bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationships between Soil Nutrients and Plant Species Composition in Everglades Peatlands
Authors: Craft Christopher B. , Richardson Curtis J. 
Published: July 2010

AbstractBase cations (Ca, Mg, K, Na) and metals (Al, Fe, Mn) were measured in peatlands of the northern and central Everglades to (i) determine the extent and degree of elemental enrichment of the peat caused by agricultural drainage and (ii) assess the relationship between cattail (Typha latifolia L.) encroachment into sawgrass (Cladium jamaicense Crantz) communities and elemental (cations, metals, P) enrichment of the peat. Soil Ca, Mg, and Na (0–10 cm) decreased, and Al and Fe increased from north to south through the northern and central Everglades. In particular, nutrient‐enriched (P) areas of northern WCA 2A had higher concentrations and accumulation rates of Ca, Mg, and Na than areas to the south. A detailed investigation along a P enrichment gradient in northern WCA 2A revealed a gradient of Ca and Na enrichment extending 1.6 to 3.4 km downstream of the Hillsboro canal, the source of agricultural drainage to WCA 2A. Rates of Ca (35 g/m2 per yr) and Na (1.5–3.2 g/m2 per yr) accumulation were 2 to 10 times greater 1.6 km below the Hillsboro canal than in areas 3.4 to 10.7 km downstream. Correlation analysis revealed that macrophyte species composition along the enrichment gradient was highly correlated with soil P (0–24 cm) but not with soil Na or Ca. The percent frequency of cattail (r = 0.74) and other species (r = 0.66) was positively correlated while sawgrass (r = −0.83) was inversely correlated with soil P content. These findings suggest that cattail encroachment into sawgrass communities is favored by enrichment of the peat with P loadings from agricultural drainage pumped into northern WCA 2A.
Heavy Metal (Copper, Lead, and Zinc) Accumulation and Excretion by the Earthworm, Dendrobaena veneta
Authors: Marinussen Mari P. J. C. , van der Zee Sjoerd E. A. T. M. , de Haan Frans A. M. , Bouwman Lydia M. , Hefting Mariet M. 
Published: July 2010

AbstractTo obtain knowledge about heavy metal kinetics in earthworms (Dendrobaena veneta), we performed accumulation and excretion experiments under laboratory conditions using soils from a heavy metal (Cu, Pb, and Zn)‐contaminated site. To determine heavy metal accumulation rate, earthworms were exposed for 1, 2, 3, 7, 14, 28, 56, or 112 d to soil MH (Cu: 815 mg kg−1, Pb: 340 mg kg−1, and Zn: 225 mg kg−1). After exposure for 28 d to soil LB (Cu 242 mg kg−1, Pb: 109 mg kg−1, Zn 72 mg kg−1) or for 112 d to soil MH, D. veneta were transferred to uncontaminated soil and sampled after 1, 2, 3, 7, 14, 28, or 56 d to determine heavy metal excretion rates. Fourteen days after the transfer to the uncontaminated soil, some earthworms were transferred back to soil LB to determine the accumulation after a short recovery period. The Cu accumulation until Day 56 could be described by a one‐compartment model. At Day 112, however, we observed an unexpected further increase in tissue Cu concentration (CCu). We observed a significant increase in CZn, only at Day 112. Excretion of Cu could be described excellently by a two compartment model, the half‐life times being t1/2;1 ≈ 0.36 d, and t1/2;2 ≈ 37 d. Excretion of Pb could be described with a one‐compartment model. After a fast initial excretion (t1/2 ≈ 0.70 d), Pb excretion stagnated. The accumulation after a 14‐d recovery period appeared to be significantly less than the initial accumulation. The Pb accumulation appeared to be slower after recovery than before.
Soil Denitrification and Nitrous Oxide Losses under Corn Irrigated with High‐Nitrate Groundwater
Authors: Qian Jin H. , Doran John W. , Weier Keith L. , Mosier Arvin R. , Peterson Todd A. , Power James F. 
Published: July 2010

AbstractInappropriate management of irrigation water and fertilizer N in irrigated corn (Zea mays L.) has resulted in excess N leaching from the rooting zone and NO−3 contamination of groundwater. A better understanding of microbially mediated conversion of plant available N to gaseous N forms is needed for more efficient N use, to evaluate the impact of radiatively important gas production such as nitrous oxide (N2O) on air quality, and to determine the potential of microbial denitrification for remediating high‐NO−3 irrigation water. Soil denitrification and N2O losses from pivot irrigated corn were measured during the 1991 and 1992 growing seasons using surface gas chambers at the Management System Evaluation Area (MSEA) site for water quality research in the Central Platte Valley near Shelton, NE. Denitrification and N2O losses remained low throughout most of the growing season, generally ranging from 10 to 50 g N ha−1 d−1, when soil water contents were generally below 60% water‐filled pore space (WFPS). Nitrous oxide was the major gaseous N product under these conditions. When soils were wetted by irrigation or rainfall to >70% WFPS, denitrification losses ranged from 0.2 to 1.4 kg N ha−1 d−1 with N2 comprising 80 to 98% of the denitrification gases measured. Monthly average denitrification losses across years were highly correlated (r = 0.693) with time of growing season, suggesting a possible link between plant growth and denitrification. Seasonal gaseous N losses via denitrification and N2O emission from irrigated corn represented 1 to 5% of the N applied as fertilizer or in irrigation water during a relatively dry 1991 season and the 1992 season with near normal precipitation. Results of our 2‐yr study indicate that under good irrigation and N management practices gaseous N losses from denitrification and N2O production pose little additional threat to atmospheric quality or N‐use efficiency but also provide little hope for bioremediation of high‐NO−3 groundwater.
Organic Phosphorus in Solutions and Leachates from Soils Treated with Animal Slurries
Authors: Chardon W. J. , Oenema O. , del Castilho P. , Vriesema R. , Japenga J. , Blaauw D. 
Published: July 2010

AbstractA substantial part of the total phosphorus (P) in soil solution and leachates can be present as dissolved organic phosphorus (DOP). The DOP may be more mobile than inorganic orthophosphate and thus it can be an important P source for surface water eutrophication. This paper describes a series of four experiments that investigated the effects of animal waste application to sandy soil on DOP leaching. The first experiment examined the effect of storing pig slurry on DOP fractionation, using gel permeation chromatography. Experiment two and three examined the immediate and long‐term effects of animal waste application to soil in laboratory columns and outdoor maize‐grown lysimeters, respectively. In the fourth experiment concentrations of DOP and total P (TP) in soil solutions at various depths were determined in a long‐term field experiment. Results indicate that DOP in pig slurry is mainly found in high molecular weight (MW) compounds (Exp. 1). From the soil column more than 90%, and from the lysimeters more than 70% of TP leached as DOP (Exp. 2 and 3). In the lysimeter experiment (Exp. 3), leaching of TP mainly occurred in periods of low Cl and NO3 concentrations, induced by high leaching rates. This may indicate that P transport in these periods was mediated by DOC or other colloidal particles. The field experiment (Exp. 4), showed that DOP as a percentage of TP in the soil solution increased from about 10% in the topsoil to more than 70% at 70 to 80 cm depth, which was mainly due to a decrease in MRP. Thus, DOP is an important form of P in leachates and in soil solutions in the subsoil, and characterization of this DOP can improve our understanding of P leaching from soils.
Testing Denitrification Functions of Dynamic Crop Models
Authors: Marchetti R. , Donatelli M. , Spallacci P. 
Published: July 2010

AbstractDenitrification (DN) has an important role in models simulating soil nitrate leaching, because denitrification losses influence the soil N budget, hence the amount of nitrate available for leaching. In spite of the importance of DN estimate, the behavior of submodels simulating DN losses is not well known. The aim of this study was to improve the knowledge of the behavior of submodels simulating DN losses in selected crop growth/N‐leaching models. To remove the interference of the other processes on the results, we isolated the algorithms predicting the denitrification rate (DNR) and applied them to three data sets selected from the available literature. Denitrification subroutines were taken from the models EPIC, CropSyst, CREAMS, GLEAMS, CERES‐N, and NLEAP. A preliminary sensitivity analysis emphasized how quite similar algorithms can give rise to considerably different predictions. The measured vs. predicted values comparison confirmed DNR to be remarkably affected by the soil water content (SW) relationship with soil water values at field capacity and/or at saturation. CERES‐N, CREAMS, GLEAMS, and EPIC submodels underestimated even up to 100% the number of occasions where DNR > 0, since they simulated the DN process only when SW values were higher than SW at field capacity, whereas in real systems DN occurs even at lower SW values. Results suggest that DN modeling should take into greater account the contribution to DN losses during aerobic conditions. The large natural variation of DNR measurements invalidates the use of statistical criteria for the comparison of measured vs. estimated DN values in deterministic models.
Pesticides in the San Joaquin River, California: Inputs from Dormant Sprayed Orchards
Authors: Domagalski Joseph L. , Dubrovsky Neil M. , Kratzer Charles R. 
Published: July 2010

AbstractRainfall‐induced runoff mobilized pesticides to the San Joaquin River and its tributaries during a 3.8‐cm rainstorm beginning the evening of 7 February and lasting through the morning of 8 Feb. 1993. Two distinct peaks of organophosphate pesticide concentrations were measured at the mouth of the San Joaquin River. These two peaks were attributed to contrasts between the soil texture, basin size, pesticide‐use patterns, and hydrology of the eastern and western San Joaquin Valley. The fine soil texture and small size of the western tributary basins contributed to rapid runoff. In western valley streams, diazinon concentrations peaked within hours of the rainfall's end and then decreased because of a combination of dilution with pesticide‐free runoff from the nearby Coast Ranges and decreasing concentrations in the agricultural runoff. Peak concentrations for the Merced River, a large tributary of the eastern San Joaquin Valley, occurred at least a day later than those of the western tributary streams. That delay may be due to the presence of well‐drained soils in the eastern San Joaquin Valley, the larger size of the Merced River drainage basin, and the management of surface‐water drainage networks. A subsequent storm on 18 and 19 February resulted in much lower concentrations of most organophosphate pesticides suggesting that the first storm had mobilized most of the pesticides that were available for rainfall‐induced transport.
Plant Response to Fish Farming Wastes in Volcanic Soils
Authors: Mazzarino M. J. , Walter I. , Costa G. , Laos F. , Roselli L. , Satti P. 
Published: July 2010

AbstractAgricultural use of aquaculture wastes appears to be a sound ecological and economical means to improve soil fertility and to decrease the potential for adverse water quality impacts in South Argentina. A 3‐mo greenhouse experiment with ryegrass (Lolium perenne L.) was conducted to determine plant availability of N and P from aquaculture wastes and compare results with previous laboratory incubations. Treatments included: (i) wastes taken from sediments under cages in a 3‐yr‐old fish farm (EA) applied at 40 and 80 Mg ha−1; (ii) wastes taken from sediments under cages in an 8‐yr‐old farm (LM), applied at 10 and 20 Mg ha−1; (iii) the lowest waste rates amended with 50 kg ha−1 synthetic N; (iv) four synthetic fertilizer treatments including a single N rate of 80 kg N ha−1 and four P levels of 30, 40, 60, and 80 kg P ha−1, and (v) a no‐fertilizer control. Although total N and P were higher in LM than in EA, and N mineralization rates in lab incubations were similar (13%), ryegrass yields and N uptake were much higher in EA than in LM. When mineralized N was estimated as the difference between added N and total N uptake, values were 50 to 63% for EA and 5 to 14% for LM. Ryegrass yields were approximately as follows: EA > FI > LM > Control. Synthetic fertilizer treatments showed the lowest values of P utilization efficiency, residual Olsen‐P in soil and plant P uptake in biomass, and the highest P retention in soils. The lowest waste rates with addition of N produced comparable ryegrass yields with the highest rates. Results emphasize: (i) the need to include living plants in mineralization potential evaluations to avoid significant errors in nutrient cycling models, and (ii) the importance of organic amendments in ameliorating plant P availability in high P‐fixing volcanic soils.
Potential Release of Phosphorus from Soil Mixed with Sewage Sludge
Authors: Rydin Emil , Otabbong Erasmus 
Published: July 2010

AbstractRetention capacities of phosphorus (P) in three soils (sandy loam, sandy clay, and sandy clay loam) and in soil mixed with 50 g kg−1 (5% ww) digested sewage sludge (Al‐ or Fe‐precipitated) were measured in a laboratory study. Artificial rainwater, continuously leached through different samples, released about 15% of the total‐P content (0.6–1.1 g P kg−1) of the soils. Adding Fe‐precipitated sludge to the soil approximately doubled the P‐concentration (1.1 to 1.7 g P kg−1) in the samples, and 20% was released. Up to 43% of the total‐P (1.1 g P kg−1) was released when Al‐precipitated sludge was mixed with the sandy loam soil. The release process was described by a first‐order decay equation, and release rates between 0.04 and 0.07 d−1 or 35 mm water passing−1 were obtained. The released amounts could be considered as potential mobile phosphate under the experimental conditions used and are compared with potentially crop‐available P. Phosphorus fractionation revealed that P adsorbed to Fe and Al was more or less exhausted, declining from about 35% at the start of the experiment to 5% of tot‐P by the end. The inert P‐pool increased, indicating that P transformations favored the production of more stable compounds. The accumulation of P in urban regions and the risk for nonpoint pollution of surface‐ and groundwaters are discussed.
Trace Element Composition of Fertilizers and Soil Amendments
Authors: Raven K. P. , Loeppert R. H. 
Published: July 2010

AbstractThe use of fertilizers and soil amendments has raised concern regarding the toxic accumulation of their trace components in the environment. The objective of this research was to evaluate the trace element and heavy metal composition of a wide variety of fertilizers and soil amendments. Thirty‐five elements, including priority pollutants, were determined in 24 materials. A microwave HNO3‐HF‐H2O2‐H3BO3 digestion procedure was used to dissolve the samples. Selected solid samples were directly analyzed by neutron activation analysis, while atomic absorption and inductively‐coupled plasma atomic emission spectrometric determinations were carried out on the digests. The trace element and heavy metal concentrations generally decreased in the following sample order: rock phosphate > sewage sludge > phosphorus fertilizer > organic amendments and liming materials > K fertilizers > N fertilizers. Relatively high concentrations of toxic elements in the sewage sludge, rock phosphate, and phosphorus fertilizer samples suggest that these materials should be the primary target materials for environmental evaluations.
Logistic Model of Nitrate in Streams of the Upper‐Midwestern United States
Authors: Mueller David K. , Ruddy Barbara C. , Battaglin William A. 
Published: July 2010

AbstractNitrate in surface water can have adverse effects on aquatic life and, in drinking‐water supplies, can be a risk to human health. As part of a regional study, nitrate as N (NO3‐N) was analyzed in water samples collected from streams throughout 10 Midwestern states during synoptic surveys in 1989, 1990, and 1994. Data from the period immediately following crop planting at 124 sites were analyzed using logistic regression to relate discrete categories of NO3‐N concentrations to characteristics of the basins upstream from the sites. The NO3‐N data were divided into three categories representing probable background concentrations (<3 mg L−1), elevated concentrations (3–10 mg L−1), and concentrations that exceeded the U.S. Environmental Protection Agency maximum contaminant level (MCL) for drinking water (>10 mg L−1). Nitrate‐N concentrations were positively correlated to streamflow, upstream area planted in corn (Zea mays L.), and upstream N‐fertilizer application rates. Elevated NO3‐N concentrations were associated with poorly drained soils and were weakly correlated with population density. Nitrate‐N and streamflow data collected during 1989 and 1990 were used to calibrate the model, and data collected during 1994 were used for verification. The model correctly estimated NO3‐N concentration categories for 79% of the samples in the calibration data set and 60% of the samples in the verification data set. The model was used to indicate where NO3‐N concentrations might be elevated or exceed the NO3‐N MCL in streams throughout the study area. The potential for elevated NO3‐N concentrations was predicted to be greatest for streams in Illinois, Indiana, Iowa, and western Ohio.
Naturally High Nitrate Concentrations in Groundwaters from the Sahel
Authors: Edmunds W. M. , Gaye C. B. 
Published: July 2010

AbstractNitrate concentrations in excess of 50 to 100 mg L−1 NO3‐N are found widely in interstitial waters from unsaturated Quaternary sands in northern Senegal. These high concentrations and correspondingly enhanced NO3/Cl ratios are being produced in the soil zone beneath both uncultivated and rain‐fed cultivated areas. High nitrate (avg. 11 mg L−1 NO3‐N) is also found extensively in shallow groundwaters. The NO3‐N signature is preserved as a result of the aerobic conditions. The unsaturated zone contains a history of N inputs over a period of approximately 50 to 400 yr. Variations in the NO3/Cl ratio are mainly related to the growth of natural or introduced leguminous vegetation. There is also evidence that high ratios relate to wetter and low values to more arid climatic periods. These results, taken together with evidence from other parts of the world, demonstrate that high nitrate concentrations are likely to be a widespread and established phenomenon of groundwaters in semiarid regions.
Nutrients and Sediment in Runoff from Creeping Bentgrass and Perennial Ryegrass Turfs
Authors: Linde Douglas T. , Watschke Thomas L. 
Published: July 2010

AbstractAlthough scientists have found little transport of nutrients to date in runoff from turfgrasses, more research is needed on a wider range of soil conditions and management scenarios. This study was designed to assess nutrient and sediment transport from creeping bentgrass (Agrostis palustris Huds.) and perennial ryegrass (Lolium perenne L.) turfs and to assess the influence that vertical mowing had on sediment transport. Sloped plots of bentgrass and ryegrass, maintained similar to a golf fairway, were irrigated to force runoff for the generation of runoff and leachate water samples. About 12 h before each runoff event, irrigation was used to equilibrate soil moisture for all plots. For four events, plots were treated with fertilizer at a rate of 4.9 g N m−2, 0.3 g P m−2, and 4.1 g K m−2 about 4 h after pre‐event irrigation and 8 h before runoff. For another four events, plots were verticut 6 h before runoff. Water samples were analyzed for NO3‐N, total Kjeldahl‐N (TKN), phosphate, and sediment. Mean NO3‐N concentrations rarely exceeded 1 mg L−1. Phosphate and TKN concentrations and losses significantly increased when runoff was forced 8 h after fertilization. On average for these events, 11% of applied P and 2% applied N was detected in runoff and 14% applied P and 3% applied N was detected in leachate. For all other events, nutrient concentrations and losses were consistently lower. Vertical mowing had little affect on sediment transport. Sediment transport from both turfs averaged 0.8 kg ha−1. On golf fairways, off‐site movement of nutrients may happen if runoff occurs soon after granular fertilizer is applied to a nearly saturated soil.
Plant Toxicity and Plant Uptake of Fluorobenzoate and Bromide Water Tracers
Authors: Bowman Robert S. , Schroeder Jill , Bulusu Rao , Remmenga Marta , Heightman Rose 
Published: July 2010

AbstractThe plant toxicity and plant uptake of pentafluorobenzoate (PFBA); 2,6‐difluorobenzoate (2,6‐DFBA); 3,4‐difluorobenzoate (3,4‐DFBA); and KBr were determined in greenhouse experiments. The germination of 11 different crop species was not inhibited by the fluorobenzoates at concentrations below 250 mg L−1 and KBr at concentrations below 500 mg L−1. Alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), and canola were planted in sealed pots in which different concentrations of the tracers were maintained in the soil solution. The threshold for plant growth inhibition by the fluorobenzoates was between 50 and 125 mg L−1; KBr did not inhibit growth even at 1000 mg L−1. At the no‐growth‐effect level of 50 mg L−1, 0.1 to 55% of the added fluorobenzoates or Br was recovered from the tissue of seedling alfalfa, barley, or canola. As much as 65% of the added fluorobenzoates was not recovered; the fluorobenzoates were presumably degraded in the soil or metabolized fallowing plant uptake. All of the added Br was recovered. The greatest mass loss was observed for 3,4‐DFBA (the isomer with the highest negative‐log acid dissociation constant); otherwise there was no correlation of plant response with fluorobenzoate properties. The results show that fluorobenzoates and Br can be readily taken up by growing plants, and that fluorobenzoate mass losses may occur when plants are present.
Tracer and Nitrate Movement to Groundwater in the Northern Great Plains
Authors: Schuh W. M. , Klinkebiel D. L. , Gardner J. C. , Meyer R. F. 
Published: July 2010

AbstractAn experiment was conducted to study the movement of surface‐applied tracers and fertilizer to groundwater on an agricultural field under dryland farming practices. Movement of surface‐applied bromide, chloride, and fluoride tracers, and fertilizer nitrate (NO3) through a coarse‐loamy glacial till soil and vadose zone to saturated glacial till at about 3 to 4 m, and to a confined aquifer at 6.8 m, were monitored for 5‐yr. Crop treatments were a dryland rotation of wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], and sunflower (Helianthus annuus L.). Applied bromide, chloride, and NO3 could be detected in trace amounts at all levels, including the aquifer, within a few days after application and following large summer storms. Within the root zone, NO3 and chloride concentrations varied with root extraction and application placement. The largest stable concentration of solute occurred within the shallow vadose zone beneath the root zone. Below the root zone, tracer and NO3 concentrations decreased exponentially with depth. Following a large rainfall the shallow vadose layer served as a “feeder zone” for solute movement to deeper layers. Elevated concentrations following recharge events were spatially sporadic, occurring at some locations and not at others. Spatially variable and temporary increases in solute concentrations were caused by spatially variable recharge, governed by microtopographic controls. Water concentrated in microtopographical “low” areas and moved in concentrated plugs to the water table carrying solute. NO3‐N did not increase in the saturated till or the aquifer over the 5‐yr period.