bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Leaching Losses from Irrigated Orchardgrass on Sandy Soils
Authors: Watts D.G. , Hergert G.W. , Nichols J.T. 
Published: July 2010

AbstractIrrigated pasture may provide an alternative forage source for livestock producers in Nebraska's Sandhills. As with any heavily fertilized crop, there is a significant potential for groundwater contamination by nitrate nitrogen (NO3‐N) leached from the crop root zone. A 3‐yr experiment was conducted in West Central Nebraska to evaluate water and nitrate (NO−3) leaching losses from irrigated orchardgrass (Dactylis glomerata L.) seeded on a Valentine fine sand (Typic Ustipsamments). Three irrigation levels (slight deficit, slight excess, and excess) and four N amounts (0, 112, 224, and 336 kg−1) were applied. Deep percolation and NO−3 leaching were measured with Duke‐Haise trough‐type extractors. All irrigation treatments had more deep percolation than expected, as the crop coefficient used for irrigation scheduling proved to be too large. The deficit irrigation treatment served as a “close management” treatment since percolation was minimal and yield was not reduced by water stress. During the first 2 yr of operation, in‐season percolation losses averaged 7, 28, and 47 cm yr−1 for low, medium, and high irrigation levels, respectively. Total in‐season NO3‐N leaching loss for the same period ranged from 6 to 228 kg ha−1, depending on N and irrigation amount. Winter and early spring N leaching losses, as estimated by soil sampling, were a significant part of total N loss. Under reduced inseason drainage and an N rate commensurate with 80 to 85% of maximum production, a minimum annual N leaching loss of 35 kg ha−1 can be expected. Greater losses are probable under average water and N applications and average management skills.
Effects of Soil‐Applied Selenium on the Growth and Selenium Content of a Forage Species
Authors: Carlson Claire L. , Adriano Domy C. , Dixon Philip M. 
Published: July 2010

AbstractThis study was conducted to determine the effects of soil‐applied selenate and selenite on the growth and Se content of a forage species, sorgrass (Sorghum vulgare var. sudanense Hitchc.), grown on acid southeastern soils under different soil conditions. A greenhouse pot study was conducted using a factorial design, with two soil types varying in clay and hydrous oxide content (Blanton sand, a loamy, siliceous, thermic Grossarenic Paleudult; and Orangeburg loamy sand, a loamy, siliceous, thermic Typic Paleudult), two soil treatments (limed and unlimed), two Se forms (selenate, SeO2−4, and selenite, SeO2−3), and four Se concentrations (0, 1, 2, and 4 mg Se kg−1 soil). Additions of Se in the selenate form had a greater toxic effect on the plants, reducing plant biomass as much as 97% and increasing plant Se concentrations to as high as 1153 mg Se kg−1. Selenite additions generally did not affect plant biomass, but still resulted in accumulations of Se in aboveground tissues to levels potentially toxic to animals. Selenium concentrations were higher in plants grown on the soil lower in clay and hydrons oxide content. Liming resulted in lower tissue Se concentrations in plants grown on either soil treated with selenate.
Soil Chemistry after Eleven Annual Applications of Cattle Feedlot Manure
Authors: Chang C. , Sommerfeldt T. G. , Entz T. 
Published: July 2010

AbstractIn a long‐term experiment at Lethbridge, AB, the effects of cattle (Bos sp.) manure on soil characteristics were determined after 11 annual applications. Manure, incorporated by cultivating, rototilling, or plowing, was applied annually from 1973 to 1983 at 30, 60, and 90 Mg ha−1 (wet wt.) and 60, 120, and 180 Mg ha−1, respectively, to nonirrigated and irrigated dark brown Chernozemic (Typic Haploborolls) clay loam soil. On both the nonirrigated and irrigated soil, the effects from manure, applied annually at greater than recommended rates for 11 yr, were minimal on Cu and NH4 content and substantial on other parameters determined. There were no significant effects due to tillage methods on these soil parameters. The effects on these soil parameters extended to greater depths under irrigation than under nonirrigation. Most of the applied NH4 was nitrified, volatilized, or fixed. The accumulation of organic matter, total N, NO3, total P, available P, soluble Na, Ca + Mg, Cl, SO4, HCO3, and Zn in the soil increased with increasing rates of manure applied. The electrical conductivity and sodium adsorption ratio of the soil increased and the soil pH in the surface 60 cm of nonirrigated and 90 cm of irrigated decreased with increased manure rates. The total NO3 accumulation in the 150‐cm soil depth was near 1 Mg ha−1, even at recommended rates, and was high enough to potentially cause soil and water pollution. The available P accumulated mostly in the surface soil and might be sufficient to interfere with the nutrient balance of some crops. Long‐term annual application of cattle manure to southern Alberta soils at maximum recommended rates [30 mg ha−1 and 60 Mg ha−1 (wet wt.) for nonirrigated and irrigated land, respectively] is not advisable.
Use of Enzymes to Detoxify Pesticide‐Contaminated Soils and Waters
Authors: Nannipieri P. , Bollag J.‐M. 
Published: July 2010

AbstractApplying enzymes to transform or degrade pesticides is an innovative treatment technique for removal of these chemicals from polluted environments. Enzyme‐catalyzed degradation of a pollutant by a parathion hydrolase may be more effective than existing chemical methods. Removal of certain pollutants (for instance phenols and aromatic amines) from wastewater may be achieved by applying phenoloxidases that can convert these chemicals to water‐insoluble polymers that can then be removed by filtration or sedimentation. Another decontamination method involves the enzyme‐catalyzed incorporation of pesticides into organic matter. This procedure reduces the mount of leachable pesticides as well as the toxicity and bioavailability of the chemicals. Pesticide‐detoxifying enzymes must be immobilized before they can be used in the environment. In spite of promising potential applications, very few enzymes have been tested as possible tools in the detoxification of pesticides. Research in this domain can contribute greatly to developing new methods for pollution control.
Arsenic and Selenium Chemistry as Affected by Sediment Redox Potential and pH
Authors: Masscheleyn P. H. , Delaune R. D. , Patrick W. H. 
Published: July 2010

AbstractThe influence of sediment redox potential and pH on As and Se speciation and solubility was studied. Hyco Reservoir (North Carolina) sediments were equilibrated under controlled redox (500, 200, 0, and −200 mV) and pH (5, natural, and 7.5) conditions. Redox potential and pH affected both speciation and solubility of As and Se. Under oxidized conditions As solubility was low and 87% of the As in solution was present as As(V). Upon reduction, As(III) became the major As species in solution, and As solubility increased. Total As in solution increased approximately 25 times upon reduction to −200 mV. No organic arsenicals were detected. In contrast to As, Se solubility reached a maximum under highly oxidized (500 mV) conditions and decreased significantly upon reduction. Selenium(VI) was the predominant dissolved Se species present at 500 mV. At 200 and 0 mV, Se(IV) became the most stable oxidation state of Se. Under strongly reduced conditions (−200 mV) oxidized Se species were no longer detectable and Se solubility was controlled by the formation of elemental Se and/or metal selenides. Biomethylation of Se was important under oxidized and moderately reduced conditions (500, 200, and 0 mV). More alkaline conditions (pH 7.5) resulted in both greater As and Se concentrations in solution. Dissolved As and Se increased up to 10 and 6 times, respectively, as compared to the more acidic equilibrations.
Off‐Field Movement and Dissipation of Soil‐Incorporated Carbofuran from Three Commercial Rice Fields
Authors: Nicosia S. , Carr N. , Gonzales D. A. , Orr M. K. 
Published: July 2010

AbstractResidues of curbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate) were detected in agricultural drain water collected in the Sacramento Valley, a major rice (Oryza sativa L.) growing region of California. Runoff water from rice fields was suspected as the major source for these residues. In response to this problem we measured soil‐incorporated carbofuran; (i) discharged in runoff, (ii) dissipated from paddy soil and water, and (iii) recovered in paddy soil vs. paddy water over time. This work was conducted in three commercial rice fields in Colusa and Glenn Counties in California. A total of 1.72, 5.40 and 11.03% of carbofuran mass applied was discharged in runoff water from Fields 1, 2, and 3, respectively, during a 54‐ to 80‐d period after flooding. Downstream concentrations, up to 4.4 µg L−1, indicated the need for reduced carbofuran discharges to meet a 1991 regional standard of 0.4 µg L−1. Most of the carbofuran lost in runoff was discharged during the first 30‐d period after initial flooding in Field 2, and during the 31‐ to 60‐d period in Fields 1 and 3. Dissipation of carbofuran mass, measured separately in rice paddy soft and rice paddy water, was a log‐linear function of time in both media. An exception occurred in paddy soil of Field 3 where carbofuran mass did not decline significantly over a 70‐d sampling period. Soil half‐lives were 58 and 43 d after flooding for Fields 1 and 2, respectively. Water half‐lives for Fields 1, 2, and 3 were 22, 26, and 18 d, respectively. Most of the carbofuran mass applied to the fields remained in paddy soil and, on average, no more than 27% of the applied mass was found in paddy water on any single day during the study. Soil‐incorporation may reduce the amount of carbofuran released into paddy water, and subsequently moved off‐field in runoff.
Response of Net Carbon Exchange Rate of Soybean to Ozone at Different Stages of Growth and its Relation to Yield
Authors: Miller Joseph E. , Pursley Walter A. , Vozzo Steven F. , Heagle Allen S. 
Published: July 2010

AbstractHigh concentrations of ozone (O3) occur episodically during the growing season, but the impacts of O3 stress on photosynthesis and crop yield when O3 episodes occur at various stages of growth are not known. Also, quantitative relationships between reduction of photosynthesis and yield suppresion by O3 have not been established for most species. Field experiments with soybean [Glycine max (Merr.) cv. Davis] were performed to determine the impact of O3 exposure at different stages of plant development on net carbon exchange rate (NCER) and to establish the relationship between NCER and yield for different O3 exposure periods. The growing season was divided into four quarters (Q1–Q4) of 31 d each for O3 treatment. In each quarter, O3 treatments in open‐top chambers were either charcoal‐filtered air (C) or nonfiltered air (N) to which O3 was added to achieve approximately 100 nL L−1 O3 (mean 7 h d−1 average for the quarter). The NCER was measured in eight O3 treatments (CCCC, NNCC, CNCN, NCCN, CNNC, NCNC, CCNN, and NNNN) where each letter indicates the O3 treatment for successive quarters. The NCER measurements during Q4 (R6–R7) provided the best relationship to yield in a linear regression model (R2 = 0.919). A significant relationship with yield was obtained also with NCER measurements from Q3 (R2–R5) (R2 = 0.626), whereas measurments during Q2 (V10‐R1) were poorly related to yield (R2 = 0.072). Good linear relationships of yield and NCER were found also when Q3 and Q4 or Q2, Q3, and Q4 data were combined. In all cases, however, Q4 data were essential to a good correlation between NCER and yield. It is likely that NCER measurements taken during Q4 correlated well with yield, because that was the period when the requirement for energy from photosynthesis is most critical for yield.
Effects of Collection Interval on Quality of Throughfall Samples in Two Northern Hardwood Stands
Authors: Liechty Hal O. , Mroz Glenn D. 
Published: July 2010

AbstractThe chemical stability of weekly and biweekly throughfall collection intervals were compared at two northern hardwood stands in the Great Lakes region. Throughfall concentrations of Cl−, NO−3, SO2−4, Ca2+, Mg2+, and K+ were not significantly (p ≤ 0.05) affected by the increased collection time, where as throughfall concentrations of NH+4 and H+ collected biweekly were significantly different (p ≤ 0.05) than concentrations of these ions in weekly samples. The 1‐wk increase in collection interval at one stand decreased concentrations of NH+4 and increased concentrations of H+ 88 and 131%, respectively. The chemical instability of these ions appeared to be related to biological assimilation and/or nitrification of NH+4. Stability of these ions decreased with increasing concentrations of inorganic N in the throughfall. These changes in concentrations of NH+4 and H+ may introduce sampling bias when estimating throughfall fluxes or concentrations of these ions from biweekly collections. The decreased stability of these ions with increased concentrations of inorganic N should be an important consideration when selecting sampling intervals for stands that receive differing deposition levels of atmospheric N or have different canopy retention rates of N.
Phosphorus Concentrations in Drainage Water in the Everglades Agricultural Area
Authors: Izuno F. T. , Sanchez C. A. , Coale F. J. , Bottcher A. B. , Jones D. B. 
Published: July 2010

AbstractPhosphorus in drainage water leaving the Everglades Agricultural Area (EAA) in southern Florida is alleged to be contributing to the accelerated eutrophication of Lake Okeechobee and the degradation of the Water Conservation Areas and the Everglades National Park ecosystems. Agricultural “best management practices” (BMPs) offer a means for achieving reductions in P in drainage water. Prior to developing and implementing BMPs, it is necessary to establish baseline EAA P concentrations. Baseline total P (TP) and total dissolved P (TDP) concentrations for various crop and field conditions in the EAA were determined. Thirty‐six 0.7‐ha plots were installed at four locations. Average TP and TDP concentrations were derived from 6 to 30 drainage events for each of five conditions between November 1988 and December 1989: sugarcane (Saccharum spp.), radish (Raphanus sativus L.), and cabbage (Brassica oleracea L.) production fields, flooded fallow fields, and drained fallow fields. Baseline TP and TDP concentrations for main farm canals and rainfall were also determined. Average TP concentrations ranged from 0.25 mg L−1 for radishes to 1.03 mg L−1 during the drain‐down of flooded fallow plots. Total dissolved P concentrations ranged from 48 to 80% of TP. Main farm canal TP concentrations averaged 0.16 mg L−1. Total P concentrations in rainfall averaged 0.07 mg L−1 Total P in drainage water during 1989 for sugarcane, cabbage, and drained fallow fields were 0.72, 1.38, and 0.59 kg ha−1, respectively. During the radish season, drainage water TP loading was 0.8 kg ha−1. Flooded fallow fields after radishes yielded a TP loading rate of 3.82 kg ha−1. Total P loading to the fields from rainfall averaged 0.70 kg ha−1. Total dissolved P loading rates ranged from 25 to 60% of TP. Potential areas for BMP development and implementation for P concentration and loading reduction in the EAA include drainage rate, volume, and timing management, fertilizer use reduction, and enhanced crop rotation strategies.
Bacterial Pollution of Waters in Pristine and Agricultural Lands
Authors: Niemi R. M. , Niemi J. S. 
Published: July 2010

AbstractConcentrations of thermotolerant coliform bacteria, presumptive E. coli, and presumptive fecal streptococci were determined from ditches, brooks, and natural ponds in six agricultural areas and 22 uninhabited pristine areas in southern Finland in the summer of 1987. For comparison, the same fecal indicators were enumerated from the effluents of three wastewater treatment plants. The objective was to compare the importance of these waters as sources of fecal indicators in receiving waters. The numbers of bacteria in waters in agricultural areas often exceeded the limit of acceptable swimming water (1000 bacteria per 100 mL), especially during wet periods, which shows that diffuse loading can be a significant source of fecal pollution. Fecal indicators were detected in about half of the samples of pristine areas, sometimes in concentrations exceeding the limit of good swimming water (100 bacteria per 100 mL). This contamination was probably caused by wild animals, especially by elk (Alces alces) and deer (Odocoileus virginianus) living in the areas. The concentrations of bacteria were higher in running waters than in ponds. The reliabilities of routine enumeration methods for the bacteria were evaluated by carrying out confirmation tests for isolated strains. Thermotolerant coliforms were reliable indicators in waters contaminated by diffuse loading. The reliability of enumeration of fecal streptococci in these waters should be studied further.
A Functional Model of Solute Transport that Accounts for Bypass
Authors: Corwin D. L. , Waggoner B. L. , Rhoades J. D. 
Published: July 2010

AbstractPublic awareness of groundwater contamination has created renewed interest in solute transport models that can be practically applied as groundwater quality management tools. Because of their simplicity with regard to input requirements, functional models of solute transport are excellent groundwater quality management tools. A functional model of one‐dimensional solute transport that accounts for hydraulic bypass is presented. The transport model, TETrans, simulates the vertical movement of nonvolatile solutes (i.e., trace elements and nonvolatile organic chemicals) through the vadose zone. Plant water uptake is taken into account assuming no solute uptake by the plant. TETrans requires minimal input data for its operation. Since TETrans uses a mass‐balance approach to solute transport, it offers the speed of an analytical solution and the versatility of a numerical approach without the need for input parameters, which are difficult to measure. TETrans is able to account for bypass with a single term, the mobility coefficient. The mobility coefficient, γ, represents the fraction of the soil liquid phase, which is subject to piston‐type displacement; therefore, 1 ‐ γ represents the fraction of the liquid phase that is bypassed. The mobility coefficient is a temporally and spatially variable parameter (within a range of 0 to 1), which is calculated from the deviation of the measured chloride concentration from the predicted concentration assuming piston displacement and assuming complete mixing of the resident soil solution and incoming water for a given irrigation and volume of soil. A constant mobility coefficient for a given depth or entire profile can be determined by averaging temporally varying mobility coefficients or averaging spatially and temporally varying mobility coefficients, respectively. In essence, the mobility coefficient simplistically accounts for three physical transport phenomena in a single term. On a microscopic level there is flow through cracks and macropores that bypasses small and dead‐end pores. On a macroscopic level there is the flow of a mobile water phase independent of stagnant immobile phase of water, and the phenomenon of dispersion‐diffusion. Simulations of chloride movement through a soil lysimeter column for an 1100‐d period were compared to measured chloride concentrations in the soil solution at field capacity. A constant mobility coefficient significantly improved the capability of TETrans to describe the data when compared to simulations performed assuming complete piston‐type displacement. However, the best simulation to the measured chloride data was for the use of a spatially and temporally variable mobility coefficient.
Deep Nitrate Movement in the Unsaturated Zone of a Simulated Urban Lawn
Authors: Exner M.E. , Burbach M.E. , Watts D.G. , Shearman R.C. , Spalding R.F. 
Published: July 2010

AbstractThe increasing incidence of NO3 contamination in municipal wells is a growing concern in the Midwest. While leachates from N fertilizers applied to agricultural lands can impact the water quality in municipal wells, there is also the potential for leachates from turfgrass fertilizers to be groundwater contaminants. In this study, five plots were treated with ammonium nitrate (34‐0‐0,N‐P‐K) at rates of 0, 1.0, 1.5, 2.0, and 2.4 kg N/100 m2 and irrigated‐ The turf received approximately 640 mm of water during the 34‐d study. Analysis of soil water from 15, 6‐m continuous cores showed that as much as 95% of the NO3 applied in late August leached below the turfgrass root zone. Average NO3 concentrations in the pulse ranged from 34 to 70 mg/L NO3‐N. Thirty‐four days after fertilization the center of the pulse was at ≈1.2 m with the leading edge at 2 to 2.5 m. This vertical rate of movement is similar to that predicted by the one‐dimensional CMLS model. The relatively high uniform NO3 concentrations in the unfertilized plot indicated that with excessive irrigation the water alone supplies NO3 in excess of the turfgrass need.
Nitrogen and Phosphorus in Eroded Sediment from Corn and Soybean Tillage Systems
Authors: McIsaac Gregory F. , Hirschi Michael C. , Mitchell J. Kent 
Published: July 2010

AbstractRunoff, soil loss and sediment bound total Kjeldahl nitrogen (TKN) and Bray P‐1 phosphorus (P) losses were measured corn (Zea mays L.) and soybean [Glycine max (L.)] tillage systems subjected to simulated rainfall. Runoff and soil loss were influenced by contouring and tillage treatment. After 60 min of simulated rainfall, there was little or no runoff or soil erosion from plots which had recently been ridge cultivated along the contour. Soil and nutrient losses from up‐and‐down slope ridge‐till plots were never significantly different than from the conventional tillage treatment. Bray P‐1 P concentration in the top 5 cm of soil and eroded sediment was significantly reduced by moldboard plowing. Concentrations of Bray P‐1 in the eroded sediment tended to decrease as soil loss increased. Bray P‐1 enrichment ratios ranged from 1.69 to 4.5, and were correlated to a greater extent with sediment concentration than with soil loss. The TKN losses were linearly related with soil loss and the average TKN enrichment ratio ranged from 1.02 to 1.28. The TKN enrichment ratio was not significantly correlated with Bray P‐1 enrichment ratio.
Denitrification in Grass and Forest Vegetated Filter Strips
Authors: Groffman Peter M. , Axelrod Eric A. , Lemunyon Jerrell L. , Sullivan W. Michael 
Published: July 2010

AbstractDenitrification was measured in two grass and two forest vegetated filter strips (VFS) in Rhode Island. The grass plots were established on a well‐drained soil and were planted to either tall fescue (Festuca arundinacea) or reed canarygrass (Phalaris arundinacea). One forest site was on an excessively well‐drained soil and was dominated by oak (Quercus sp.), and the other was on a poorly drained soil and was dominated by red maple (Acer rubrum). Denitrification was measured using soil cores under aerobic and anaerobic conditions with a range of treatments: no amendment, acetylene, water, nitrate (NO−3), NO−3 plus C. Unamended rates of denitrification were low in all plots. Nitrate and NO−3‐plus‐C amended rates were consistently higher in the grass plots than in the forest plots. Nitrate‐plus carbon‐amended rates were higher than NO−3‐amended rates in all plots, but the differences were significant (P < 0.05) in the forest plots only. Denitrification enzyme activity (DEA) was measured in 14 additional forest sites of varying natural drainage classes and was related to soil moisture (r2 = 0.56, P < 0.01) and pH (r2 = 0.43, P < 0.01) at these sites. The results suggest that the ability of VFS to support denitrification varies strongly with vegetation, soil type and pH, and that denitrification in VFS may be amenable to management.