate that due to rapid sorption of nicosulfuron on smectites its potential to leach to the groundwater should be relatively low in the loamy and clayey soils that contain expandable 2:1 layer silicates.

Nicosulforon (2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide) is a new, low-rate, sulfonylurea herbidde that is being promoted for weed control in corn (Zea mays L.) ; however, there is a lack of published information on its behavior in soils. In this study nicosulfuron sorption was measured in batch experiments, at a 1 :2 soil/solution ratio, for 10 Iowa and four Brazilian soils. Adsorption isotherms were nonlinear with K t,ads values ranging from 0.21 to 8.78 with the highest values obtained for Iowa soils. Nicosulfuron K t,ads values in Iowa soils were correlated with clay content (r = 0.92), while in Brazilian soils the K t,ads values were correlated with organic C content (r = 0.97). These differences are interpreted in terms of different clay mineralogy of Iowa (expandable 2 :1 clay minerals) and Brazilian soils (kaolinite, Al and Fe oxides). Nicosulfuron desorption isotherms, obtained using one-step extraction with 5 x 10 -3 M CaCl 2 , were nearly single valued with adsorption isotherms in soils with pH >5.5, while hysteresis was observed in soils with pH < 5.5. Up to 100% of the nicosulfuron was desorbed from Brazilian soils in one desorption step with a 2 :1 acetonitrile/water mixture. Only 50 to 70% of adsorbed nicosulfuron could be desorbed with the same extractant from Iowa soils, possibly due to chemisorption of nicosulfuron on 2 :1 clay minerals. This study suggests that nicosulfuron will not be highly mobile in the soils with a 2 :1 clay mineralogy indicating that in such soils its potential to leach to groundwater may be lower than that of other sulfonylurea herbicides.