bluuebunny/crossref_metadata_2025 huggingface dataset:
No‐Till Row Crop Response to Starter Fertilizer in Eastern Nebraska: I. Irrigated and Rainfed Corn
Authors: Wortmann C. S. , Xerinda S. A. , Mamo M. , Shapiro C. A.
Published: January 2006

Early corn (Zea mays L.) growth is often slowed by cool soil temperatures in no‐till production systems. This inhibitory effect may be reduced through use of starter fertilizer and result in increased grain yield, but research findings have been inconsistent. Field research was conducted in four counties of eastern Nebraska to determine the probability and magnitude of corn response to starter fertilizer under varying field conditions for different combinations of nutrients and placement methods. Soils at trial sites included Typic Eutrudepts, Udic Ustorthents, and several Mollisols. Placements of N + P and N + P + S in‐furrow, over‐the‐row, and 50×50 mm were compared for effects on early growth and grain yield. Early growth was increased with starter fertilizer by 30% over all irrigated trials and by 10% for three of five responsive rainfed trials. In the irrigated trials, starter fertilizer increased grain yield by 0.86 Mg ha−1. Starter fertilizer had a minimal effect on grain yield in rainfed trials. Including S in the starter fertilizer did not result in increased yield. In‐furrow and over‐the‐row were as effective as 50 × 50 mm placement in increasing yield. Grain yield response to starter fertilizer was greatest and most profitable with irrigated corn produced under low soil test P (STP ≤ 15 mg kg−1) conditions. Conversion of early growth response into yield response to starter fertilizer appears to depend on soil water availability and on STP.
No‐Till Row Crop Response to Starter Fertilizer in Eastern Nebraska II. Rainfed Grain Sorghum
Authors: Wortmann C. S. , Xerinda S. A. , Mamo M.
Published: January 2006

Early grain sorghum [Sorghum bicolor (L.) Moench] plant growth is often slowed by cool soil temperatures in no‐till production systems. This inhibitory effect may be reduced through use of starter fertilizer with a grain yield response. Twelve trials were conducted in southeastern Nebraska to determine sorghum response to different starter fertilizer nutrient combinations and placement methods at different topographic positions within locations. Soil orders at trial sites included Mollisols, Alfisols, and an Entisol. Placements of N + P and N + P + S in furrow, over the row, and 50 mm deep and 50 mm to the side of the seed (50 by 50 mm) were compared for effects on early growth, grain yield, and grain water content. Treatment by topographic position interaction effects occurred at one location for early growth and grain water content and at three locations for yield. The mean effect of starter fertilizer treatments was a 48% increase in early growth in five of seven trials with low soil test P (STP; Bray‐P1 ≤ 15 mg kg−1); however, yield and grain water content responses to starter were not related to STP. Including S in the starter fertilizer did not increase yield. Placement effects were not consistently significant. The frequency and magnitude of no‐till grain sorghum response to starter fertilizer were not sufficient for starter fertilizer use to be profitable, irrespective of STP and topographic position.
Integrated Use of Tebuconazole and Fusarium Head Blight–Resistant Barley Genotypes
Authors: Horsley R. D. , Pederson J. D. , Schwarz P. B. , McKay K. , Hochhalter M. R. , McMullen M. P.
Published: January 2006

All malting barley (Hordeum vulgare L.) cultivars adapted for production in the upper midwestern USA are susceptible to Fusarium head blight (FHB), incited primarily by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein)]. Quality of FHB‐infected barley is reduced due to a mycotoxin called deoxynivalenol (DON) that is produced by the pathogen. Malting barley buyers severely discount or refuse to purchase barley with DON concentrations >0.5 mg kg−1. Individually, use of genetic resistance or fungicides has not successfully reduced DON concentrations to acceptable limits. The objective of this research was to determine if the integrated use of the fungicide tebuconazole (α‐[2‐(4‐chlorophenyl) ethyl]‐α‐(1,1‐dimethylethyl)‐1H‐1,2,4‐triazole‐1‐ethanol) and barley genotypes with partial FHB resistance could reduce DON to acceptable concentrations. Field research, using two rates of tebuconazole (0 and 118 mL a.i. ha−1) and 13 barley genotypes with varying levels of FHB resistance, was conducted in North Dakota from 2000 to 2002. No supplemental inoculum or irrigation was used in any of the environments. Data for FHB severity, DON concentration, foliar disease severity, and kernel color were collected and analyzed. Deoxynivalenol was detected in all environments at concentrations >0.5 mg kg−1. Overall, the response of the FHB‐resistant and moderately resistant genotypes to tebuconazole was inconsistent for FHB severity and DON accumulation. Furthermore, tebuconazole applied to FHB‐resistant or moderately resistant genotype did not consistently result in DON concentration of ≤0.5 mg kg−1 in any of the environments. Thus, the integrated use of FHB‐resistant or moderately resistant genotypes and tebuconazole will not reduce DON.
Adaptation of the Biological Simulation Model MAESTRA for Use in a Generic User Interface
Authors: Bauerle William L. , Timlin Dennis J. , Pachepsky Yakov A. , Anantharamu Shruthi
Published: January 2006

Application of process‐based models beyond the research community has been limited, in part because they do not operate in an intuitive graphical user‐friendly environment. This article describes the procedure of adapting a spatially explicit biological‐process model, MAESTRA (Multi‐Array Evaporation Stand Tree Radiation A), to run in a standard graphical user interface (GUI). The methods used to adapt the MAESTRA model are generally applicable to other individual tree process‐based models and, therefore, should simplify other coupling attempts. The three primary changes to MAESTRA were the placement of the MAESTRA code inside a Microsoft Windows API (application programming interface) function called WINMAIN, rearrangement of the input file structure to fit the hierarchical file structure used by the Graphical User Interface for Crop Simulations (GUICS), and the addition of iteration counters to read array‐based data read for each array within the MAESTRA input files. The procedure of adapting MAESTRA's input structure and interface design should allow other forest stand process‐based models to work within GUICS.
Within‐Field Variation in Corn Yield and Grain Quality Responses to Nitrogen Fertilization and Hybrid Selection
Authors: Miao Yuxin , Mulla David J. , Robert Pierre C. , Hernandez Jose A.
Published: January 2006

This study was conducted in Paris, IL, from 2001 to 2003 involving three corn (Zea mays L.) hybrids, five N rates (0, 112, 168, 224, and 336 kg ha−1), and six site‐year comparisons to determine the significance of within‐field variation in corn yield and quality responses to N fertilization, differences between hybrids in yield and quality, and the feasibility of within‐field variable hybrid selection. On average, N fertilization significantly increased corn yield, protein content, and test weight, but decreased corn oil and starch content. The overall economically optimum nitrogen rate (EONR) was 125 kg ha−1, but EONR varied from 93 to 195 kg ha−1 in different environments. The N rates that would maximize protein content and test weight (MAXN) varied from 143 to 303 kg ha−1 and 0 to 235 kg ha−1 in different environments, respectively. Significant within‐field variability in N response was detected in five of six environments for yield, but not in more than two environments for any quality parameter. Hybrid differences were significant in all six environments for test weight, followed by oil content (five), protein and starch content (four), and yield (three). Hybrid differences between 33G26 and 33J24 in test weight response to N were consistent across environments, showing the potential of hybrid‐specific N management for this quality parameter. However, hybrid differences in yield and quality did not vary significantly over space in most environments, showing limited potential of within‐field variable hybrid selection. Further studies involving more diverse within‐field soil–landscape conditions and hybrids are needed.
Growth, Yield, Quality, and Economics of Corn Silage under Different Row Spacings
Authors: Cox William J. , Hanchar John J. , Knoblauch Wayne A. , Cherney Jerome H.
Published: January 2006

Corn (Zea mays L.) silage in the northeastern USA yields more in narrow (0.38 m) than conventional (0.76 m) rows. Dairy producers, however, have considered converting from conventional to twin rows (0.19 m on 0.76 m centers) because twin rows are more compatible than narrow rows for herbicide application on glyphosate‐resistant corn. Two hybrids were planted in field‐scale studies in New York in 2003 and 2004 to evaluate growth, yield, quality, and economics of corn silage under conventional, narrow, and twin row production systems. Narrow rows had greater dry matter yield (17.6 Mg ha−1) than twin (17.2 Mg ha−1) and conventional rows (16.6 Mg ha−1). Row spacing did not affect in vitro true digestibility. Narrow and twin rows had greater fixed and variable costs associated with equipment requirements. Partial budget analyses indicated greater expected increases in annual profit with the conversion from conventional to narrow rows for 262 ($18 201) and 525 ha ($38 317) or to twin rows for 262 ($8246) and 525 ha ($17 584) of corn silage. The use of glyphosate‐resistant corn in twin rows may provide an advantage by delaying herbicide application until mid‐June, thereby increasing the probability of a timely first harvest of perennial forages. Dry matter content at harvest averaged 326 g kg−1 in narrow versus 314 g kg−1 in twin rows, increasing the probability of corn silage harvest before a fall frost. Dairy producers should consider economics and timely harvests when considering corn silage row‐spacing systems.
Phosphorus Seed Coating Enhancement on Early Growth and Yield Components in Oat
Authors: Peltonen‐Sainio Pirjo , Kontturi Markku , Peltonen Jari
Published: January 2006

Availability of P reserves for seedling growth in germinating oat (Avena sativa L.) grain is likely to be reduced in comparison with that in other temperate cereals. Environmental concerns have resulted in reduced P and N fertilizer application, which may, with transformation of P into unavailable forms in soil, result in suboptimal P availability especially at seedling growth. A field experiment was arranged with oat cultivars (Belinda, Fiia, and Salo) in main plots and P seed coating in subplots. The experiment was done in 2003 and 2004 at two locations in Finland that differed in soil type and were all low in soil P content. A third experiment also having low soil P content included three cultivation methods (1, control, with 80 kg N and 18 kg P ha−1 and herbicide application; 2, 80 kg N and 18 kg P ha−1 and herbicide application, supplemented with 40 kg sulfur (S) ha−1; and 3, 80 kg N and 18 kg P ha−1 and herbicide application, supplemented with 40 kg S ha−1 and fungicide application). It was sown with two oat cultivars (Belinda and Fiia) with and without P seed coating. Seedling emergence, biomass accumulation, relative growth rate, growth duration, grain yield, and 20 plant stand structure traits were measured. Seed coating with P resulted in alterations to many of the recorded plant stand structure traits. All significant changes represented improvements over the control. The effect, however, changed depending on experiment, location, cultivation method, and cultivar. Most often, enhanced biomass accumulation (up to 22%) and grain set (up to 15%) occurred. This was not, however, associated with increased grain yield in any of the experiments, even in cases where biomass and grain yield per unit area were increased by P coating. Small kernels were probably lost during harvest, as in most cases grain weight of hand‐threshed samples was lower (by 8% in average) than that in harvested yield. In conclusion, P seed coating promoted early oat growth without increasing economic yield.
Site‐Specific Irrigation and Nitrogen Management for Cotton Production in the Southern High Plains
Authors: Bronson K. F. , Booker J. D. , Bordovsky J. P. , Keeling J. W. , Wheeler T. A. , Boman R. K. , Parajulee M. N. , Segarra E. , Nichols R. L.
Published: January 2006

Upland cotton (Gossypium hirsutum L.) production in the Southern High Plains is usually limited by water and N. The most prevalent means of irrigation in this region is center‐pivot, and injection and/or ground application of liquid urea ammonium nitrate is the most common N management. The declining Ogallala aquifer has led to interest in variable‐rate or variable‐speed irrigation using center pivots. Variability in yields, soil properties, and elevation within the typical 48‐ha center‐pivot fields suggests that N fertilizer use efficiency might be improved by variable‐rate N applications. We conducted a 3‐yr experiment on a 14‐ha area within a 48‐ha center pivot in a terminated‐rye (Secale cereale L.) conservation tillage cotton system. The objectives were to assess lint yield response to irrigation level for different landscape positions and to compare the effects of variable‐rate N, blanket‐rate N, and zero N on lint yields at varying irrigation levels and landscape positions. Lint yield response to irrigation was linear in 2002 and 2003. Increased rainfall in 2004 limited irrigation response. Contrary to our hypothesis, cotton lint yield response to irrigation was not less in the bottomslope than in the sideslopes. Nitrogen fertilizer resulted in greater lint yields in all 3 yr, but the magnitude of the response was less than that of irrigation in 2002 and 2003. Nitrogen response did not interact with landscape position or with irrigation rate. Variable‐rate N resulted in more consistent lint yield response than did blanket‐rate N in all years. However, when the costs of implementing variable‐rate management were considered, the dollar returns to N fertilizer were favorable for variable‐rate fertilization in only 1 of 3 yr.
Effects of Soil Type on Bermudagrass Response to Broiler Litter Application
Authors: Adeli A. , Rowe D. E. , Read J. J.
Published: January 2006

A greenhouse study was conducted to determine the effects of soil type on the response of ‘Russell’ bermudagrass [Cynodon dactylon(L.) Pers.] to broiler litter applications. Soils included Leeper clay loam (fine, smectitic, nonacid, thermic Vertic Epiaquept), Marietta silt loam (fine‐silty, mixed, active, thermic Oxyaquic Fraglossudalf), and Ruston sandy loam (fine‐loamy, siliceous, semiactive, thermic Typic Paleudult). The experimental design was a randomized complete block with a split plot arrangement of treatments replicated three times. Soil was used as main plot factor and broiler litter rates of 0, 4.6, 9.2, and 13.8 Mg ha−1equivalent to approximately 0, 175, 350, and 525 kg total N ha−1yr−1were considered as subplot. The changes in dry matter yield (DMY) decreased in the order of Ruston > Leeper > Marietta. Regardless of soil type, broiler litter rates > 350 kg total N ha−1did not increase DMY yield and nutrient uptake. Bermudagrass N concentration increased as broiler litter rate increased and the greatest value was recorded for Marietta soil, 24.2 g kg−1. The large DMY observed in Ruston soil diluted plant N concentration to about 23.7 g kg−1despite high percentage N recovery. Bermudagrass P concentration was not affected by either broiler litter rate or soil type. Bermudagrass K concentration increased as broiler litter rate increased and was greatest on Ruston soil (23.5 g kg−1). Recovery efficiency for N and K was approximately 60% greater in Ruston than in Marietta and Leeper soils and was reflected in residual soil NO3–N and P concentrations that decreased in the order of Marietta > Leeper > Ruston. Application of broiler litter to bermudagrass grown on the Ruston soil appears to be more sustainable.
Fate of Diuron and Linuron in a Field Lysimeter Experiment
Authors: Guzzella L. , Capri E. , Di Corcia A. , Barra Caracciolo A. , Giuliano G.
Published: January 2006

The environmental fate of herbicides can be studied at different levels: in the lab with disturbed or undisturbed soil columns or in the field with suction cup lysimeters or soil enclosure lysimeters. A field lysimeter experiment with 10 soil enclosures was performed to evaluate the mass balance in different environmental compartments of the phenylurea herbicides diuron [3‐(3,4‐diclorophenyl)‐1,1‐dimethyl‐urea] and linuron [3‐(3,4‐dichlorophenyl)‐1‐methoxy‐1‐methylurea]. After application on the agricultural soil, the herbicides were searched for in soil, pore water, and air samples. Soil and water samples were collected at different depths of the soil profile and analyzed to determine residual concentrations of both the parent compounds and of their main transformation products, to verify their persistence and their leaching capacity. Air volatilization was calculated using the theoretical profile shape method. The herbicides were detected only in the surface layer (0–10 cm) of soil. In this layer, diuron was reduced to 50% of its initial concentration at the end of the experiment, while linuron was still 70% present after 245 d. The main metabolites detected were DCPMU [3‐(3,4‐dichlorophenyl)‐1‐methylurea] and DCA (3,4‐dichloroaniline). In soil pore water, diuron and linuron were detected at depths of 20 and 40 cm, although in very low concentrations. Therefore the leaching of these herbicides was quite low in this experiment. Moreover, volatilization losses were inconsequential. The calculated total mass balance showed a high persistence of linuron and diuron in the soil, a low mobility in soil pore water (less than 0.5% in leachate water), and a negligible volatilization effect. The application of the Pesticide Leaching Model (PELMO) showed similar low mobility of the chemicals in soil and water, but overestimated their volatilization and their degradation to the metabolite DCPMU. In conclusion, the use of soil enclosure lysimeters proved to be a good experimental design for studying mobility and transport processes of herbicides in field conditions.
Ammonia Emissions from Swine Waste Lagoons in the Utah Great Basin
Authors: Harper Lowry A. , Weaver Kim H. , Dotson Richard A.
Published: January 2006

In animal production systems (poultry, beef, and swine), current production, storage, and disposal techniques present a challenge to manage wastes to minimize the emissions of trace gases within relatively small geographical areas. Physical and chemical parameters were measured on primary and secondary lagoons on three different swine farming systems, three replicates each, in the Central Great Basin of the United States to determine ammonia (NH3) emissions. Nutrient concentrations, lagoon water temperature, and micrometeorological data from these measurements were used with a published process model to calculate emissions. Annual cycling of emissions was determined in relation to climatic factors and wind speed was found the predominating factor when the lagoon temperatures were above about 3°C. Total NH3 emissions increased in the order of smallest to largest: nursery, sow, and finisher farms. However, emissions on an animal basis increased from nursery animals being lowest to sow animals being highest. When emissions were compared to the amount of nitrogen (N) fed to the animals, NH3 emissions from sows were lowest with emissions from finisher animals highest. Ammonia emissions were compared to similar farm production systems in the humid East of the United States and found to be similar for finisher animals but had much lower emissions than comparable humid East sow production. Published estimates of NH3 emissions from lagoons ranged from 36 to 70% of feed input (no error range) compared to our emissions determined from a process model of 9.8% with an estimated range of ±4%.
Phosphorus Fractions in Manure from Growing Pigs Receiving Diets Containing Micronized Peas and Supplemental Enzymes
Authors: Ige D. V. , Akinremi O. O. , Nyachoti C. M. , Guenter W.
Published: January 2006

Different livestock feeds manipulations have been reported to reduce the total P concentration in manure. Information on the influence of these dietary manipulation strategies on the forms of P in manure is, however, limited. This study was, therefore, conducted to investigate the effect of diet manipulation through feed micronization and enzyme supplementation on the forms of P in swine manure. Eight growing pigs were fed four diets: barley–raw pea (BRP), barley–micronized pea (BMP), barley–raw pea with enzyme (BRPE), and barley–micronized pea with enzyme (BMPE) in a 4 × 4 Latin square design. Because we are interested in the effect of enzyme cocktail and pea micronization on manure P, we did not reduce the non‐phytate P with enzyme addition in this study. The fecal material and urine were collected and analyzed for total P. Fecal material was fractionated to determine the total P in H2O‐, NaHCO3–, NaOH‐, and HCl‐extractable fractions. The total P in the residual fractions was also determined. About 98% of the total P excreted by the pigs was found in the fecal material. Inclusion of micronized pea in pig diet did not have any significant effect (p > 0.1) on either the total P or the different P fractions in the manure. The labile P (the sum of H2O‐P and NaHCO3–P) was significantly reduced (p < 0.05) by the addition of enzyme to swine diets. Pigs fed the BRPE and BMPE had 14 and 18% lower labile P, respectively, compared with pigs fed the BRP. Enzyme addition to pig diets reduced not only the total P in manure, but also the labile P fraction, which is of great environmental concern. Thus, the potential of P loss to runoff and the subsequent eutrophication can be reduced by enzyme addition to pig diets.
A Model for Linking the Effects of Parathion in Soil to its Degradation and Bioavailability Kinetics
Authors: Saffih‐Hdadi K. , Bruckler L. , Lafolie F. , Barriuso E.
Published: January 2006

Parathion is an insecticide of a group of highly toxic organophosphorus compounds. To investigate the dissipation and toxicological impact of parathion [O,O‐diethyl O‐(4‐nitrophenyl) phosphorothioate] and its highly toxic metabolite, paraoxon, soil laboratory experiments were conducted in columns during a 19‐d experiment under variably saturated conditions. Water and pesticide transport, sorption, and biodegradation of parathion were measured in three soil pools (soluble phase, weakly and strongly sorbed phases) using C‐labeled pesticide. The effects of parathion and its metabolite on the mobility of soil nematodes were observed and then modeled with an effective variable, which combined pesticide concentration and time of application. Results showed that parathion was highly sorbed and slowly degraded to a mixture of metabolites. The parent compound and its metabolites remained located in the top 0.06‐m soil layer. A kinetic model describing the sorption, biodegradation, and allocation into different soil pools of parathion and its metabolites was coupled with heat and water transport equations to predict the fate of parathion in soil. Simulated results were in agreement with experimental data, showing that the products remained in the upper soil layers even in the case of long‐term (11‐mo) simulation. The strongly sorbed fraction may be regarded as a pesticide reservoir that regularly provides pesticide to the weakly sorbed phase, and then, liquid phase, respectively. From both modeling and observations, no major toxicological damage of parathion and paraoxon to soil nematodes was found, although some effects on nematodes were possible, but at the soil surface only (0.01‐ and 0.02‐m depth).
Nitrogen and Phosphorus Leaching from Growing Season versus Year‐Round Application of Wastewater on Seasonally Frozen Lands
Authors: Zvomuya Francis , Rosen Carl J. , Gupta Satish C.
Published: January 2006

Land application of wastewater has become an important disposal option for food‐processing plants operating year‐round. However, there are concerns about nutrient leaching from winter wastewater application on frozen soils. In this study, P and N leaching were compared between nongrowing season application of tertiary‐treated wastewater plus growing season application of partially treated wastewater (NGS) vs. growing season application of partially treated wastewater (GS) containing high levels of soil P. As required by the Minnesota Pollution Control Agency (MPCA), the wastewater applied to the NGS fields during October through March was treated such that it contained ≤6 mg L−1 total phosphorus (TP), ≤10 mg L−1 NO3–N, and ≤20 mg L−1 total Kjeldahl nitrogen (TKN). The only regulation for wastewater application during the growing season (April through September) was that cumulatively it did not exceed the agronomic N requirements of the crop in any sprayfield. Application of tertiary‐treated wastewater during the nongrowing season plus partially treated wastewater during the growing season did not significantly increase NO3−N leaching compared with growing season application of nonregulated wastewater. However, median TP concentration in leachate was significantly higher from the NGS (3.56 mg L−1) than from the GS sprayfields (0.52 mg L−1) or nonirrigated sites (0.52 mg L−1). Median TP leaching loss was also significantly higher from the NGS sprayfields (57 kg ha−1) than from the GS (7.4 kg ha−1) or control sites (6.9 kg ha−1). This was mainly due to higher hydraulic loading from winter wastewater application and limited or no crop P uptake during winter. Results from this study indicate that winter application of even low P potato‐processing wastewater to high P soils can accelerate P leaching. We conclude that the regulation of winter wastewater application on frozen soils should be based on wastewater P concentration and permissible loading. We also recommend that winter irrigation should take soil P saturation into consideration.
Diuron in Surface Runoff and Tile Drainage from Two Grass‐Seed Fields
Authors: Rupp David E. , Peachey R. Edward , Warren Kristina L. , Selker John S.
Published: January 2006

The typical method of cool‐season grass‐seed production in Mediterranean climates briefly exposes surface waters to potentially high concentrations of the herbicide diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethyl urea] during the initial season of growth. To better understand the process, and the degree, of diuron transport from agricultural fields, two grass‐seed fields in the Willamette Valley of Oregon were monitored for diuron loss in surface runoff and tile drainage during the first wet season after planting. Initial diuron concentrations in surface runoff were high (>1000 μg L−1 in one field and >100 μg L−1 in the other), though they decreased by two orders of magnitude by the end of the season. Concentrations in the tile drains were as much as 1000 times lower than in the surface runoff during the first few weeks of runoff events, and they remained lower than surface water concentrations throughout the season. Total losses in surface runoff were between 1.3 and 3% of the amount applied—much higher than losses via the tile drains. It is also shown by means of a simple first‐order decay model that, when little information is available, it may be best to describe diuron depletion in runoff water as a function of cumulative rainfall during the wet season.
Adaptation of the Ion Exchange Method for the Determination of the Free Ionic Fraction of Cadmium in Solution
Authors: Schneider André
Published: January 2006

The understanding of the availability of a metal in soil necessitates a minimum knowledge about its speciation in the soil solution. Here, we evaluated an alternative to the use of ion exchangers for estimating the free ionic fraction of cadmium (FCd) in solution. It is based on the exchange selectivity coefficient (VK) rather than the distribution coefficient (DK) to estimate FCd Because VK for the Cd–Ca exchange for the used Amberlite resin was independent of the solution Ca concentration (0.5–7.5 mM) and pH (range: 4.5–6), the experiment on a solution mimicking the analyzed solution to estimate VK was not necessary. The influence of variable Ca and Mg concentrations in solution on FCd was assessed in synthetic solutions containing either citrate or malate. The best way to estimate FCd seemed to treat the exchange data as if Ca was solely present. However, neither the proposed approach nor those applying DK prevent the overestimation of FCd when Ca is partly complexed in the analyzed solution. A method intending to estimate two replicates of FCd for a given, unique solution was also studied on solutions issued from sorption–desorption experiments performed on a humic podzol. It consists of two successive supplies of a known resin mass to a unique sample. Both estimates were close and not significantly different.
Upland Disturbance Affects Headwater Stream Nutrients and Suspended Sediments during Baseflow and Stormflow
Authors: Houser Jeffrey N. , Mulholland Patrick J. , Maloney Kelly O.
Published: January 2006

Because catchment characteristics determine sediment and nutrient inputs to streams, upland disturbance can affect stream chemistry. Catchments at the Fort Benning Military Installation (near Columbus, Georgia) experience a range of upland disturbance intensities due to spatial variability in the intensity of military training. We used this disturbance gradient to investigate the effects of upland soil and vegetation disturbance on stream chemistry. During baseflow, mean total suspended sediment (TSS) concentration and mean inorganic suspended sediment (ISS) concentration increased with catchment disturbance intensity (TSS: R2 = 0.7, p = 0.005, range = 4.0–10.1 mg L−1; ISS: R2 = 0.71, p = 0.004, range = 2.04–7.3 mg L−1); dissolved organic carbon (DOC) concentration (R2 = 0.79, p = 0.001, range = 1.5–4.1 mg L−1) and soluble reactive phosphorus (SRP) concentration (R2 = 0.75, p = 0.008, range = 1.9–6.2 μg L−1) decreased with increasing disturbance intensity; and ammonia (NH4+), nitrate (NO3−), and dissolved inorganic nitrogen (DIN) concentrations were unrelated to disturbance intensity. The increase in TSS and ISS during storms was positively correlated with disturbance (R2 = 0.78 and 0.78, p = 0.01 and 0.01, respectively); mean maximum change in SRP during storms increased with disturbance (r = 0.7, p = 0.04); and mean maximum change in NO3− during storms was marginally correlated with disturbance (r = 0.58, p = 0.06). Soil characteristics were significant predictors of baseflow DOC, SRP, and Ca2+, but were not correlated with suspended sediment fractions, any nitrogen species, or pH. Despite the largely intact riparian zones of these headwater streams, upland soil and vegetation disturbances had clear effects on stream chemistry during baseflow and stormflow conditions.
Greenhouse Gas Emissions from Conventional, Agri‐Environmental Scheme, and Organic Irish Suckler‐Beef Units
Authors: Casey J. W. , Holden N. M.
Published: January 2006

The problems of overproduction within the European Union countries and the environmental impact of agriculture have lead to the introduction of schemes that aim to reduce both. Beef (Bos taurus) production forms a large component of the Irish agricultural industry and accounts for more than one quarter of agricultural economic output. Recently, the European CAP (Common Agricultural Policy) has been re‐evaluated to include supplementary measures that encompass the environmental role of agriculture rather than just the production role. A life cycle assessment (LCA) method was adopted to estimate emissions per kilogram of CO2 equivalent per kilogram of live weight (LW) leaving the farm gate per annum (kg CO2 kg−1 LW yr−1) and per hectare (kg CO2 ha−1 yr−1). Fifteen units engaged in suckler‐beef production (five conventional, five in an Irish agri‐environmental scheme, and five organic units) were evaluated for emissions per unit product and area. The average emissions from the conventional units were 13.0 kg CO2 kg−1 LW yr−1, from the agri‐environmental scheme units 12.2 kg CO2 kg−1 LW yr−1, and from the organic units 11.1 kg CO2 kg LW yr−1 The average emissions per unit area from the conventional units was 5346 kg CO2 ha−1 yr−1, from the agri‐environmental scheme units 4372 kg CO2 ha−1 yr−1, and from the organic units 2302 kg CO2 ha−1 yr−1 Results indicated that moving toward extensive production could reduce emissions per unit product and area but live weight production per hectare would be reduced.
Sorption Kinetics and Equilibria of Organic Pesticides in Carbonatic Soils from South Florida
Authors: Nkedi‐Kizza P. , Shinde D. , Savabi M. R. , Ouyang Y. , Nieves L.
Published: January 2006

A batch reactor was used to determine sorption kinetic parameters (k2, F, and K*) and the equilibrium sorption coefficient (K). The two‐site nonequilibrium (TSNE) batch sorption kinetics model was used to calculate the kinetic parameters. Two probe organic pesticides, atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine] and diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea] were studied using three carbonatic soils from South Florida (Chekika, Perrine, and Krome), one noncarbonatic soil from Iowa (Webster), and one organic soil (Lauderhill) from South Florida. Carbonatic soils contained more than 600 g kg−1 CaCO3 Sorption is initially very fast up to 3 h and then slowly reaches equilibrium. All soil–chemical combinations reached sorption equilibrium after about 24 h and all sorption isotherms were linear. The sorption kinetics data were well described by the TSNE model for all soil‐chemical combinations except for the marl soil data (Perrine–Atrazine), which were better described by the one‐site nonequilibrium (OSNE) model. Diuron, with higher K, undergoes slower sorption kinetics than atrazine. The Lauderhill soil containing organic carbon (OC) of 450 g kg−1 exhibited slowest sorption kinetics for both pesticides. An inverse relationship between k2 and K was observed for atrazine and diuron separately in Chekika, Webster, and Lauderhill soils but not in Perrine and Krome soils. The sorption kinetic parameters were used to distinguish the sorption behavior between atrazine and diuron and to identify differences between soils. Normalizing the sorption coefficient (K) to OC showed that atrazine and diuron had Koc values in carbonatic soils that were a third of reported literature values for noncarbonatic soils. Using existing literature Koc values in solute transport models will most likely underestimate the mobility of atrazine, diuron, and other neutral organic chemicals in carbonatic soils.
Effects of Plants on the Removal of Hexavalent Chromium in Wetland Sediments
Authors: Xu Shangping , Jaffé Peter R.
Published: January 2006

The effect of two wetland plants, Typha latifolia L. (cattail) and Phragmites australis (Cav.) Trin. ex Steud (common reed), on the fate of Cr(VI) in wetland sediments was investigated using greenhouse bench‐scale microcosm experiments. The removal of Cr(VI) was monitored based on the vertical profiles of aqueous Cr(VI) in the sediments. The Cr(VI) removal rates were estimated taking into account plant transpiration, which was found to significantly concentrate dissolved species in the sediments. After correcting for evapotranspiration, the actual Cr(VI) removal rates were significantly higher than would be inferred from uncorrected profiles. On average, the Cr(VI) removal rates were 0.005 to 0.017 mg L−1 d−1, 0.0003 to 0.08 mg L−1 d−1, and 0.004 to 0.13 mg L−1 d−1 for the control, T. latifolia, and P. australis microcosms, respectively. The fate of the removed Cr(VI) was examined by determining the quantity and chemical speciation of the Cr in the sediment and plant materials. Chromium(III) was the dominant form of Cr in both the sediment and plants, and precipitation of Cr(III) in the sediment was the major pathway responsible for the disappearance of aqueous Cr(VI) from the pore water. Incubation results showed that abiotic reduction was the primary mechanism underlying Cr(VI) removal in the microcosm sediments. Organic compounds produced by plants, including root exudates and mineralization products of dead roots, are thought to be the factor that is either directly or indirectly responsible for the gap between Cr(VI) removal efficiencies in the sediments of the vegetated and unvegetated microcosms.
Nitrogen and Phosphorus Status of Soils and Trophic State of Lakes Associated with Forage‐Based Beef Cattle Operations in Florida
Authors: Sigua G. C. , Williams M. J. , Coleman S. W. , Starks R.
Published: January 2006

Forage‐based livestock systems have been implicated as major contributors to deteriorating water quality, particularly for phosphorus (P) from commercial fertilizers and manures affecting surface and ground water quality. Little information exists regarding possible magnitudes of nutrient losses from pastures that are managed for both grazing and hay production and how these might impact adjacent bodies of water. We examined the changes that have occurred in soil fertility levels of rhizoma peanut (Arachis glabrataBenth.)‐based beef cattle pastures (n= 4) in Florida from 1988 to 2002. These pastures were managed for grazing in spring followed by haying in late summer and were fertilized annually with P (39 kg P2O5ha−1) and K (68 kg K2O ha−1). Additionally, we investigated trends in water quality parameters and trophic state index (TSI) of lakes (n= 3) associated with beef cattle operations from 1993 to 2002. Overall, there was no spatial or temporal buildup of soil P and other crop nutrients despite the annual application of fertilizers and daily in‐field loading of animal waste. In fact, soil fertility levels showed a declining trend for crop nutrient levels, especially soil P (y= 146.57 − 8.14 × year;r2= 0.75), even though the fields had a history of P fertilization and the cattle were rotated into the legume fields. Our results indicate that when nutrients are not applied in excess, cow‐calf systems are slight exporters of P, K, Ca, and Mg through removal of cut hay. Water quality in lakes associated with cattle production was “good” (30–46 TSI) based on the Florida Water Quality Standard. These findings indicate that properly managed livestock operations may not be major contributors to excess loads of nutrients (especially P) in surface water.
Leaching of N‐Nitrosodimethylamine (NDMA) in Turfgrass Soils during Wastewater Irrigation
Authors: Gan J. , Bondarenko S. , Ernst F. , Yang W. , Ries S. B. , Sedlak D. L.
Published: January 2006

N‐nitrosodimethylamine (NDMA) is a carcinogenic by‐product of chlorination that is frequently found in municipal wastewater effluent. NDMA is miscible in water and negligibly adsorbed to soil, and therefore may pose a threat to ground water when treated wastewater is used for landscape irrigation. A field study was performed in the summer months under arid Southern California weather conditions to evaluate the leaching potential of NDMA in turfgrass soils during wastewater irrigation. Wastewater was used to irrigate multiple turfgrass plots at 110 to 160% evapotranspiration rate for about 4 mo, and leachate was continuously collected and analyzed for NDMA. The treated wastewater contained relatively high levels of NDMA (114–1820 ng L−1; mean 930 ng L−1). NDMA was detected infrequently in the leachate regardless of the soil type or irrigation schedule. At a method detection limit of 2 ng L−1, NDMA was only detected in 9 out of 400 leachate samples and when it was detected, the NDMA concentration was less than 5 ng L−1 NDMA was relatively persistent in the turfgrass soils during laboratory incubation, indicating that mechanisms other than biotransformation, likely volatilization and/or plant uptake, contributed to the rapid dissipation. Under conditions typical of turfgrass irrigation with wastewater effluent it is unlikely that NDMA will contaminate ground water.
Loss Pathways of N‐Nitrosodimethylamine (NDMA) in Turfgrass Soils
Authors: Arienzo M. , Gan J. , Ernst F. , Qin S. , Bondarenko S. , Sedlak D. L.
Published: January 2006

N‐nitrosodimethylamine (NDMA) is a potent carcinogen that is often present in municipal wastewater effluents. In a previous field study, it was observed that NDMA did not leach through turfgrass soils following 4 mo of intensive irrigation with NDMA‐containing wastewater effluent. To better understand the loss pathways for NDMA in landscape irrigation systems, a mass balance approach was employed using in situ lysimeters treated with 14C‐NDMA. When the lysimeters were subjected to irrigation and field conditions after NDMA application, very rapid dissipation of NDMA was observed for both types of soil used in the field plots. After only 4 h, total 14C activity in the lysimeters decreased to 19.1 to 26.1% of the applied amount, and less than 1% of the activity was detected below the 20‐cm depth. Analysis of plant materials showed that less than 3% of the applied 14C was incorporated into the plants, suggesting only a minor role for plant uptake in removing NDMA from the vegetated soils. The rapid dissipation and limited downward movement of NDMA in the in situ lysimeters was consistent with the negligible leaching observed in the field study, and suggests volatilization as the only significant loss pathway. This conclusion was further corroborated by rapid NDMA volatilization found from water or a thin layer of soil under laboratory conditions. In a laboratory incubation experiment, prolonged wastewater irrigation did not result in enhanced NDMA degradation in the soil. Therefore, although NDMA may be present at relatively high levels in treated wastewater, gaseous diffusion and volatilization in unsaturated soils may effectively impede significant leaching of NDMA, minimizing the potential for ground water contamination from irrigation with treated wastewater.
An Examination of Spin–Lattice Relaxation Times for Analysis of Soil and Manure Extracts by Liquid State Phosphorus‐31 Nuclear Magnetic Resonance Spectroscopy
Authors: McDowell R. W. , Stewart I. , Cade‐Menun B. J.
Published: January 2006

Phosphorous (P)‐31 nuclear magnetic resonance (NMR) spectroscopy is used in the analysis of P forms in extracts of soils and manures for environmental and agronomic purposes. Quantitative spectra require knowledge about spin–lattice relaxation times (T1) to ensure adequate delays between pulses. This paper determined T1 values of P forms in reconstituted (0.2 g in 0.7 mL−1) samples of freeze‐dried 0.25 M NaOH plus 50 mM EDTA extracts of eight diverse soils (Aquept, Dystrochrept × 2, Hapludand, Rendoll, Udand, Haplostoll, and Orthod), three different manures (dairy cattle, deer, and sheep), and one epiphyte moss. Total concentrations in the reconstituted samples ranged from 5 to 175 mg Fe mL−1, 2 to 62 mg Mn mL−1, and 72 to 837 mg P mL−1 Values of T1 for orthophosphate monoesters, orthophosphate diesters, and pyrophosphate varied from 0.42 to 1.69 s in soils and from 0.89 to 2.59 s in manures and the epiphyte. In contrast, T1 for orthophosphate varied from 0.78 to 1.94 s in soils and 1.45 to 5.82 s in manures and the epiphyte. For quantitative 31P NMR, delay times should be three to five times the T1 value, translating to delays of 3 to 5 s for soils and up to 25 s for manures. If the required delay is too long then strategies such as adding paramagnetics could shorten T1, provided this does not increase line‐broadening too much. A regression relationship was obtained between orthophosphate T1 values and the ratio of P concentration to Fe and Mn concentration on a w/v basis (r2 = 0.97, P < 0.001), and between the T1 for all other compound classes and the ratio of P to Fe and Mn (r2 = 0.70, P < 0.01). By combining measurement of Fe, Mn, and P in the reconstituted extract and these relationships, T1 can be estimated and the appropriate delay time used. If T1 is not considered and the delay time is too short, some peaks will be under‐ or over‐represented and the relative distribution of P forms not quantitative.
Semen Parameters in Norwegian Fertile Men
Authors: Haugen Trine B. , Egeland Thore , Magnus Øystein
Published: January 2006

ABSTRACT: The World Health Organization (WHO) provides guidelines for assessing the various semen variables. A set of reference ranges is given in the WHO Laboratory Manual for the Examination of Human Semen and Sperm‐Cervical Mucus Interaction, but several studies indicate that the values should be revised. Furthermore, semen parameters obtained at different laboratories are not directly comparable even if the same methods are used. Thus, it is recommended that each laboratory establish its own reference ranges. In this study, semen from 99 men who had recently achieved a pregnancy were analyzed to establish reference ranges for semen variables. The reference values were based on the group with time to pregnancy (TTP) 12 cycles or less (92%) and abstinence time from 2 to 7 days. The 5th and 10th percentiles for sperm concentration were 10.6 and 16.9 × 106/mL, respectively, and 33% (5th percentile) and 43% (10th percentile) for spermatozoa with progressive motility. These values were below the WHO lower limit. The percentages of ideal spermatozoa (percentage with normal morphology according to WHO strict criteria) were 3 (5th percentile) and 4 (10th percentile). Thirty‐nine percent reported that their partners became pregnant during the first cycle after they had stopped using contraception. The semen parameters in this group were compared with the others. Overall, the semen parameters were more favorable in the group with TTP = 1 cycle than in the group with TTP > 1. Sperm concentration, progressive motility, and percentage of ideal spermatozoa according to WHO strict criteria were significantly different in the 2 groups. However, when analyzed by multiple logistic regression, only “total numbers of sperm with progressive motility” remained in the model (P = .002). This is in accordance with previous studies indicating that a combination of semen characteristics provides a better predictor of male fertility potential than the single parameters. In conclusion, new reference ranges for semen variables deviating from the WHO values are established for our laboratory.
Effect of External Anal Sphincter Contraction on the Ischiocavernosus Muscle and Its Suggested Role in the Sexual Act
Authors: Shafik Ahmed , Shafik Ismail , El‐Sibai Olfat , Shafik Ali A.
Published: January 2006

ABSTRACT:Whereas the bulbocavernosus muscle shares its contractile activity with the external anal sphincter (EAS), the response of the ischiocavernosus muscle (ICM) to EAS contraction could not be traced in the literature. We investigated the hypothesis that the ICM contracts reflexly upon EAS contraction. The response of the ICM to EAS squeeze and stimulation was recorded in 21 healthy volunteers (13 men, 8 women, age 36.8 ± 10.7 [SD] years). An electromyographic (EMG) needle (stimulating) electrode was introduced into the EAS and another (recording) one was inserted into the ICM. The test was repeated after individual anesthetization of the EAS and ICM and after muscle infiltration with normal saline instead of lidocaine. EAS electrostimulation (10 stimuli, 200 μs duration, 0.2 Hz frequency, 0–100 mA intensity) produced an increase of ICM EMG activity to a mean of 267.8 ± 42.7 μV, whereas anal squeeze effected an increase to a mean of 224.5 ± 45.3 μV. The ICM did not respond to stimulation of the EAS after individual anesthetization of the ICM and EAS, but it did after saline infiltration. The results were reproducible. ICM contracted upon EAS contraction. This effect seems to be mediated through a reflex that we call “anocavernosal excitatory reflex.” The ICM lever action is suggested to share in the erectile mechanism by elevating the penile shaft to above the horizontal level. The reflex may prove of diagnostic significance in sexual function disorders, a point that needs further study.