bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrate Leaching beneath a Containerized Nursery Crop Receiving Trickle or Overhead Irrigation
Authors: Colangelo David J. , Brand Mark H.
Published: June 2010

Container production of nursery crops is intensive and a potential source of nitrogen release to the environment. This study was conducted to determine if trickle irrigation could be used by container nursery producers as an alternative to standard overhead irrigation to reduce nitrogen release into the environment. The effect of overhead irrigation and trickle irrigation on leachate nitrate N concentration, flow‐weighted nitrate N concentration, leachate volume, and plant growth was investigated using containerized rhododendron (Rhododendron catawbiense Michx. ‘Album’) supplied with a controlled‐release fertilizer and grown outdoors on top of soil‐monolith lysimeters. Leachate was collected over two growing seasons and overwinter periods, and natural precipitation was allowed as a component of the system. Precipitation accounted for 69% of the water entering the overhead‐irrigated system and 80% of the water entering the trickle‐irrigated system. Leachate from fertilized plants exceeded the USEPA limit of 10 mg L−1 at several times and reached a maximum of 26 mg L−1 with trickle irrigation. Average annual loss of nitrate N in leachate for fertilized treatments was 51.8 and 60.5 kg ha−1 for the overhead and trickle treatments, respectively. Average annual flow‐weighted concentration of nitrate N in leachate of fertilized plants was 7.2 mg L−1 for overhead irrigation and 12.7 mg L−1 for trickle irrigation. Trickle irrigation did not reduce the amount of nitrate N leached from nursery containers when compared with overhead irrigation because precipitation nullified the potential benefits of reduced leaching fractions and irrigation inputs provided under trickle irrigation.
Bioavailability of Biosolids Molybdenum to Soybean Grain
Authors: O'Connor G. A. , Granato T. C. , Basta N. T.
Published: June 2010

Legumes grown in biosolids‐amended soils and then fed to ruminants can represent problematic sources of molybdenum (Mo), but few field data are available to quantify the risk. We used a set of fields amended to high cumulative biosolids Mo loads (>18 kg ha−1) over 27 yr to generate additional data. Soybean [Glycine max (L.) Merr.] was grown on 29 fields (pH values >6.8) amended to a wide range of soil Mo loads. Soybean grain harvested from each field was analyzed for Mo and the concentrations regressed against soil Mo loads estimated from actual soil Mo concentrations in the 0‐ to 15‐cm depth. Slopes of such linear regressions represent uptake coefficients (UC values) used by the USEPA to assess risk of biosolids Mo to ruminants fed forage grown on biosolids‐amended land. The UC value for all 29 fields was estimated as 1.66, which agrees with the few soybean grain data in the literature. The UC value, however, is well below a conservative UC value of 4, recently recommended for all fresh legume materials fed to cattle. Soybean grain can contain high concentrations of Mo (>10 mg kg−1) and have low (<2:1) Cu to Mo ratios, which can exacerbate molybdenosis problems in cattle. However, soybean grain normally constitutes only ∼10% of dairy cattle diet, and other constituents (e.g., corn grain, stover, mineral supplements) are sufficient, or can be manipulated, to control molybdenosis.
Enzymatic Characterization of Organic Phosphorus in Animal Manure
Authors: He Zhongqi , Honeycutt C. Wayne
Published: June 2010

Information on the forms of P present in animal manure may improve our ability to manage manure P. In most investigations of manure P composition, only inorganic and total P are determined, and the difference between them is assigned as organic P. In this study, we explored the possibility of identifying and quantifying more specific organic P forms in animal manure with orthophosphate‐releasing enzymes. Pig (Sus scrofa) manure and cattle (Bos taurus) manure were first sequentially fractionated into water‐soluble P, NaHCO3–soluble P, NaOH‐soluble P, HCl‐soluble P, and residual P. The fractions were separately incubated with wheat phytase, alkaline phosphatase, nuclease P1, nucleotide pyrophosphatase, or their combinations. The released orthophosphate was determined by a molybdate blue method. Part of the organic P in those fractions could be identified by the enzymatic treatments as phytate (i.e., 39% for pig manure and 17% for cattle manure in water‐soluble organic P), simple phosphomonoesters (i.e., 43% for pig manure and 15% for cattle manure in NaOH‐soluble organic P), nucleotide‐like phosphodiesters (2–12%), and nucleotide pyrophosphate (0–4%). Our data indicate that the enzymatic treatment is an effective approach to identify and quantify the organic P forms present in animal manures.
Phosphorus Losses from Grasslands Fertilized with Broiler Litter: EPIC Simulations
Authors: Pierson S. T. , Cabrera M. L. , Evanylo G. K. , Schroeder P. D. , Radcliffe D. E. , Kuykendall H. A. , Benson V. W. , Williams J. R. , Hoveland C. S. , McCann M. A.
Published: June 2010

Broiler litter, a mixture of poultry excreta and bedding material, is commonly used to fertilize grasslands in the southeastern USA. Previous work has shown that under certain situations, application of broiler (Gallus gallus domesticus) litter to grasslands may lead to elevated levels of phosphorus (P) in surface runoff. The EPIC simulation model may be a useful tool to identify those situations. This work was conducted to evaluate EPIC's ability to simulate event and annual runoff volume and losses of dissolved reactive phosphorus (DRP) from tall fescue (Festuca arundinacea Schreb.)–bermudagrass [Cynodon dactylon (L.) Pers.] paddocks fertilized with broiler litter. The EPIC simulations of event runoff volume showed a trend toward underestimation, particularly for runoff events > 30 mm. On an annual basis, EPIC also tended to underestimate runoff, especially at runoff volumes > 100 mm. Both event and annual runoff estimations were strongly associated with observed values, indicating that model calibration could improve the simulation of surface runoff volume. The relationship between simulated and observed values of DRP loss was relatively poor on an event basis (r = 0.65), but was stronger (r = 0.75) on an annual basis. In general, EPIC tended to underestimate annual DRP losses. This underestimation was apparently caused by the lack of an explicit mechanism to model broiler litter on the soil surface. These results suggested that additional work on the EPIC P submodel would be warranted to improve its simulation of surface application of broiler litter to grasslands.
Kraft Mill Residues Effects on Monterey Pine Growth and Soil Microbial Activity
Authors: Jordan Miguel , Sánchez Miguel Angel , Padilla Leandro , Céspedes Ricardo , Osses Miguel , González Bernardo
Published: June 2010

The production of bleached Kraft pulp generates inorganic and organic residues that are usually deposited on the soil surface or land‐filled. Studies conducted to address the impact of these wastes on the environment are scarce. In this work, Monterey pine (Pinus radiata D. Don), an important tree for pulping, was evaluated for germination and development under greenhouse conditions in forest soils exposed to solid residues of the cellulose industry using the Kraft process. Soils exposed to 10 to 60% ashes, 10 to 70% fly ashes, or 10 to 30% dregs allowed substantial seed germination and seedling growth. In contrast, soils exposed to low proportions of brown rejects, grits, or a mixture of all these residues were detrimental for germination, plant growth, or both. The strongest negative effect (no germination) was observed with as low as 10% grits. The changes in pH and/or water content caused by solid wastes did not correlate with detrimental effects observed in various soil–residue combinations. No significant changes in the microbial community of soils exposed to these solid residues were observed by determination of culturable counts, or by terminal‐restriction fragment length polymorphism analysis of the microbial community DNA. The presence of organic residues did not affect the ability of the soil microbial community to remove typical pulp bleaching chloroaromatics. However, inorganic wastes strongly decreased the removal of such compounds.
Temperature and Wetland Plant Species Effects on Wastewater Treatment and Root Zone Oxidation
Authors: Allen Winthrop C. , Hook Paul B. , Biederman Joel A. , Stein Otto R.
Published: June 2010

Constructed wetlands are widely used for wastewater treatment, but there is little information on processes affecting their performance in cold climates, effects of plants on seasonal performance, or plant selection for cold regions. We evaluated the effects of three plant species on seasonal removal of dissolved organic matter (OM) (measured by chemical oxygen demand and dissolved organic carbon) and root zone oxidation status (measured by redox potential [Eh] and sulfate [SO2−4]) in subsurface‐flow wetland (SSW) microcosms. A series of 20‐d incubations of simulated wastewater was conducted during a 28‐mo greenhouse study at temperatures from 4 to 24°C. Presence and species of plants strongly affected seasonal differences in OM removal and root zone oxidation. All plants enhanced OM removal compared with unplanted controls, but plant effects and differences among species were much greater at 4°C, during dormancy, than at 24°C, during the growing season. Low temperatures were associated with decreased OM removal in unplanted controls and broadleaf cattail (Typha latifolia L.) microcosms and with increased removal in beaked sedge (Carex rostrata Stokes) and hardstem bulrush [Schoenoplectus acutus (Muhl. ex Bigelow) A. & D. Löve var. acutus] microcosms. Differences in OM removal corresponded to species' apparent abilities to increase root zone oxygen supply. Sedge and bulrush significantly raised Eh values and SO2−4 concentrations, particularly at 4°C. These results add to evidence that SSWs can be effective in cold climates and suggest that plant species selection may be especially important to optimizing SSW performance in cold climates.
Seasonal Dynamics of Denitrification along Topohydrosequences in Three Different Riparian Wetlands
Authors: Clément Jean‐Christophe , Pinay Gilles , Marmonier Pierre
Published: June 2010

We investigated the seasonal patterns of denitrification rates and potentials in soil profiles along the topohydrosequence formed at the upland–wetland interface in three riparian wetlands with different vegetation cover (i.e., forest, understory vegetation, and grass). Denitrification was measured using the acetylene inhibition method on soil cores and slurries, which provided a means of comparing the relative activity of this process in different locations. We evaluated, on a seasonal basis, the respective importance of the vegetative cover and the hydromorphic gradient as factors limiting denitrification. Regardless of the season, vegetation type, or lateral position along each topohydrosequence in the riparian wetlands, strong significant gradients of both in situ and potential denitrification rates were measured within a soil profile. Results confirm that the upper organic soil horizon is the most active, when in contact with the ground water. In deeper soil horizons, denitrification activity was low (from 0.004 to 0.5 mg N kg−1dry soil d−1), but contributed significantly to the reduction of ground water NO−3load along the riparian ground water flowpath (from 9.32 to 0.98 mg NO3–N L−1). Along the soil topohydrosequence, the denitrifying community of the upper soil horizons did not vary significantly on a seasonal basis despite the large seasonal ground water fluctuations. Along each topohydrosequence, the denitrification‐limiting factor gradually shifted from anaerobiosis to NO−3supply. In situ denitrification rates in the forested, understory vegetation and grass sites were not significantly different. This result emphasizes the importance of the topography of the valley rather than the vegetation cover in controlling denitrification activity in riparian wetlands.
Solution Chemistry Influence on Metal Mobility in Biosolids‐Amended Soils
Authors: Al‐Wabel M. A. , Heil D. M. , Westfall D. G. , Barbarick K. A.
Published: June 2010

Many studies have implicated dissolved organic carbon (DOC) as an important contributor to the elevated mobility of trace metals in soils amended with biosolids. Few of these studies, however, have quantified both DOC and metal concentrations. We completed laboratory leaching column studies on a dryland Platner loam (fine, smectitic, mesic Aridic Paleustoll) and an irrigated Osgood sand (loamy, mixed, mesic Arenic Ustollic Haplargid), both with a history of biosolids application. The soils were neutral to slightly alkaline in pH prior to amendment. We performed an additional application of biosolids to one set of columns in the laboratory at a rate of 28 Mg ha−1 to investigate the effect of time following application on metal mobility. The effect of electrolyte concentration was studied by using both distilled water and simulated irrigation water. Biosolids application increased both DOC and Cu in the column effluents resulting in a positive correlation between Cu and DOC across application treatments for both soils. Both Cu and Pb were mobilized under conditions of low electrical conductivity (EC). This may be the result of the release of a strong metal‐binding component of DOC under these conditions. Conversely, Zn mobility was positively correlated with EC, suggesting that either cation exchange or the formation of inorganic complexes influences Zn mobility. Anodic stripping voltammetry measurements indicated that only a small percentage of the total dissolved metals existed as free ions or inorganic complexes; the remainder appears to be complexed to DOC.
Chemical Transport from Paired Agricultural and Restored Prairie Watersheds
Authors: Schilling Keith E.
Published: June 2010

A five‐year record of streamflow and chemical sampling data was evaluated to assess the effects of large‐scale prairie restoration on transport of NO3–N, Cl, and SO4loads from paired 5000‐ha watersheds located in Jasper County, Iowa. Water quality conditions monitored during land use conversion from row crop agriculture to native prairie in the Walnut Creek watershed were compared with a highly agricultural control watershed (Squaw Creek). Combining hydrograph separation with a load estimation program, baseflow and stormflow loads of NO3–N, Cl, and SO4were estimated at upstream and downstream sites on Walnut Creek and a downstream site on Squaw Creek. Chemical export in both watersheds was found to occur primarily with baseflow, with baseflow transport greatest during the late summer and fall. Lower Walnut Creek watershed, which contained the restored prairie areas, exported less NO3–N and Cl compared with upper Walnut Creek and Squaw Creek watersheds. Average flow‐weighted concentrations of NO3–N exceeded 10 mg/L in upper Walnut Creek and Squaw Creek, but were estimated to be 6.6 mg/L in lower Walnut Creek. Study results demonstrate the utility of partitioning loads into baseflow and stormflow components to identify sources of pollutant loading to streams.
Picloram and Napropamide Sorption as Affected by Polymer Addition and Salt Concentration
Authors: Lu Jianhang , Wu Laosheng , Letey John , Farmer Walter J.
Published: June 2010

Polymer application to soil is a growing practice to improve soil physical properties and reduce soil erosion. Polymer addition can potentially influence herbicide and pesticide sorption in soil. The one‐point distribution coefficient Kd values of two herbicides in the absence and presence of each of 10 polymers (7 polyacrylamides and 3 polysaccharides) were determined by the batch equilibrium method. The results showed that nonionic napropamide [2‐(alpha‐naphthoxy)‐N,N‐diethyl propionamide] sorption was essentially unaffected by the presence of any of the polymers. The influence of polymers on anionic picloram (4‐amino‐3,5,6‐trichloropicolinic acid) sorption depends on the charge characteristics of polymers and salt concentrations in the solution. Electrostatic interaction and competition for sorption sites are two primary underlying mechanisms for the polymer influence. At low salt concentration, the increased picloram sorption in the presence of both cationic and anionic polymers was attributed to different electrostatic interactions and polymer partitioning between soil and solution phases. At high salt levels, the presence of polymers had either no influence or a slightly negative influence on the picloram sorption, which was attributed to competition for sorption sites. In field conditions, it is more likely that polymers have no or a slightly negative influence on herbicide sorption due to the presence of salts.
Simulated Effects of Crop Rotations and Residue Management on Wind Erosion in Wuchuan, West‐Central Inner Mongolia, China
Authors: Wang Erda , Harman Wyatte L. , Williams Jimmy R. , Xu Cheng
Published: June 2010

For decades, wind erosion has triggered dust and sand storms, buffeting Beijing and areas of northwestern China to the point of being hazardous to human health while rapidly eroding crop and livestock productivity. The EPIC (Environmental Policy Integrated Climate) field‐scale simulation model was used to assess long‐term effects of improved crop rotations and crop residue management practices on wind erosion in Wuchuan County in Inner Mongolia. Simulation results indicate that preserving crop stalks until land is prepared by zone tillage for the next year's crop in lieu of using them as a source of heating fuel or livestock fodder significantly reduces wind erosion by 60%. At the same time, grain and potato (Solanum tuberosum L.) yields were maintained or improved. Significant reductions in erosion, 35 to 46%, also resulted from delaying stalk removal until late January through late April. Yearly wind erosion was concentrated in April and May, the windiest months. Additionally, the use of alternative crop rotations resulted in differences in wind erosion, largely due to a difference in residue stature and quality and differences in biomass produced. As a result, altering current crop rotation systems by expanding corn (Zea mays L.), wheat (Triticum aestivum L.), and millet [Sorghum bicolor (L.) Moench] and reducing potato and pea (Pisum sativum L.) production significantly reduced simulated wind erosion, thus diminishing the severity of dust and sand storms in northwestern China. Saving and protecting topsoil over time will sustain land productivity and have long‐term implications for improving conditions of rural poverty in the region.
Effects of Flooding and Drought on Water Quality in Gulf Coastal Plain Streams in Georgia
Authors: Golladay Stephen W. , Battle Juliann
Published: June 2010

Since 1994, water‐quality constituents have been measured monthly in three adjacent Coastal Plain watersheds in southwestern Georgia. During 1994, rainfall was 650 mm above annual average and the highest flows on record were observed. From November 1998 through November 2000, 19 months had below average rainfall. Lowest flows on record were observed during the summer of 2000. The watersheds are human‐dominated with row‐crop agriculture and managed forestlands being the major land uses. However, one watershed (Chickasawhatchee Creek) had 10 to 13% less agriculture and greater wetland area, especially along the stream. Suspended particles, dissolved organic carbon, NH4–N, and soluble reactive phosphorus concentrations were greater during wet and flood periods compared with dry and drought periods for each stream. Regional hydrologic conditions had little effect on NO3–N or dissolved inorganic carbon. Chickasawhatchee Creek had significantly lower suspended sediment and NO3–N concentrations and greater organic and inorganic carbon concentrations, reflecting greater wetland area and stronger connection to a regional aquifer system. Even though substantial human land use occurred within all watersheds, water quality was generally good and can be attributed to low stream drainage density and relatively intact floodplain forests. Low drainage density minimizes surface runoff into streams. Floodplain forests reduce nonpoint‐source pollutants through biological and physical absorption. In addition to preserving water quality, floodplain forests provide important ecological functions through the export of nutrients and organic carbon to streams. Extreme low flows may be disruptive to aquatic life due to both the lack of water and to the scarcity of biologically important materials originating from floodplain forests.
Gaseous Contaminant Emissions as Affected by Burning Scrap Tires in Cement Manufacturing
Authors: Carrasco F. , Bredin N. , Heitz M.
Published: June 2010

We studied the environmental impact (gaseous emissions) of using scrap tires as a fuel substitute at a cement plant that produces one million tons of cement per year. Using a combination of tires and coal as opposed to only coal caused variations in the pollutant emission rate. The study recorded a 37% increase in the rate of emission for CO, a 24% increase for SO2, an 11% decrease for NOx, and a 48% increase for HCl when tires were included. The rate of emission for metals increased 61% for Fe, 33% for Al, 487% for Zn, 127% for Pb, 339% for Cr, 100% for Mn, and 74% for Cu, and decreased 22% for Hg. On the other hand, the emission rate of organic compounds dropped by 14% for polycyclic aromatic hydrocarbons, 8% in naphthalene, 37% in chlorobenzene, and 45% in dioxins and furans. We used a Gaussian model of atmospheric dispersion to calculate the average pollutant concentration (1‐h, 24‐h, and annual concentrations) in the ambient air at ground level with the help of the ISC‐ST2 software program developed by the USEPA. When tires were used, we observed (i) a 12 to 24% increase in particulate matter, this range considering the concentration variation depending on the average used (1‐h, 24‐h, and annual basis), 31 to 52% in CO, 22 to 34% in SO2, 39 to 52% in HCl, 12 to 27% in Fe, −3 to 8% in Al, 30 to 37% in Zn, and 270 to 885% in Pb; (ii) a decrease of 8 to 13% in NOx, 9 to 13% in polycyclic aromatic hydrocarbons, 6 to 7% in naphthalene, 32 to 39% in chlorobenzene, and 32 to 45% in dioxins and furans. The results obtained showed that the maximum ground‐level concentrations were well within the environmental standards (for operation with only coal as well as for operation with a combination of coal and tires).
Changes in the Rhizosphere of Metal‐Accumulating Plants Evidenced by Chemical Extractants
Authors: Hammer D. , Keller C.
Published: June 2010

The plants Salix viminalis L. (common osier) and Thlaspi caerulescens J. Presl & C. Presl have been studied often because of their high potential to extract heavy metals from soils. The soil properties favoring this phytoextraction are not yet fully known. In this study we compared three frequently used single‐extracting agents (NaNO3, diethylenetriaminepentaacetic acid [DTPA], and ethylenediaminetetraacetic acid [EDTA]) with a sequential extraction procedure to describe changes in the different Cd, Cu, and Zn pools in the rhizosphere of S. viminalis and T. caerulescens grown on calcareous and acidic Swiss soils in a pot experiment. The sequential extraction was used to assess the chemical affinities of these heavy metals (HM) in the soil whereas the single extractants were used for estimating the bioavailable HM pools in the soils. Cadmium depletion in several pools was most apparent in the acidic soil, with a significant decrease observed in the NaNO3‐, DTPA‐, and EDTA‐extractable fractions following T. caerulescens growth compared with control pots. The sequential extraction showed that most Cd extracted by the plant from the acidic soil originated from the organic pool, which implies that heavy metals bound to organic matter may constitute a significant part of the bioavailable Cd pool in soils. In the calcareous soil only a small amount of Cd was taken up by T. caerulescens, and this came mainly from the carbonate‐bound fraction. This study shows that T. caerulescens, and to a lesser extent S. viminalis, can alter the heavy metal distribution in different soil pools within 90 d.
Ion Cycling in Hemlock–Northern Hardwood Forests of the Southern Lake Superior Region
Authors: Bockheim J. G. , Crowley S. E.
Published: June 2010

Upland forests of the southern Lake Superior region are diverse and contain a shifting mosaic of eastern hemlock [Tsuga canadensis (L.) Carr.] and northern hardwood forests dominated by sugar maple (Acer saccharum Marsh.). In this study, we survey the relative effects of management practice (old growth vs. managed), forest cover type (hemlock vs. northern hardwood), and soil great group (Entic Haplorthod vs. Alfic Oxyaquic Fragiorthod) on ion cycling as a precursor to a longer‐term, more detailed study. Bulk precipitation, throughfall, and soil leachates at three depths were collected for two growing seasons in eight stands on the Ottawa National Forest in the Upper Peninsula of Michigan. A total of 1210 solutions were analyzed for pH, Na, K, Mg, Ca, Cl, NO3, and SO4 Losses of base cations (Ca, Mg, K) and SO4 from the bottom of the rooting zone generally were greater in old‐growth than in managed northern hardwoods on both fragic and nonfragic soils. Leaching losses of base cations and NO3 usually were greater beneath old‐growth northern hardwoods than beneath old‐growth hemlock on both soil types and for both forest cover types and management practices on fragic than nonfragic soils. Management practice, forest cover type, and soil type all appear to affect ion cycling within these forests. All of the stands featured striking losses of base cations that probably are influenced strongly by NO3 and SO4 in atmospheric deposition.
Imazaquin Adsorbed on Pillared Clay and Crystal Violet–Montmorillonite Complexes for Reduced Leaching in Soil
Authors: Polubesova Tamara , Nir Shlomo , Gerstl Zev , Borisover Mikhail , Rubin Baruch
Published: June 2010

Ground water pollution due to herbicide leaching has become a serious environmental problem. Imazaquin [2‐(4‐isopropyl‐4‐methyl‐5‐oxo‐2‐imidazolin‐2‐yl)quinoline‐3‐carboxylic acid] is an herbicide used to control broadleaf weeds in legume crops. Imazaquin is negatively charged at the basic pH of calcareous soils and exhibits high leaching potential in soils. Our aim was to design formulations of imazaquin to reduce herbicide leaching. Imazaquin sorption on pillared clay (PC) and crystal violet (CV)–montmorillonite complexes was studied. The CV–montmorillonite complexes become positively charged with adsorption of CV above the cation exchange capacity (CEC) of montmorillonite, and thus can sorb imazaquin. The Langmuir equation provides a good fit to isotherms of imazaquin sorption on PC and CV–montmorillonite complexes, but for charged complexes an equation that combines electrostatics with specific binding was preferred. Maximal imazaquin sorption was 17.3 mmol kg−1 for PC and 22.2 mmol kg−1 for CV–montmorillonite complexes. The extents of imazaquin desorption into water were 21% for PC and 5% for CV–clay complexes. The presence of anions decreased imazaquin sorption on both sorbents in the sequence phosphate > acetate > sulfate. Reduction of imazaquin sorption by the anions and the extent of its desorption in electrolyte solutions were higher for PC than for CV–clay complexes. Leaching of imazaquin from CV–montmorillonite formulations through soil (Rhodoxeralf) columns was two times less than from PC formulations and four times less than that of technical imazaquin. The CV–montmorillonite complexes at a loading above the CEC appear to be suitable for preparation of organo–clay–imazaquin formulations that may reduce herbicide leaching significantly.
Solute Transport Modeling under Cultivated Sandy Soils and Transient Water Regime
Authors: Gasser M. O. , Caron J. , Laverdière M. R. , Lagacé R.
Published: June 2010

Drainable lysimeters offer the possibility to integrate heterogeneous solute leaching conditions caused by row crops and transient water regime, and to conveniently measure water and solute fluxes at the drainage outlet. To compare solute leaching behavior in and around drainable lysimeters operating under a transient water regime in potato (Solanum tuberosum L.) fields, parameters of the convective lognormal transfer (CLT) function model were fitted using bromide (Br−) flux concentrations (Cf) measured in lysimeters and from Br− resident concentrations (Cr) measured in adjacent soil cores. Expected mean values Ez(I) obtained from Cr and Cf CLT parameters were equivalent and well correlated (R2 = 0.78). However, estimated median values μ of the CLT function were smaller when derived from Cr (1.05 to 1.28) compared with Cf (1.23 to 2.14). Most μ values were also smaller than previously reported values for a 30‐cm reference depth, indicating that 50% of solute mass would leach more readily in these coarse sandy soils. Higher variance and dispersion of Cr compared with those of Cf could be related to a smaller sampling support (sample size/sampling area) in the case of Cr measured by soil coring, or to disruption of solute transport mechanisms in the repacked lysimeter. Retained Br− in the top soil layer after 12 to 17 cm of cumulative drainage was indicated by measured Cr Neither CLT function simulated well residual topsoil Cr values, indicating that Br− plant cycling or preferential flow probably interfered even though tuber Br− uptake was relatively small.
Soil Quality in New Zealand
Authors: Lilburne L. R. , Hewitt A. E. , Sparling G. P. , Selvarajah N.
Published: June 2010

Soil depletion and degradation have been increasingly recognized as important environmental issues in many parts of the world. Over the last decade a number of political and legislative measures have been introduced to encourage and enforce sustainable soil management in New Zealand. Application of the new legislation has highlighted gaps in our knowledge of soil quality and a lack of scientific methods to assess and monitor soil quality. This paper describes the legislative measures and outlines the scientific response to the needs of regulatory agencies responsible for maintaining environmental quality. The research recommended a set of indicators to assess soil quality. Each soil quality attribute has an associated “target range” defining the acceptable value for the attribute. The paper also discusses the communication of results to end‐users, including the development of a computerized assessment tool. The legislative measures and scientific response have fostered a closer relationship between the policy and science communities, leading to more well‐focused research, but greater collaboration is still required.
Transport and Degradation of Toluene and o‐Xylene in an Unsaturated Soil with Dipping Sedimentary Layers
Authors: Søvik Anne Kristine , Alfnes Eli , Breedveld Gijs D. , French Helen K. , Pedersen Tor Simon , Aagaard Per
Published: June 2010

A lysimeter trench was established at the Gardermoen delta (50 km north of Oslo, Norway) to study the flow of water and transport and degradation of aromatic jet fuel components (toluene and o‐xylene) in the undisturbed unsaturated zone. Site investigations with ground‐penetrating radar revealed the presence of dipping sedimentary layers within the foreset unit. This study has shown that the foreset bed of the Gardermoen delta structure provided a preferential flow path for the transport of the solute plumes, but did not have dramatic effects on the degradation potential under the current conditions. The degradation potential for toluene and o‐xylene in the unsaturated zone at Gardermoen was very high and almost all of the injected hydrocarbons were biodegraded before reaching the saturated zone. However, the horizontal displacement of the plume showed that knowledge about sedimentary structures in the unsaturated zone is important for a sufficient monitoring of contaminant transport and for remediation purposes. Carbon dioxide and O2 were measured in situ simultaneously with extraction of water samples, and indicated aerobic biodegradation of toluene and o‐xylene. Overall, first‐order degradation coefficients were calculated to be in the range of 0.19 to 0.21 d−1 and 0.10 to 0.11 d−1 for toluene and o‐xylene, respectively.
Distribution of Inorganic Nitrogen and Phosphorus Concentrations in Stream Flow of Two Southern Piedmont Watersheds
Authors: Franklin D. H. , Steiner J. L. , Cabrera M. L. , Usery E. L.
Published: June 2010

Innate distributions or variability of nutrient concentrations within the fluvial system must be better understood to establish nutrient guidelines that are applicable and to discern which areas or landscape positions within the watershed are more vulnerable to nutrient losses. This work was conducted to (1) determine the system‐wide spatial distribution of N and P concentrations in biweekly stream samples from two Southern Piedmont watersheds, and (2) determine the relationship between N and P concentrations in biweekly samples and watershed morphological features. From December 1998 through December 2000 samples were collected biweekly from 17 sampling sites located on Rose Creek and from 18 sampling sites located on Greenbrier Creek. The samples were analyzed for ammonium (NH4), nitrate (NO3), and dissolved reactive phosphorus (DRP) concentrations. We found that spatial autocorrelation of nitrate concentrations was evident and that some spatial autocorrelation of DRP concentrations was also present. We further found that the fluvial network morphological feature, drainage density, explained part of the spatial autocorrelation found for nitrate but did not for DRP. These results indicate that innate variability of nutrient concentrations within streams exists and suggest that decision makers should begin to consider location within the watershed when making nutrient management guidelines and decisions.
Copper and Zinc Speciation in the Solution of a Soil–Sludge Mixture
Authors: Vulkan R. , Mingelgrin U. , Ben‐Asher J. , Frenkel H.
Published: June 2010

Only a small fraction of the transition metals content in sludge‐amended soils is soluble, and yet this fraction is a major contributor to the mobility and bioavailability of the metals. The chemical species of zinc (Zn) and copper (Cu) in the soluble fractions of soil–sludge mixtures were characterized with respect to their charge, molecular weight, and stoichiometry using ion exchange resin and gel chromatography procedures. The change in the metals' species with time after sludge application was followed for 100 d. Copper in the water extracts of the sludge–sand mixtures was found almost exclusively in low molecular weight (below 1000 Da) complexes. Higher molecular weight (around 2500 Da) dissolved organic carbon (DOC) was present in the extracts as well, but this DOC fraction exhibited little complexation. Copper was present in the extracts mainly as negatively charged species throughout the incubation period, and zinc tended to form zwitter ions. As incubation progressed, the relative content of positively charged Zn in solution increased. Complexation capacity of DOC in sludge water extract, extrapolated to infinite dilution, was 8.75 mM Cu g−1 DOC. When the complexation capacity of the extract is near saturation, a mean Cu–DOC complex can be defined. It consists of 1.9 Cu atoms attached to DOC species containing 5.6 C atoms. Thus, the organic Cu complexes consist primarily of about two Cu ions attached to DOC species containing only five or six C atoms. Amino acids and small peptides or polycarboxylic acids, such as citric acid, thus may be important complexing agents of the metal.
Transport of Di(2‐ethylhexyl)phthalate (DEHP) Applied with Sewage Sludge to Undisturbed and Repacked Soil Columns
Authors: de Jonge H. , de Jonge L. W. , Blicher B. W. , Moldrup P.
Published: June 2010

Municipal sewage sludge is often used on arable soils as a source of nitrogen and phosphorus, but it also contains organic contaminants that may be leached to the ground water. Di(2‐ethylhexyl)phthalate (DEHP) is a priority pollutant that is present in sewage sludge in ubiquitous amounts. Column experiments were performed on undisturbed soil cores (20‐cm depth × 20‐cm diameter) with three different soil types: a sand, a loamy sand, and a sandy loam soil. Dewatered sewage sludge was spiked with 14C‐labeled DEHP (60 mg kg−1) and bromide (5 g kg−1). Sludge was applied to the soil columns either as five aggregates, or homogeneously mixed with the surface layer. Also, two leaching experiments were performed with repacked soil columns (loamy sand and sandy loam soil). The DEHP concentrations in the effluent did not exceed 1.0 μg L−1, and after 200 mm of outflow less than 0.5% of the applied amount was recovered in the leachate in all soils but the sandy loam soil with homogeneous sludge application (up to 3.4% of the applied amount recovered). In the absence of macropore flow, DEHP in the leachate was primarily sorbed to mobilized dissolved organic macromolecules (DOM, 30.3 to 81.3%), while 2.4 to 23.6% was sorbed to mobilized mineral particles. When macropore flow occurred, this changed to 16.5 to 37.4% (DOM) and 36.9 to 40.6% (mineral particles), respectively. The critical combination for leaching of considerable amounts of DEHP was homogeneous sludge application and a continuous macropore structure.
Nitrogen Removal and Nitrate Leaching for Forage Systems Receiving Dairy Effluent
Authors: Woodard Kenneth R. , French Edwin C. , Sweat Lewin A. , Graetz Donald A. , Sollenberger Lynn E. , Macoon Bisoondat , Portier Kenneth M. , Wade Brett L. , Rymph Stuart J. , Prine Gordon M. , Van Horn Harold H.
Published: June 2010

Florida dairies need year‐round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO−3–N) concentrations in soil water below the rooting zone for two forage systems during four 12‐mo cycles (1996–2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha−1 per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)–rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha−1 per cycle for the low loading rate, 528 kg ha−1 for the medium rate, and 585 kg ha−1 for the high. For the corn (Zea mays L.)–forage sorghum [Sorghum bicolor (L.) Moench]–rye system (CSR), N removals were 320 kg ha−1 per cycle for the low rate, 327 kg ha−1 for the medium, and 378 kg ha−1 for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1–24.2 g kg−1) than in corn and forage sorghum (10.3–14.7 g kg−1). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO−3–N leaching. For CSR, NO−3–N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy closure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO−3–N concentrations below the rooting zone.
Influence of Plant Age and Size on Simazine Toxicity and Uptake
Authors: Knuteson S. L. , Whitwell T. , Klaine S. J.
Published: June 2010

Improper pesticide management can lead to environmental problems such as water quality degradation and ecological stress. Recent research in our laboratory has focused on development of constructed wetlands to assimilate pesticide‐contaminated water. For improved aesthetics, these wetlands have been established with ornamental plant species. The effectiveness of a plant species for phytoremediation depends in part on its tolerance for the contaminant. Plant tolerance for pesticides may vary depending on plant age and size. This study examined the influence of plant age and size on the uptake, distribution, and toxicity of the herbicide simazine [2‐chloro‐4,6‐bis(ethylamino)‐1,3,5‐triazine] in two ornamental wetland plants: parrot feather [Myriophyllum aquaticum (Vell.) Verdc.] and canna (Canna × hybrida L. ‘Yellow King Humbert’). Plants of different ages and sizes were exposed to simazine in 10% Hoagland's nutrient solution. Toxicity was characterized using plant growth, water uptake, and photosynthetic yield during exposure and postexposure periods. In addition, other plants were exposed to [14C] simazine in nutrient medium to characterize pesticide uptake and translocation. Four‐week‐old parrot feather and canna were more tolerant of simazine than two‐week‐old plants. The two‐week‐old plant tissues of both species had higher tissue burdens of simazine than four‐week‐old plants. Simazine was primarily accumulated in the leaves of both parrot feather and canna. These results suggest that plants in a constructed wetland designed for simazine assimilation would be more vulnerable to simazine toxicity shortly after emergence.
Evaluation of Commercial Odor Control Agents for Suppressing Escherichia coli in Swine Manure Slurry
Authors: Johnston Della , Chapman Ralph , Massé Daniel , Topp Edward
Published: June 2010

Ten commercially available manure odor control agents were evaluated in bench‐scale laboratory microcosms for their ability to inhibit or kill Escherichia coli, a commonly used indicator of fecal pollution and a potential pathogen. At manufacturer recommended rates, none of the agents reduced viable populations of E. coli in pure cultures or in swine manure slurry. However, at rates 10‐fold higher than those recommended by the manufacturer, EnviroPur rapidly reduced viable populations of E. coli Accelerated death of E. coli was observed at temperatures as low as 4°C. Chemical analysis of EnviroPur indicated that it contains alkylphenol polyethoxylates, common industrial surfactants. These results suggest that at manufacturer‐recommended rates, the odor‐controlling agents would not be effective at suppressing E. coli in stored swine manure slurry.
Phosphorus Loss to Runoff Water Twenty‐Four Hours after Application of Liquid Swine Manure or Fertilizer
Authors: Tabbara Hadi
Published: June 2010

Phosphorus (P) added to soil from fertilizer or manure application could pose a threat to water quality due to its role in eutrophication of fresh water resources. Incorporating such amendments into the soil is an established best management practice (BMP) for reducing soluble P losses in runoff water, but could also lead to higher erosion. The objective of this study was to test whether incorporation of manure or fertilizer 24 h before an intense rain could also reduce sediment‐bound and total phosphorus (TP) losses in runoff. A rainfall simulation study was conducted on field plots (sandy loam with 6–7% slope, little surface residue, recently cultivated) that received two application rates of liquid swine manure or liquid ammonium polyphosphate fertilizer, using either surface‐broadcast or incorporated methods of application. Incorporation increased the total suspended solids (TSS) concentrations in runoff but mass losses were not affected. Incorporation also reduced flow‐weighted concentrations and losses of dissolved reactive phosphorus (DRP) and TP by as much as 30 to 60% depending on source (fertilizer vs. manure) and application rate. Phosphorus is moved below the mixing zone of interaction on incorporation, and thus the effect of the amount and availability of P in this zone is more important than cultivation on subsequent P losses in runoff. Incorporating manure or fertilizer in areas of intense erosive rain, recent extensive tillage, and with little or no surface residue is therefore a best management practice that should be adhered to in order to minimize contamination of surface water. Results also show comparatively lower P losses from manure than fertilizer.
Effect of Broadcast Manure on Runoff Phosphorus Concentrations over Successive Rainfall Events
Authors: Kleinman Peter J. A. , Sharpley Andrew N.
Published: June 2010

Concern over eutrophication has directed attention to manure management effects on phosphorus (P) loss in runoff. This study evaluates the effects of manure application rate and type on runoff P concentrations from two, acidic agricultural soils over successive runoff events. Soils were packed into 100‐ × 20‐ × 5‐cm runoff boxes and broadcast with three manures (dairy, Bos taurus; layer poultry, Gallus gallus; swine, Sus scrofa) at six rates, from 0 to 150 kg total phosphorus (TP) ha−1 Simulated rainfall (70 mm h−1) was applied until 30 min of runoff was collected 3, 10, and 24 d after manure application. Application rate was related to runoff P (r2 = 0.50–0.98), due to increased concentrations of dissolved reactive phosphorus (DRP) in runoff; as application rate increased, so did the contribution of DRP to runoff TP. Varied concentrations of water‐extractable phosphorus (WEP) in manures (2–8 g WEP kg−1) resulted in significantly lower DRP concentrations in runoff from dairy manure treatments (0.4–2.2 mg DRP L−1) than from poultry (0.3–32.5 mg DRP L−1) and swine manure treatments (0.3–22.7 mg DRP L−1). Differences in runoff DRP concentrations related to manure type and application rate were diminished by repeated rainfall events, probably as a result of manure P translocation into the soil and removal of applied P by runoff. Differential erosion of broadcast manure caused significant differences in runoff TP concentrations between soils. Results highlight the important, but transient, role of soluble P in manure on runoff P, and point to the interactive effects of management and soils on runoff P losses.
Studies on Mobility and Degradation Pathways of Terbuthylazine Using Lysimeters on a Field Scale
Authors: Guzzella L. , Rullo S. , Pozzoni F. , Giuliano G.
Published: June 2010

Terbuthylazine [N2‐tert‐butyl‐6‐chloro‐N4‐ethyl‐1,3,5‐triazine‐2,4‐diamine] degradation pathways in agricultural soils were evaluated by following the appearance and mobility of its main transformation products: dealkylated and hydroxylated derivatives. Three experimental degradation studies in open field were performed in different hydraulic conditions: constant hydraulic head on topsoil, achieved to simulate the highest‐risk situation for the aquifer; intermittent artificial precipitation to simulate a medium‐risk situation; and natural precipitation to reproduce the lowest‐risk condition. Concentrations of terbuthylazine transformation products derived from dealkylation and hydroxylation reactions were measured in leachates and soil samples collected during the three experiments. Desethylterbuthylazine (DET) and deethylterbuthylazine‐2‐hydroxide [DETH; 4‐amino‐6‐terbutylamino‐(1,3,5)‐triazine‐2‐OH] were found to be the highest‐leaching compounds and therefore can be considered as potential pollutants for aquifer contamination.