bluuebunny/crossref_metadata_2025_split huggingface dataset:
Narrow‐Waveband Reflectance Ratios for Remote Estimation of Nitrogen Status in Cotton
Authors: Read J. J. , Tarpley L. , McKinion J. M. , Reddy K. R. 
Published: June 2010

ABSTRACTTailoring nitrogen (N) fertilizer applications to cotton (Gossypium hirsutum L.) in response to leaf N status may optimize N use efficiency and reduce off‐site effects of excessive fertilizer use. This study compared leaf and canopy reflectance within the 350 to 950 nm range in order to identify reflectance ratios sensitive to leaf chlorophyll (Chl), and hence N status, in cotton. Plants were grown outdoors in large pots using half‐strength Hoagland's (control) solution until some three‐row plots received a restricted supply of N. Treatments comprised control, 20% of control N at first flower bud (square) onward; 0 and 20% of control N at first flower onward; and 0% of control N at fruit‐filling onward. Despite leaf N values ranging from 51 to 19 g kg−1 across treatments and sampling dates, a weak correlation was obtained between Chl and N (r2 = 0.32, df = 70). In general, N stress led to increased reflectance at 695 ± 2.5 nm (R695) and decreased reflectance at R410, and changes in leaf N were best correlated with either R695 or R755 in leaves and either R410 or R700 in canopies. The strongest associations between leaf constituent and canopy reflectance ratio were Chl vs. R415/R695 (r2 = 0.72), carotenoids vs. R415/R685 (r2 = 0.79), and N vs. R415/R710 (r2 = 0.70). The R415 measure appears to be a more stable spectral feature under N stress, as compared with more pronounced changes along the reflectance red edge (690–730 nm). Multiple regression identified a three‐waveband canopy reflectance model that explained 80% of the variability in leaf N. Results indicate that remote sensing of N status in cotton is feasible using narrow‐waveband reflectance ratios that involve the violet or blue region of the spectrum (400 to 450 nm) and the more commonly featured red‐edge region.
Spectral Properties of Salt Crusts Formed on Saline Soils
Authors: Howari F. M. , Goodell P. C. , Miyamoto S. 
Published: June 2010

ABSTRACTRapid identification and large‐scale mapping of salt‐affected lands will help improve salinity management in watersheds and ecosystems. This study was conducted to examine spectral reflectance of soils treated with saline solutions containing NaCl, NaHCO3, Na2SO4, and CaSO4·2H2O. Spectral reflectance was measured upon salt crusts formed on two soils (Torrifluvents) subirrigated with saline solutions of 500, 1000, and 1500 mmolc L−1 with a spectroradiometer in the visible and near‐infrared region (400–2500 nm). Spectral analyses revealed that samples of gypsum crusts have diagnostic absorption features near 1023, 1225, 1457, 1757, 1800, and 2336 nm, whereas halite crusts have diagnostic absorption features near 1442, 1851, 1958, and 2226 nm. Several broad absorption features were seen in the spectra of the crusts of sodium bicarbonate at 1243, 1498, 1790, 1988, and 2356 nm. The spectrum of soils treated with sodium sulfate exhibited absorption features at 1243, 1472, 1677, 1774, 1851, 1968, and 2245 nm. Crystal size or salt concentrations did not affect the positions of the absorption bands of the salt crusts. However, reflectance increased as particle sizes decreased or with increasing presence of salt crusts. Spectroscopy can be used under certain conditions to identify the presence of primary diagnostic spectral features of gypsum, nahcolite, thenardite, and halite crusts.
Environmental Risks of Applying Sewage Sludge Compost to Vineyards
Authors: Korboulewsky Nathalie , Dupouyet Sylvie , Bonin Gilles 
Published: June 2010

ABSTRACTBiosolids are applied to vineyards to supply organic matter. However, there is concern that this practice can increase the concentration of macronutrients and heavy metals in the soil, some of which can leach. We evaluated the environmental hazard of sewage sludge compost applied in March 1999 at 10, 30, and 90 Mg ha−1 fresh weight in a vineyard in southeastern France. Soil organic matter increased in all plots by 3 g kg−1 18 mo after the amendment. Neither total nor available heavy metal concentrations increased in the soil. Mineral nitrogen (N) in the topsoil of amended plots of 10, 30, and 90 Mg ha−1 increased by 5, 14, and 26 kg (NO−3–N + NH+4–N) ha−1, respectively, the first summer and by 2, 5, and 10 kg NO−3–N + NH+4–N ha−1, respectively, the second summer compared with controls. At the recommended rate, risks of N leaching is very low, but phosphorus (P) appeared to be the limiting factor. Phosphorus significantly increased only in plots amended with the highest rate in the topsoil and subsoil. At lower rates, although no significant differences were observed, P added was greater than the quantities absorbed by vines. In the long run, P will accumulate in the soil and may reach concentrations that will pose a risk to surface waters and ground water. Therefore, although the current recommended rate (10 Mg ha−1) increased soil organic matter without the risk of N leaching, total sewage sludge loading rates on vineyards should be based on P concentrations.
Application of Classification‐Tree Methods to Identify Nitrate Sources in Ground Water
Authors: Spruill Timothy B. , Showers William J. , Howe Stephen S. 
Published: June 2010

ABSTRACTA study was conducted to determine if nitrate sources in ground water (fertilizer on crops, fertilizer on golf courses, irrigation spray from hog (Sus scrofa) wastes, and leachate from poultry litter and septic systems) could be classified with 80% or greater success. Two statistical classification‐tree models were devised from 48 water samples containing nitrate from five source categories. Model 1 was constructed by evaluating 32 variables and selecting four primary predictor variables (δ15N, nitrate to ammonia ratio, sodium to potassium ratio, and zinc) to identify nitrate sources. A δ15N value of nitrate plus potassium >18.2 indicated animal sources; a value <18.2 indicated inorganic or soil organic N. A nitrate to ammonia ratio >575 indicated inorganic fertilizer on agricultural crops; a ratio <575 indicated nitrate from golf courses. A sodium to potassium ratio >3.2 indicated septic‐system wastes; a ratio <3.2 indicated spray or poultry wastes. A value for zinc >2.8 indicated spray wastes from hog lagoons; a value <2.8 indicated poultry wastes. Model 2 was devised by using all variables except δ15N. This model also included four variables (sodium plus potassium, nitrate to ammonia ratio, calcium to magnesium ratio, and sodium to potassium ratio) to distinguish categories. Both models were able to distinguish all five source categories with better than 80% overall success and with 71 to 100% success in individual categories using the learning samples. Seventeen water samples that were not used in model development were tested using Model 2 for three categories, and all were correctly classified. Classification‐tree models show great potential in identifying sources of contamination and variables important in the source‐identification process.
Relating Net Nitrogen Input in the Mississippi River Basin to Nitrate Flux in the Lower Mississippi River
Authors: McIsaac Gregory F. , David Mark B. , Gertner George Z. , Goolsby Donald A. 
Published: June 2010

ABSTRACTA quantitative understanding of the relationship between terrestrial N inputs and riverine N flux can help guide conservation, policy, and adaptive management efforts aimed at preserving or restoring water quality. The objective of this study was to compare recently published approaches for relating terrestrial N inputs to the Mississippi River basin (MRB) with measured nitrate flux in the lower Mississippi River. Nitrogen inputs to and outputs from the MRB (1951 to 1996) were estimated from state‐level annual agricultural production statistics and NOy (inorganic oxides of N) deposition estimates for 20 states that comprise 90% of the MRB. A model with water yield and gross N inputs accounted for 85% of the variation in observed annual nitrate flux in the lower Mississippi River, from 1960 to 1998, but tended to underestimate high nitrate flux and overestimate low nitrate flux. A model that used water yield and net anthropogenic nitrogen inputs (NANI) accounted for 95% of the variation in riverine N flux. The NANI approach accounted for N harvested in crops and assumed that crop harvest in excess of the nutritional needs of the humans and livestock in the basin would be exported from the basin. The U.S. White House Committee on Natural Resources and Environment (CENR) developed a more comprehensive N budget that included estimates of ammonia volatilization, denitrification, and exchanges with soil organic matter. The residual N in the CENR budget was weakly and negatively correlated with observed riverine nitrate flux. The CENR estimates of soil N mineralization and immobilization suggested that there were large (2000 kg N ha−1) net losses of soil organic N between 1951 and 1996. When the CENR N budget was modified by assuming that soil organic N levels have been relatively constant after 1950, and ammonia volatilization losses are redeposited within the basin, the trend of residual N closely matched temporal variation in NANI and was positively correlated with riverine nitrate flux in the lower Mississippi River. Based on results from applying these three modeling approaches, we conclude that although the NANI approach does not address several processes that influence the N cycle, it appears to focus on the terms that can be estimated with reasonable certainty and that are correlated with riverine N flux.
Secondary Metabolite Concentrations and Terpene Emissions of Scots Pine Xylem after Long‐Term Forest Fertilization
Authors: Turtola S. , Manninen A.‐M. , Holopainen J. K. , Levula T. , Raitio H. , Kainulainen P. 
Published: June 2010

ABSTRACTSecondary compounds are known to be associated with the resistance of conifer xylem against insects and fungi. The effects of long‐term forest fertilization with nitrogen (N) or with N, calcium (Ca), and phosphorus (P) on secondary compounds in the xylem of 50‐yr‐old Scots pine (Pinus sylvestris L.) trees were examined. Xylem samples were collected from trees growing in three locations in southern Finland: Vilppula, Padasjoki, and Punkaharju. Forests were fertilized every fifth (Vilppula and Padasjoki) or tenth (Punkaharju) year since the 1950s. We compared concentrations of individual and total monoterpenes and resin acids in the heartwood and sapwood of Scots pine. Terpene emissions were analyzed from the sapwood and total phenolics from the heartwood. Fertilization did not have any significant effect on the concentrations and emissions of xylem monoterpenes. Concentrations of several individual terpenes in sapwood were positively correlated with the corresponding terpene emission. The concentrations of individual resin acids (i.e., abietic and dehydroabietic) decreased significantly in Punkaharju, but increased in the sapwood of N‐fertilized trees compared with control ones at Padasjoki and Vilppula. The concentrations of resin acids in the heartwood were not significantly affected by fertilization. Both fertilization treatments decreased the total phenolic concentration in the heartwood of trees growing in Padasjoki. There was a significant positive correlation between the total phenolics and total resin acid concentration. Overall, resin acids and phenolics seemed be more responsive than monoterpenes to N treatment. These results suggest that forest fertilization might cause slight changes in secondary compound concentrations of xylem, and thus might have significance in the decay resistance of wood.
Bioavailability of Organic Phosphorus in a Submerged Aquatic Vegetation–Dominated Treatment Wetland
Authors: Pant H. K. , Reddy K. R. , Dierberg F. E. 
Published: June 2010

ABSTRACTEnzymatic hydrolysis and mineralization of organic phosphorus (P) were determined in surface water samples collected from inflow and outflow of a submerged aquatic vegetation (SAV)–dominated treatment wetland of the Florida Everglades. Water samples were fractionated into three size fractions (>0.4 μm, <0.4 to >0.05 μm, and <0.05 μm) with a sequential flow filtration technique. The fractionated water samples were incubated to hydrolyze with alkaline phosphatase (APase) and phosphodiesterase (PDEase), and to mineralize at different redox and pH. Unlike APase, which hydrolyzed ≤10% of organic P, PDEase hydrolyzed ≥71% of organic P in unfiltered water from both inflow and outflow waters, suggesting the domination of bioavailable diester P in the water. Phosphodiesterase completely hydrolyzed organic P in the <0.4‐ to >0.05‐μm and <0.05‐μm fractions, as compared with ≤35% in the >0.4‐μm fraction. However, the P mineralization in inflow and outflow waters at different redox and pH showed that P associated with particulate > 0.4 μm had been mineralized the most. Phosphorus‐31 nuclear magnetic resonance (NMR) spectroscopy showed that surficial sediments from the inflow region contained a high proportion of polynucleotides, nucleoside monophosphates, and previously unreported glycerophosphoethanolamine and phosphoenolpyruvates. However, at the outflow, the relative proportion of polynucleotides and nucleoside monophosphates was reduced substantially. This suggests that the SAV wetland may sequester P via accretion of organic matter.
Hydrogen Sulfide Effects on Ammonia Removal by a Biofilter Seeded with Earthworm Casts
Authors: Lee E. Y. , Cho K. S. , Han H. D. , Ryu H.W. 
Published: June 2010

ABSTRACTAmmonia (NH3) removal efficiencies were evaluated when hydrogen sulfide (H2S) and NH3 in binary mixture gases were supplied to a ceramic biofilter seeded with earthworm (Lumbricus terrestris) casts. The effect of inlet H2S concentration and space velocity (SV) on the removal of NH3 was investigated after the acclimation of the biofilter with NH3 gas. When NH3 was singly supplied to the biofilter, NH3 removal was maintained at almost 100% until inlet NH3 concentration was increased up to 600 μL L−1 and SV up to 330 h−1, at which the elimination capacity of NH3 was 148 g N m−3 h−1 When H2S was supplied simultaneously, however, the accumulation of toxic sulfide ions showed dual effects on NH3 removal efficiencies. First, no effects were observed at inlet H2S loading below 60 g S m−3 h−1; however, inhibition by H2S at higher loading was observed above 60 g S m−3 h−1 The point at which loading achieved a maximum of more than 99% NH3 removal efficiency was 139 g N m−3 h−1, when inlet H2S concentration was held under 100 μL L−1, but it dropped to 76 and 30 g N m−3 h−1 when the inlet H2S concentration increased to 220 and 460 μL L−1, respectively. The critical points of inlet H2S loading that guaranteed over 99% NH3 removal were determined as 100, 100, 60, and 40 g S m−3 h−1 at inlet NH3 concentrations of 100, 200, 400, and 600 μL L−1, respectively. Inlet NH3 loading had synergic effects of increasing the inhibition of inlet H2S loading on the NH3 removability of the biofilter.
Application Technique and Slurry Co‐Fermentation Effects on Ammonia, Nitrous Oxide, and Methane Emissions after Spreading
Authors: Wulf S. , Maeting M. , Clemens J. 
Published: June 2010

ABSTRACTThe aim of this study was to investigate the effect of different application techniques on greenhouse gas emission from co‐fermented slurry. Ammonia (NH3), nitrous oxide (N2O), and methane (CH4) emissions were measured in two field experiments with four different application techniques on arable and grassland sites. To gather information about fermentation effects, unfermented slurry was also tested, but with trail hose application only. Co‐fermented slurry was applied in April at a rate of 30 m3 ha−1 Measurements were made every 4 h on the first day after application and were continued for 6 wk with gradually decreasing sampling frequency. Methane emissions were <150 g C ha−1 from co‐fermentation products and seemed to result from dissolved CH4 Only in the grassland experiment were emissions from unfermented slurry significantly higher, with wetter weather conditions probably promoting CH4 production. Nitrous oxide emission was significantly increased by injection on arable and grassland sites two‐ and threefold, respectively. Ammonia emissions were smallest after injection or trail shoe application and are discussed in the preceding paper. We evaluated the climatic relevance of the measured gas emissions from the different application techniques based on the comparison of CO2 equivalents. It was evident that NH3 emission reduction, which can be achieved by injection, is at least compensated by increased N2O emissions. Our results indicate that on arable land, trail hose application with immediate shallow incorporation, and on grassland, trail shoe application, bear the smallest risks of high greenhouse gas emissions when fertilizing with co‐fermented slurry.
Irrigation of Broccoli and Canola with Boron‐ and Selenium‐Laden Effluent
Authors: Bañuelos G. S. 
Published: June 2010

ABSTRACTSelenium (Se), boron (B), and salinity contamination of agricultural drainage water is potentially hazardous for water reuse strategies in central California. To demonstrate the feasibility of using plants to extract Se from drainage water, Se accumulation was determined in canola (Brassica napus L.) and broccoli (Brassica oleracea L.) irrigated with drainage effluent in the San Joaquin Valley, California. In the 2‐yr field study, both crops were irrigated with a typical drainage water containing Se (150 μg L−1), B (5 mg L−1), and a sulfate dominated salinity (EC of 7 dS m−1). Total dry matter yields were at least 11 Mg ha−1 for both canola and broccoli, and plant tissue Se concentrations did not exceed 7 mg kg−1 DM for either crop. Based on the amount of soluble Se applied to crops with drainage water and the estimated amount of soluble Se remaining in soil to a depth of 90 cm at harvest, both canola and broccoli accumulated at least 40% of the estimated soluble Se lost from the soil for both years. Applied Se not accounted for in plant tissue or as soluble Se in the soil was presumably lost by biological volatilization. This study suggests that irrigating two high value crops such as canola and broccoli with Se‐laden effluent helps manage Se‐laden effluent requiring treatment, and also produces economically viable Se‐enriched crops. Future research should focus on managing residual salt and B in the soil for sustaining long time water reuse strategies.
Low‐Temperature Chromium(VI) Biotransformation in Soil with Varying Electron Acceptors
Authors: Tseng Julia K. , Bielefeldt Angela R. 
Published: June 2010

ABSTRACTEffective and low‐cost strategies for remediating chromium (Cr)‐contaminated soil are needed. Chromium(VI) leaching from contaminated soil into ground water and surface water threatens water supplies and the environment. This study tested indigenous Cr(VI) microbial transformation in batch systems at 10°C in the presence of various electron acceptors. The effects of carbon addition, spiked Cr(VI), and mixing highly contaminated soil with less contaminated soil were investigated. The results indicated that Cr(VI) can be biotransformed in the presence of different electron acceptors including oxygen, nitrate, sulfate, and iron. Sugar addition had the greatest effect on enhancing Cr(VI) removal. Less dissolved organic carbon (DOC) was consumed per amount of Cr(VI) transformed under anaerobic conditions [0.8–93 mg DOC/mg Cr(VI)] compared with aerobic conditions [1.4–265 mg DOC/mg Cr(VI)]. Toxicity of high concentrations (<160 mg/L) of spiked Cr(VI) were not evident. At Cr(VI) concentrations > 40 mg/L, aerobic conditions promoted faster Cr(VI) reduction than anaerobic conditions with nitrate or sulfate present. Biotransformation of Cr(VI) in highly contaminated soil (22 000 mg Cr/kg) was facilitated by mixing with less‐contaminated soil. The study results provide a framework for evaluating indigenous Cr(VI) microbial transformation and enhance the ability to develop strategies for soil treatment.
Soil Quality at a National Scale in New Zealand
Authors: Sparling G. P. , Schipper L. A. 
Published: June 2010

ABSTRACTNew Zealand is a signatory to international conventions on environmental performance, and soil quality information is needed for reporting both at a national and regional level. Soil quality was measured at 222 sites in five regions of New Zealand (12 soil orders and 9 land‐use categories). Topsoil (0–100 mm) properties measured were total carbon and nitrogen, potentially mineralizable N, pH, Olsen P, cation exchange capacity, bulk density, total porosity, macroporosity, and total available and readily available water. Our objectives were to gauge the representativeness of the sample, determine the contribution from land use or soil order to variability, rationalize the data set, and identify concerns for long‐term sustainable land use. Soil and land use combinations were both under‐ or overrepresented in the data set compared with national distribution. Soil order and land‐use categories explained 55 to 76% of the variance in soil properties. Total C contents of pastures were comparable with indigenous forest soils, but pastures were less acidic and with higher N and P contents. Plantation forests had characteristics similar to indigenous forests on comparable soils. Cropland soils comprised <1% of the national land cover and generally had high inorganic fertility and low organic matter, with evidence of compaction. Seven characteristics (total C, total N, mineralizable N, pH, Olsen P, bulk density, and macroporosity) explained 87% of the total variability. The findings are being used by monitoring agencies to raise awareness about soil quality in the wider community, set land management guidelines, and develop policies.
pH‐Dependent Release of Cadmium, Copper, and Lead from Natural and Sludge‐Amended Soils
Authors: Sukreeyapongse Orathai , Holm Peter E. , Strobel Bjarne W. , Panichsakpatana Supamard , Magid Jakob , Hansen Hans Christian Bruun 
Published: June 2010

ABSTRACTThe pH‐dependent release of cadmium, copper, and lead from soil materials was studied by use of a stirred flow cell to quantify their release and release rates, and to evaluate the method as a test for the bonding strength and potential mobility of heavy metals in soils. Soil materials from sludge‐amended and nonamended A horizons from a Thai coarse‐textured Kandiustult and a Danish loamy Hapludalf were characterized and tested. For each soil sample, release experiments with steady state pH values in the range 2.9 to 7.1 and duration of 7 d were performed. The effluent was continuously collected and analyzed. Release rates and total releases were higher for the Hapludalf than the Kandiustult and higher for the sludge‐amended soils than the nonamended soils. With two exceptions the relative release rates (release rate/total content of metal in soil) plotted vs. steady state pH followed the same curves for each metal, indicating similar bonding strengths. These curves could be described by a rate expression of the form: relative release rate = k[H+]a, with specific a (empirical constant) and k (rate constant) parameters for each metal demonstrating that metal release in these systems can be explained by proton‐induced desorption and dissolution reactions. With decreasing pH, pronounced increases in release rates were observed in the sequence cadmium > lead > copper, which express the order of metal lability in the soils. The flow cell system is useful for comparison of metal releases as a function of soil properties, and can be used as a test to rank soils with respect to heavy metal leaching.